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操纵BGP AS-PATH 属性案例
(2006-11-27 09:20:30)| 分类： ~~~ BGP ~~~ |
BGP总是优先选择具有最短AS路径的路由。本案例中，我们将配置R1，将1.0.0.0通告给R2、R3之前预先添加两个额外的AS路径到1.0.0.0上（AS300、AS400）
具体配置如下：
//// r1 ////
int f2/0
int f3/0
int lo0
int lo1
router bgp 100
access-list 1 permit 1.0.0.0
0.255.255.255
route-map aspath 10
route-map aspath 20
//// r2 ////
int f2/0
int f4/0
router os 1
router bgp 200
//// r3 ////
int f3/0
int f5/0
router os 1
router bgp 200
//// r4 ////
int f4/0
int f5/0
int lo0
router os 1
router bgp 200
验证：
r3#sh ip b
Network
Next
Hop
Metric LocPrf Weight Path
*>i1.0.0.0
192.1.1.1
0
100
0 100 i
*
193.1.1.1
0
0 100 300 400 i
*
i2.0.0.0
192.1.1.1
0
100
0 100 i
*>
193.1.1.1
0
0 100 i
*>i4.0.0.0
195.1.1.4
0
100
0 i
*>i1.0.0.0
*
*>
*>i4.0.0.0
r3#sh ip ro
B
1.0.0.0/8 [200/0] via 192.1.1.1, 00:05:23
B 2.0.0.0/8
[20/0] via 193.1.1.1, 00:05:23
4.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
O
4.4.4.4/32 [110/65] via 195.1.1.4, 00:10:38, Serial5/0
B
4.0.0.0/8 [200/0] via 195.1.1.4, 00:10:13
C
193.1.1.0/24 is directly connected, Serial3/0
O
192.1.1.0/24 [110/192] via 195.1.1.4, 00:10:38, Serial5/0
C
195.1.1.0/24 is directly connected, Serial5/0
O
194.1.1.0/24 [110/128] via 195.1.1.4, 00:10:38, Serial5/0
B
O
B
C
O
C
O
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