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BGP 基础配置实例
(2006-11-22 15:42:55)| 分类： ~~~ BGP ~~~ |
这次做一个BGP基本的实例：
//// r1 ////
int lo1
int lo2
int f1/1
router bgp 100
//// r2 ////
int f1/1
int f3/3
int f4/4
router bgp 200
//// r3 ////
int f3/3
router bgp 300
//// r4 ////
int f4/4
router bgp 400
基础配置完成后，一定要验证：
show ip bgp summary
r2#sh ip bgp su
BGP router identifier 194.1.1.2, local AS number 200
BGP table version is 8, main routing table version 8
7 network entries and 7 paths using 931 bytes of memory
3 BGP path attribute entries using 180 bytes of memory
2 BGP AS-PATH entries using 48 bytes of memory
0 BGP route-map cache entries using 0 bytes of memory
0 BGP filter-list cache entries using 0 bytes of memory
BGP activity 7/46 prefixes, 7/0 paths, scan interval 15 secs
BGP router identifier 194.1.1.2, local AS number 200
BGP table version is 8, main routing table version 8
7 network entries and 7 paths using 931 bytes of memory
3 BGP path attribute entries using 180 bytes of memory
2 BGP AS-PATH entries using 48 bytes of memory
0 BGP route-map cache entries using 0 bytes of memory
0 BGP filter-list cache entries using 0 bytes of memory
BGP activity 7/46 prefixes, 7/0 paths, scan interval 15 secs
Neighbor
V AS MsgRcvd
MsgSent
TblVer InQ OutQ Up/Down
State/PfxRcd
192.1.1.1
4
100
46
49
8
0 0
00:42:37
2
193.1.1.3
4
200
46
52
8
0 0
00:42:06
0
194.1.1.4
4
300
56
58
8
0 0
00:39:26
2
193.1.1.3
194.1.1.4
show ip bgp
r2#sh ip bgp
BGP table version is 8, local router ID is 194.1.1.2
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal
Origin codes: i - IGP, e - EGP, ? - incomplete
BGP table version is 8, local router ID is 194.1.1.2
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal
Origin codes: i - IGP, e - EGP, ? - incomplete
*> 192.1.24.0
*> 192.1.25.0
*> 192.1.26.0
*> 192.1.27.0
r2#
show ip ro
r2#sh ip ro
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter
area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type
2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter
area
* - candidate default, U - per-user static route, o - ODR
P - periodic downloaded static route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
Gateway of last resort is not set
B
192.1.25.0/24 [20/0] via 192.1.1.1, 00:43:46
B
192.1.24.0/24 [20/0] via 192.1.1.1, 00:43:46
B
192.1.27.0/24 [20/0] via 194.1.1.4, 00:38:14
B
192.1.26.0/24 [20/0] via 194.1.1.4, 00:38:14
C
193.1.1.0/24 is directly connected, Serial0/0
C
192.1.1.0/24 is directly connected, FastEthernet0/0
C
194.1.1.0/24 is directly connected, FastEthernet0/1
B
B
B
C
C
C
排错：
我们在验证过程中，可观察到r1上的路由条目：
show ip ro
B
192.1.27.0/24 [20/0] via 192.1.1.2, 00:38:14
B
192.1.26.0/24 [20/0] via 192.1.1.2, 00:38:14
B
C
192.1.1.0/24 is directly connected, f0/0
路由表中含有26 27的路径，我们接下来用ping进一步验证。
ping 192.1.26.1
.....
结果却出乎意料，不通。。。。。。
仔细检查各路由器的路由表：
r2# show ip ro
B
192.1.25.0/24 [20/0] via 192.1.1.1, 00:43:46
B
192.1.24.0/24 [20/0] via 192.1.1.1, 00:43:46
B
192.1.27.0/24 [20/0] via 194.1.1.4, 00:38:14
B
192.1.26.0/24 [20/0] via 194.1.1.4, 00:38:14
C
193.1.1.0/24 is directly connected, Serial0/0
C
192.1.1.0/24 is directly connected, FastEthernet0/0
C
194.1.1.0/24 is directly connected, FastEthernet0/1
B
B
B
C
C
C
r2上也有到达目的网段的路径：192.1.26.0，我们在R2上ping目的网段进行尝试：
ping 192.1.26.1
!!!!!
问题集中到r4上了，我们看下它的路由表：
r4# show ip ro
B
192.1.25.0/24 [20/0] via 192.1.1.1, 00:43:46
B
192.1.24.0/24 [20/0] via 192.1.1.1, 00:43:46
B
C
192.1.26.0/24 is directly connected, lo1
C
192.1.27.0/24 is directly connected, lo2
C
194.1.1.4/24 is directly connected, f4/4
r1发出的ping包可以正确被转发至r2、r4。
ping是双向的，当我们在r1上发起ping后，是利用的r1的f0/0口IP地址做为其源地址，即192.1.1.1。
当ping包到达了r4后，在给源做回应时，却发现其路由表中没有到达192.1.1.1的地址，包被丢弃。所以我们见不到!!!!!
原因找到了，我们在验证时可以使用扩展ping把ping的源地址改为192.168.25.1即可。
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