下記構成でBGPpeerグループを作りました。
IBGPの設定する際は、大体下記３コマンドはネイバー毎に入れてると思いますが
Config量を増え、ルータ自体の負荷も高くなるので、ネイバー毎の共通設定はまとめよう。みたいな感じですかね
IBGPとEBGP両方使えますが、ネイバーのメンバーはどちらか片方しかメンバーにできないです。
LoopBackIFでネイバー作りました。
【設定Config】
StaticRouteは、各ルータのLoopBackIF向けです。
R1
R1#conf t
R1(config)#router bgp 10
R1(config-router)# neighbor peer peer-group
R1(config-router)# neighbor peer remote-as 10
R1(config-router)# neighbor peer update-source Loopback1
R1(config-router)# neighbor peer next-hop-self
R1(config-router)# neighbor 2.2.2.2 peer-group peer
R1(config-router)# neighbor 3.3.3.3 peer-group peer
R1(config-router)# neighbor 4.4.4.4 peer-group peer
R1(config-router)#exit
R1(config)#ip route 2.2.2.2 255.255.255.255 GigabitEthernet0/0
R1(config)#ip route 3.3.3.3 255.255.255.255 GigabitEthernet0/2
R1(config)#ip route 4.4.4.4 255.255.255.255 GigabitEthernet0/0
R2
R2#conf t
R2(config)#router bgp 10
R2(config-router)# neighbor peer peer-group
R2(config-router)# neighbor peer remote-as 10
R2(config-router)# neighbor peer update-source Loopback1
R2(config-router)# neighbor peer next-hop-self
R2(config-router)# neighbor 1.1.1.1 peer-group peer
R2(config-router)# neighbor 3.3.3.3 peer-group peer
R2(config-router)# neighbor 4.4.4.4 peer-group peer
R2(config-router)#exit
R2(config)#ip route 2.2.2.2 255.255.255.255 GigabitEthernet0/0
R2(config)#ip route 3.3.3.3 255.255.255.255 GigabitEthernet0/2
R2(config)#ip route 4.4.4.4 255.255.255.255 GigabitEthernet0/0
R3
R3#conf t
R3(config)#router bgp 10
R3(config-router)# neighbor peer peer-group
R3(config-router)# neighbor peer remote-as 10
R3(config-router)# neighbor peer update-source Loopback1
R3(config-router)# neighbor peer next-hop-self
R3(config-router)# neighbor 1.1.1.1 peer-group peer
R3(config-router)# neighbor 2.2.2.2 peer-group peer
R3(config-router)# neighbor 4.4.4.4 peer-group peer
R3(config-router)#exit
R3(config)#ip route 1.1.1.1 255.255.255.255 GigabitEthernet0/2
R3(config)#ip route 2.2.2.2 255.255.255.255 GigabitEthernet0/2
R3(config)#ip route 4.4.4.4 255.255.255.255 GigabitEthernet0/0
R4
R4#conf t
R4(config)#router bgp 10
R4(config-router)# neighbor peer peer-group
R4(config-router)# neighbor peer remote-as 10
R4(config-router)# neighbor peer update-source Loopback1
R4(config-router)# neighbor peer next-hop-self
R4(config-router)# neighbor 1.1.1.1 peer-group peer
R4(config-router)# neighbor 2.2.2.2 peer-group peer
R4(config-router)# neighbor 3.3.3.3 peer-group peer
R4(config-router)#exit
R4(config)#ip route 1.1.1.1 255.255.255.255 GigabitEthernet0/2
R4(config)#ip route 2.2.2.2 255.255.255.255 GigabitEthernet0/2
R4(config)#ip route 3.3.3.3 255.255.255.255 GigabitEthernet0/0
【確認】
R1#sh ip bgp peer-group
BGP peer-group is peer, remote AS 10
BGP version 4
Neighbor sessions:
0 active, is not multisession capable (disabled)
Do log neighbor state changes (via global configuration)
Default minimum time between advertisement runs is 0 seconds
For address family: IPv4 Unicast
BGP neighbor is peer, peer-group internal, members:
2.2.2.2 3.3.3.3 4.4.4.4
Index 0, Advertise bit 0
NEXT_HOP is always this router for eBGP paths
Update messages formatted 0, replicated 0
Number of NLRIs in the update sent: max 0, min 0
R1#
R2#sh ip bgp peer-group
BGP peer-group is peer, remote AS 10
BGP version 4
Neighbor sessions:
0 active, is not multisession capable (disabled)
Do log neighbor state changes (via global configuration)
Default minimum time between advertisement runs is 0 seconds
For address family: IPv4 Unicast
BGP neighbor is peer, peer-group internal, members:
1.1.1.1 3.3.3.3 4.4.4.4
Index 0, Advertise bit 0
NEXT_HOP is always this router for eBGP paths
Update messages formatted 0, replicated 0
Number of NLRIs in the update sent: max 0, min 0
R3#sh ip bgp peer-group
BGP peer-group is peer, remote AS 10
BGP version 4
Neighbor sessions:
0 active, is not multisession capable (disabled)
Do log neighbor state changes (via global configuration)
Default minimum time between advertisement runs is 0 seconds
For address family: IPv4 Unicast
BGP neighbor is peer, peer-group internal, members:
1.1.1.1 2.2.2.2 4.4.4.4
Index 0, Advertise bit 0
NEXT_HOP is always this router for eBGP paths
Update messages formatted 0, replicated 0
Number of NLRIs in the update sent: max 0, min 0
R4#
R4#sh ip bgp peer-group
BGP peer-group is peer, remote AS 10
BGP version 4
Neighbor sessions:
0 active, is not multisession capable (disabled)
Do log neighbor state changes (via global configuration)
Default minimum time between advertisement runs is 0 seconds
For address family: IPv4 Unicast
BGP neighbor is peer, peer-group internal, members:
1.1.1.1 2.2.2.2 3.3.3.3
Index 0, Advertise bit 0
NEXT_HOP is always this router for eBGP paths
Update messages formatted 0, replicated 0
Number of NLRIs in the update sent: max 0, min 0
ちなみに、設定入れた後pingで疎通確認行いましたが、
直接つながってないルータ(R4ならR1)に対してpingNGとなり
設定確認しても問題なし。３０分くらい悩んで末、原因は単純に物理ポートのネットワークを広報していなかったからでした。。
各ルータが学習してる経路は、各ルータのloopbackIFと直接接続のネットワークです。
ping LoopbackIFだと、送信元は、物理IFのアドレスなので、当然折り返しできないです。ping loopbackIF source LoopbackIFなら、疎通できます。
(こんな単純な事にもっと早く気づけるようになりたい。。)
