思科BGP AS-PATH配置实例

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　　Cisco BGP AS-PATH配置实例如下图示：

R1:
interface Loopback0
ip address 1.1.1.1 255.255.255.255
interface FastEthernet0/0
ip address 12.1.1.1 255.255.255.0
interface FastEthernet0/1
ip address 14.1.1.1 255.255.255.0
router eigrp 1
network 1.1.1.1 0.0.0.0
network 12.1.1.0 0.0.0.255
network 14.1.1.0 0.0.0.255
no auto-summary
router bgp 100
bgp router-id 1.1.1.1
bgp log-neighbor-changes
no synchronization
neighbor 2.2.2.2 remote-as 100
neighbor 2.2.2.2 update-source Loopback0
neighbor 2.2.2.2 next-hop-self
neighbor 3.3.3.3 remote-as 100
neighbor 3.3.3.3 update-source Loopback0
neighbor 3.3.3.3 next-hop-self
neighbor 4.4.4.4 remote-as 200
neighbor 4.4.4.4 ebgp-multihop 255
neighbor 4.4.4.4 update-source Loopback0
neighbor 4.4.4.4 next-hop-self
no auto-summary
R2:
interface Loopback0
ip address 2.2.2.2 255.255.255.255
interface FastEthernet0/0
ip address 12.1.1.2 255.255.255.0
interface FastEthernet0/1
ip address 23.1.1.2 255.255.255.0
router eigrp 1
network 2.2.2.2 0.0.0.0
network 12.1.1.0 0.0.0.255
network 23.1.1.0 0.0.0.255
no auto-summary
router bgp 100
no synchronization
bgp router-id 2.2.2.2
bgp log-neighbor-changes
neighbor 1.1.1.1 remote-as 100
neighbor 1.1.1.1 update-source Loopback0
neighbor 1.1.1.1 next-hop-self
neighbor 3.3.3.3 remote-as 100
neighbor 3.3.3.3 update-source Loopback0
neighbor 3.3.3.3 next-hop-self
no auto-summary
R3:
interface Loopback0
ip address 3.3.3.3 255.255.255.255
interface FastEthernet0/0
ip address 34.1.1.3 255.255.255.0
interface FastEthernet0/1
ip address 23.1.1.3 255.255.255.0
router eigrp 1
network 3.3.3.3 0.0.0.0
network 23.1.1.0 0.0.0.255
network 34.1.1.0 0.0.0.255
no auto-summary
router bgp 100
no synchronization
bgp router-id 3.3.3.3
bgp log-neighbor-changes
neighbor 1.1.1.1 remote-as 100
neighbor 1.1.1.1 update-source Loopback0
neighbor 1.1.1.1 next-hop-self
neighbor 2.2.2.2 remote-as 100
neighbor 2.2.2.2 update-source Loopback0
neighbor 2.2.2.2 next-hop-self
neighbor 4.4.4.4 remote-as 200
neighbor 4.4.4.4 ebgp-multihop 255
neighbor 4.4.4.4 update-source Loopback0
neighbor 4.4.4.4 next-hop-self
no auto-summary
R4:
interface Loopback0
ip address 4.4.4.4 255.255.255.255
interface FastEthernet0/0
ip address 34.1.1.4 255.255.255.0
interface FastEthernet0/1
ip address 14.1.1.4 255.255.255.0
router eigrp 1
network 4.4.4.4 0.0.0.0
network 14.1.1.0 0.0.0.255
network 34.1.1.0 0.0.0.255
no auto-summary
ip prefix-list 1 seq 5 permit 4.4.4.4/32
route-map as_path permit 10
match ip address prefix-list 1
set as-path prepend 600 700
router bgp 200
no synchronization
bgp log-neighbor-changes
neighbor 1.1.1.1 remote-as 100
neighbor 1.1.1.1 ebgp-multihop 255
neighbor 1.1.1.1 update-source Loopback0
neighbor 1.1.1.1 next-hop-self
neighbor 3.3.3.3 remote-as 100
neighbor 3.3.3.3 ebgp-multihop 255
neighbor 3.3.3.3 update-source Loopback0
neighbor 3.3.3.3 next-hop-self
neighbor 3.3.3.3 route-map as_path out
no auto-summary


R4(config-router)#do ping 1.1.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 32/36/40 ms
R4(config-router)#do traceroute 1.1.1.1
Type escape sequence to abort.
Tracing the route to 1.1.1.1
1 34.1.1.3 8 msec 12 msec 24 msec
2 23.1.1.2 32 msec 36 msec 44 msec
3 12.1.1.1 32 msec 44 msec 32 msec
R4(config-router)#
R4(config-router)#do show ip route
Codes: C - connected, S - static, 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
i - IS-IS, su - IS-IS summary, 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
Gateway of last resort is not set
34.0.0.0/24 is subnetted, 1 subnets
C       34.1.1.0 is directly connected, FastEthernet0/0
1.0.0.0/32 is subnetted, 1 subnets
D       1.1.1.1 [90/460800] via 34.1.1.3, 00:05:23, FastEthernet0/0
2.0.0.0/32 is subnetted, 1 subnets
D       2.2.2.2 [90/435200] via 34.1.1.3, 00:03:07, FastEthernet0/0
3.0.0.0/32 is subnetted, 1 subnets
D       3.3.3.3 [90/409600] via 34.1.1.3, 00:05:25, FastEthernet0/0
4.0.0.0/32 is subnetted, 1 subnets
C       4.4.4.4 is directly connected, Loopback0
23.0.0.0/24 is subnetted, 1 subnets
D       23.1.1.0 [90/307200] via 34.1.1.3, 00:05:36, FastEthernet0/0
12.0.0.0/24 is subnetted, 1 subnets
D       12.1.1.0 [90/332800] via 34.1.1.3, 00:03:10, FastEthernet0/0
14.0.0.0/24 is subnetted, 1 subnets
D       14.1.1.0 [90/358400] via 34.1.1.3, 00:05:37, FastEthernet0/0