BGP路由策略与选路控制
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BGP路由策略与选路控制
一、实验目标：
根据BGP路由选择原则，用BGP属性控制BGP路由
二、网络拓扑图：
三、配置：
IP地址如图所示
用OSPF实现IGP路由可达
BGP配置如下：no synchronization
No auto-summary
Update-source lo0
Next-hop-self
R3和R4为同簇路由反射器，R1,R2分别为R3和R4的客户端
R3，R4建立普通IBGP邻居
R3，R4都发布10.0.0.0/16，10.2.0.0/16，10.4.0.0/16，10.3.0.0/16到BGP
R5，R6发布10.5.0.0/16，10.6.0.0/16到BGP
R1与R5，R2与R6建立EBGP
现分析下面路由
RT1#show ip bgp
Network Next Hop Metric LocPrf Weight Path
* i10.5.0.0/16 10.0.0.2 0 100 0 65001 i
*> 10.0.15.2 0 0 65001 i
* i10.6.0.0/16 10.0.0.2 0 100 0 65001 i
*> 10.0.15.2 0 0 65001 i 根据EBGP路由优先于IBGP路由
RT1#show ip bgp 10.5.0.0
BGP routing table entry for 10.5.0.0/16, version 11
Paths: (2 available, best #2, table Default-IP-Routing-Table)
Advertised to update-groups:
2
65001
10.0.0.2 (metric 101) from 10.0.0.4 (10.0.0.4)
Origin IGP, metric 0, localpref 100, valid, internal
Originator: 10.0.0.2, Cluster list: 10.0.0.4 来自IBGP10.0.0.4反射的路由65001
10.0.15.2 from 10.0.15.2 (10.5.0.1) 来自EBGP10.0.15.2的路由
Origin IGP, metric 0, localpref 100, valid, external, best
RT2#show ip bgp R2同R1
Network Next Hop Metric LocPrf Weight Path
*> 10.5.0.0/16 10.0.26.2 0 0 65001 i
* i 10.0.0.1 0 100 0 65001 i
*> 10.6.0.0/16 10.0.26.2 0 0 65001 i
* i 10.0.0.1 0 100 0 65001 i
RT2#show ip bgp 10.5.0.0
BGP routing table entry for 10.5.0.0/16, version 10
Paths: (2 available, best #1, table Default-IP-Routing-Table)
Advertised to update-groups:
2
65001
10.0.26.2 from 10.0.26.2 (10.6.0.1)
Origin IGP, metric 0, localpref 100, valid, external, best
65001
10.0.0.1 (metric 101) from 10.0.0.3 (10.0.0.3)
Origin IGP, metric 0, localpref 100, valid, internal
Originator: 10.0.0.1, Cluster list: 10.0.0.3
RT3#show ip bgp
Network Next Hop Metric LocPrf Weight Path
* i10.5.0.0/16 10.0.0.2 0 100 0 65001 i
* i 10.0.0.2 0 100 0 65001 i
*>i 10.0.0.1 0 100 0 65001 i
* i10.6.0.0/16 10.0.0.2 0 100 0 65001 i
* i 10.0.0.2 0 100 0 65001 i
*>i 10.0.0.1 0 100 0 65001 i
根据到达下一跳IGP开销小的
RT3#show ip bgp 10.5.0.0
BGP routing table entry for 10.5.0.0/16, version 18
Paths: (3 available, best #3, table Default-IP-Routing-Table)
Advertised to update-groups:
1 2
65001, (Received from a RR-client)
10.0.0.2 (metric 201) from 10.0.0.2 (10.0.0.2) 来自IBGP10.0.0.2
Origin IGP, metric 0, localpref 100, valid, internal
65001
10.0.0.2 (metric 201) from 10.0.0.4 (10.0.0.4)
Origin IGP, metric 0, localpref 100, valid, internal
Originator: 10.0.0.2, Cluster list: 10.0.0.4 10.0.0.4反射得来，只反射最佳路由65001, (Received from a RR-client)
10.0.0.1 (metric 101) from 10.0.0.1 (10.0.0.1) 来自IBGP10.0.0.1
Origin IGP, metric 0, localpref 100, valid, internal, best
注：R3上该路由的最佳路由来自RT1，所以不会反射回给RT1
同理，RT4不会反射给RT2
RT4#show ip bgp R4同R3
Network Next Hop Metric LocPrf Weight Path
*>i10.5.0.0/16 10.0.0.2 0 100 0 65001 i
* i 10.0.0.1 0 100 0 65001 i
* i 10.0.0.1 0 100 0 65001 i
*>i10.6.0.0/16 10.0.0.2 0 100 0 65001 i
* i 10.0.0.1 0 100 0 65001 i
* i 10.0.0.1 0 100 0 65001 i
RT4#show ip bgp 10.5.0.0
BGP routing table entry for 10.5.0.0/16, version 8
Paths: (3 available, best #1, table Default-IP-Routing-Table)
Advertised to update-groups:
1 2
65001, (Received from a RR-client)
10.0.0.2 (metric 101) from 10.0.0.2 (10.0.0.2)
Origin IGP, metric 0, localpref 100, valid, internal, best