Cisco提供一種方式強IGP路由優先于EBGP路由.這個概念也就是"后門鏈路"(backdoor link).EBGP路由可以標記為后門鏈路,它將設置這些路由的管理距離與BGP本地或200相同.因為這個管理距離要高于IGP,所以***IGP路由.
以下是具體配置:
//// r1 ////
int lo0
ip ad 1.1.1.1 255.255.255.0 int e1/0
ip ad 192.1.1.1 255.255.255.0 router os 1
network 0.0.0.0 255.255.255.255 a 0 //將所有接口宣告進OSPF router bgp 200
no syn //關閉同步,同時也注定了全互連的拓撲
neighbor 192.1.1.2 remote-as 200
neighbor 192.1.1.2 update-source lo0 //以lo0接口IP作為更新源地址 |
int lo0
ip ad 2.2.2.2 255.255.255.0 int e1/0
ip ad 192.1.1.2 255.255.255.0 int e0/0
ip ad 193.1.1.2 255.255.255.0 int e2/0
ip ad 195.1.1.2 255.255.255.0 router os 1
network 0.0.0.0 255.255.255.255 a 0 //宣告所有接口進OSPF router bgp 200
no syn
neighbor 192.1.1.1 remote-as 200
neighbor 192.1.1.1 update-source lo0
neighbor 192.1.1.1 next-hop-self
neighbor 195.1.1.5 remote-as 100
network 192.1.1.0 mask 255.255.255.0 |
//// r3 ////
int lo0
ip ad 3.3.3.3 255.255.255.0
int e0/0
ip ad 193.1.1.3 255.255.255.0
int e1/0
ip ad 194.1.1.3 255.255.255.0
int e3/0
ip ad 196.1.1.3 255.255.255.0
router os 1
netw 0.0.0.0 255.255.255.255 a 0
router bgp 300
no syn
neighbor 196.1.1.5 remote-as 100
neighbor 194.1.1.4 remote-as 300
neighbor 194.1.1.4 update-source lo0
neighbor 194.1.1.4 next-hop-self
network 194.1.1.0 mask 255.255.255.0 |
//// r4 ////
int lo0
ip ad 4.4.4.4 255.255.255.0 int e0/0
ip ad 194.1.1.3 255.255.255.0
router os 1
network 0.0.0.0 255.255.255.255 a 0 router bgp 300
no syn
neighbor 194.1.1.3 remote-as 300
neighbor 194.1.1.3 update-source lo0
network 192.1.1.0 mask 255.255.255.0 backdoor |
//// r5 ////
int lo0
ip ad 5.5.5.5 255.255.255.0 int e2/0
ip ad 195.1.1.5 255.255.255.0 int e3/0
ip ad 196.1.1.5 255.255.255.0 router bgp 100
no syn
neighbor 195.1.1.2 remote-as 200
neighbor 196.1.1.3 remote-as 300 |
驗證:
//后門鏈路作用前
r2#sh ip bgp
Network Next Hop Metric LocPrf Weight Path
*> 192.1.1.0 0.0.0.0 0 32768 i
*> 194.1.1.0 195.1.1.5 0 100 300 i
r2#
r2#
r2#
r2#sh ip ro bgp
B 194.1.1.0/24 [20/0] via 195.1.1.5, 00:00:49 r3#sh ip bgp
Network Next Hop Metric LocPrf Weight Path
*> 192.1.1.0 196.1.1.5 0 100 200 i
*> 194.1.1.0 0.0.0.0 0 32768 i
r3#sh ip ro bgp
B 192.1.1.0/24 [20/0] via 196.1.1.5, 00:02:28 |
r3#sh ip ro //后門鏈路作用前
1.0.0.0/32 is subnetted, 1 subnets
O 1.1.1.1 [110/21] via 193.1.1.2, 00:04:22, Ethernet0/0
2.0.0.0/32 is subnetted, 1 subnets
O 2.2.2.2 [110/11] via 193.1.1.2, 00:04:22, Ethernet0/0
3.0.0.0/24 is subnetted, 1 subnets
C 3.3.3.0 is directly connected, Loopback0
4.0.0.0/32 is subnetted, 1 subnets
O 4.4.4.4 [110/11] via 194.1.1.4, 00:04:22, Ethernet1/0
C 196.1.1.0/24 is directly connected, Serial3/0
C 193.1.1.0/24 is directly connected, Ethernet0/0
B 192.1.1.0/24 [20/0] via 196.1.1.5, 00:00:06
O 195.1.1.0/24 [110/74] via 193.1.1.2, 00:04:22, Ethernet0/0
C 194.1.1.0/24 is directly connected, Ethernet1/0 |
//后門鏈路作用后
r3#sh ip ro
1.0.0.0/32 is subnetted, 1 subnets
O 1.1.1.1 [110/21] via 193.1.1.2, 00:06:38, Ethernet0/0
2.0.0.0/32 is subnetted, 1 subnets
O 2.2.2.2 [110/11] via 193.1.1.2, 00:06:38, Ethernet0/0
3.0.0.0/24 is subnetted, 1 subnets
C 3.3.3.0 is directly connected, Loopback0
4.0.0.0/32 is subnetted, 1 subnets
O 4.4.4.4 [110/11] via 194.1.1.4, 00:06:38, Ethernet1/0
C 196.1.1.0/24 is directly connected, Serial3/0
C 193.1.1.0/24 is directly connected, Ethernet0/0
O 192.1.1.0/24 [110/20] via 193.1.1.2, 00:00:06, Ethernet0/0
O 195.1.1.0/24 [110/74] via 193.1.1.2, 00:06:38, Ethernet0/0
C 194.1.1.0/24 is directly connected, Ethernet1/0
|
【編輯推薦】
- CCNP：BGP協議***路徑選擇算法揭秘
- 6.3.5 配置和核實BGP
- CCNP901：BGP路由過濾及默認路由實驗配置
