EI CCNP培训学习教材分享：BGP路由黑洞-路由反射器实验_ WOLFLAB沃尔夫网络实验室-hcie培训-ccie培训-ccna学习-hcip培训

EI CCNP培训学习教材分享：BGP路由黑洞-路由反射器实验

发布日期：2022-06-30 浏览次数：1443 来源：杨广成

EI CCNP培训学习教材分享：BGP路由黑洞-路由反射器实验

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图片 1.png

接口ip地址请结合课程视频的地址规划，实验拓扑如上图所示：

1、如图所示建立BGP，在R2 R3 R4之间运行OSPF使AS234内部全网互通；在R1和R2之间通过直连接口建立eBGP邻居，在R4 R5之间通过直连接口建立eBGP邻居，在R2和R3、R3和R4之间通过环回口建立iBGP邻居，全部路由器 no synchronization，no auto-summary直连建立邻居。

R1:

interface loopback 0

ip address 1.1.1.1 255.255.255.0

interface s1/0

ip address 192.168.12.1 255.255.255.0

router bgp 100

bgp router-id 1.1.1.1

neighbor 192.168.12.2 remote-as 234

R5:

interface loopback 0

ip address 5.5.5.5 255.255.255.0

interface s1/0

ip address 192.168.45.5 255.255.255.0

router bgp 500

bgp router-id 5.5.5.5

neighbor 192.168.45.4 remote-as 234R4:

R2:

interface loopback 0

ip address 2.2.2.2 255.255.255.0

interface s1/0

ip address 192.168.12.2 255.255.255.0

interface Ethernet0/0

ip address 1.1.23.2 255.255.255.0

router ospf 1

router-id 2.2.2.2

network 2.2.2.2 0.0.0.0 area 0

network 1.1.23.2 0.0.0.0 area 0

router bgp 234

bgp router-id 2.2.2.2

neighbor 192.168.12.1 remote-as 100

neighbor 3.3.3.3 remote-as 234

neighbor 3.3.3.3 update-source loopback 0

R4:

interface loopback 0

ip address 4.4.4.4 255.255.255.0

interface Ethernet0/1

ip address 1.1.34.4 255.255.255.0

interface s1/0

ip address 192.168.45.4 255.255.255.0

router ospf 1

router-id 4.4.4.4

network 1.1.34.4 0.0.0.0 area 0

network 4.4.4.4 0.0.0.0 area 0

router bgp 234

bgp router-id 4.4.4.4

neighbor 192.168.45.5 remote-as 500

neighbor 3.3.3.3 remote-as 234

neighbor 3.3.3.3 update-source loopback 0

R3:

interface loopback 0

ip address 3.3.3.3 255.255.255.0

interface Ethernet0/0

ip address 1.1.23.3 255.255.255.0

interface Ethernet0/1

ip address 1.1.34.3 255.255.255.0

router ospf 1

router-id 3.3.3.3

network 1.1.23.3 0.0.0.0 area 0

network 1.1.34.3 0.0.0.0 area 0

network 3.3.3.3 0.0.0.0 area 0

router bgp 234

bgp router-id 3.3.3.3

neighbor 2.2.2.2 remote-as 234

neighbor 2.2.2.2 update-source loopback 0

neighbor 4.4.4.4 remote-as 234

neighbor 4.4.4.4 update-source loopback 0

2、在R1上BGP中宣告1.1.1.0/24和192.168.12.0/24，在R5上BGP宣告5.5.5.0/24和192.168.45.0/24，注意要使这几条路由在R3上可以优化。

R1:

router bgp 100

network 192.168.12.0 mask 255.255.255.0

network 1.1.1.0 mask 255.255.255.0

R5:

router bgp 500

network 192.168.45.0 mask 255.255.255.0

network 5.5.5..0 mask 255.255.255.0

R2:

router bgp 234

neighbor 3.3.3.3 next-hop-self

R4:

router bgp 234

neighbor 3.3.3.3 next-hop-self

3、注意此时R1和R5能否相互看到对端的路由？

解析：R1和R5均看不到对端路由。因为路由传递至R3上，由于IBGP水平分割，从IBGP邻居收到的路由，不会再传递至IBGP邻居。

4、将R2 R3 R4的BGP进程no掉。在R2-R3之间建立AS234内部的联邦AS64523，在R4上建立AS234内部的联邦AS64544，通过建立联邦解决非full-mesh BGP网络中路由传递和数据黑洞问题。

R2:

router bgp 64523

bgp router-id 2.2.2.2

neighbor 192.168.12.1 remote-as 100

neighbor 3.3.3.3 remote-as 64523

neighbor 3.3.3.3 update-source Loopback0

neighbor 3.3.3.3 next-hop-self

R3:

router bgp 64523

bgp router-id 3.3.3.3

neighbor 2.2.2.2 remote-as 64523

neighbor 2.2.2.2 update-source Loopback0

neighbor 4.4.4.4 remote-as 64544

neighbor 4.4.4.4 ebgp-multihop 255

neighbor 4.4.4.4 update-source Loopback0

R4：

router bgp 64544

bgp router-id 4.4.4.4

neighbor 192.168.45.5 remote-as 500

neighbor 3.3.3.3 remote-as 64523

neighbor 3.3.3.3 ebgp-multihop 255

neighbor 3.3.3.3 update-source Loopback0

neighbor 3.3.3.3 next-hop-self //联邦的IBGP和EBGP邻居之间传递路由，下一跳不变。

R2 R3 R4 BGP进程下：

bgp confederation identifier 234 //联邦内的路由器上均需要指出属于哪个大AS

R3：

bgp confederation peers 64544

R4:

bgp confederation peers 64523

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5、将第4题的BGP进程no掉，还原到第三题的配置部分，在R3上设置路由反射器，将R2作为客户端，观察R1 R5的路由传递情况，在R1和R5上能否ping通对端？

R2：

router bgp 234

bgp router-id 2.2.2.2

neighbor 192.168.12.1 remote-as 100

neighbor 3.3.3.3 remote-as 234

neighbor 3.3.3.3 update-source loopback 0

neighbor 3.3.3.3 next-hop-self

R4：

router bgp 234

bgp router-id 4.4.4.4

neighbor 192.168.45.5 remote-as 500

neighbor 3.3.3.3 remote-as 234

neighbor 3.3.3.3 update-source loopback 0

neighbor 3.3.3.3 next-hop-self

R3：

router bgp 234

bgp router-id 3.3.3.3

neighbor 2.2.2.2 remote-as 234

neighbor 2.2.2.2 update-source loopback 0

neighbor 4.4.4.4 remote-as 234

neighbor 4.4.4.4 update-source loopback 0

neighbor 2.2.2.2 route-reflector-client //配置R2成为路由反射器的客户端，即R3为路由反射器。

6、如果此时将R4也作为R3的客户端，在R4上show ip bgp 1.1.1.0，和R3上看到的这条BGP路由有什么不同？这样的区别意义何在？

R3:

router bgp 234

neighbor 4.4.4.4 route-reflector-client

R3：

show ip bgp 1.1.1.0

BGP routing table entry for 1.1.1.0/24, version 8

Paths: (1 available, best #1, table Default-IP-Routing-Table)

Advertised to non peer-group peers:

4.4.4.4

100, (Received from a RR-client)

2.2.2.2 (metric 20) from 2.2.2.2 (2.2.2.2)

Origin IGP, metric 0, localpref 100, valid, internal, best

R4：

show ip bgp 1.1.1.0

BGP routing table entry for 1.1.1.0/24, version 9

Paths: (1 available, best #1, table Default-IP-Routing-Table)

Advertised to non peer-group peers:

192.168.45.5

100

2.2.2.2 (metric 30) from 3.3.3.3 (3.3.3.3)

Origin IGP, metric 0, localpref 100, valid, internal, best

Originator: 2.2.2.2, Cluster list: 3.3.3.3

解析：R4上的路由经过R3路由反射后，路由中就会带有Originator，即为AS234中始发此路由的router-id，Cluster list：3.3.3.3，表明此路由已经经过路由反射器R3，就将路由反射器的router-id存放在Cluster list里面。此时路由再传递至R2或R3上的时候，包含自己的router-id，将拒绝接收这条路由，这样设计的目的在于防止路由反射器FULL-MESH时产生的环路。

图片 1.png

7、BGP第三方下一跳问题。如图所示建立运行OSPF，R1-R2之间直连建立EBGP邻居，R2-R3之间直连建立IBGP邻居。在R3上将3.3.3.0/24宣告进BGP，在R1上观察，此条路由下一跳指向哪里？

R1：

interface Loopback0

ip address 1.1.1.1 255.255.255.0

interface FastEthernet0/0

ip address 192.168.123.1 255.255.255.0

router ospf 1

router-id 1.1.1.1

network 1.1.1.1 0.0.0.0 area 0

network 192.168.123.1 0.0.0.0 area 0

router bgp 100

bgp router-id 1.1.1.1

neighbor 192.168.123.2 remote-as 23

network 1.1.1.0 mask 255.255.255.0

R2：

interface Loopback0

ip address 2.2.2.2 255.255.255.0

interface FastEthernet0/0

ip address 192.168.123.2 255.255.255.0

router ospf 1

router-id 2.2.2.2

network 2.2.2.2 0.0.0.0 area 0

network 192.168.123.2 0.0.0.0 area 0

router bgp 23

bgp router-id 2.2.2.2

neighbor 192.168.123.1 remote-as 100

neighbor 192.168.123.3 remote-as 23

R3:

interface Loopback0

ip address 3.3.3.3 255.255.255.0

interface FastEthernet0/0

ip address 192.168.123.3 255.255.255.0

router ospf 1

router-id 3.3.3.3

network 3.3.3.3 0.0.0.0 area 0

network 192.168.123.3 0.0.0.0 area 0

router bgp 23

bgp router-id 3.3.3.3

neighbor 192.168.123.2 remote-as 23

network 3.3.3.0 mask 255.255.255.0

R1：

R1#show ip bgp

Network Next Hop Metric LocPrf Weight Path

*> 1.1.1.0/24 0.0.0.0 0 32768 i

*> 3.3.3.0/24 192.168.123.3 0 23 i

8、如果上题中将R2-R3之间的BGP邻居关系改为用环回口建立，此时R1上观察到的3.3.3.0/24路由的下一跳有没有变化？

R2：

router bgp 23

neighbor 3.3.3.3 remote-as 23

neighbor 3.3.3.3 update-source Loopback0

R3：

router bgp 23

neighbor 2.2.2.2 remote-as 23

neighbor 2.2.2.2 update-source Loopback0

解析：此时R1上看到的3.3.3.0/24路由的下一跳为192.168.123.3。

9、如果R2-R3之间改回用直连口建邻居，而在R1 R2之间用环回口建立邻居，这时R1观察到的3.3.3.0/24路由的下一跳有没有变化，分析产生上述现象的原因

R2：

router bgp 23

neighbor 192.168.23.3 remote-as 23

neighbor 1.1.1.1 remote-as 100

neighbor 1.1.1.1 ebgp-multihop 255

neighbor 1.1.1.1 update-source Loopback0

R3：

router bgp 23

neighbor 192.168.23.2 remote-as 23

R1:

router bgp 100

neighbor 2.2.2.2 remote-as 23

neighbor 2.2.2.2 ebgp-multihop 255

neighbor 2.2.2.2 update-source Loopback0

R1:show ip bgp

Network Next Hop Metric LocPrf Weight Path

*> 1.1.1.0/24 0.0.0.0 0 32768 i

*> 3.3.3.0/24 2.2.2.2 0 23 i

解析：BGP的第三方下一跳：收到BGP路由的下一跳（递归完的下一跳）与建邻居的Neighbor地址是在同一网段，保持下一跳地址不变，例如上述实验8和实验9；不在同一网段，则正常改变下一跳，例如上述实验10。实验8和实验9，在R2上看到3.3.3.0/24，下一跳为192.168.123.3，若此时R2通过直连与R1建EBGP邻居，即R2上Neighbor 192.168.123.1 remote-as 100，与建邻居的Neighbor地址属同一网段，下一跳不变。

10、R2-R3之间改回环回口建邻居。并在R1 R2 R3之间开启BGP的认证。

R1：

router bgp 100

neighbor 2.2.2.2 password cisco

R2:

router bgp 23

neighbor 1.1.1.1 password cisco

neighbor 3.3.3.3 password cisco

R3:

router bgp 23

neighbor 2.2.2.2 password cisco

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