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S7-200通过自由口控制Modbus变频器正负转频率写入等

S7-200通过自由口控制Modbus变频器正负转频率写入等西门子S7-200通过自由口需要控制英威腾变频器的正负转停止和故障复位，运行频率控制以及分二次读取运行速度等12条变频器信息。

程序略微变动适应所有Modbus RTU需要控制。

下面是程序，可以直接导入程序后写入PLC试验ORGANIZATION_BLOCK 主程序:OB1TITLE=BEGINNetwork 1// 主程序，初始化并查执各变频器指令// 一．功能介绍// 该程序专为英威腾CHF系列变频器编写。

英威腾CHF系列变频器内置国际标准的MODBUS通信协议。

程序运行时，变频器作为MODBUS协议从站接收来自CPU224 PLC 的通信指令，实现起停、频率给定、监控等功能。

// CHF系列矢量变频器在与CPU224通信前须做好以下准备工作：// 1．确认己安装好CHF系列变频器的通讯卡，并将卡上的端口跳线置于RS485端；// 2．用一根带9针阳性插头的串口通信电缆连接在CPU224 PLC的自由通信口端，电缆另一端的第5、3、8线分别接在CHF变频器RS485通讯卡的GND、485+、485一端子上，其余线屏蔽不用；// 3．预先设置变频器以下参数：// PC.00＝1 //变频器通讯地址为1// PC.01＝3 //通讯波特率9．6K// PC.02＝1 //通讯数据偶校验8位数据位1位停止位// P0.03＝2 //变频器的运行指令采用通讯方式// P3.01＝7 //变频器的A频率设定采用通讯方式（注意P3.04/P3.05对P3.01通讯频率的影响）// 二．程式结构说明// 该程序由1个主程序3个子程序及2个中断程序组成。

子程序里包含了变频器的起停、复位、查询功能指令，由主程序调用。

中断程序为发送及接收指令提供中断支持。

// main //主程式，初始化并查执各变频器指令// sbr0 //CRC校验子程序// sbr1 //通讯端口初始化子程序// sbr2 //发送变频器写入06/读取03指令，共8个字节// intO //接收完成中断程序// int1 //发送完成中断程序LD SM0.1CALL SBR1 //调用初始化子程序，使能PORT0自由口模式Network 2// 接收完成后延时10mS M4.4接通，运行下一次发送数据LDN M4.0AN M4.1TON T35, 1 // 通讯完成后延时10mS M4.4＝1，允许下一次通讯，A T35= M4.4 //主要是为了Modbus RTU二次通讯中间3.5字符间隔时间Network 3// 如果发送或接收超时，延时0.2秒复位M4.0/M4.1，这里暂时设置5秒是为了方便调试LD M4.0O M4.1TON T199, 50A T199R M4.0, 2 //发送或接收超过0.2秒没有完成，复位发送/接收Network 4 // 调用Modbus06写入指令，通讯成功,这里暂时不用,可以作打手频率设定,不知道是否支持广播写入,广播写入主要是变频器故障复位和三个打手频率设定.给棉变频器如果需要用PID控制没有必要用PLC的PID// 当VW110≠VW300时把VW110写入变频器，VW110范围（+10000～-10000）÷10000×50Hz// 地址为变频器地址；字节为发送的字节数量＝8个字节；指令＝03为读取指令，06为写入指令；数据地址＝2000H为英威腾变频器设置频率的地址；数据内容为写入2000H的内容，范围+10000～0～-10000// 运行命令权限最高，如果运行命令没有完成，程序将会一直执行下去，直到运行命令完成LDN M8.1 //没有发送运行命令，当运行命令发送过程中不能够发送频率写通讯AW<> VW300, VW110 //发送的数据VW110与通讯完成返回的数据不等A M4.4 //允许发送S M8.0, 1 //发送为写运行速度命令，为了接收信息时保存到VW300用CALL SBR3, 1, 8, 6, 16#2000, VW110 //把VW110数据写入到变频器地址1的2000H寄存器Network 5// 控制变频器正负转停止和故障复位同时有几个输入时执行最后的指令LD SM0.0LPSA I5.1 //运行命令MOVW 1, VW304LRDA I5.3 //反转命令MOVW 2, VW304LRDA I5.2 //停车命令MOVW 5, VW304LPPA I5.4 //故障复位命令MOVW 7, VW304Network 6 // 设定英威腾变频器1000H通信控制命令，来控制变频器正负转和停止等操作命令// 控制变频器运转英威腾变频器地址1000H 01正转运行02反转运行03正转点动04反转点动05停车06自由停车07故障复位08点动停车LDW<> VW304, VW302 //运行命令VW304与接收的返回信息比较，不相等将一直发送下去A M4.4S M8.1, 1 //为了把返回信息的保存到VW302寄存器CALL SBR3, 1, 8, 6, 16#1000, VW304 //把命令内容VW304写入到英威腾变频器的1000H 地址Network 7 // 调用Modbus读取，不要读取范围以外的内容，不然会报错误// 读取变频器状态3000H 运行速度3001H 设定速度3002H 母线电压3003H 输出电压3004H 输出电流3005H 运转速度// 当有其他重要的读写命令时该通讯暂停// 分2次读取英威腾变频器3000H～3005H 3008H～3013H信息，本来英威腾变频器说明书说可以连续读取16条信息，不过我读取16条信息返回数据没有CRC校验内容，不知为何，本来是试验程序，有时需要连续读取多条信息，就试验读取2次12条信息LDN M8.0AN M8.1 //程序没有发送写频率和运行命令时才能够读取变频器数据A M4.4LPS //调用查询变频器INCB VB270 //启动T37延时断开计时器A V270.0S M8.2, 1MOVW 16#3000, VW272 //读取3000H开头的连续6条信息LRDAN V270.0S M8.3, 1MOVW 16#3008, VW272 //读取3008H开头的连续6条信息LPPCALL SBR3, 1, 8, 16#03, VW272, 6END_ORGANIZATION_BLOCKSUBROUTINE_BLOCK 初始化:SBR1TITLE=通讯端口初始化子程序// 该程序在PLC的第一个扫描周期运行，主要是设置CPU224自由端口的通信格式、数据接收格式及复位各寄存区(参见西门子S7-200编程手册)。

第六章路由及工作原理(10课时)

课堂教学教案•对多种网络层协议的支持；•增强的距离矢量能力；•100％无环路；•易于配置；•增量更新；•对VLSM、不连续网络和无类别路由的支持；•EIGRP最多支持6条（默认4条）到给定目的网络的路径；•与IGRP兼容6.5.4.2 EIGRP综合度量•带宽•延迟•可信程度•负载•最大传输单元6.5.4.3 配置EIGRPRouter(config)#router eigrp autonomous-systemRouter(config-router)#network network-numberRouter(config-router)#variance multiplierRouter(config-router)#traffic-share{ balanced | min }6.5.4.4 验证EIGRP配置•Router#show ip protocol–显示路由协议的配置情况。

•Router#show ip route eigrp–显示路由表中有关EIGRP的条目。

•Router#show ip eigrp traffic–显示发送和接收的EIGRP数据包的数量。

•Router#debug eigrp packets–显示发送和接收的EIGRP数据包类型。

6.5.5 配置OSPF•是开放标准•使用最短路径优先（SPF）算法•典型的链路状态路由协议6.5.5.2 OSPF协议的特点•采用Cost作为度量值•支持变长子网掩码（VLSM）•不需要定期更新、收敛速度快•将网络划分为多个区域，区域间支持路由汇总•只有路由验证•较好的支持负载均衡6.5.5.3 OSPF基本算法•SPF算法及最短路径树•链路状态算法6.5.5.4 配置OSPFRouter(config)#router ospf process-idRouter(config-router)#network address mask area area-id6.5.5.4 通配符：如何检查对应的地址检验条件: 检验所有的地址位（匹配所有的）•例子172.30.16.29 0.0.0.0 检验所有的地址位•可以缩写这个通配符用IP地址为host(host172.30.16.29)6.5.5.5 匹配任何IP地址的通配符•接受任何地址: 0.0.0.0 255.255.255.255•缩写这种表达用any6.5.6 在单区域内配置OSPF6.5.6.1 验证OSPF配置•show ip protocols可以显示路由协议的配置情况•show ip route可以显示当前的路由表，路由条目带有“O”标记的就是OSPF协议所生成的路由。

S7-200英威腾CHF系列变频器

ORGANIZATION_BLOCK 主程序:OB1TITLE=BEGINNetwork 1// 主程序，初始化并查执各变频器指令// 一．功能介绍// 该程序专为英威腾CHF系列变频器编写。

英威腾CHF系列变频器内置国际标准的MODBUS通信协议。

程序运行时，变频器作为MODBUS协议从站接收来自CPU224 PLC的通信指令，实现起停、频率给定、监控等功能。

子程序里包含了变频器的起停、复位、查询功能指令，由主程序调用。

中断程序为发送及接收指令提供中断支持。

// main //主程式，初始化并查执各变频器指令// sbr0 //CRC校验子程序// sbr1 //通讯端口初始化子程序// sbr2 //发送变频器写入06/读取03指令，共8个字节// intO //接收完成中断程序// int1 //发送完成中断程序LD SM0.1CALL SBR1 //调用初始化子程序，使能PORT0自由口模式Network 2// 接收完成后延时10mS M4.4接通，运行下一次发送数据LDN M4.0AN M4.1TON T35, 1 // 通讯完成后延时10mS M4.4＝1，允许下一次通讯，A T35= M4.4 //主要是为了Modbus RTU二次通讯中间3.5字符间隔时间Network 3// 如果发送或接收超时，延时0.2秒复位M4.0/M4.1，这里暂时设置5秒是为了方便调试LD M4.0O M4.1TON T199, 50A T199R M4.0, 2 //发送或接收超过0.2秒没有完成，复位发送/接收Network 4 // 调用Modbus06写入指令，通讯成功,这里暂时不用,可以作打手频率设定,不知道是否支持广播写入,广播写入主要是变频器故障复位和三个打手频率设定.给棉变频器如果需要用PID控制没有必要用PLC 的PID// 当VW110≠VW300时把VW110写入变频器，VW110范围（+10000～-10000）÷10000×50Hz// 地址为变频器地址；字节为发送的字节数量＝8个字节；指令＝03为读取指令，06为写入指令；数据地址＝2000H为英威腾变频器设置频率的地址；数据内容为写入2000H的内容，范围+10000～0～-10000 // 运行命令权限最高，如果运行命令没有完成，程序将会一直执行下去，直到运行命令完成LDN M8.1 //没有发送运行命令，当运行命令发送过程中不能够发送频率写通讯AW<> VW300, VW110 //发送的数据VW110与通讯完成返回的数据不等A M4.4 //允许发送S M8.0, 1 //发送为写运行速度命令，为了接收信息时保存到VW300用CALL SBR3, 1, 8, 6, 16#2000, VW110 //把VW110数据写入到变频器地址1的2000H寄存器Network 5// 控制变频器正负转停止和故障复位同时有几个输入时执行最后的指令LD SM0.0LPSA I5.1 //运行命令MOVW 1, VW304LRDA I5.3 //反转命令MOVW 2, VW304LRDA I5.2 //停车命令MOVW 5, VW304LPPA I5.4 //故障复位命令MOVW 7, VW304Network 6 // 设定英威腾变频器1000H通信控制命令，来控制变频器正负转和停止等操作命令// 控制变频器运转英威腾变频器地址1000H 01正转运行02反转运行03正转点动04反转点动05停车06自由停车07故障复位08点动停车LDW<> VW304, VW302 //运行命令VW304与接收的返回信息比较，不相等将一直发送下去A M4.4S M8.1, 1 //为了把返回信息的保存到VW302寄存器CALL SBR3, 1, 8, 6, 16#1000, VW304 //把命令内容VW304写入到英威腾变频器的1000H地址Network 7 // 调用Modbus读取，不要读取范围以外的内容，不然会报错误// 读取变频器状态3000H 运行速度3001H 设定速度3002H 母线电压3003H 输出电压3004H 输出电流3005H 运转速度// 当有其他重要的读写命令时该通讯暂停// 分2次读取英威腾变频器3000H～3005H 3008H～3013H信息，本来英威腾变频器说明书说可以连续读取16条信息，不过我读取16条信息返回数据没有CRC校验内容，不知为何，本来是试验程序，有时需要连续读取多条信息，就试验读取2次12条信息LDN M8.0AN M8.1 //程序没有发送写频率和运行命令时才能够读取变频器数据A M4.4LPS //调用查询变频器INCB VB270 //启动T37延时断开计时器A V270.0S M8.2, 1MOVW 16#3000, VW272 //读取3000H开头的连续6条信息LRDAN V270.0S M8.3, 1MOVW 16#3008, VW272 //读取3008H开头的连续6条信息LPPCALL SBR3, 1, 8, 16#03, VW272, 6END_ORGANIZATION_BLOCKSUBROUTINE_BLOCK 初始化:SBR1TITLE=通讯端口初始化子程序// 该程序在PLC的第一个扫描周期运行，主要是设置CPU224自由端口的通信格式、数据接收格式及复位各寄存区(参见西门子S7-200编程手册)。

Transition Networks E-100BTX-FX-06 快联网 Fast Ethern

E‐100BTX‐FX‐06Stand‐Alone Media ConverterUser Guide∙Fast Ethernet∙Copper to Fiber∙100Base‐TX to 100Base‐FX∙Active Link Pass Through, Far‐End‐Fault Detection, and Pause∙Auto‐Negotiation, Auto‐MDI/MDIX, and Automatic Link RestorationContentsIntroduction (1)Ordering Information (2)Accessories (2)Family Portrait (3)Installation (4)4‐Position DIP Switch (4)Installing the Fiber Cable (5)Installing the Copper Cable (5)Powering the Media Converter (6)Operation (6)Status LEDs (6)Auto‐Negotiation (6)Pause Control (6)Auto MDI/MDIX (6)Active Link Pass‐Through (ALPT) (7)Far‐End Fault (8)Specifications (8)Cable Specifications (8)Technical Specifications (10)Troubleshooting (11)Contact Us (12)Compliance Information (12)Declaration of Conformity (12)Record of Revisions (13)IntroductionTransition Networks E‐100BTX‐FX‐06 Fast Ethernet media converters connect 100Base‐TX shielded or unshielded twisted‐pair copper cable to 100Base‐FX fiber‐optic cable.The E‐100‐TBX‐FX‐06 converter family of simple “Plug‐and‐Play” converters can be used at the edge of a network to provide Fast Ethernet connections for devices in challenging locations.Ordering InformationPart Number Port One - Copper100Base-TXPort Two - Fiber -100BaseFXE-100BTX-FX-06(SFP) RJ-45100 m (328 ft)*Open SFP Slot (supports 100Mbps SFP modules)E-100BTX-FX-06 RJ-45100 m (328 ft)*ST, 1300 nm multimode2 km (1.2 miles)*E-100BTX-FX-06(SC) RJ-45100 m (328 ft)*SC, 1300 nm multimode2 km (1.2 miles)*E-100BTX-FX-06(LC) RJ-45100 m (328 ft)*LC, 1300 nm multimode2 km (1.2 miles)*E-100BTX-FX-06(SM) RJ-45100 m (328 ft)*SC, 1300 nm multimode20 km (12.4 miles)*E-100BTX-FX-06(SMLC) RJ-45100 m (328 ft)*LC, 1300 nm single mode20 km (12.4 miles)** Typical maximum cable distance. Actual distance depends on the physical characteristics of the network installation. For more information, see https:///.AccessoriesAccessories are sold and packaged separately.Part Number DescriptionSPS‐2460‐SA Optional External Power Supply; 24‐60 VDC and 24‐42 VRMS Stand‐Alone Wide‐Input; Output: 12.25 VDC, 1.0 AE‐MCR‐05 12‐Slot Media Converter Rack (includes universal internal power supply) 17 x 15 x 5 in. (432 x 381 x 127 mm)RMS19‐SA4‐02 4‐Slot Media Converter ShelfWMBL Optional Wall Mount Brackets; 4.0 in. (102 mm)WMBV Optional Vertical Mount Bracket; 5.0 in. (127 mm)WMBD Optional DIN Rail Mount Bracket; 5.0 in. (127 mm)WMBD‐FS Optional DIN Rail Mount Bracket (flat, small); 3.1in. (79 mm) SFPs See the Transition Networks SFP webpage for our full line of SFPs.Family PortraitInstallationCaution: Wear a grounding device and observe electrostatic discharge precautions when setting the4‐position DIP switch and jumpers. Failure to observe this caution could result in failure of the media converter. 4‐Position DIP SwitchThe 4‐position DIP switch is located on the side of the media converter. Use a small flat‐blade screwdriver or a similar tool to set the recessed switches.1. Auto‐NegotiationUp Enables Auto‐Negotiation for the copper connection.Down Disables Auto‐Negotiation for the copper connection.2. Pause ControlUp EnabledDown Disabled3. Active Link Pass‐ThroughUp EnabledDown Disabled4. Far‐End FaultUp EnabledDown DisabledNote: The media converters are shipped from the factory with all DIP switches in the Up (enabled) position.Installing the Fiber Cable1. Locate a 100Base‐FX compliant fiber cable with male, two‐stranded TX to RX connectors installed at both ends.2. Connect the fiber cables to the media converter as described:• Connect the male TX cable connector to the female TX port.• Connect the male RX cable connector to the female RX port.3. Connect the fiber cables to the other device (another media converter, Ethernet Switch, etc.) as described:• Connect the male TX cable connector to the female RX port.• Connect the male RX cable connector to the female TX port.Installing the Copper Cable1. Locate a 100Base‐TX compliant copper cable with male, RJ‐45 connectors installed at both ends.2. Connect the RJ‐45 connector at one end of the cable to the RJ‐45 port on the media converter.3. Connect the RJ‐45 connector at the other end of the cable to the RJ‐45 port on the other device (switch, workstation, etc.).Powering the Media ConverterPower Cord Included: to order the corresponding country‐specific AC power cord, add the Country Code extension to the end of the SKU; NA = North America, LA = Latin America, EU =Europe, UK = United Kingdom,SA = South Africa, JP = Japan, OZ = Australia, BR = Brazil.AC1. Install the power cord barrel connector into the back of the media converter.2. Connect the power adapter plug into AC power.3. Verify that the media converter is powered up by noting that the power LED is lit.DCSee the SPS‐2460‐xx DC External Power Supply User Guide 33455 for more information.OperationStatus LEDsUse the status LEDs to monitor the E‐100BTX‐FX‐06 media converter operation in the network: LED Description MeaningPower Power On = Connected to external AC power.SDF Signal Detect/Fiber On = Fiber link is detected.SDC Signal Detect/Copper On = Copper link is detected.RXC Receive/Copper Flashing = A signal is being received on the copper link.RXF Receive/Fiber Flashing = A signal is being received on the fiber link.Auto‐NegotiationWhen the Auto‐Negotiation feature is activated, the media converter configures itself to achieve the best possible mode of operation over a link, automatically. The media converter broadcasts its speed (100 Mb/s) and duplex capabilities (either fullor half‐duplex) and negotiates the best mode of operation between the two devices. Pause ControlThe Pause feature can improve network performance by allowing one end of the link to signal the other to discontinue frame transmission for a set period of time to relieve buffer congestion.Note: If the Pause feature is available on ALL network devices attached to the media converter(s), enable the Pause feature on the media converter(s); otherwise, disable the Pause feature.Auto MDI/MDIXThe Auto MDI/MDIX feature allows either straight‐through (MDI) or crossover (MDI‐X) cables to be used when connecting to devices such as hubs, transceivers, or network interface cards (NICs). AutoCross determines the characteristics of the cable connection and automatically configures the unit to link up, regardless of the cable configuration.Active Link Pass‐Through (ALPT)Link Pass‐Through is a troubleshooting feature that allows the media converter to monitor both the fiber and copper RX ports for loss of signal. With the loss of RX signal on one media port, the converter will automatically disable the TX signal of the other media port, thus “passing through” the link loss.∙End device automatically notified of link loss∙Prevents loss of valuable data unknowingly transmitted over invalid linkActive LPT is a form of LPT that requires the links to become Active before LPT becomes Active.With Active LPT there are 2 states: Diagnostic and Active.The media converter enters the Diagnostic state when either of the following conditions is met: ∙Upon power‐up of the converter.∙Upon losing Link on either the copper or fiber ports.In the Diagnostic state, the link for each of the media converter’s ports can come up independently of each other, just like a converter that has no LPT functionality, or a converter that has LPT is disabled. The Diagnostic state is helpful during first power up, before all links of a circuit are connected, as it allows the installer to see each link turn on as the cables are plugged in. It’s also helpful for finding the location of a fault, if one exists.The media converter remains in the Diagnostic state until the following condition is met:∙The link status for both of the media converter’s ports is up, simultaneously.After that condition is met, ALPT enters the Active state. It remains in the Active state until the converter is either powered down, or either the copper port or the fiber port loses Link. In the Active state, Active LPT works as shown below (the same as when regular LPT is enabled).Far‐End FaultFar‐End Fault is a valuable feature used in a media converter when it loses Receive Fiber link, but still has a valid Fiber Transmit link.When a fault occurs on an incoming fiber link (1), the media converter transmits a Far‐End Fault signal on the outgoing fiber link (2). In addition, the Far‐End Fault signal also activates the Link Pass‐Through, which in turn disables the link on the copper portion of the network (3) and (4).SpecificationsThe fiber optic cable physical characteristics must meet or exceed IEEE 802.3ae specification.Cable SpecificationsThe physical characteristics must meet or exceed IEEE 802.3™ specifications.Copper CableCategory 5: (minimum requirement)Gauge: 24 to 22 AWGAttenuation: 22.0 db /100m @ 100 MHzMaximum Cable Distance: 100 meters∙Straight-through or crossover cable may be used.∙Shielded twisted-pair (STP) or unshielded twisted-pair (UTP) may be used∙Pins 1&2 and 3&6 are the two active pairs in an Ethernet network∙RJ-45 Pin-out: Pin 1 = TD+, Pin 2 = TD-, Pin 3 = RD+, Pin 6 = RD-∙Use only dedicated wire pairs for the active pins: (e.g., blue/white & white/blue, orange/white & white/orange, etc.)∙Do not use flat or silver satin wire.Fiber CableBit Error Rate: <10‐9Single mode fiber (recommended): 9 μmMultimode fiber (recommended): 62.5/125 μmMultimode fiber (optional): 100/140, 85/140, 50/125 μmE‐100BTX‐FX‐06 1300 nm multimodeFiber Optic Transmitter Power: min: ‐19.0 dBm max: ‐14.0 dBmFiber Optic Receiver Sensitivity: min: ‐30.0 dBm max: ‐14.0 dBmLink Budget: 11.0 dbmE‐100BTX‐FX‐06(SC) & (LC) 1300 nm multimodeFiber Optic Transmitter Power: min: ‐19.0 dBm max: ‐14.0 dBmFiber Optic Receiver Sensitivity: min: ‐30.0 dBm max: ‐14.0 dBmLink Budget: 11.0 dbmE‐100BTX‐FX‐06(SM) 1310 nm single modeFiber‐optic Transmitter Power: min: ‐15.0 dBm max: ‐8.0 dBmFiber‐optic Receiver Sensitivity: min: ‐31.0 dBm max: ‐8.0 dBmLink Budget: 16.0 dbmE‐100BTX‐FX‐06(SMLC) 1310 nm single modeFiber‐optic Transmitter Power: min: ‐15.2 dBm max: ‐8.0 dBmFiber‐optic Receiver Sensitivity: min: ‐32.5 dBm max: ‐3.0 dBmLink Budget: 17.3 dbmThe fiber optic transmitters on this device meet Class I Laser safety requirements per IEC‐825/CDRH standards and comply with 21 CFR1040.10 and 21CFR1040.11.Technical Specifications Standards IEEE 802.3 Data Rate 100 Mb/sDIP Switch SW1: Auto‐Negotiation On/Off SW2: Pause TX On/OffSW3: LPT On/OffSW4: FEF On/OffStatus LEDs PWR (Power): Lit for normal operationSDF (Signal Detect Fiber): Lit for fiber link SDC (Signal Detect Copper): Lit for copper link RXF (Receive Fiber): Flashing = RX dataRXC (Receive Copper): Flashing = RX dataDimensions Width: 3" [76 mm] x Depth: 4.7” [119 mm] x Height: 1" [25 mm]Power Supply External AC/DC required; Output: 12 VDC. 0.41Amps; input 120‐240VAC, unregulated; standardPower Consumption 1.75 Watts (Fixed optics models) 1 Watt plus the SFP (SFP models)Environment Tmra* (Standard temp): 0°C to 50°C (32 to 122°F) Storage Temperature: ‐15°C to 65°C (5 to 149°F) Humidity: 5% to 95% (non‐condensing) Altitude: 0 – 10,000 ft.Weight 6 oz. (181 g) approximatelyCompliance Safety: Wall Mount Power Supply: UL Listed, cUL Listed (Canada). FCC Part 15 Class A, EN 55032:2012, EN 55024:2010Directive 2014/30/EULow‐Voltage Directive 2014/35/EUIEC /EN 60950‐1:2006+A2:20132011/65/EU EN 50581:2012CE MarkMTBF Greater than 46,768 hours (MIL‐HDBK‐217F) Greater than 123,861 hours (Bellcore7 V5.0)Warranty Lifetime* Manufacturer’s rated ambient temperature.CAUTION: Visible and invisible laser radiation when open. Do not stare into beam or view directly with optical instruments.CAUTION: Use of controls, adjustments or the performance of procedures other than those specified herein may result in hazardous radiation exposure.CAUTION: Copper based media ports, e.g., Twisted Pair (TP) Ethernet, USB, RS232, RS422, RS485, DS1, DS3, Video Coax, etc., are intended to be connected to intrabuilding (inside plant) link segments that are not subject to lightening transients or power faults. Copper based media ports, e.g., Twisted Pair (TP) Ethernet, USB, RS232, RS422, RS485, DS1, DS3, Video Coax, etc., are NOT to be connected to inter‐building (outside plant) link segments that are subject to lightening transients or power faults. Failure to observe this caution could result in damage to equipment.TroubleshootingIf the media converter fails, isolate and correct the fault by answering the following questions and then taking the indicated action. Note: DIP switch positions 3 and 4 must be DOWN before starting the troubleshooting process.1. Is the Power LED lit?NO• Is the power adapter the correct model (check I/O voltage and Hz)?• Verify the voltage and frequency of the AC outlet.• Are the power barrel connector and wall plug of the power adapter properly inserted in the media converter and plugged into a live AC wall outlet?• Contact Tech Support. See Contact Us on page 18 below.YES: Proceed to step 2.2. Is the SDC (signal detect/copper) LED lit?NO• Check the twisted‐pair cables for proper connection.• Contact Tech Support. See Contact Us on page 18 below.YES: Proceed to step 3.3. Is the SDF LED (signal detect/fiber) illuminated?NO• Check the fiber cables for proper connection.• Verify that the TX and RX cables on the media converter are connected to the RX and TX ports, respectively, on the other device.• Contact Tech Support. See Contact Us on page 18 below.YES: Proceed to step 4.4. Is the RXC (receive/copper) LED flashing?NO• If there is no activity on the UTP/STP port, proceed to step 5.• If there is activity on the UTP/STP port, disconnect and reconnect the twisted‐pair cable to restart the initialization process.• Contact Tech Support. See Contact Us on page 18 below.YES: Proceed to step 5.5. Is the RXF (receive/fiber) LED flashing?NO• If there is no activity on the fiber port, contact Tech Support.• If there is activity on the fiber port, disconnect / reconnect the fiber cable to restart initialization process.• Contact Tech Support. See Contact Us on page 18 below.YES: Contact Tech Support. See Contact Us on page 18 below.33791 Rev. A / Page 11 of 1333791 Rev. A https:// Page 12 of 13 Contact UsTechnical Support : Technical support is available 24‐hours a dayUS and Canada: 1‐800‐260‐1312International: 00‐1‐952‐941‐7600Main Officetel: +1.952.941.7600 | toll free: 1.800.526.9267 | fax: 952.941.2322******************** | ************************** | ******************************AddressTransition Networks10900 Red Circle DriveMinnetonka, MN 55343, U.S.A.Web : https://Compliance InformationDeclaration of Conformity33791 Rev. A / Page 13 of 13FCC regulationsThis equipment has been tested and found to comply with the limits for a Class A digital device, pursuant to Part 15 of the FCC rules. These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment. This equipment generates, uses and can radiate radio frequency energy and, if not installed and used in accordance with the instruction manual, may cause harmful interference to radio communications.Operation of this equipment in a residential area is likely to cause harmful interference, in which case the user will be required to correct the interference at the user's own expense.Canadian regulationsThis digital apparatus does not exceed the Class A limits for radio noise for digital apparatus set out on the radio interference regulations of the Canadian Department of Communications.Le présent appareil numérique n'émet pas de bruits radioélectriques dépassant les limites applicables aux appareils numériques de la Class A prescrites dans le Règlement sur le brouillage radioélectrique édicté par le ministère des Communications du Canada.European regulationsWarning : This is a Class A product. In a domestic environment this product may cause radio interference in which case the user may be required to take adequate measures.Achtung ! : Dieses ist ein Gerät der Funkstörgrenzwertklasse A. In Wohnbereichen können bei Betrieb dieses Gerätes Rundfunkstörungen auftreten. In diesem Fäll is der Benutzer für Gegenmaßnahmen verantwortlich. Attention ! : Ceci est un produit de Classe A. Dans un environment domestique, ce produit risque de créer des interférences radioélectriques, il appartiendra alors à l'utilsateur de prende les measures spécifiques appropriées.In accordance with European Union Directive 2002/96/EC of the European Parliament and of the Council of 27 January 2003, Transition Networks will accept post usage returns of this product for properdisposal. The contact information for this activity can be found in the 'Contact Us' portion of thisdocument.CAUTION: RJ connectors are NOT INTENDED FOR CONNECTION TO THE PUBLIC TELEPHONE NETWORK. Failure to observe this caution could result in damage to the public telephone network.Der Anschluss dieses Gerätes an ein öffentlickes Telekommunikationsnetz in den EGMitgliedstaaten verstösst gegen die jeweligen einzelstaatlichen Gesetze zur Anwendung der Richtlinie 91/263/EWG zur Angleichung der Rechtsvorschriften der Mitgliedstaaten über Telekommunikationsendeinrichtungen einschliesslich der gegenseitigen Anerkennung ihrer Konformität.Record of RevisionsRevDate NoteA7/25/19 Initial release. Trademark notice : All trademarks and registered trademarks are the property of their respective owners.Copyright restrictions : © 2019 Transition Networks. All rights reserved. No part of this work may be reproduced or used in any form or by any means ‐ graphic, electronic or mechanical ‐ without written permission from Transition Networks.。

network配置

RedHat Linux网络配置过程笔记2011-06-24 10:52:02 来源：互联网在Linux 系统中，TCP/IP 网络是通过若干个文本文件进行配置的，需要编辑这些文件来完成联网工作。

在RedHat linux刚安装好后可以通过图形化界面来配置，以下介绍通过命令行配置网络在Linux 系统中，TCP/IP 网络是通过若干个文本文件进行配置的，需要编辑这些文件来完成联网工作。

在RedHat linux刚安装好后可以通过图形化界面来配置，以下介绍通过命令行配置网络用cat命令查看默认安装后关于网络配置的文件信息1.cat /etc/sysconfig/network2.cat /etc/resolv.conf3.cat /etc/sysconfig/network-scripts/ifcfg-ethN （eth0为默认的，需要根据自己的情况而定）我们依次来配置了解和配置一下上面的三个文件/etc/sysconfig/network 网络设置该文件用来指定服务器上的网络配置信息，包含了控制和网络有关的文件和守护程序的行为的参数。

下面是一个例子文件：NETWORKING=yesHOSTNAME=machine1GATEWAY=210.34.6.2FORWARD_IPV4=yesGATEWAYDEV=其中，NETWORK=yes/no 表示网络是否被配置；HOSTNAME=hostname hostname 表示服务器的主机名；GATEWAY=gw-ip gw-ip 表示网络网关的IP 地址；FORWARD_IPV4=yes/no 是否开启IP 转发功能；GAREWAYDEV=gw-dev gw-dw 表示网关的设备名，如：eth0 等。

注：改完/etc/init.d/network 需要重新启动才能生效命令：# /etc/rc.d/init.d/network start 启动network# /etc/rc.d/init.d/network stop 停止network# /etc/rc.d/init.d/network restart 重启network以下是我的文件内容NETWORKING=yesHOSTNAME=localhost.localdomain#GATEWAY=192.168.1.1 （注：这里的GATEWAY最好注释掉，因为在/etc/sysconfig/network-scripts/ifcfg-eth0 中也有GATEWAY配置，）/etc/resolv.conf 配置DNS 客户文件/etc/resolv.conf 配置DNS 客户，它包含了主机的域名搜索顺序和DNS服务器的地址，每一行应包含一个关键字和一个或多个的由空格隔开的参数。

06-以太网系列板卡介绍

U
SDH
U
SDH SDH SDH SDH SDH SDH
U
U
7
U
U
U
U
U
ISA-Eth应用
STM-16/64
FE or GbE
Interface Aggregation! STM-4/1 STM-4/1
Ethernet Users
8
SLA specs consistency with ISA-PR & PR ISAEA
Input data traffic (e.g. 3 data streams)
FREE FOR MORE PAYING TRAFFIC
5
数据传输减少端口
POP Switch
q在POP点有大量的电缆 q端口管理成本高
POP Switch
q q
在POP点节省了大量的电缆端口利用率大大增加
6
MSTP城域网解决方案的优势
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网络相关国家标准

8GB/T30269.401-2015信息技术传感器网络第401部分：协同信息处理：支撑协同信息处理的服务及接口Information technology—Sensor networks—Part 401: Collaborativeinformation processing: Services and interfaces supporting collaborativeinformation processing现行国标委综合[2010]87号9GB/T26790.3-2015工业无线网络WIA规范第3部分：WIA-PA协议一致性测试规范Industrial wireless networks WIA Specification—Part 3: WIA-PA protocolconformance test specification现行国标委综合[2007]100号10GB/T26790.2-2015工业无线网络WIA规范第2部分：用于工厂自动化的WIA系统结构与通信规范Industrial wireless networks WIA specification—Part 2: WIA Systemarchitecture and communication specification for factory automation (WIA-FA)现行国标委计[2007]47号11GB/T2900.96-2015电工术语计算机网络技术Electrotechnical terminology—Computer network technology现行12GB/T 31951-2015电子商务信用网络交易信用主体分类E-commerce credit—Classification for subject of credit in network transactions现行13GB/Z25320.7-2015电力系统管理及其信息交换数据和通信安全第7部分：网络和系统管理（NSM）的数据对象模型Power systems management and associated information exchange—Data andcommunications security—Part 7: Network and system management (NSM)data object models现行14GB/T 20279-2015信息安全技术网络和终端隔离产品安全技术要求Information security technology—Security technical requirements of networkand terminal separation products现行15GB/T31843.3-2015海上导航和无线电通讯设备及系统数字接口第3部分：串行数据设备网络Maritime navigation and radiocommunication equipment and systems—Digitalinterfaces—Part 3：Serial data instrument network现行16GB/T 31491-2015无线网络访问控制技术规范Wireless network access control technical specification现行17GB/T 20277-2015信息安全技术网络和终端隔离产品测试评价方法Information security technology—Testing and evaluation approaches ofnetwork and terminal separation products现行18GB/T 17963-2000信息技术开放系统互连网络层安全协议Information technology--Open Systems Interconnection--Network layersecurity protocol现行2000-08-01实施19GB/T21642.1-2008基于IP网络的视讯会议系统设备技术要求第1部分：多点控制器（MC）The technical requirements for video conference system devices based on IP-based network - Part 1: Multipoint Controller现行2008-11-01实施20GB/T 20275-2013信息安全技术网络入侵检测系统技术要求和测试评价方法Information security technology—Technical requirements and testing andevaluation approaches for network-based intrusion detection system现行2013年第27号公告21GB/T30246.4-2013家庭网络第4部分：终端设备规范音视频及多媒体设备Home network―Part4: Terminal device specification―Audio video andmultimedia devices现行2013年第27号公告22GB/T30269.301-2014信息技术传感器网络第301部分：通信与信息交换：低速无线传感器网络网络层和应用支持子层规范Information technology—Sensor networks—Part 301：Communication andinformation exchange: Network layer and application support sublayer technicalspecifications for low-rate wireless sensor networks现行2014年第27号公告23GB/T30246.8-2013家庭网络第8部分：设备描述文件规范XML格式Home network—Part 8：Device description file specification—XML format现行2013年第27号公告24GB/T30246.2-2013家庭网络第2部分：控制终端规范Home network—Part 2：Control terminal specification现行2013年第27号公告25GB/T21645.5-2012自动交换光网络(ASON）技术要求第5部分：用户-网络接口(UNI)Technical requirements for automatically switched optical network - Part 5:User-Network Interface(UNI)现行2012年第13号公告26GB/Z29496.3-2013控制与通信网络CC-Link Safety 规范第3部分：实现Control & communication network CC-Link Safety Specification - Part 3:Implementation现行2013年第10号公告27GB/T 20965-2013控制网络HBES技术规范住宅和楼宇控制系统Control network HBES technical specification - Home and building controlsystem现行2013年第10号公告28GB/T21642.4-2012基于IP网络的视讯会议系统设备技术要求第4部分：网守（GK）Technical requirements for IP video conference system devices - Part 4:Gatekeeper现行2012年第13号公告29GB/T 29111-2012道路交通信息服务通过蜂窝网络发布的交通信息Road traffic information service - Traffic information distributed via cellnetwork现行2012年第41号公告30GB/T 29232-2012650nm百兆以太网塑料光纤网络适配器Network adapter of 650nm 100Mbps ethernet for plastic optical fiber现行2012年第41号公告31GB/T25068.1-2012信息技术安全技术IT网络安全第1部分：网络安全管理Information technology - Security techniques - IT network security - Part 1:Network security management现行2012年第13号公告32GB/T29910.3-2013工业通信网络现场总线规范类型20：HART规范第3部分：应用层服务定义Industrial communication networks―Fieldbus specifications―Type 20 HARTspecification―Part 3: Application layer service definition现行2013年第25号公告33GB/T28029.1-2011牵引电气设备列车总线第1部分：列车通信网络Electric railway equipment - Train bus - Part 1: Train communication network现行34GB/T 自动交换光网络(ASON)技术要求Technical requirements for automatically switched optical network －Part 7: 现行2011-04-01实施21645.7-2010第7部分：自动发现Automatic discovery35GB/T 26858-2011基于联邦模型的P2P网络管理方法Federation based solution for Peer-to-Peer network management现行36GB/T24367.1-2009自动交换光网络(ASON)节点设备技术要求第1部分：基于SDH的ASON节点设备技术要求Technical requirements for automatically switched optical network (ASON)node - Part 1: Technical requirements for SDH-based ASON node现行2009-12-01实施37GB/T 26269-2010网络入侵检测系统技术要求Technical requirements for network intrusion detection system现行2011-06-01实施38GB/T 26333-2010工业控制网络安全风险评估规范Evaluation specification for security in industrial control network现行2011-06-01实施39GB/T 29234-2012基于公用电信网的宽带客户网络安全技术要求Security technical requirements for broadband customer network based ontelecommunication network现行2012年第41号公告40GB/T 29229-2012基于以太网方式的无源光网络（EPON）技术要求Technical requirements for ethernet passive optical network (EPON)现行2012年第41号公告41GB/T30246.11-2013家庭网络第11部分：控制网络接口一致性测试规范Home network―Part11：Specification for conformance test of interfaces incontrol network现行2013年第27号公告42GB/T19760.1-2008CC-Link控制与通信网络规范第1部分：CC-Link 协议规范CC-Link ( Control & communication Link ) specification - Part 1: CC-Linkoverview, protocol现行2009-06-01实施,代替GB/Z 19760-200543GB/T 信息技术信息设备资源共享协同Information technology - Information device intelligent grouping and resource 现行2012年第41号公告29265.406-2012服务第406部分：网络多媒体终端及应用sharing - Part 406: Network multimedia terminal and application44GB/T21642.3-2012基于IP网络的视讯会议系统设备技术要求第3部分：多点控制单元（MCU）Technical requirements for IP video conference system devices - Part 3:multipoint control unit现行2012年第13号公告45GB/T 18729-2011基于网络的企业信息集成规范Specification of enterprise information integration in network environment现行46GB/T 21644-2008网络远程教育平台总体要求General Description of Networks Distance Learning现行2008-11-01实施47GB/T26790.1-2011工业无线网络WIA规范第1部分：用于过程自动化的WIA系统结构与通信规范Industrial wireless network WIA specification - Part 1: WIA Systemarchitecture communication specification for process automation (WIA-PA)现行48GB/T25105.2-2014工业通信网络现场总线规范类型10：PROFINET IO规范第2部分：应用层协议规范Industrial communication networks―Fieldbus specifications―Type10:PROFINET IO Specifications―Part 2: Application layer protocol specification现行2014年第22号公告49GB/T25105.1-2014工业通信网络现场总线规范类型10：PROFINET IO规范第1部分：应用层服务定义Industrial communication networks―Fieldbus specifications―Type10PROFINET IO Specifications―Part 1: Application layer service definition现行2014年第22号公告50GB/T 31243-2014通信网络产品可拆卸设计规范Specification of design for disassembly of telecommunication infrastructureequipment现行2014年第27号公告51GB/T30269.501-2014信息技术传感器网络第501部分：标识：传感节点标识符编制规则Information technology―Sensor networks―Part 501: Identification: Identifierencoding rules for sensor node现行2014年第27号公告52GB/T30269.701-2014信息技术传感器网络第701部分：传感器接口：信号接口Information technology―Sensor network―Part701：Sensor interface：Signalinterface现行2014年第27号公告53GB/T25105.3-2014工业通信网络现场总线规范类型10：PROFINET IO规范第3部分：PROFINET IO通信行规Industrial communication networks―Fieldbus specifications―Type10PROFINET IO specifications―Part 3: PROFINET IO communication profile现行2014年第22号公告54GB/T30850.3-2014电子政务标准化指南第3部分：网络建设Standardized guidelines for e-government―Part 3: Network construction现行2014年第14号公告55GB/T30246.5-2014家庭网络第5部分：终端设备规范家用和类似用途电器Home network—Part 5: Terminal device specification—Home appliances andsimilar electrical appliances现行2014年第14号公告56GB/T25740.2-2013PROFIBUS & PROFINET 技术行规PROFIdrive 第2部分：行规到网络技术的映射PROFIBUS & PROFINET technical profile PROFIdrive—Part 2: Mapping ofprofile to network technologies现行2013年第27号公告57GB/T30246.1-2013家庭网络第1部分：系统体系结构及参考模型Home network―Part 1：System architecture and reference model现行2013年第27号公告58GB/T30246.3-2013家庭网络第3部分：内部网关规范Home network—Part 3：Internal gateway specification现行2013年第27号公告59GB/T30246.7-2013家庭网络第7部分：控制网络通信协议Home network—Part 7：Control network communication protocol现行2013年第27号公告60GB/T30246.6-2013家庭网络第6部分：多媒体与数据网络通信协议Home network—Part 6: Multimedia and data network communication protocol现行2013年第27号公告61GB/T 20278-2013信息安全技术网络脆弱性扫描产品安全技术要求Information security technology—Security technical requirements for networkvulnerability scanners现行2013年第27号公告62GB/T30289.1-2013基于网络传输的导航电子地图数据更新规范第1部分：应用于车载终端编译的增量更新模式Network-based data updating specification for navigation electronic map－Part1: Incremental update mode for the on-board compiling现行2013年第27号公告63GB/T29910.6-2013工业通信网络现场总线规范类型20：HART规范第6部分：应用层附加服务定义和协议规范Industrial communication networks—Fieldbus specifications—Type 20 HARTspecification―Part6: Additional application layer service definition andprotocol specification现行2013年第25号公告64GB/T29910.5-2013工业通信网络现场总线规范类型20：HART规范第5部分：WirelessHART 无线通信网络及通信行规Industrial communication networks―Fieldbus specifications―Type 20 HARTspecification―Part5: Wireless HART wireless communication network andcommunication profile现行2013年第25号公告65GB/T29910.4-2013工业通信网络现场总线规范类型20：HART规范第4部分：应用层协议规范Industrial communication networks―Fieldbus specifications―Type 20 HARTspecification―Part 4: Application layer protocol specification现行2013年第25号公告66GB/T29910.2-2013工业通信网络现场总线规范类型20：HART规范第2部分：HARTIndustrial communication networks―Fieldbus specifications―Type 20 HARTspecification―Part 2: HART wired network data link layer service definition现行2013年第25号公告有线网络数据链路层服务定义和协议规范and protocol specification67GB/T29910.1-2013工业通信网络现场总线规范类型20：HART规范第1部分：HART有线网络物理层服务定义和协议规范Industrial communication networks―Fieldbus specifications―Type 20 HARTspecification―Part 1: HART wired network physical layer service definitionand protocol specification现行2013年第25号公告68GB/T30269.2-2013信息技术传感器网络第2部分：术语Information technology―Sensor networks―Part 2: Terminology现行2013年第27号公告69GB/T30246.9-2013家庭网络第9部分：设备描述文件规范二进制格式Home network―Part 9：Device description file specification―Binary format现行2013年第27号公告70GB/Z29496.2-2013控制与通信网络CC-Link Safety 规范第2部分：行规Control & communication network CC-Link Safety Specification - Part 2:Profiles现行2013年第10号公告71GB/Z29496.1-2013控制与通信网络CC-Link Safety 规范第1部分:概述/协议Control & communication network CC-Link Safety Specification - Part 1:Overview / Protocol现行2013年第10号公告72GB/T 30095-2013网络化制造环境中业务互操作协议与模型Networked manufacturing environment - Business interoperability protocol andmodel现行2013年第25号公告73GB/T13400.1-2012网络计划技术第1部分：常用术语Network planning techniques - Part 1: General terms现行2012年第41号公告74GB/T 30169-2013地理信息基于网络的要素服务Geographic information―Web feature service现行2013年第25号公告75GB/T 29236-2012通信网络设备可回收性能评价准则Criteria for evaluating recoverability of telecommunication infrastructureequipment现行2012年第41号公告76GB/T21645.9-2012自动交换光网络(ASON)技术要求第9部分：外部网络-网络接口(E-NNI)Technical requirements for automatically switched optical network (ASON) -Part 9: External network to network interface(E-NNI)现行2012年第41号公告77GB/T 29097-2012道路交通管理数据字典交通网络Road traffic management data dictionary - Traffic network现行2012年第41号公告78GB/T25068.2-2012信息技术安全技术IT网络安全第2部分：网络安全体系结构Information technology - Security techniques - IT network security - Part 2:Network security architecture现行2012年第13号公告79GB/T 28451-2012信息安全技术网络型入侵防御产品技术要求和测试评价方法Information security technology - Technical requirements and testing andevaluation approaches for network-based intrusion prevention system products现行2012年第13号公告80GB/T 28508-2012基于公用电信网的宽带客户网络总体技术要求General technical requirements for broadband customer network based ontelecommunication network现行2012年第13号公告81GB/T 28523-2012通信网络设备可回收利用率计算方法Method of calculating recoverability rate of telecommunication infrastructureequipment现行2012年第13号公告82GB/T 28749-2012企业能量平衡网络图绘制方法The method of drawing energy balance network diagram for enterprises现行2012年第28号公告83GB/Z 28586-2012地理信息基于网络的数据分发规范Geographic information - Web-based data dissemination specification现行2012年第13号公告84GB/T 基于IP网络的视讯会议终端设备Technical requirement for IP video terminal equipment - Part 1: terminal based 现行2012年第13号公告28499.1-2012技术要求第1部分：基于ITU-TH.323协议的终端on ITU-T H.32385GB/T21078.3-2011银行业务个人识别码的管理与安全第3部分：开放网络中PIN处理指南Banking - Personal identification number (PIN) management and security - Part3: Guidelines for PIN handling in open networks现行86GB/T26875.3-2011城市消防远程监控系统第3部分：报警传输网络通信协议Remote-monitoring system of urban fire protection - Part 3: Communicationprotocol for alarm transmission network现行87GB/T21645.8-2012自动交换光网络(ASON）技术要求第8部分：路由Technical requirements for automatically switched optical network - Part 8:Routing现行2012年第13号公告88GB/T28515.1-2012自动交换光网络（ASON）测试方法第1部分：基于SDH的ASONTest specifications for automatically switched optical network（ASON）- Part1：Test specifications for SDH-based ASON现行2012年第13号公告89GB/T 28512-2012用于IP网络的Diameter基础协议Diameter base protocol for IP network现行2012年第13号公告90GB/T 28517-2012网络安全事件描述和交换格式Network incident object description and exchange format现行2012年第13号公告91GB/T28029.2-2011牵引电气设备列车总线第2部分：列车通信网络一致性测试Electric railway equipment - Train bus - Part 2: Train communication networkconformance testing现行92GB/T 26318-2010物流网络信息系统风险与防范Logistics network information systems risk and prevention现行2011-05-01实施93GB/T 26268-网络入侵检测系统测试方法Test method for network intrusion detection system现行2011-06-01实施201094GB/Z26157.4-2010测量和控制数字数据通信工业控制系统用现场总线类型2：ControlNet和EtherNet/IP规范第4部分：网络层及传输层Digital data communication for measurement and control - Fieldbus for use inindustrial control systems - Type 2: ControlNet and EtherNet/IP specification -Part 4: Network and transport layer现行2011-06-01实施95GB/T21645.2-2010自动交换光网络(ASON)技术要求第2部分：术语和定义Technical requirements for automatically switched optical networks - Part2：Terms and definitions现行2011-04-01实施96GB/T 26336-2010工业通信网络工业环境中的通信网络安装Industrial communication networks - Installation of communication networks inindustrial premises现行2011-06-01实施97GB/T 25931-2010网络测量和控制系统的精确时钟同步协议Precision clock synchronization protocol for networked measurement andcontrol systems现行2011-05-01实施98GB/T 25487-2010网络化制造系统应用实施规范Networked manufacturing system implementing specification现行2011-05-01实施99GB/T 25488-2010网络化制造系统集成模型Integrated model for networked manufacturing system现行2011-05-01实施100GB/T 25489-2010网络化制造系统功能规划技术规范Technical specification for the functional planning of networked manufacturingsystem现行2011-05-01实施101GB/T 25486-2010网络化制造技术术语Networked manufacturing - Technical terminology现行2011-05-01实施102GB/Z 电力系统管理及其信息交换数据Power systems management and associated information exchange - Data and 现行2011-05-01实施25320.3-2010和通信安全第3部分：通信网络和系统安全包含TCP/IP的协议集communications security - Part 3: Communication network and system security -Profiles including TCP/IP103GB/Z25320.1-2010电力系统管理及其信息交换数据和通信安全第1部分：通信网络和系统安全安全问题介绍Power systems management and associated information exchange - Data andcommunications security - Part 1: Communication network and system security-Introduction to security issues现行2011-05-01实施104GB/T 25484-2010网络化制造ASP工作流程及服务接口Workflow and service interface for ASP in networked manufacturing现行2011-05-01实施105GB/T21645.4-2010自动交换光网络(ASON）技术要求第4部分：信令技术Technical requirements for automatically switched optical network - Part4：Technical specification of signalling现行2011-04-01实施106GB/T25068.3-2010信息技术安全技术IT网络安全第3部分：使用安全网关的网间通信安全保护Information technology - Security techniques - IT network security - Part 3:Securing communications between networks using security gateways现行2011-02-01实施107GB/T25068.5-2010信息技术安全技术IT网络安全第5部分：使用虚拟专用网的跨网通信安全保护Information technology - Security techniques - IT network security - Part 5:Securing communications across networks using virtual private networks现行2011-02-01实施108GB/T25068.4-2010信息技术安全技术IT网络安全第4部分：远程接入的安全保护Information technology - Security techniques - IT network security - Part 4:Securing remote access现行2011-02-01实施109GB/T 25111-2010网络化制造环境下的制造资源分类Networked manufacturing environment - Manufacturing resource class现行2010-12-01实施110GB/T 自动交换光网络(ASON)技术要求Technical requirements for automatically switched optical network - Part 6: 现行2009-12-01实施21645.6-2009第6部分：管理平面Management plane111GB/T21645.3-2009自动交换光网络(ASON)技术要求第3部分：数据通信网(DCN)Technical requirements for automatically switched optical network - Part 3:Data communication network现行2009-12-01实施112GB/T 24895-2010粮油检验近红外分析定标模型验证和网络管理与维护通用规则Inspection of grain and oils - General regulations for model authentication ofnear-infrared analysis and administration and maintenance of network现行2011-01-01实施113GB/T20063.15-2009简图用图形符号第15部分：安装图和网络图Graphical symbols for diagrams - Part 15: Installation diagrams and networkmaps现行2010-09-01实施114GB/T13400.3-2009网络计划技术第3部分：在项目管理中应用的一般程序Network planning techniques - Part 3: General process used in projectmanagement现行2009-11-01实施,代替GB/T 13400.3-1992115GB/T16901.3-2009技术文件用图形符号表示规则第3部分：连接点、网络的分类及其编码Rules for the presentation of graphical symbols - Graphical symbols for use inthe technical documentation of products - Part 3: Classification of connect notes,networks and their encoding现行2009-11-01实施116GB/T 23429-2009船舶和海上技术船队管理系统网络实施导则Ships and marine technology - Guidelines for implementation of a fleetmanagement system network现行2009-11-01实施117GB/Z 16506-2008信息技术系统间远程通信和信息交换提供和支持OSI网络服务的协议组合Information technology - Telecommunications and information exchangebetween systems - Protocol combinations to provide and support the OSInetwork service现行2009-01-01实施,代替GB/T 16506.1-1996,GB/T 16506.2-1996,GB/T 16506.3-1996118GB/T13400.2-2009网络计划技术第2部分：网络图画法的一般规定Network planning techniques - Part 2: General rules for representation ofnetwork diagram现行2009-11-01实施,代替GB/T 13400.2-1992119GB/Z20177.3-2006控制网络LONWORKS技术规范第3部分：自由拓扑双绞线信道规范Control network LONWORKS technology specification Part 3: Free-topologytwisted-pair channel specification现行2006-12-01实施120GB/T 20030-2005HFC网络设备管理系统规范Specification of Equipment Management System for HFC Network现行2006-05-01实施121GB/T 20270-2006信息安全技术网络基础安全技术要求Information security technology Basis security techniques requirement fornetwork现行2006-12-01实施122GB/Z 19219-2003工业自动化时限通信体系结构时限通信系统的用户需求和网络管理Industrial automation--Time-critical communications architectures--Userrequirements and network management for time-critical communicationssystems现行2004-01-01实施123GB 19286-2003电信网络设备的电磁兼容性要求及测量方法Electromagnetic compatibility requirement and measurement methods fortelecommunication network equipment现行2004-05-01实施124GB/T 16654-1996ISDN(2B+D)NT1用户-网络接口设备技术要求Technical requirements for ISDN(2B+D)NT1 user-network interfaceequipment现行1997-07-01实施125GB/T17154.1-1997ISDN用户-网络接口第三层基本呼叫控制技术规范及测试方法第1部分:第三层基本呼叫控制技术规范ISDN user-network interface layer 3 specification and testing method for basiccall control--Part 1:Layer 3 specification for basic call control现行1998-08-01实施126GB/T ISDN用户-网络接口第三层基本呼ISDN user-network interface layer 3 specification and testing method for basic 现行1998-08-01实施17154.2-1997叫控制技术规范及测试方法第2部分:第三层基本呼叫控制协议测试方法call control procedure--Part 2:Testing method for layer 3 basic call control protocol127GB/T 7340-1987电子设备用固定电阻器第六部分:空白详细规范阻值和功耗不同，各电阻器可单独测量的固定电阻网络评定水平 E (可供认证用)Fixed resistors for use in electronic equipment--Part 6:Blank detailspecification--Fixed resistor networks with individually measurable resistor ofeither different resistance values or different rated dissipations--Assessmentlevel E现行1987-11-01实施128GB/T2900.54-2002电工术语无线电通信:发射机、接收机、网络和运行Electrotechnical terminology--Radiocommunications:transmitters，receivers，networks and operations现行2002-08-01实施129GB/T 16700-1996集中网络控制装置的标准频率Standard frequencies for centralized network control installations现行1997-12-01实施130GB/T 7339-1987电子设备用固定电阻器第六部分:空白详细规范阻值和功耗相同，各电阻器可单独测量的固定电阻网络评定水平 E (可供认证用)Fixed resistors for use in electronic equipment--Part 6:Blank detailspecification--Fixed resistor networks with individually measurable resistors，all of equal value and equal dissipation--Assessment level E现行1987-11-01实施131GB/T 7338-1996电子设备用固定电阻器第6部分:分规范各电阻器可单独测量的固定电阻网络Fixed resistors for use in electronic equipment--Part 6:Sectional specification--Fixed resistor networks with individually measurable resistors现行1997-01-01实施,代替GB 7338-1987132GB/T4958.16-1992地面无线电接力系统所用设备的测量方法第二部分:分系统的测量第三节射频分支网络Methods of measurement for equipment used in terrestrial radio-relay systems--Part 2:Measurements for sub-systems--Section three--R.F. branching networks现行1993-05-01实施133GB/T 16966-1997信息技术连接到综合业务数字网(ISDN)的包式终端设备提供OSI连接方式网络服务Information technology--Provision of the OSI connection-mode networkservice by packet mode terminal equipment connected to an Integrated ServicesDigital Network(ISDN)现行1998-04-01实施134GB/T 16976-1997信息技术系统间远程通信和信息交换使用X.25提供OSI连接方式网络服务Information technology -- Telecommunications and information exchangebetween systems--Use of X.25 to provide the OSI Connection-mode NetworkService现行1998-04-01实施135GB/T 3660-1983测量视频连续随机杂波用的统一加权网络Unified weighting network for measuring video continuous random noise现行1984-03-01实施136GB/T 15654-1995电子设备用膜固定电阻网络第1部分:总规范Fixed film resistor networks for use in electronic equipment--Part 1:Genericspecification现行1996-04-01实施137GB/T 15882-1995电子设备用膜固定电阻网络第2部分:按能力批准程序评定质量的膜电阻网络分规范Fixed film resistor networks for use in electronic equipment--Part 2:Sectionalspecification for film resistor networks of assessed quality on the basis of thecapability approval procedure现行1996-08-01实施138GB/T 17180-1997信息处理系统系统间远程通信和信息交换与提供无连接方式的网络服务协议联合使用的端系统到中间系统路由选择交换协议Information processing systems--Telecommunications and informationexchange between systems--End system to intermediatesystem routeingexchange protocol for use in conjunction with the protocol for providing theconnectionless-mode network service现行1998-08-01实施139GB/T 15274-1994信息处理系统开放系统互连网络层的内部组织结构Information processing systems--Open systems interconnection--Internalorganization of the network layer现行1995-08-01实施140GB/T 1526-1989信息处理数据流程图、程序流程图、系统流程图、程序网络图和系统资Information processing--Documentation symbols and conventionsfor data，program and system flowcharts，program network charts and system resources现行1990-01-01实施,代替GB 1526-1979源图的文件编制符号及约定charts141GB/T 15883-1995电子设备用膜固定电阻网络第2部分:按能力批准程序评定质量的膜电阻网络空白详细规范评定水平EFixed film resistor networks for use in electronic equipment--Part 2:Blank detailspecification for film resistor networks of assessedquality on the basis of thecapability approval procedure--Assessment level E现行1996-08-01实施142GB/T17904.1-1999ISDN用户-网络接口数据链路层技术规范及一致性测试方法第1部分:用户-网络接口数据链路层技术规范ISDN user-network interface data link layer specification and conformancetesting method--Part 1:User-network interface data linklayer specification现行2000-06-01实施143GB/T17179.3-2000信息技术提供无连接方式网络服务的协议第3部分:由X.25子网提供低层服务Information technology--Protocol for providing the connectionless-modenetworkservice--Part 3:Provision of the underlying service by an X.25subnetwork现行2000-08-01实施144GB/T17179.2-2000信息技术提供无连接方式网络服务的协议第2部分:由GB/T15629(ISO/IEC 8802)子网提供低层服务Information technology--Protocol for providing the connectionless-modenetwork service--Part 2:Provision of the underlying service by a GB/T15629(ISO/IEC 8802) subnetwork现行2000-08-01实施145GB/T17179.4-2000信息技术提供无连接方式网络服务的协议第4部分:由提供OSI数据链路服务的子网提供低层服务Information technology--Protocol for providing the connectionless-modenetwork service--Part 4:Provision of the underlying service by a subnetwork thatprovides the OSI data link service现行2000-08-01实施146GB/T17904.2-1999ISDN用户-网络接口数据链路层技术规范及一致性测试方法第2部分:数据链路层协议一致性测试方法ISDN user-network interface data link layer specification and conformancetesting method--Part 2:Data link layer protocol conformance testing method现行2000-06-01实施147GB/T 17900-1999网络代理服务器的安全技术要求Security requirements for proxy server现行2000-05-01实施148GB/T 17438-1998由4∶2∶2标准定义的数字电视信号馈送和一次分配网络传输技术要求Technical requirements for the transmission through contribution and primarydistribution networks of digital television signals defined according to the 4∶2∶2standard现行1999-05-01实施149GB/T19668.4-2007信息化工程监理规范第4部分：计算机网络系统工程监理规范Information system project surveillance specification - Part 4: Computernetwork system project surveillance specification现行2008-01-01实施150GB/T 21061-2007国家电子政务网络技术和运行管理规范The specification of electronic government network technology and usingmanagement现行2008-03-01实施151GB/T 21640-2008基于IP网络的视讯会议系统设备互通技术要求Technical standards for cooperation between equipments of IP-based videoconference system现行2008-11-01实施152GB/T 21050-2007信息安全技术网络交换机安全技术要求（评估保证级3）Information security techniques - Security requirements for network switch(EAL3)现行2008-01-01实施153GB/T20299.4-2006建筑及居住区数字化技术应用第4部分: 控制网络通信协议应用要求Digital technique application of building and residence community - Part 4:Application requirements of control network communication protocol现行2006-12-01实施154GB/T18802.21-2004低压电涌保护器第21部分:电信和信号网络的电涌保护器(SPD)----性能要求和试验方法Low-voltage surge protective devices--Part 21:Surge protective devicesconnected to telecommunications and signalling networks--Performancerequirements and testing methods现行2004-06-01实施155GB/T 19263-MPEG-2信号在SDH网络中的传Technical specification of transport of MPEG-2 signals in SDH network现行2004-08-01实施。

google network实现原理

google network实现原理全文共四篇示例，供读者参考第一篇示例：Google Network是指谷歌基础设施中的网络部分，是支持谷歌服务正常运行的关键组成部分。

Google Network的实现原理非常复杂，是谷歌多年研发和积累的成果。

本文将重点介绍Google Network的实现原理，包括底层网络架构、数据中心网络、全球网络互联等方面。

1. 底层网络架构Google Network的底层网络架构是建立在Google自主设计的数据中心网络之上的。

在数据中心内部，谷歌采用了全自主设计的网络设备，包括交换机、路由器、负载均衡器等。

这些设备通过高速光纤互联，构成了一个高效、稳定的数据中心网络。

在数据中心网络中，谷歌采用了多层架构，包括核心层、汇聚层和接入层。

核心层负责数据中心之间的互联，汇聚层负责数据中心内部的流量聚合，而接入层则连接着服务器和各种网络设备。

2. 数据中心网络数据中心网络是Google Network的核心部分，是支持Google各种云服务正常运行的基础设施。

在数据中心网络中，谷歌采用了大量的创新技术，包括软件定义网络（SDN）、可编程交换机等。

SDN技术使得数据中心网络变得更加灵活、可扩展，可以根据需求对网络拓扑进行动态调整，提高了数据中心网络的利用率和性能。

可编程交换机则使得谷歌能够更加灵活地控制网络流量的处理方式，根据具体应用来定制网络规则，提高了网络的安全性和性能。

3. 全球网络互联Google拥有全球化的网络基础设施，可以使得用户可以在全球范围内使用Google的云服务。

Google在全球范围内建立了大量的数据中心和网络设备，通过高速光纤连接，构成了一个强大的全球网络。

在全球网络互联方面，Google采用了由BGP协议构建的全球负载均衡系统，可以动态地将用户的请求导向到最近的数据中心，提高了用户体验和服务的可用性。

Google还使用了大量的网络加速技术，包括CDN、TCP加速等，提高了网络传输速度和安全性。

英语network是什么中文意思

英语network是什么中文意思英语单词network是由两个简单的单词构成，但还有不少人是不了解它具体表达的是什么中文意思的。

下文是店铺为大家搜集整理的英语单词network的中文意思及例句，欢迎大家阅读参考!英语单词network的中文意思英 [ˈnetwɜ:k] 美 [ˈnetwɜ:rk]名词网; (电视与计算机)网络; 网状物; 广播网及物/不及物动词将…连接成网络; 建立工作关系及物动词把(地方节目)编排到广播网(或电视网)联播; 使(全国)联播; (如)用网覆盖; 广泛分布不及物动词沟通，互助及物动词1. They have made a decision about which programmes are to be networked.关于哪些节目将被联播他们已作出了决定。

名词1. They have developed marketing networks.他们已经形成了一个销售网络。

2. The President's speech was broadcast on a national television network.总统演说由全国电视网联播。

英语单词network的词典解释1. 网状物;网状系统A network of lines, roads, veins, or other long thin things is a large number of them which cross each other or meet at many points.e.g. ...Strasbourg, with its rambling network of medieval streets...中世纪街道纵横交织的斯特拉斯堡e.g. The uterus is supplied with a rich network of blood vessels and nerves.密布的血管和神经网向子宫输送养料。

network

在线会议问与答1、Q: networker和legato是2个产品？A:不是。

Networker是产品名称，而legato不是产品名称，它是公司名称。

以前我们经常听到Legato NetWorker，它指的是Legato公司的NetWorker产品，现在Legato公司已经被EMC 收购，现在的产品名称为EMC NetWorker。

2、Q: Networker就是备份和恢复软件吗？A:对，Networker是一个备份和恢复的专业软件。

它主要用来做数据的备份和恢复，并且提供了许多先进的技术，像重复数据删除、连续的数据备份功能、以及跟我们的虚拟磁带库能做集成，即在EMC磁盘库里面集成Networker的介质管理软件模块。

3、Q: 请再详解下server和storage node的区别，他们不能在一个server上吗？A: networker有3个角色（部件）组成。

第一叫Backup server，就是备份服务器，其次是storage node，是一个管理备份设备的软件模块，这个模块只负责管理备份设备，这两个角色的功能可以放在一台serve上面。

还有就是Backup Client，备份客户端，以上三个角色的功能可以放在一台server上，三个模块也可以分开部署。

4、Q: network在出保修期后也需要收服务费用吗？A: network在出保修期后是需要收服务费用的。

5、Q: networker是安装在服务器当中控制磁盘阵列将数据备份到磁带库的吗？A: networker有一款软件模块叫Powersnap，Powersnap可以与主流的磁盘阵列结合，用磁盘阵列的快照功能将数据备份到磁带库里面。

Networker并不在磁盘阵列里面安装，它是利用磁盘阵列本身的快照功能，来实现Serverless的备份。

6、Q: 一定要有storage node才可备份吗，如果只有server和client可以备份吗?A: Networker里面一定要有storage node，如果没有storage node不可能对数据进行备份。

因特网简介_06

Mil 军事机构 Net主干系统或网络组织 Net主干系统或网络组织 Org 非赢利性的组织
IE浏览器简介 IE浏览器简介目前, 目前,常用的浏览器软件主要 Explorer, 有Internet Explorer,Netscape Navigator两个系列两个系列. Navigator两个系列.目前比较流行的是Firefox Opera. Firefox, 行的是Firefox, Opera.
无线局域网(WLAN) 无线局域网(WLAN) 指以无线信道作为传输媒介的局域网. 指以无线信道作为传输媒介的局域网. AP
TCP/IP协议 TCP/IP协议 1,为什么要添加TCP/IP协议呢? 为什么要添加TCP/IP协议呢? TCP/IP协议呢 2,简单的说,IP协议负责数据简单的说,IP协议负责数据通信, TCP协议负责数据传输通信,而TCP协议负责数据传输的正确性. 的正确性.
域名域名代表了IP地址. 域名代表了IP地址. IP地址
为例, 以www. 为例,四段分别表示为服务器的名字( 分别表示为服务器的名字(通常都是3w),单位名机构,国别. 3w),单位名, 都是3w),单位名,机构,国别.
表示机构的还有: 表示机构的还有: Com Edu Gov 商业组织教育机构非军事的国家政府机构
ADSL(非对称数字用户环路) ADSL(非对称数字用户环路) 非对称数字用户环路非对称上行速率640kbps 1Mbps, 640kbps～非对称上行速率640kbps～1Mbps, 下行速率1Mbps 8Mbps, 1Mbps～下行速率1Mbps～8Mbps,数据传输带宽是由每一个用户独享的. 带宽是由每一个用户独享的. 通过电缆线提供宽带数据的技术, 通过电缆线提供宽带数据的技术, 下行速率高,频带宽,安装方便, 下行速率高,频带宽,安装方便, 不需交纳电话费. 不需交纳电话费. 在同一电缆上同时传送数字, 在同一电缆上同时传送数字,模拟信所以上网的同时可以打电话. 号,所以上网的同时可以打电话. 但它受线路质量影响较大. 但它受线路质量影响较大.

专题06网络安全 -备战2022年中考英语阅读理解热点话题模拟练

06 网络安全As we know, the time of 5G technology（技术）is coming. Recently, there's a lot of information about 5G. But what is this technology and how might it bring to our lives?What is 5G?5G means the fifth generation（第五代）mobile networks（网络）, a better technology than 4G. And we know, 4G comes after 3G and makes the network run faster than 3G.When will 5G come to our life?Before we can all use 5G, there must be a new system（系统）for 5G to work. In the USA, some cities will first use 5G this year. Experts say it will take a few more years or even longer to reach every place. In China, a few cities are using 5G now. And more and more cities will join this group: Next year, 5G will become national, even in the countryside.What can 5G do?Experts say 5G will help to build future "smart cities" with the help of sensor networks（传感器网络）. Such networks will be able to help the police with the traffic. They can help us know what’s happening in our homes when we are at work. They can even help to made it possible for doctors to perform an operation（手术）far away.________In the future, more information and more kinds of information will be travelling across 5G networks. Much of the information could be about persons, businesses or government organization（政府组织）. So we can see the wider （更广泛地）use of a 5G network means any mistake of the system would cause serious results. Then they may bring problems of public security（安全）and world economic（经济）activity.1．According to the passage, 5G is ________.A．a kind of phone B．a kind of computer C．a kind of network D．a kind of website（网站）2．The underlined word “They” refers to ________.A．Experts B．The police C．Doctors D．The networks3．Which of the following is NOT mentioned about “smart cities” in this passage?A．House building. B．Traffic. C．Home security. D．Operations.4．The underlined word “national” in the passage means “________” in Chinese.A．民族的B．国立的C．全国性的D．普通的5．Which sentence is the best for the place ________A．Who will use 5G? B．Why will 5G be popular?C．How will people use 5G? D．What are the security problems?Passage2The night of Nov.3 was very special to Australian tennisplayer Ashleigh Barty,23. She won her first single title(单打冠军)at the 2019 Women's Tennis Association (WTA) Finalsin Shenzhen. Barty took home a record $4.42 million (31million yuan) prize for the title, the biggest prize in tennis.She has held the WTA World No.1 title for 15 weeks.becoming the first Australian woman to do so.China has built the world's largest high-speed rail network,which is still expanding(扩张).Last year, the total length ofthe network reached 29,000 kilometers. The trains haveattracted millions of travelers and greatly reduced travelingtime around the country. For example, travel time fromBeijing to Shanghai has been reduced from ten hours to fivehours. China is also sharing this technology with many othercountries.Over the past decades, many people have made greatcontribution(贡献) to China’s development, helping itgrow through their hard work. On Sept. 29, ahead ofNational Day, Chinese President Xi Jinping presentednational medals and honorary titles(荣誉称号) to some ofthese contributors,, including thirty-six Chinese citizens andsix foreigners. President Xi helped them put on the medalsand shook hands with them.Sept 16 to 22 is China's sixth annual Cyber Security Week(网络安全周). An opening ceremony and major activitieswere held Tianjin. First held in 2014, the event aims toremind people of the importance of fighting online threats(威胁)and cyber attacks. The theme of this year's event is"cyber security for the people and by the people". One of thegoals of this year’s event is to teach people how to protecttheir personal data(数据).6．About Ashleigh Barty, which of the following is TRUE?A．She won a single title at WIA Finals in Shenzhen, China last year.B．She got a prize of 3,100,000 yuan for her first single title at WTA．C．She has held the WTA World No.1 title for more than one year.D．She was the first Austrian woman to win the single title at WIA．7．From the above reading, we learn that _________.A．the total length of the network reached 29,000 meters last year.B．China has got the largest high-speed rail network in the world.C．it only took 5 hours from Shanghai to Shenzhen by high-speed train.D．China shares the high-speed rail technology with few other countries.8．According to the passage, how many people were awarded national metals and honorary titles? A．38 B．36 C．6 D．42 9．According to the passage.the purpose of Cyber Secuity Week is to _________.A．hold a wonderful opening ceremony and different kinds of activities.B．help people know that it is important to fight online threats and cyber attacks.C．help people know what is cyber secuity and how to protect themselves.D．teach people how to protect their personal data.Since May 12, a computer virus named WannaCry has infected (感染) more than 300,000computers in over 150 countries, according to Reuters.Wannacry is spread by using a weakness in Microsoft's Windows operating system. Once the virus gets into the computer, it locks all the papers and asks the user for money to unlock them. At first, it asks for $300, but if the user doesn't send the money in 72 hours, the price doubled. Papers are locked forever if the user doesn't pay in seven days.The virus has brought bad results. For example, in the UK, the virus left the country’sNational Health Service in a mess. Some hospitals had to cancel patient appointments(预约), reported The Telegraph. In China, the virus has hit thousands of computers, according to Qihoo360. One of the most hard-hit groups in China were university users. Many students' graduation papers were locked. They felt nervous and frightened. Also many gas stations were seriously hit, and the payment syst em didn’t work.WanaCry is the latest example of the cyber security(网络安全) problem. Matthew Hickey, who set up the security company Hacker House, said, "The attack is not surprising. It shows that many organizations do not use updates(更新) fast enough. Accor ding to a survey, nearly half of the people said, “We are not satisfied with the way software updates work.”As China Daily wrote, “We can’t completely protect our computers against these kinds of viruses, as this cat and mouse game will continue forever. The best choice for most users is to take care online and always install(安装)software updates.”10．What is WannaCry?A．A video game. B．A computer software. C．A computer virus. D．A TV programme.11．If your papers are locked by Wannacry, how much do you need to pay if you don’t send the money in 72 hours? A．$150. B．$300. C．$600. D．$900.12．According to the passage, the writer shows the bad results by ________.A．giving reasons B．giving examples C．comparing computers D．comparing numbers 13．From the last two paragraphs, we can know that________.A．Matthew Hickey thinks the attack on computers is very surprisingB．all the people are pleased with the way software updates workC．the computers can be completely protected against these virusesD．we should take care online and update software fast enoughPassage4Slowly but surely, we’re moving closer and closer to 5G world. From smart-home security to self-driving cars, all the internet-connected devices（装置）in your life will be able to talk to each other at lightning-fast speeds. Objectively speaking, the fastest 4G download speeds in the U.S. top out at an average of 19.42 Mbps. But by comparison 5G promises gigabit（千兆）speeds.“5G is one of those signs, along with artificial intelligence（人工智能）, of this coming data age.” said Steve Koenig, senior director of market research for the Consumer Technology Association. The self-driving vehicle is a great emblem of this data age,and that is to say, it is a sign of time, because with one single task, driving, you have large amounts of data coming from the vehicle itself, and a variety of sensors（传感器）are collecting a lot of information to model its environment as it moves. It’s pulling in data from other vehicles about road conditions. It could be weather information, but also connected infrastructure construction（基础设施建设）. There’s lots of data behind that task, which is why we need high speed.Augmented reality glasses（实境眼镜）and virtual headset haven’t yet broken the mainstream（主流）, but tech companies are joyfully betting that these devices will finally take the place of our smartphones. With 5G, that could actually happen. This is notable because companies such as Apple are reportedly developing AR glasses to give help-or perhaps even replace-smartphones.Ericsson stated at Febr uary’s Mobile World Congress how smart glasses could become faster and lighter with a 5G connection,because instead of being weighed down with components, the glasses could depend on hardware for processing power.But don’t get too excited. There’s still a lot of work to be done, including various ways to make sure the radios play nicely with hardware and infrastructure construction so 5G isn’t used only in big cities.14．What does the author want to stress in Paragraph 1?A．The lighting-fast speed of 5G.B．The expectation of SG world.C．The difference between 4G and 5G.D．The internet-connected devices in our life.15．What does the underlined word "emblem"in Paragraph 2 mean________?A．Show. B．Success. C．Symbol D．Explanation16．We can infer from the text that ________A．5G world won’t come without AR glassesB．5G helps to create the artificial intelligence vehicleC．Apple company is developing AR glasses worldwideD．Tech companies will face the fact that smartphones may be replaced17．What will the author probably tell us next？A．How to make 5G cover more areas..B．Smart glasses will become faster and lighter.C．Why 5G Isn’t used in big cities.D．The importance of infrastructure construction.A few young students are talking about something on WeChat.Hi everyone! I like sports very much and play basketball almost every day. I also like to eat fast food, but my parents ask me to eat it only once a month.——Bill Sorry to hear that, Bill. However, maybe your parents are right. Fast food isn’t go od for you. I seldom eat it. On weekends, I often do some housework to make my parents relax ( 放松). And I use the Internet only once a week. I have a lot of homework to do every day.——Kate Yes, we students are always busy with our studies. But on Friday evening, I usually go shopping with my mother. It’s really fun. I enjoy watching TV, too. And I do it almost every day. So my parents are kind of unhappy sometimes.——Tony All parents like that. My parents never let me watch TV or play computer games! On weekends, they always want me to study almost every minute. But luckily, I can go to movies with them every Saturday. And on Sunday they let me go out with my friends when I finish my homework. Sometimes they are really good!——Lisa 18．Kate often ________ at the weekend.A．plays basketball B．helps with houseworkC．goes to the movies D．uses the Internet19．Who usually buys things on Friday evening?A．Bill. B．Kate. C．Tony. D．Lisa.20．Lisa can go to the movies ________.A．everyday B．once a week C．twice a week D．on weekdays21．From the passage, we can know that ________.A．Bill often eats fast foodB．Kate never uses the InternetC．Tony often watches TVD．Lisa can go out with her friends at any time22．What are these young students mainly (主要地) talking about?A．Their parents and their life. B．Their eating habits (习惯).C．Their free time. D．Their studying habits.Whether from news, reports or social media articles, you may know that 5G is coming.5G is the 5th generation network. It is a new network after 1G, 2G, 3G and 4G and it can connect everyone and everything together. 5G means super-fast data (数据) speed. One can download a two-hour movie in fewer than 10 seconds, and it is making our lives more and more convenient.5G will make self-driving cars possible. For safety, self-driving cars need super-fast data transmission (传输) to communicate with their nearby environment. 5G is just what makes self-driving cars achieve this. Even airplanes will become “smart” in the near future.5G will be a big help for students who take online classes. Students all over the world will be able to see places like the Great Wall without leaving their rooms.It will be also easier for doctors to treat patients remotely by 5G. It means caring for patients from far away.The facts listed above are only part of what 5G will make possible and popular. Just as in the early days of the Internet in the 1990s, few could see how it could change the world. The same will surely be true of 5G. With 5G,many things do not seem like dre ams to anyone. Now let’s get ready to say goodbye to 4G and welcome the coming of 5G.23．How long may it take to download a two-hour movie with 5G?A．15 seconds. B．8 seconds. C．10 minutes. D．2 hours.24．From the last paragraph, we can know that ________.A．4G is no more used in our daily life now B．the writer is worried about the coming of 5GC．with 5G, some of our dreams will come true for sure one day D．in the 1990s, all the people believed that the Internet would change our life25．5G will make the following things more and more popular EXCEPT ________.A．self-driving cars B．“smart” airplanes C．online classes D．hospitals with doctorsRecently a university in Nanjing, Jiangsu Province has set up facial recognition systems（人脸识别系统）in the classrooms to watch students’ behavior. As a result, it has caused a big discussion on the Internet.China Pharmaceutical University put the systems in two test classrooms as well as school gates, dormitory entrances（宿舍入口）, the library and laboratory buildings.Acc ording to Xu Jianzhen, director of the university’s library and information center, the systems will help teachers check if students are in class and watch what they are doing during the lectures.“In the past, some students were absent from class after t eachers took attendance（考勤）or asked other students to answer “Present!” for them. So it was difficult to take control of them. Now with facial recognition, that would no longer be a problem,” he said.“As soon as you enter the classroom, the camera will wa tch you all the way through and record how long you put down your head, whether you’re playing with a smartphone, you’re sleeping or you’re reading other books,” he added.The news has raised wide discussion online. Many people are questioning if the cameras will infringe on students’ privacy（隐私）. However, this is not the first university to use facial recognition technology in school. Many universities across the country have put cameras at the school gates to make sure of safety.26．Where can facial recognition systems be seen in China Pharmaceutical University?A．In all the classrooms.B．In the dining hall.C．In all the university buildings.D．In the places where students appear often.27．Why is the university using facial recognition systems?A．To help their students stay safer.B．To manage their students better.C．To help their students get better grades.D．To find out why the students don’t like attending classes.28．What can we infer from the passage?A．Almost everyone thinks the university should use facial recognition systems.B．No students will be absent from class in China Pharmaceutical University.C．Facial recognition technology is widely used in Chinese schools.D．Technology can change our life and make our life better.29．What’s the main idea o f the passage?A．Facial recognition systems have many advantages and universities should use them.B．College students are hard to deal with and universities are finding ways to solve the problem.C．China Pharmaceutical University started using facial recognition technology and people have different opinions on it.D．Facial recognition technology is important in helping students stay safe in school.Many children use the Internet to get useful knowledge (知识) and information, and to relax in their free time. But some of them are not using it in a good way. Here are some rules to make sure you are safe and have fun on the Internet.Make rules for Internet use with your parents. For example, when you can go online, for how long and what activities you can go online.Don’t give your password (密码) to anyone else, and never leak out the following information—your real name, home address, age, school, phone number or other personal information.Check with your parent before giving out a credit card (信用卡) number.Never send a photo yourself to someone in e-mail unless your parents say it’s OK.Check with your parents before going into a chat room. Different chat rooms have different rules and attractdifferent kinds of people. You and your parents must make sure it's a right place for you.Never agree to meet someone you met on the Internet without your parent’s permission (允许). Never meet anyone you met online alone.Always remember people online may not be who they say they are. Treat everyone online as strangers.If something you see or read online makes you uncomfortable, leave it at once. Tell it your parents or your teachers right away.Treat (对待) other people as you like to be treated. Never use bad language.Remember—not everything you read on the Internet is true.30．If you want a true friend on the Internet, you can ________.A．tell the people what your name is B．meet the people online aloneC．write an e-mail about yourself D．get your parent’s permission31．The underline phrase “leak out” in the third paragraph may mean ________.A．捐款B．离开C．泄露D．放好32．This passage is mainly about ________.A．how to use computers B．surfing on the InternetC．information on the internet D．internet safety rules33．If your parents don’t agree, never ________.A．read anything on the InternetB．relax in your free timeC．have a face-to-face meeting with anyone you met onlineD．treat other people as you would like to be treated【答案】1．C2．D3．A4．C5．C【分析】本文主要讲了什么是5G网络，5G网络能做什么以及未来怎样运用5G网络。

Network的含义

Network的含义Network的含义Network是在路由进程下的一条命令的其作用是：如果接口下配置了ip地址，那么被network 匹配到的接口就加入进了路由选择协议的进程中，那么这些接口就会发送hello包来建邻居，当然rip是没有hello包的，这个network的宣告可以只包含一个接口也可以包含几个接口还可以是一个或多个网段的接口，总之只要network宣告中包含的接口都会加入到这个进程中(前提是接口是打开的且有地址和掩码)，但network宣告并不影响路由条目的掩码位数，network宣告的不同只是包括的ip地址的范围的大小而已，network可以将路由表中直连的接口宣告进来，可以是打C的或者S的(静态路由写的是出接口而不是下一跳地址)格式：network + 网段或单个地址+反掩码子网掩码子网掩码：子网掩码(IP subnet mask)是用在接口下配置地址时用的，用连续的数个1开头的二进制位表示的，连续的1后面是连续的0，用于表示ip地址的掩码，如：1.1.1.1 255.255.255.0 其中255.255.255.0就是一个子网掩码，子网掩码也是32位的和ip地址其实是对应的，子网掩码的第一位对应ip地址的第一位，第二位对应第二位以此类推直到第32位，子网掩码的1表示它所对应的ip地址为网络位，0表示他所对应的ip地址为主机位，由于ip地址前面连续的是网络位而后面连续的是主机位，所以这就要求子网掩码前面必须是连续的1后面必须是连续的0，否则是不正确的且无法输入到路由器当中。

反掩码反掩码：之所以叫反掩码(wild card bits)是因为它的写法和子网掩码(IP subnet mask)是相反的子网掩码是连续的1开头后面是连续的0跟随，而反掩码是连续的0开头连续的1跟随。

0表示精确匹配network后面的网络号的二进制位1表示忽略不匹配network后面的网络号的二进制位比如进程下network 12.1.1.0 0.0.0.255网络号12.1.1.0 划为二进制是00001100 00000001 00000001 0000000反掩码0.0.0.255划为二进制是00000000 00000000 00000000 1111111通过上面的比较可以看出网络号的前24位被匹配到了，而因为反掩码的后8位为1，1表示忽略就是说只要有接口的ip地址的前24位为00001100 00000001 00000001 的ip地址都被宣告进了路由协议的进程中，那又因为12.1.1.1--12.1.1.254的ip地址的前24位都为00001100 00000001 00000001 所以只要是这些地址都被宣告进了路由协议的进程中其实就是network后面的反掩码跟network后面的网络号相比较(0就复制1就不进行比较)得出的结果，再跟network后面的反掩码与接口ip地址相比较得出的结果进行对比，相同就表明该接口宣告进了路由进程，不同就表示没有宣告进进程，network 0.0.0.0 0.0.0.0 这条命令除外，0.0.0.0 表示匹配所有在show run中会显示network 0.0.0.0如果写成network 0.0.0.0255.255.255.255 那么show run中显示的还是network 0.0.0.0,当在ospf的进程中输入network 0.0.0.0 0.0.0.0命令时路由器会自动翻译成0.0.0.0 255.255.255.255，因为0.0.0.0表示匹配所有，而255.255.255.255表示忽略那所以就是匹配了所有，而在eigrp 中显示的是network 0.0.0.0把所有接口都宣告进了路由进程中，如果写反掩码时写成连续的1开头连续的0跟随那么系统会自动把1转换成0，把0转换成1。

VMware NSXvSphere6.0

VM1
VM2
Uplink QoS Management (pNic)
dvPortGroup dvPortgroup
VDS
ESX host
Traffic Shares Limit Reservation vMotion 50 Mgmt 50 NFS 50 iSCSI 50 FT 50 VM 50 700 Mbps 600Mbps VSAN 50
• Long-Distance vMotion • Multiple TCP/IP Stack
4
Any Application: Today’s hallenges
Today’s Challenges • Inability to prioritize VM traffic over infrastructure traffic • Inability to guarantee performance at VM level for multitenant environments • Multicast is delivered to uninterested VMs
Networking in vSphere 6.0
VDS and NSX Updates
CK Kong
© 2014 VMware Inc. All rights reserved.
Agenda
• What’s New in vSphere 6.0 – Networking
– Features & Benefits – Pre-requisites & Network Design Impacts
Public Cloud
Management and Automation Compute

网络安全法英文

网络安全法英文Network Security LawThe Network Security Law, also known as the Cybersecurity Law, is a piece of legislation enacted by the Chinese government in 2016. This law aims to safeguard the security of networks and protect the rights and interests of individuals, organizations, and society as a whole in cyberspace.The Network Security Law consists of seven chapters with a total of 79 articles. It covers various aspects of network security, including the protection of critical information infrastructure, security management for network operators, and the punishment of cybercrimes.One of the key provisions of the Network Security Law is the requirement for critical information infrastructure operators to undergo a security assessment. These operators are required to conduct regular risk assessments and establish security management systems to ensure the protection of important data.The law also requires network operators to cooperate with authorities in the handling of cyber incidents and the investigation of cybercrimes. They must provide necessary support and technical assistance to security agencies and assist in the preservation of digital evidence.Individuals and organizations that engage in cyber activities that compromise national security or the public interest can be held liable under the Network Security Law. This includes activitiessuch as hacking, spreading malware, and engaging in online fraud. Penalties can range from fines to criminal prosecution depending on the severity of the offense.The Network Security Law also stipulates measures to protect personal information and prevent the unauthorized collection and use of personal data. Network operators are required to take appropriate measures to ensure the security of personal information and obtain consent from individuals before collecting their personal data.In addition to protecting network security and personal data, the Network Security Law also promotes international cooperation in cybersecurity. It encourages the sharing of information and technology among countries to fight against cybercrimes and safeguard global cyberspace security.However, the Network Security Law has also faced criticism from some international observers who argue that it can be used as a tool for government surveillance and censorship. They raise concerns about the potential infringement of privacy and individual freedoms.In conclusion, the Network Security Law is a comprehensive legislation that aims to ensure the security of networks in China. It establishes guidelines for network operators, individual responsibilities, and penalties for cybercrimes. While it has been praised for its efforts to enhance cybersecurity, it has also faced scrutiny for its potential impacts on privacy and freedom of expression.。

network_复习

一、1、internet组成：边缘：pc（资源子网）核心：router \switch（通讯子网）2、电路，分组和报文交换的优缺点：电路：面向连接传送计算机数据效率低通信线路的利用率很低报文：不需预先分配传输带宽，在传输突发数据时可提高整个网络的信道利用率。

报文长度较长，不便于传输分组：高效动态分配传输带宽，对通信链路是逐段占用。

灵活以分组为传送单位和查找路由。

迅速不必先建立连接就能向其他主机发送分组。

可靠保证可靠性的网络协议；分布式的路由选择协议使网络有很好的生存性。

分组在各结点存储转发时需要排队，这就会造成一定的时延。

分组必须携带的首部（里面有必不可少的控制信息）也造成了一定的开销。

3、网络协议定义：网络协议(network protocol)，简称为协议，是为进行网络中的数据交换而建立的规则、标准或约定。

语法数据与控制信息的结构或格式。

语义需要发出何种控制信息，完成何种动作以及做出何种响应。

同步事件实现顺序的详细说明。

4、服务与协议关系：●在协议的控制下，两个对等的实体间的通信使得本层能向上一层提供服务，要实现本层协议，还要使用下面一层所提供的服务。

●本层的服务用户只能看见服务而无法看见下面的协议。

下面的协议对上面的服务用户是透明的。

●协议是“水平的”，即协议是控制对等实体之间通信的规则。

●服务是“垂直的”，即服务是由下层向上层通过层间接口提供的。

●PDU(协议数据单元)：对等层之间传送的数据单元●SDU(服务数据单元)：层与层之间传送的数据单元●SAP(服务访问点)：逻辑接口5、协议体系结构（OSI 、TCP/IP 、5层）分层好处：各层之间是独立的。

灵活性好。

结构上可分割开。

易于实现和维护。

能促进标准化工作。

1、OSI：物理，数据链路，网络，传输，会话，表示，应用2、TCP/IP 是四层的体系结构：应用层、运输层、网际层和网络接口层。

3、二、1、数据通讯组成：源系统（源点，发送器）、传输系统、目的系统（接收器，终点）2、有关信号的几个基本概念：单向通信（单工通信）——只能有一个方向的通信而没有反方向的交互。

社交网络 Social Network

社交网络Social Network社交网络是一个社交结构由个人或组织组成。

他们由友谊，血缘关系，共同利益等关系连接起来.A social network is a social structure made up of individuals (or organizations) called nodes , which are tied (connected) by one or more specific types of interdependency, such as friendship, kinship, common interest, financial exchange, dislike, sexual relationships, or relationships of beliefs, knowledge or prestige.Social Networks are groups of people who share interests and who interact in a variety of ways via software on websites. These include file-sharing, chatting, messaging, exchanging photos/video etc. Social network sites are usually free to join. IncludeMyspace,Facebook,Bebo,Orkut,LinkedIn and so on.We define social network sites as web-based services that allow individuals to construct a public or semi-public profile within a bounded system, articulate a list of other users with whom they share a connection, and view and traverse their list of connections and those made by others within the system. The nature and nomenclature of these connections may vary from site to site.The Importance of Social Networking1.Social networking can help a business gain contacts, clients, andincreased public awareness.2.Even entrepreneurs who run small businesses from their homes can take advantage of this resource to set up a global presence.3.To make the most of social networking, it"s important to fully understand the concept of social networking and how it can be applied in ways that will help you grow your business.4.Social networking is making its mark in history these days. In fact, it is progressing so fast, it is leaving the news media in the dust. Everyday people are reporting news faster than a whole news team.社交网络是是由个人（或组织）构成的社会结构称为节点，是由一个或多个相互依存的具体类型连接起来的，比如友情、亲情、共同兴趣爱好、经济交易、厌恶、性关系、信仰、知识或声望。

draft-ietf-l2vpn-vpls-mcast-06

Network Working Group R. Aggarwal (Editor) Internet Draft Juniper Networks Category: Standards TrackExpiration Date: September 2010 Y. Kamite NTT CommunicationsL. Fang Cisco Systems, IncMarch 08, 2010 Multicast in VPLSdraft-ietf-l2vpn-vpls-mcast-06.txtStatus of this MemoThis Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79.Internet-Drafts are working documents of the Internet EngineeringTask Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts.Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as referencematerial or to cite them other than as "work in progress."The list of current Internet-Drafts can be accessed at/ietf/1id-abstracts.txt.The list of Internet-Draft Shadow Directories can be accessed at/shadow.html.Copyright and License NoticeCopyright (c) 2010 IETF Trust and the persons identified as thedocument authors. All rights reserved.This document is subject to BCP 78 and the IETF Trust’s LegalProvisions Relating to IETF Documents(/license-info) in effect on the date ofpublication of this document. Please review these documentscarefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must Raggarwa, Kamite & Fang [Page 1]Internet Draft draft-ietf-l2vpn-vpls-mcast-06.txt March 2010 include Simplified BSD License text as described in Section 4.e ofthe Trust Legal Provisions and are provided without warranty asdescribed in the Simplified BSD License.This document may contain material from IETF Documents or IETFContributions published or made publicly available before November10, 2008. The person(s) controlling the copyright in some of thismaterial may not have granted the IETF Trust the right to allowmodifications of such material outside the IETF Standards Process.Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modifiedoutside the IETF Standards Process, and derivative works of it maynot be created outside the IETF Standards Process, except to formatit for publication as an RFC or to translate it into languages other than English.AbstractThis document describes a solution for overcoming a subset of thelimitations of existing VPLS multicast solutions. It describesprocedures for VPLS multicast that utilize multicast trees in thesevice provider (SP) network. One such multicast tree can be shared between multiple VPLS instances. Procedures by which a singlemulticast tree in the SP network can be used to carry trafficbelonging only to a specified set of one or more IP multicast streams from one or more VPLSes are also described.Raggarwa, Kamite & Fang [Page 2]Internet Draft draft-ietf-l2vpn-vpls-mcast-06.txt March 2010 Table of Contents1 Specification of requirements (4)2 Contributors (4)3 Terminology (5)4 Introduction (5)5 Existing Limitations of VPLS Multicast (5)6 Overview (6)6.1 Inclusive and Selective Multicast Trees (6)6.2 BGP-Based VPLS Membership Auto-Discovery (7)6.3 IP Multicast Group Membership Discovery (8)6.4 Advertising P-Multicast Tree to VPLS/C-Multicast Binding ..8 6.5 Aggregation (9)6.6 Inter-AS VPLS Multicast (10)7 Intra-AS Inclusive P-Multicast Tree A-D/Binding (10)7.1 Originating intra-AS VPLS auto-discovery routes (11)7.2 Receiving intra-AS VPLS auto-discovery routes (12)8 Demultiplexing P-Multicast Tree Traffic (13)8.1 One P-Multicast Tree - One VPLS Mapping (13)8.2 One P-Multicast Tree - Many VPLS Mapping (13)9 Establishing P-Multicast Trees (14)9.1 Common Procedures (14)9.2 RSVP-TE P2MP LSPs (15)9.2.1 P2MP TE LSP - VPLS Mapping (15)9.3 Receiver Initiated MPLS Trees (16)9.3.1 P2MP LSP - VPLS Mapping (16)9.4 Encapsulation of Aggregate P-Multicast Trees (16)10 Inter-AS Inclusive P-Multicast Tree A-D/Binding (16)10.1 VSIs on the ASBRs (17)10.1.1 Option (a) (17)10.1.2 Option (e) (17)10.2 Option (b) - Segmented Inter-AS Trees (18)10.2.1 Segmented Inter-AS Trees VPLS Inter-AS A-D/Binding (18)10.2.2 Propagating BGP VPLS A-D routes to other ASes: Overview (19)10.2.2.1 Propagating Intra-AS VPLS A-D routes in E-BGP (20)10.2.2.2 Inter-AS A-D route received via E-BGP (21)10.2.2.3 Leaf A-D Route received via E-BGP (23)10.2.2.4 Inter-AS A-D Route received via I-BGP (23)10.3 Option (c) (24)11 Optimizing Multicast Distribution via Selective Trees . 25 11.1 Protocol for Switching to Selective Trees (27)11.2 Advertising C-(S, G) Binding to a Selective Tree (28)Raggarwa, Kamite & Fang [Page 3]Internet Draft draft-ietf-l2vpn-vpls-mcast-06.txt March 2010 11.3 Receiving S-PMSI A-D routes by PEs (30)11.4 Inter-AS Selective Tree (31)11.4.1 VSIs on the ASBRs (32)11.4.1.1 VPLS Inter-AS Selective Tree A-D Binding (32)11.4.2 Inter-AS Segmented Selective Trees (32)11.4.2.1 Handling S-PMSI A-D routes by ASBRs (33)11.4.2.1.1 Merging Selective Tree into an Inclusive Tree (34)11.4.3 Inter-AS Non-Segmented Selective trees (35)12 BGP Extensions (35)12.1 Inclusive Tree/Selective Tree Identifier (35)12.2 MCAST-VPLS NLRI (36)12.2.1 S-PMSI auto-discovery route (36)12.2.2 Leaf auto-discovery route (37)13 Aggregation Methodology (38)14 Data Forwarding (38)14.1 MPLS Tree Encapsulation (38)15 VPLS Data Packet Treatment (39)16 Security Considerations (40)17 IANA Considerations (41)18 Acknowledgments (41)19 Normative References (42)20 Informative References (42)21 Author’s Address (43)1. Specification of requirementsThe key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT","SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119].2. ContributorsRahul AggarwalYakov RekhterJuniper NetworksYuji KamiteNTT CommunicationsLuyuan FangAT&TChaitanya KodeboniyaRaggarwa, Kamite & Fang [Page 4]Internet Draft draft-ietf-l2vpn-vpls-mcast-06.txt March 2010 3. TerminologyThis document uses terminology described in [RFC4761] and [RFC4762].4. Introduction[RFC4761] and [RFC4762] describe a solution for VPLS multicast thatrelies on ingress replication. This solution has certain limitations for certain VPLS multicast traffic profiles.This document describes procedures for overcoming the limitations of existing VPLS multicast solutions. It describes procedures for VPLSmulticast that utilize multicast trees in the Sevice Provider (SP)network. The procedures described in this document are applicable to both [RFC4761] and [RFC4762].It provides mechanisms that allow a single multicast distributiontree in the Service Provider (SP) network to carry all the multicast traffic from one or VPLS sites connected to a given PE, irrespective of whether these sites belong to the same or different VPLSes. Such a tree is referred to as an "Inclusive tree" and more specifically asan "Aggregate Inclusive tree" when the tree is used to carrymulticast traffic from more than one VPLS.This document also provides procedures by which a single multicastdistribution tree in the SP network can be used to carry trafficbelonging only to a specified set of IP multicast streams, originated in one or more VPLS sites connected to a given PE, irrespective ofwhether these sites belong to the same or different VPLSes. Such atree is referred to as a "Selective tree" and more specifically as an "Aggregate Selective tree" when the IP multicast streams belong todifferent VPLSes. This allows multicast traffic, by default, to becarried on an Inclusive tree, while traffic from some specificmulticast streams, e.g., high bandwidth streams, could be carried on one of the "Selective trees".5. Existing Limitations of VPLS MulticastOne of the limitations of existing VPLS multicast solutions described in [RFC4761] and [RFC4762] is that they rely on ingress replication. Thus the ingress PE replicates the multicast packet for each egressPE and sends it to the egress PE using a unicast tunnel.This may be an acceptable model when the bandwidth of the multicasttraffic is low or/and the number of replications performed on anaverage on each outgoing interface for a particular customer VPLS Raggarwa, Kamite & Fang [Page 5]Internet Draft draft-ietf-l2vpn-vpls-mcast-06.txt March 2010 multicast packet is small. If this is not the case it is desirable to utilize multicast trees in the SP network to transmit VPLS multicast packets [MCAST-VPLS-REQ]. Note that unicast packets that are flooded to each of the egress PEs, before the ingress PE learns thedestination MAC address of those unicast packets, MAY still useingress replication.6. OverviewThis document describes procedures for using multicast trees in theSP network to transport VPLS multicast data packets. RSVP-TE P2MPLSPs described in [RFC4875] are an example of such multicast trees.The use of multicast trees in the SP network can be beneficial whenthe bandwidth of the multicast traffic is high or when it isdesirable to optimize the number of copies of a multicast packettransmitted on a given link. This comes at a cost of state in the SP network to build multicast trees and overhead to maintain this state. This document describes procedures for using multicast trees for VPLS multicast when the provider tunneling technology is either P2MP RSVP- PE or mLDP [MLDP]. The protocol architecture described herein isconsidered to be flexible to support other P-tunneling technologiesas well.This document uses the prefix ’C’ to refer to the customer control or data packets and ’P’ to refer to the provider control or datapackets. An IP (multicast source, multicast group) tuple isabbreviated to (S, G).6.1. Inclusive and Selective Multicast TreesMulticast trees used for VPLS can be of two types:1. Inclusive trees. This option supports the use of a singlemulticast distribution tree, referred to as an Inclusive P-Multicast tree, in the SP network to carry all the multicast traffic from aspecified set of VPLS sites connected to a given PE. A particular P- Multicast tree can be set up to carry the traffic originated by sites belonging to a single VPLS, or to carry the traffic originated bysites belonging to different VPLSes. The ability to carry the traffic of more than one VPLS on the same tree is termed of the VPLSes thatare using the tree. This implies that a PE may receive multicasttraffic for a multicast stream even if it doesn’t have any receivers that are interested in receiving traffic for that stream.An Inclusive P-Multicast tree as defined in this document is a P2MPtree. A P2MP tree is used to carry traffic only for VPLS sites that Raggarwa, Kamite & Fang [Page 6]Internet Draft draft-ietf-l2vpn-vpls-mcast-06.txt March 2010 are connected to the PE that is the root of the tree.2. Selective trees. A Selective P-Multicast tree is used by a PE to send IP multicast traffic for one or IP more specific multicaststreams, originated within sites connected to the PE, that belong to the same or different VPLSes, to a subset of the PEs that belong tothose VPLSes. Each of the PEs in the subset should be on the path to a receiver of one or more multicast streams that are mapped onto the tree. The ability to use the same tree for multicast streams thatbelong to different VPLSes is termed a PE the ability to createseparate SP multicast trees for specific multicast streams, e.g. high bandwidth multicast streams. This allows traffic for these multicast streams to reach only those PE routers that have receivers in thesestreams. This avoids flooding other PE routers in the VPLS.A SP can use both Inclusive P-Multicast trees and Selective P-Multicast trees or either of them for a given VPLS on a PE, based on local configuration. Inclusive P-Multicast trees can be used forboth IP and non-IP data multicast traffic, while Selective P-Multicast trees can be used only for IP multicast data traffic.A variety of transport technologies may be used in the SP network.For inclusive P-Multicast trees, these transport technologies include point-to-multipoint LSPs created by RSVP-TE or mLDP. For selective P- Multicast trees, only unicast PE-PE tunnels (using MPLS or IP/GREencapsulation) and P2MP LSPs are supported, and the supported P2MPLSP signaling protocols are RSVP-TE, and mLDP.This document also describes the data plane encapsulations forsupporting the various SP multicast transport options.6.2. BGP-Based VPLS Membership Auto-DiscoveryIn order to establish Inclusive P-Multicast trees for one or moreVPLSes, when Aggregation is performed or when the tunnelingtechnology is P2MP RSVP-TE, the root of the tree must be able todiscover the other PEs that have membership in one or more of theseVPLSes. This document uses the BGP-based procedures described in[RFC4761] and [L2VPN-SIG] for discovering the VPLS membership of all PEs.The leaves of the Inclusive P-Multicast trees must also be able toauto-discover the identifier of the tree. This is described insection 6.4.Raggarwa, Kamite & Fang [Page 7]Internet Draft draft-ietf-l2vpn-vpls-mcast-06.txt March 2010 6.3. IP Multicast Group Membership DiscoveryThe setup of a Selective P-Multicast tree for one or more IPmulticast (S, G)s, requires the ingress PE to learn the PEs that have receivers in one or more of these (C-S, C-G)s, in the followingcases:+ When aggregation is used OR+ When the tunneling technology is P2MP RSVP-TE+ If ingress replication is used and the ingress PE wants to send traffic for (C-S, C-G)s to only those PEs that are on the path to receivers to the (C-S,C-G)s.For discovering the IP multicast group membership, this documentdescribes procedures that allow an ingress PE to enable explicittracking. Thus an ingress PE can request the IP multicast membership from egress PEs for one or more C-multicast streams. These procedures are described in section "Optimizing Multicast Distribution viaSelective Trees".These procedures are applicable when IGMP is used as the multicastrouting protocol between the VPLS CEs. They are also applicable when PIM is used as the multicast routing protocol between the VPLS CEsand PIM join suppression is disabled on all the CEs. However theseprocedures do not apply when PIM is used as the multicast routingprotocol between the VPLS CEs and it not possible to disable PIM join suppression on all the CEs. Procedures for this case are for further study.The leaves of the Selective P-Multicast trees must also be able todiscover the identifier of the tree. This is described in section6.4.6.4. Advertising P-Multicast Tree to VPLS/C-Multicast BindingThis document describes procedures based on BGP VPLS Auto-Discovery(A-D) that are used by the root of an Aggregate P-Multicast tree toadvertise the Inclusive or Selective P-Multicast tree binding and the de-multiplexing information to the leaves of the tree. This document uses the PMSI Tunnel Attribute [BGP-MVPN] for this purpose.Once a PE decides to bind a set of VPLSes or customer multicastgroups to an Inclusive P-Multicast tree or a Selective P-Multicasttree, it needs to announce this binding to other PEs in the network. Raggarwa, Kamite & Fang [Page 8]Internet Draft draft-ietf-l2vpn-vpls-mcast-06.txt March 2010 This procedure is referred to as Inclusive P-Multicast tree orSelective P-Multicast tree binding distribution and is performedusing BGP.When an Inclusive P-Multicast tree is used by an ingress PE, thisdiscovery implies that an ingress PE MUST announce the binding of all VPLSes bound to the Inclusive P-Multicast tree to the other PEs. The inner label assigned by the ingress PE for each VPLS MUST beincluded, if more than one VPLS is bound to the same P-Multicasttree. The Inclusive P-Multicast tree Identifier MUST be included.For a Selective P-Multicast tree this discovery implies announcingall the specific <C-S, C-G> entries bound to this P-Multicast treealong with the Selective P-Multicast tree Identifier. The inner label assigned for each <C-S, C-G> MUST be included if <C-S, C-G>s fromdifferent VPLSes are bound to the same P-Multicast tree. The labelsMUST be distinct on a per VPLS basis and MAY be distinct on a per <C- S, C-G> basis. The Selective P-Multicast tree Identifier MUST beincluded.6.5. AggregationAs described above the ability to carry the traffic of more than one VPLS on the same P-Multicast tree is termed ’Aggregation’. BothInclusive and Selective P-Multicast trees support aggregation.Aggregation enables the SP to place a bound on the amount ofmulticast tree forwarding and control plane state which the P routers must have. Let us call the number of VPLSes aggregated onto a single P-Multicast tree as the "Aggregation Factor". When Inclusive sourceP-Multicast trees are used the number of trees that a PE is the root of is proportional to:+ (Number of VPLSes on the PE / Aggregation Factor).In this case the state maintained by a P router, is proportional to: + ((Average number of VPLSes on a PE / Aggregation Factor) * number of PEs) / (Average number of P-Multicast trees that transit agiven P router)Thus the state does not grow linearly with the number of VPLSes.Aggregation requires a mechanism for the egresses of the P-Multicast tree to demultiplex the multicast traffic received over the P-Raggarwa, Kamite & Fang [Page 9]Internet Draft draft-ietf-l2vpn-vpls-mcast-06.txt March 2010Multicast tree. This document describes how upstream-assigned labels can be assigned and distributed by the root of aggregate P-Multicast tree and then used by the egresses to perform this demultiplexing.6.6. Inter-AS VPLS MulticastThis document supports three models of inter-AS VPLS service, option(a), (b) and (c) which are very similar conceptually to option (a),(b) and (c) specified in [RFC4364] for IP VPNs. The three optionsdescribed here are also similar to the three options described in in [RFC4761], which in turn extends the concepts of [RFC4364] to inter- AS VPLS.For option (a) and option (b) support this document specifies a model where Inter-AS VPLS service can be offered without requiring a single P-Multicast tree to span multiple ASes. There are two variants ofthis model and they are described in section 10.For option (c) support this document specifies a model where Inter-AS VPLS service is offered by requiring a single P-Multicast tree tospan multiple ASs. This is because in the case of option (c) theASBRs do not exchange BGP-VPLS NLRIs or A-D routes.7. Intra-AS Inclusive P-Multicast Tree A-D/BindingThis section specifies procedures for the intra-AS auto-discovery (A- D) of VPLS membership and the distribution of information used toinstantiate P-Multicast Tunnels.VPLS auto-discovery/binding consists of two components: intra-AS and inter-AS. The former provides VPLS auto-discovery/binding within asingle AS. The latter provides VPLS auto-discovery/binding acrossmultiple ASes. Inter-AS auto-discovery/binding is described insection 10.VPLS auto-discovery using BGP as described in [RFC4761, L2VPN-SIG]enables a PE to learn the VPLS membership of other PEs. A PE thatbelongs to a particular VPLS announces a BGP Network LayerReachability Information (NLRI) that identifies the Virtual SwitchInstance (VSI). This NLRI is constructed from the <Route-Distinguisher (RD), VPLS Edge Device Identifier (VE-ID)> tuple. TheNLRI defined in [RFC4761] comprises the <RD, VE-ID> tuple and labelblocks for PW signaling. The VE-ID in this case is a two octetnumber. The NLRI defined in [L2VPN-SIG] comprises only the <RD, VE-ID> where the VE-ID is a four octet number.Raggarwa, Kamite & Fang [Page 10]Internet Draft draft-ietf-l2vpn-vpls-mcast-06.txt March 2010 The procedures for constructing Inclusive intra-AS and inter-AS trees as specified in this document require the BGP A-D NLRI to carry only the <RD, VE-ID>. Hence these procedures can be used for both BGP-VPLS and LDP-VPLS with BGP A-D.It is to be noted that BGP A-D is an inherent feature of BGP-VPLS.However it is not an inherent feature of LDP-VPLS. Infact there aredeployments and/or implementations of LDP-VPLS that requireconfiguration to enable a PE in a particular VPLS to determine other PEs in the VPLS and exchange PW labels using FEC 128 [RFC4447]. Theuse of BGP A-D for LDP-VPLS [L2VPN-SIG], to enable automatic setup of PWs, requires FEC 129 [RFC4447]. However FEC 129 is not required inorder to use BGP A-D for the setup of P-Multicast trees for LDP-VPLS as described in this document. An LDP-VPLS implementation thatsupports P-Multicast trees described in this document, MUST supportthe BGP A-D procedures to setup P-Multicast trees and it MAY support FEC 129 to automate the signaling of PWs.7.1. Originating intra-AS VPLS auto-discovery routesTo participate in the VPLS auto-discovery/binding a PE router thathas a given VSI of a given VPLS originates an BGP VPLS intra-AS auto- discovery route and advertises this route in I-BGP. The route isconstructed as described in [RFC4761] and [L2VPN-SIG].The route carries a single L2VPN NLRI with the RD set to the RD ofthe VSI, and the VE-ID set to the VE-ID of the VSI.If an Inclusive P-Multicast tree is used to instantiate the provider tunnel for VPLS multicast on the PE, the advertising PE MUSTadvertise the type and the identity of the P-Multicast tree in thethe PMSI Tunnel attribute [BGP-MVPN]. This attribute is described in section 12.1.A PE that uses an Inclusive P-Multicast tree to instantiate theprovider tunnel MAY aggregate two or more VPLSes present on the PEonto the same tree. If the PE decides to perform aggregation after it has already advertised the intra-AS VPLS auto-discovery routes forthese VPLSes, then aggregation requires the PE to re-advertise these routes. The re-advertised routes MUST be the same as the originalones, except for the PMSI Tunnel attribute. If the PE has notpreviously advertised intra-AS auto-discovery routes for theseVPLSes, then the aggregation requires the PE to advertise (new)intra-AS auto-discovery routes for these VPLSes. The P-Tunnelattribute in the newly advertised/re-advertised routes MUST carry the identity of the P-Multicast tree that aggregates the VPLSes, as well as an MPLS upstream-assigned label [RFC5331]. Each re-advertised Raggarwa, Kamite & Fang [Page 11]Internet Draft draft-ietf-l2vpn-vpls-mcast-06.txt March 2010 route MUST have a distinct label.Discovery of PE capabilities in terms of what tunnels types theysupport is outside the scope of this document. Within a given AS PEs participating in a VPLS are expected to advertise tunnel bindingswhose tunnel types are supported by all other PEs that areparticipating in this VPLS and are part of the same AS.7.2. Receiving intra-AS VPLS auto-discovery routesWhen a PE receives a BGP Update message that carries an intra-AS A-D route such that (a) the route was originated by some other PE within the same AS as the local PE, (b) at least one of the Route Targets of the route matches one of the import Route Targets configured for aparticular VSI on the local PE, (c) the BGP route selectiondetermines that this is the best route with respect to the NLRIcarried by the route, and (d) the route carries the PMSI Tunnelattribute, the PE performs the following.If the route carries the PMSI Tunnel attribute then:+ If the Tunnel Type in the PMSI Tunnel attribute is set to LDPP2MP LSP, the PE SHOULD join the P-Multicast tree whose identity is carried in the PMSI Tunnel Attribute.+ If the Tunnel Type in the PMSI Tunnel attribute is set to RSVP-TE P2MP LSP, the receiving PE has to establish the appropriate state to properly handle the traffic received over that LSP. The PEthat originated the route MUST establish an RSVP-TE P2MP LSP with the local PE as a leaf. This LSP MAY have been established before the local PE receives the route.+ If the PMSI Tunnel attribute does not carry a label, then allpackets that are received on the P-Multicast tree, as identified by the PMSI Tunnel attribute, are forwarded using the VSI thathas at least one of its import Route Targets that matches one of the Route Targets of the received auto-discovery route.+ If the PMSI Tunnel attribute has the Tunnel Type set to LDP P2MP LSP or RSVP-TE P2MP LSP, and the attribute also carries an MPLSlabel, then the egress PE MUST treat this as an upstream-assigned label, and all packets that are received on the P-Multicast tree, as identified by the PMSI Tunnel attribute, with that upstreamlabel are forwarded using the VSI that has at least one of itsimport Route Target that matches one of the Route Targets of the received intra-AS auto-discovery route.Raggarwa, Kamite & Fang [Page 12]Internet Draft draft-ietf-l2vpn-vpls-mcast-06.txt March 2010 If the local PE uses RSVP-TE P2MP LSP for sending (multicast)traffic, originated by VPLS sites connected to the PE, to the sitesattached to other PEs then the local PE MUST use the OriginatingRouter’s IP address information carried in the intra-AS A-D route to add the PE, that originated the route, as a leaf node to the LSP.This MUST be done irrespective of whether the received Intra-AS A-Droute carries the PMSI Tunnel attribute or not.8. Demultiplexing P-Multicast Tree TrafficDemultiplexing received VPLS traffic requires the receiving PE todetermine the VPLS instance the packet belongs to. The egress PE can then perform a VPLS lookup to further forward the packet. It alsorequires the egress PE to determine the identity of the ingress PEfor MAC learning, as described in section 15.8.1. One P-Multicast Tree - One VPLS MappingWhen a P-Multicast tree is mapped to only one VPLS, determining thetree on which the packet is received is sufficient to determine theVPLS instance on which the packet is received. The tree is determined based on the tree encapsulation. If MPLS encapsulation is used, eg:RSVP-TE P2MP LSPs, the outer MPLS label is used to determine thetree. Penultimate-hop-popping MUST be disabled on the MPLS LSP (RSVP- TE P2MP LSP or LDP P2MP LSP).8.2. One P-Multicast Tree - Many VPLS MappingAs traffic belonging to multiple VPLSes can be carried over the same tree, there is a need to identify the VPLS the packet belongs to.This is done by using an inner label that determines to the VPLS for which the packet is intended. The ingress PE uses this label as theinner label while encapsulating a customer multicast data packet.Each of the egress PEs must be able to associate this inner labelwith the same VPLS and use it to demultimplex the traffic receivedover the Aggregate Inclusive tree or the Aggregate Selective tree.This document requires the use of upstream label assignment by theingress PE [RFC5331]. Hence the inner label is assigned by theingress PE. When the egress PE receives a packet over an Aggregatetree, the outer encapsulation [in the case of MPLS P2MP LSPs, theouter MPLS label] specifies the label space to perform the innerlabel lookup. The same label space MUST be used by the egress PE for all P-Multicast trees that have the same root [RFC5331].Raggarwa, Kamite & Fang [Page 13]。

network命令

network命令的含义network命令的含义：为协议进程添加接口。

当一个接口的IP地址属于network宣告的范围内时，那么该接口就会被加入该协议进程。

所以要想把一个接口加入协议，只要network的范围涵盖了该接口的IP地址，那么该接口就被加入协议进程了。

如：==================================================================== router ripnetwork 12.0.0.0RIP中，network后面只能接主类。

就算你输入的是一个详细地址（如：12.1.1.1），RIP也会自动的变成该地址的主类前缀12.0.0.0。

所以，只要IP地址属于network命令所宣告的主类范围的接口都会参与RIP进程，发送RIP 报文。

范围很大。

不过可以通过passive-interface命令将不希望参与RIP报文发送的接口置为被动状态。

==================================================================== router eigrp 100network A.B.C.D [ A.B.C.D ]EIGRP中，network后面不但可以输入前缀，还可以加反掩码（可选）。

不加反掩码时，路由器通过宣告的前缀的主类来判断所加的反掩码该是多少。

如果前缀属于A类（1~126），则反掩码为0.255.255.255如果前缀属于B类（128~191），则反掩码为0.0.255.255如果前缀属于C类（192~223），则反掩码为0.0.0.255这样就类似RIP中的宣告了，范围是整个主类空间的IP地址。

--------------------------------------------------------------------由于反掩码的加入，可以使EIGRP的宣告更加精确。

前缀+ 反掩码= 一个IP地址范围最小可以精确到只有一个地址的范围。

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URL 的一般形式
由以冒号隔开的两大部分组成，并且在 URL 中的字符对大写或小写没有要求。 URL 的一般形式是： <协议>://<主机>:<端口>/<路径> ftp —— 文件传送协议 FTP http —— 超文本传送协议 HTTP News —— USENET 新闻
URL 的一般形式（续）
举例：根域名服务器 f 的地点分布图
共 40 个机器 • 根域名服务器并不直接把域名直接转换成 IP 地址。 • 在使用迭代查询时，根域名服务器把下一步应当找的顶级域名服务器的 IP 地址告诉本地域名服务器。
顶级域名服务器
（即 TLD 服务器）
这些域名服务器负责管理在该顶级域名服务器注册的所有二级域名。当收到 DNS 查询请求时，就给出相应的回答（可能是最后的结果，也可能是下一步应当找的域名服务器的 IP 地址）。
域名的解析过程
主机向本地域名服务器的查询一般都是采用递归查询。如果主机所询问的本地域名服务器不知道被查询域名的 IP 地址，那么本地域名服务器就以 DNS 客户的身份，向其他根域名服务器继续发出查询请求报文。本地域名服务器向根域名服务器的查询通常是采用迭代查询。当根域名服务器收到本地域名服务器的迭代查询请求报文时，要么给出所要查询的 IP 地址，要么告诉本地域名服务器：“你下一步应当向哪一个域名服务器进行查询”。然后让本地域名服务器进行后续的查询。
计算机网络（第 5 版）
第 6 章应用层
应用层协议的特点
每个应用层协议都是为了解决某一类应用问题，而问题的解决又往往是通过位于不同主机中的多个应用进程之间的通信和协同工作来完成的。应用层的具体内容就是规定应用进程在通信时所遵循的协议。应用层的许多协议都是基于客户服务器方式。客户(client)和服务器(server)都是指通信中所涉及的两个应用进程。客户服务器方式所描述的是进程之间服务和被服务的关系。客户是服务请求方，服务器是服务提供方。
万维网必须解决的问题
(3) 怎样使各种万维网文档都能在因特网上的各种计算机上显示出来，同时使用户清楚地知道在什么地方存在着超链？超文本标记语言 HTML (HyperText Markup Language)使得万维网页面的设计者可以很方便地用一个超链从本页面的某处链接到因特网上的任何一个万维网页面，并且能够在自己的计算机屏幕上将这些页面显示出来。
——最高层次的域名服务器——
根域名服务器是最重要的域名服务器。所有的根域名服务器都知道所有的顶级域名服务器的域名和 IP 地址。不管是哪一个本地域名服务器，若要对因特网上任何一个域名进行解析，只要自己无法解析，就首先求助于根域名服务器。在因特网上共有13 个不同 IP 地址的根域名服务器，它们的名字是用一个英文字母命名，从 a 一直到 m（前13 个字母）。
提高域名服务器的可靠性
DNS 域名服务器都把数据复制到几个域名服务器来保存，其中的一个是主域名服务器，其他的是辅助域名服务器。当主域名服务器出故障时，辅助域名服务器可以保证 DNS 的查询工作不会中断。主域名服务器定期把数据复制到辅助域名服务器中，而更改数据只能在主域名服务器中进行。这样就保证了数据的一致性。
顶级域名 TLD （续）
(3) 基础结构域名(infrastructure domain)：这种顶级域名只有一个，即 arpa，用于反向域名解析，因此又称为反向域名。
新增加了下列的通用顶级域名
.aero （航空运输企业） .biz （公司和企业） .cat （加泰隆人的语言和文化团体） .coop （合作团体） .info （各种情况） .jobs （人力资源管理者） .mobi （移动产品与服务的用户和提供者） .museum （博物馆） .name （个人） .pro （有证书的专业人员） .travel （旅游业）
6.4 万维网 WWW
6.4.1 万维网概述
万维网 WWW (World Wide Web)并非某种特殊的计算机网络。万维网是一个大规模的、联机式的信息储藏所。万维网用链接的方法能非常方便地从因特网上的一个站点访问另一个站点，从而主动地按需获取丰富的信息。这种访问方式称为“链接”。
万维网提供分布式服务
本地域名服务器采用迭代查询
根域名服务器迭代查询顶级域名服务器
本地域名服务器
权限域名服务
递归查询
的 IP 地址需要查找的 IP 地址

本地域名服务器采用递归查询
（比较少用）
顶级域名 TLD
(Top Level Domain)
(1) 国家顶级域名 nTLD：如: .cn 表示中国，.us 表示美国，.uk 表示英国，等等。 (2) 通用顶级域名 gTLD：最早的顶级域名是： gTLD
.com （公司和企业） .net （网络服务机构） .org （非赢利性组织） .edu （美国专用的教育机构（） .gov （美国专用的政府部门） .mil （美国专用的军事部门） .int （国际组织）
根域名服务器共有 13 套装置（不是 13 个机器）
这些根域名服务器相应的域名分别是 … 到 2006 年底全世界已经安装了一百多个根域名服务器机器，分布在世界各地。这样做的目的是为了方便用户，使世界上大部分 DNS 域名服务器都能就近找到一个根域名服务器。
6.1 域名系统 DNS
6.1.1 域名系统概述
许多应用层软件经常直接使用域名系统 DNS (Domain Name System)，但计算机的用户只是间接而不是直接使用域名系统。因特网采用层次结构的命名树作为主机的名字，并使用分布式的域名系统 DNS。名字到 IP 地址的解析是由若干个域名服务器程序完成的。域名服务器程序在专设的结点上运行，运行该程序的机器称为域名服务器。
万维网必须解决的问题
(4) 怎样使用户能够很方便地找到所需的信息？为了在万维网上方便地查找信息，用户可使用各种的搜索工具（即搜索引擎）。
6.4.2 统一资源定位符 URL
1. URL的格式
统一资源定位符 URL 是对可以从因特网上得到的资源的位置和访问方法的一种简洁的表示。 URL 给资源的位置提供一种抽象的识别方法，并用这种方法给资源定位。只要能够对资源定位，系统就可以对资源进行各种操作，如存取、更新、替换和查找其属性。 URL 相当于一个文件名在网络范围的扩展。因此 URL 是与因特网相连的机器上的任何可访问对象的一个指针。
权限域名服务器
这就是前面已经讲过的负责一个区的域名服务器。当一个权限域名服务器还不能给出最后的查询回答时，就会告诉发出查询请求的 DNS 客户，下一步应当找哪一个权限域名服务器。
本地域名服务器
本地域名服务器对域名系统非常重要。当一个主机发出 DNS 查询请求时，这个查询请求报文就发送给本地域名服务器。每一个因特网服务提供者 ISP，或一个大学，甚至一个大学里的系，都可以拥有一个本地域名服务器，这种域名服务器有时也称为默认域名服务器。
因特网的域名空间
根顶级域名
aero
… com
cctv
net
org
edu
gov
… cn … edu
uk
…
com
二级域名
… ibm
hp
bj
三级域名
mail
… www
mail
tsinghua
…
www
pku
四级域名
…
6.1.3 域名服务器
一个服务器所负责管辖的（或有权限的）范围叫做区(zone)。各单位根据具体情况来划分自己管辖范围的区。但在一个区中的所有节点必须是能够连通的。每一个区设置相应的权限域名服务器，用来保存该区中的所有主机的域名到IP地址的映射。 DNS 服务器的管辖范围不是以“域”为单位，而是以“区”为单位。
根域名服务器顶级域名服务器根域名服务器
org 域名服务器
com 域名服务器
edu 域名服务器
…
权限域名服务器
域名服务器域名服务器
abc 公司有两个权限域名服务器
域名服务器有以下四种类型
根域名服务器顶级域名服务器权限域名服务器本地域名服务器
根域名服务器
万维网站点 A
万维网站点 B
万维网站点 C
万维网站点 D
万维网站点 E
超媒体与超文本
万维网是分布式超媒体(hypermedia)系统，它是超文本(hypertext)系统的扩充。一个超文本由多个信息源链接成。利用一个链接可使用户找到另一个文档。这些文档可以位于世界上任何一个接在因特网上的超文本系统中。超文本是万维网的基础。超媒体与超文本的区别是文档内容不同。超文本文档仅包含文本信息，而超媒体文档还包含其他表示方式的信息，如图形、图像、声音、动画，甚至活动视频图像。
根域名服务器递归查询顶级域名服务器
本地域名服务器递归查询
权限域名服务
的 IP 地址需要查找的 IP 地址

名字的高速缓存
每个域名服务器都维护一个高速缓存，存放最近用过的名字以及从何处获得名字映射信息的记录。可大大减轻根域名服务器的负荷，使因特网上的 DNS 查询请求和回答报文的数量大为减少。为保持高速缓存中的内容正确，域名服务器应为每项内容设置计时器，并处理超过合理时间的项（例如，每个项目只存放两天）。当权限域名服务器回答一个查询请求时，在响应中都指明绑定有效存在的时间值。增加此时间值可减少网络开销，而减少此时间值可提高域名转换的准确性。
万维网的工作方式
万维网以客户服务器方式工作。浏览器就是在用户计算机上的万维网客户程序。万维网文档所驻留的计算机则运行服务器程序，因此这个计算机也称为万维网服务器。客户程序向服务器程序发出请求，服务器程序向客户程序送回客户所要的万维网文档。在一个客户程序主窗口上显示出的万维网文档称为页面(page)。