BGP和OSPF在路由重分发时的注意点

RGNOSv10.3(3)
BGP和OSPF在路由重分发时的注意点
2008-5-15
福建星网锐捷网络有限公司
版权所有侵权必究
前言
本文档介绍了RGNOS V10.3(3)中BGP和OSPF路由重发布时的一些
实现特点。

由于这些特点区别于友商CISCO的BGP功能实现，在具体的项目实
施过程中需要注意。

1.☹本文档仅限公司内部使用，严禁外传。

1.☺如果您在阅读中产生疑问，请与文档维护人联系。

目录
1. 1OSPF重分发BGP路由
1. 1.1注意点
1. 这里Cisco验证的版本为c7200-adventerprisek9-mz.124-9.T1.bin
2. 1.2应用实例
1. 1.
2.1网络拓扑
四台设备之间建立EBGP/IBGP/EBGP连接。

C1为CISCO 3550、C2、
C3是Cisco模拟器，R1是我司设备，实验设备为RG-S5750。

C1和
R1建立EBGP连接，R1和C2建立IBGP连接，C2和C3建立EBGP
连接。

其中C1和C3主要是发送路由，具体的操作在R1和C2。

2. 1.2.2配置文件
C1 简化配置
C1#sho running-config
Building configuration...
Current configuration : 2557 bytes
!
version 12.2
no service pad
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname C1
!
!
no aaa new-model
ip subnet-zero
ip routing
!
!
!
!
!
!
no file verify auto
spanning-tree mode pvst
spanning-tree extend system-id
!
vlan internal allocation policy ascending
!
!
interface Loopback0
ip address 1.1.1.1 255.255.255.255
!
interface FastEthernet0/1
no switchport
ip address 192.168.16.1 255.255.255.248
!
interface FastEthernet0/2
switchport mode dynamic desirable
!
interface FastEthernet0/3
switchport mode dynamic desirable
!
...
!
router bgp 1
no synchronization
bgp log-neighbor-changes
redistribute static
neighbor 192.168.16.2 remote-as 23
no auto-summary
!
ip classless
ip route 192.168.111.0 255.255.255.0 Loopback0
ip route 192.168.112.0 255.255.255.0 Loopback0
ip http server
ip http secure-server
!
!
!
control-plane
!
!
line con 0
line vty 0 4
privilege level 15
password w
login
!
!
end
C1#
C2简化配置
C2#sho runn
Building configuration...
Current configuration : 1450 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname C2
!
boot-start-marker
warm-reboot
boot-end-marker
!
!
no aaa new-model
!
resource policy
!
ip cef
!
!
!
!
interface Loopback0
ip address 192.168.125.1 255.255.255.0 secondary ip address 192.168.126.1 255.255.255.0 secondary ip address 2.2.2.2 255.255.255.255
!
interface FastEthernet0/0
ip address 192.168.26.2 255.255.255.248
duplex full
!
interface Ethernet1/0
no ip address
shutdown
duplex half
!
interface Ethernet1/1
no ip address
shutdown
duplex half
!
interface Ethernet1/2
no ip address
shutdown
duplex half
!
interface Ethernet1/3
ip address 192.168.23.1 255.255.255.248
duplex full
!
router ospf 1
log-adjacency-changes
network 2.2.2.2 0.0.0.0 area 0
network 192.168.26.0 0.0.0.7 area 0
!
router bgp 23
no synchronization
bgp log-neighbor-changes
network 192.168.125.0
network 192.168.126.0
neighbor 6.6.6.6 remote-as 23
neighbor 6.6.6.6 update-source Loopback0
neighbor 6.6.6.6 next-hop-self
neighbor 192.168.23.2 remote-as 3
no auto-summary
!
no ip http server
no ip http secure-server
!
!
...
!
line con 0
stopbits 1
line aux 0
line vty 0 4
privilege level 15
password w
login
!
!
end
C2#
C3简化配置
C3#sho runn
Building configuration...
Current configuration : 1178 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname C3
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
!
resource policy
!
ip cef
!
!
!
!
!
!
interface Loopback0
ip address 3.3.3.3 255.255.255.255
!
interface FastEthernet0/0
no ip address
shutdown
duplex full
!
interface Ethernet1/0
no ip address
shutdown
duplex half
!
interface Ethernet1/1
no ip address
shutdown
duplex half
!
interface Ethernet1/2
no ip address
shutdown
duplex half
!
interface Ethernet1/3
ip address 192.168.23.2 255.255.255.248
duplex full
!
router bgp 3
no synchronization
bgp log-neighbor-changes
redistribute static
neighbor 192.168.23.1 remote-as 23
no auto-summary
!
ip route 192.168.131.0 255.255.255.0 Loopback0
ip route 192.168.132.0 255.255.255.0 Loopback0
no ip http server
no ip http secure-server
!
!
!
logging alarm informational
!
...
!
line con 0
stopbits 1
line aux 0
line vty 0 4
privilege level 15
password w
login
!
!
end
C2#
R1简化配置
R1#show runn
Building configuration...
Current configuration : 2080 bytes
!
version RGNOS 10.3.00(3), Release(38105)(Fri Apr 25 15:29:44 CST 2008 -ngcf31)
hostname R1
co-operate enable
!
!
!
!
route-map ospf_redist permit 10
match route-type external
!
vlan 1
!
!
!
!
!
interface GigabitEthernet 0/1
no switchport
no ip proxy-arp
ip address 192.168.26.1 255.255.255.248
!
interface GigabitEthernet 0/2
!
...
!
interface GigabitEthernet 0/23
!
interface GigabitEthernet 0/24
no switchport
no ip proxy-arp
ip address 192.168.16.2 255.255.255.248
!
interface Loopback 0
ip address 6.6.6.6 255.255.255.255
ip address 192.168.165.1 255.255.255.0 secondary
ip address 192.168.166.1 255.255.255.0 secondary
!
!
!
!
!
!
!
!
router bgp 23
neighbor 2.2.2.2 remote-as 23
neighbor 2.2.2.2 update-source Loopback 0
neighbor 192.168.16.1 remote-as 1
!
address-family ipv4
network 192.168.165.0
network 192.168.166.0
neighbor 2.2.2.2 activate
neighbor 2.2.2.2 next-hop-self
neighbor 192.168.16.1 activate
exit-address-family
!
!
router ospf 1
router-id 6.6.6.6
network 6.6.6.6 0.0.0.0 area 0
network 192.168.26.0 0.0.0.7 area 0
!
!
!
ip route 192.168.161.0 255.255.255.0 Loopback 0
ip route 192.168.162.0 255.255.255.0 Loopback 0
!
!
line con 0
line vty 0 10
privilege level 15
login
password w
!
!
end
3. 1.2.3检验配置效果
C2
使用show ip bgp可以看到125.0/126.0是源发路由，
111.0/112.0/165.0/166.0是IBGP路由，131.0/132.0是EBGP路由。

使用show ip ospf database可以看到，OSPF中没有外部路由。

C2#show ip bgp
BGP table version is 25, local router ID is 2.2.2.2
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*>i192.168.111.0 6.6.6.6 0 100 0 1 ?
*>i192.168.112.0 6.6.6.6 0 100 0 1 ?
*> 192.168.125.0 0.0.0.0 0 32768 i
*> 192.168.126.0 0.0.0.0 0 32768 i
*> 192.168.131.0 192.168.23.2 0 0 3 ?
*> 192.168.132.0 192.168.23.2 0 0 3 ?
*>i192.168.165.0 6.6.6.6 0 100 0 i
*>i192.168.166.0 6.6.6.6 0 100 0 i
C2#show ip ospf data
OSPF Router with ID (2.2.2.2) (Process ID 1)
Router Link States (Area 0)
Link ID ADV Router Age Seq# Checksum Link count
2.2.2.2 2.2.2.2 91 0x80000009 0x00B640 2
6.6.6.6 6.6.6.6 498 0x80000004 0x00CD20 2
Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
192.168.26.2 2.2.2.2 91 0x80000003 0x00C1CF
C2#
R1
使用show ip bgp可以看到165.0/166.0是源发路由，
125.0/126.0/131.0/132.0是IBGP路由，111.0/112.0是EBGP路由。

使用show ip ospf database可以看到，OSPF中没有外部路由。

R1#show ip bgp
BGP table version is 9, local router ID is 192.168.166.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Path
*> 192.168.111.0 192.168.16.1 0 1 ?
*> 192.168.112.0 192.168.16.1 0 1 ?
*>i192.168.125.0 2.2.2.2 0 100 i
*>i192.168.126.0 2.2.2.2 0 100 i
*>i192.168.131.0 2.2.2.2 0 100 3 ?
*>i192.168.132.0 2.2.2.2 0 100 3 ?
*> 192.168.165.0 0.0.0.0 0 i
*> 192.168.166.0 0.0.0.0 0 i
Total number of prefixes 8
R1#show ip ospf data
OSPF Router with ID (6.6.6.6) (Process ID 1)
Router Link States (Area 0.0.0.0)
Link ID ADV Router Age Seq# CkSum Link count
2.2.2.2 2.2.2.2 254 0x80000009 0xb640 2
6.6.6.6 6.6.6.6 659 0x80000004 0xcd20 2
Network Link States (Area 0.0.0.0)
Link ID ADV Router Age Seq# CkSum
192.168.26.2 2.2.2.2 253 0x80000003 0xc1cf
4. 1.2.4重分发BGP的直连路由
C2
配置OSPF重分发BGP路由：
router ospf 1
redistribute bgp 23 subnets
使用show ip ospf database可以看到EBGP路由(131.0/132.0)和直连路
由(125.0/126.0)都重分发给OSPF，而IBGP路由没有重分发给OSPF。

因此可以看出Cisco会向下通告BGP的直连路由（这里是通过network
命令配置的路由）。

C2#sho ip ospf database
OSPF Router with ID (2.2.2.2) (Process ID 1)
Router Link States (Area 0)
Link ID ADV Router Age Seq# Checksum Link count
2.2.2.2 2.2.2.2 14 0x8000000A 0x00BA39 2
6.6.6.6 6.6.6.6 931 0x80000004 0x00CD20 2
Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
192.168.26.2 2.2.2.2 524 0x80000003 0x00C1CF
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
192.168.125.0 2.2.2.2 13 0x80000001 0x00D6ED 0
192.168.126.0 2.2.2.2 13 0x80000001 0x00CBF7 0
192.168.131.0 2.2.2.2 13 0x80000001 0x00CAF0 3
192.168.132.0 2.2.2.2 13 0x80000001 0x00BFFA 3
R1
配置OSPF重分发BGP路由：
router ospf 1
redistribute bgp subnets
使用show ip ospf database可以看到IBGP路由
(125.0/126.0/131.0/132.0)和EBGP路由(111.0/112.0)都重分发给OSPF
的，而这里没有直连路由(165.0/166.0)。

因为现在的实现中，BGP的
直连路由是不下发的，因此重分发BGP路由的时候BGP的直连路由
是不会被重分发的。

R1#sho ip ospf database
OSPF Router with ID (6.6.6.6) (Process ID 1)
Router Link States (Area 0.0.0.0)
Link ID ADV Router Age Seq# CkSum Link count
2.2.2.2 2.2.2.2 781 0x80000011 0xa648 2
6.6.6.6 6.6.6.6 9 0x80000014 0xb328 2
Network Link States (Area 0.0.0.0)
Link ID ADV Router Age Seq# CkSum
192.168.26.2 2.2.2.2 1544 0x80000008 0xb7d4
AS External Link States
Link ID ADV Router Age Seq# CkSum Route Tag
192.168.111.0 6.6.6.6 8 0x80000001 0xbc24 E2 192.168.111.0/24 0
192.168.112.0 6.6.6.6 8 0x80000001 0xb12e E2 192.168.112.0/24 0
192.168.125.0 6.6.6.6 8 0x80000001 0x22b0 E2 192.168.125.0/24 0
192.168.126.0 6.6.6.6 8 0x80000001 0x17ba E2 192.168.126.0/24 0
192.168.131.0 6.6.6.6 8 0x80000001 0xdfec E2 192.168.131.0/24 0
192.168.132.0 6.6.6.6 8 0x80000001 0xd4f6 E2 192.168.132.0/24 0
因此需要重分发BGP的直连路由，就必须手工的在OSPF中配置BGP
的直连路由。

比如：
router ospf 1
network 192.168.165.0 0.0.0.255 area 0
network 192.168.166.0 0.0.0.255 area 0
5. 1.2.5重分发IBGP路由
C2
配置OSPF重分发BGP路由：
router ospf 1
redistribute bgp 23 subnets
使用show ip ospf database可以看到IBGP路由(111.0/112.0/165.0/166.0)
是不会重分发给OSPF，而EBGP路由(131.0/132.0)和源发路由
(125.0/126.0)会重分发给OSPF。

因此可以看出Cisco默认缺省是不重
分发IBGP路由的，其它的EBGP路由和源发路由是可以被重分发的。

C2#sho ip ospf database
OSPF Router with ID (2.2.2.2) (Process ID 1)
Router Link States (Area 0)
Link ID ADV Router Age Seq# Checksum Link count
2.2.2.2 2.2.2.2 14 0x80000010 0x00AE3F 2
6.6.6.6 6.6.6.6 215 0x8000000F 0x00C2DE 4
Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
192.168.26.2 2.2.2.2 538 0x80000008 0x00B7D4
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
192.168.125.0 2.2.2.2 13 0x80000001 0x00D6ED 0
192.168.126.0 2.2.2.2 13 0x80000001 0x00CBF7 0
192.168.131.0 2.2.2.2 13 0x80000001 0x00CAF0 3
192.168.132.0 2.2.2.2 13 0x80000001 0x00BFFA 3
Cisco可以在BGP模式下使用bgp redistribute-internal命令允许IBGP
路由重分发给IGP协议：
router bgp 23
bgp redistribute-internal
此时使用show ip ospf database可以看到，IBGP路由被重分发到OSPF
中：
C2#sho ip ospf database
OSPF Router with ID (2.2.2.2) (Process ID 1)
Router Link States (Area 0)
Link ID ADV Router Age Seq# Checksum Link count
2.2.2.2 2.2.2.2 146 0x80000010 0x00AE3F 2
6.6.6.6 6.6.6.6 348 0x8000000F 0x00C2DE 4
Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
192.168.26.2 2.2.2.2 671 0x80000008 0x00B7D4
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
192.168.111.0 2.2.2.2 4 0x80000001 0x00834E 1
192.168.112.0 2.2.2.2 4 0x80000001 0x007858 1
192.168.125.0 2.2.2.2 145 0x80000001 0x00D6ED 0
192.168.126.0 2.2.2.2 145 0x80000001 0x00CBF7 0
192.168.131.0 2.2.2.2 145 0x80000001 0x00CAF0 3
192.168.132.0 2.2.2.2 145 0x80000001 0x00BFFA 3
192.168.165.0 2.2.2.2 4 0x80000001 0x001D7F 0
192.168.166.0 2.2.2.2 5 0x80000001 0x001289 0
R1
配置OSPF重分发BGP路由：
router ospf 1
redistribute bgp subnets
使用show ip ospf database可以看到IBGP路由
(125.0/126.0/131.0/132.0)和EBGP路由(111.0/112.0)都重分发给OSPF
的(这里没有源发路由)。

这就是与Cisco不一致的地方：Cisco缺省不
重分发IBGP路由，而Ruijie是重分发所有BGP路由的。

R1#sho ip ospf database
OSPF Router with ID (6.6.6.6) (Process ID 1)
Router Link States (Area 0.0.0.0)
Link ID ADV Router Age Seq# CkSum Link count
2.2.2.2 2.2.2.2 354 0x80000011 0xa648 2
6.6.6.6 6.6.6.6 8 0x80000012 0xb726 2
Network Link States (Area 0.0.0.0)
Link ID ADV Router Age Seq# CkSum
192.168.26.2 2.2.2.2 1117 0x80000008 0xb7d4
AS External Link States
Link ID ADV Router Age Seq# CkSum Route Tag 192.168.111.0 6.6.6.6 7 0x80000001 0xbc24 E2 192.168.111.0/24 0 192.168.112.0 6.6.6.6 7 0x80000001 0xb12e E2 192.168.112.0/24 0 192.168.125.0 6.6.6.6 7 0x80000001 0x22b0 E2 192.168.125.0/24 0 192.168.126.0 6.6.6.6 7 0x80000001 0x17ba E2 192.168.126.0/24 0 192.168.131.0 6.6.6.6 7 0x80000001 0xdfec E2 192.168.131.0/24 0 192.168.132.0 6.6.6.6 7 0x80000001 0xd4f6 E2 192.168.132.0/24 0 R1#
如果要实现和Cisco缺省行为的一致，可以在OSPF重分发BGP路由
的时候使用route-map，在route-map中应用match route-type规则：router ospf 1
redistribute bgp subnets route-map ospf_redist
route-map ospf_redist
match route-type external
这样使用show ip ospf database就可以看到IBGP路由
(125.0/126.0/131.0/132.0)就不会重分发给OSPF了。

R1#sho ip ospf database
OSPF Router with ID (6.6.6.6) (Process ID 1)
Router Link States (Area 0.0.0.0)
Link ID ADV Router Age Seq# CkSum Link count
2.2.2.2 2.2.2.2 602 0x80000011 0xa648 2
6.6.6.6 6.6.6.6 257 0x80000012 0xb726 2
Network Link States (Area 0.0.0.0)
Link ID ADV Router Age Seq# CkSum
192.168.26.2 2.2.2.2 1365 0x80000008 0xb7d4
AS External Link States
Link ID ADV Router Age Seq# CkSum Route Tag 192.168.111.0 6.6.6.6 256 0x80000001 0xbc24 E2 192.168.111.0/24 0 192.168.112.0 6.6.6.6 256 0x80000001 0xb12e E2 192.168.112.0/24 0。