春风十里不如你 —— Taozi - IEGP
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【BGP】路由器反射器
https://www.xiongan.host/index.php/archives/197/
2023-04-10T14:12:28+08:00
BGP路由反射器各接口和环回口ip地址如上图//R2上新添加一个loopback1
ip add 10.2.2.2 24在R2、R3路由器上测试连通性<R2>ping -c 1 10.123.12.1
PING 10.123.12.1: 56 data bytes, press CTRL_C to break
Reply from 10.123.12.1: bytes=56 Sequence=1 ttl=255 time=220 ms
--- 10.123.12.1 ping statistics ---
1 packet(s) transmitted
1 packet(s) received
0.00% packet loss
round-trip min/avg/max = 220/220/220 ms
<R2>ping -c 1 10.123.23.3
PING 10.123.23.3: 56 data bytes, press CTRL_C to break
Reply from 10.123.23.3: bytes=56 Sequence=1 ttl=255 time=100 ms
--- 10.123.23.3 ping statistics ---
1 packet(s) transmitted
1 packet(s) received
0.00% packet loss
round-trip min/avg/max = 100/100/100 ms
<R2>ping -c 1 10.123.24.4
PING 10.123.24.4: 56 data bytes, press CTRL_C to break
Reply from 10.123.24.4: bytes=56 Sequence=1 ttl=255 time=170 ms
--- 10.123.24.4 ping statistics ---
1 packet(s) transmitted
1 packet(s) received
0.00% packet loss
round-trip min/avg/max = 170/170/170 ms<R3>ping -c 1 10.123.34.4
PING 10.123.34.4: 56 data bytes, press CTRL_C to break
Reply from 10.123.34.4: bytes=56 Sequence=1 ttl=255 time=40 ms
--- 10.123.34.4 ping statistics ---
1 packet(s) transmitted
1 packet(s) received
0.00% packet loss
round-trip min/avg/max = 40/40/40 ms配置ospfR1、R2、R3、R4使用Loopback0接口地址作为Router ID，在各个设备的互联接口、Loopback0接口激活OSPF。[R1-ospf-1-area-0.0.0.0]dis this
[V200R003C00]
#
area 0.0.0.0
network 10.0.1.1 0.0.0.0
network 10.123.12.1 0.0.0.0
#
return
[R2-ospf-1-area-0.0.0.0]dis this
[V200R003C00]
#
area 0.0.0.0
network 10.0.2.2 0.0.0.0
network 10.123.12.2 0.0.0.0
network 10.123.23.2 0.0.0.0
network 10.123.24.2 0.0.0.0
#
return
[R3-ospf-1-area-0.0.0.0]dis this
[V200R003C00]
#
area 0.0.0.0
network 10.0.3.3 0.0.0.0
network 10.123.23.3 0.0.0.0
network 10.123.34.3 0.0.0.0
#
return
[R4-ospf-1-area-0.0.0.0]dis this
[V200R003C00]
#
area 0.0.0.0
network 10.0.4.4 0.0.0.0
network 10.123.24.4 0.0.0.0
network 10.123.34.4 0.0.0.0
#
return查看R2、R3上的ospf邻居信息查看R4的OSPF路由表可以看出来已经学到了全网路由配置IBGP对等体bgp 64511在R2、R3上查看IBGP对等体状态AS内的IBGP对等体关系成功建立配置路由反射器[R2]bgp 64511
[R2-bgp]peer 10.123.12.1 reflect-client
[R3]bgp 64511
[R3-bgp]peer 10.123.23.2 reflect-client
[R4]bgp 64511
[R4-bgp]peer 10.123.34.3 reflect-client在本步骤中，我们将在R2上发布BGP路由10.2.2.0/24，并观察该路由依次经路由反射器R3、R4反射后，被通告回R2从而引发潜在路由环路风险的情况。缺省情况下，R2发布BGP路由后，该路由将被R2直接通告给R4，另一方面也会通过R3反射给R4，此时R4将优选R2直接通告过来的路由，从而不会再将R3反射过来的路由再反射回给R2。为此，我们需要在R2上部署路由策略，使R2不直接向R4通告10.2.2.0/24路由。配置路由策略//在BGP中调用路由策略
[R2]bgp 64511
[R2-bgp]peer 10.123.24.4 route-policy bgp export
//在R2上发布路由
[R2]bgp 64511
[R2-bgp] network 10.2.2.0 24在R2、R3上查看BGP路由10.2.2.0/24信息在R4上查看BGP路由10.2.2.0/24的信息//让R4重新发送Update报文
<R2>refresh bgp 10.123.24.4 import查看R2上Update报文收发数量验证Cluster_List实现路由防环取消R2上的BGP路由发布[R2]bgp 64511
[R2-bgp] undo network 10.2.2.0 24一次查看R1、R2、R3、R4上BGP路由的10.1.1.0/24的信息R1为BGP路由10.1.1.0/24的始发者，R1将路由通告给了R2（10.0.12.2）来自路由反射器客户端R1的BGP路由10.1.1.0/24，R2将其反射给了R3（10.0.23.3）来自路由反射器客户端R2的BGP路由10.1.1.0/24，R2反射时添加了Cluster_List属性，值为10.0.2.2，R3将该条路由反射给了R4（10.0.34.4）来自路由反射器客户端R3的BGP路由10.1.1.0/24，R3反射时添加了Cluster_List属性的值，当前值为10.0.3.3，10.0.2.2，R4将该条路由反射给了R2（10.0.24.2）再次查看R2的BGP路由表在R2上查看BGP对等体10.123.24.4的详细信息R2从R4收到了1个Update报文，未向R4发送Update报文（路由策略限制），但是本地BGP路由表中没有R4通告的BGP路由10.1.1.0/24。在R2上触发入方向的软复位，让R4重新发送Update报文<R2>refresh bgp 10.123.24.4 import
<R2>display bgp peer 10.123.24.4 verbose | in Update
Update-group ID: 1
Update messages 2
Update messages 0接收的Update报文数量增加，R2从R4收到了BGP路由10.1.1.0/24的通告。再次查看R2上BGP路由10.1.1.0 24的明细信息依旧只有来自R1通告的1条BGP路由，R4通告的BGP路由其Cluster_List属性值中包含了R2的Cluster-ID，R2忽略了该路由通告。