分类: ~~~ BGP ~~~ |
Cisco提供一种方式强IGP路由优先于EBGP路由.这个概念也就是"后门链路"(backdoor
link).EBGP路由可以标记为后门链路,它将设置这些路由的管理距离与BGP本地或200相同.因为这个管理距离要高于IGP,所以首选IGP路由.
以下是具体配置:
//// r1 ////
int lo0
int e1/0
router os 1
router bgp 200
//// r2 ////
int lo0
int e1/0
int e0/0
int e2/0
router os 1
router bgp 200
//// r3 ////
int lo0
int e0/0
int e1/0
int e3/0
router os 1
router bgp 300
//// r4 ////
int lo0
int e0/0
router os 1
router bgp 300
//// r5 ////
int lo0
int e2/0
int e3/0
router bgp 100
验证:
//后门链路作用前
r2#sh ip bgp
*>
192.1.1.0
*>
194.1.1.0
r2#
r2#
r2#
r2#sh ip ro bgp
B
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
*> 192.1.1.0
*> 194.1.1.0
r3#sh ip ro bgp
B
r3#sh ip
ro
//后门链路作用前
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
O
O
C
O
C
C
B
C
//后门链路作用后
r3#sh ip ro
r3#sh ip ro
O
O
C
O
C
C
O
O
C