BGP Customers of Different Providers with a Backup Link - Scenario from Halabi Book

From: Mannan Venkatesan (venkat_m@xxxxxxx)
Date: Wed Apr 04 2001 - 12:13:37 GMT-3


   
HI,

 r1(AS1)---------r4(AS4)
     | |
     | |
r2(AS2)----------r3(AS3)

Objective : AS2 uses AS1 as its primary path and AS3 uses AS4 as its primary
path. AS2 and AS3 use the private link for accessing each other and the
private link is used as backup if the primary links goes down.

I am trying this with community attribute, but could n't get it working. Any
advice? Sorry for the long email. Wouldn't able to set local perf on r1 and
r4. Here are the configs,

r1#
r1#
r1#sh run
!
interface Loopback0
 ip address 1.1.1.1 255.0.0.0
!
interface Loopback2
 ip address 2.2.2.2 255.0.0.0
!
interface Serial0
 no ip address
 encapsulation frame-relay
!
interface Serial0.1 point-to-point
 ip address 10.0.0.2 255.0.0.0
 frame-relay interface-dlci 104
!
interface Serial1
 ip address 3.3.3.1 255.0.0.0
!
router bgp 1
 no synchronization
 redistribute connected
 neighbor 3.3.3.2 remote-as 2
 neighbor 3.3.3.2 route-map chkmap in
 neighbor 10.0.0.1 remote-as 4
 neighbor 10.0.0.1 send-community
 neighbor 10.0.0.1 route-map chkmap in
 neighbor 10.0.0.1 route-map com out
 no auto-summary
!
ip community-list 20 permit 460
ip community-list 20 permit 340
route-map chkmap permit 10
 match as-path 10
 set local-preference 40
!
route-map chkmap permit 20
 match as-path 20
 set local-preference 60
!
route-map chkmap permit 30
 set local-preference 100
!
route-map com permit 10
 set community 160
!

r1# sh ip bgp
BGP table version is 13, local router ID is 2.2.2.2
Status codes: s suppressed, d damped, h history, * valid, > best, i -
internal
Origin codes: i - IGP, e - EGP, ? - incomplete

   Network Next Hop Metric LocPrf Weight Path
*> 1.0.0.0 0.0.0.0 0 32768 ?
*> 2.0.0.0 0.0.0.0 0 32768 ?
*> 3.0.0.0 0.0.0.0 0 32768 ?
* 3.3.3.2 0 100 0 2 ?
*> 4.0.0.0 3.3.3.2 0 100 0 2 ?
* 5.0.0.0 10.0.0.1 100 0 4 3 ?
*> 3.3.3.2 0 100 0 2 ?
* 6.0.0.0 10.0.0.1 100 0 4 3 ?
*> 3.3.3.2 100 0 2 3 ?
*> 7.0.0.0 10.0.0.1 0 100 0 4 ?
* 3.3.3.2 100 0 2 3 ?
*> 8.0.0.0 10.0.0.1 0 100 0 4 ?
*> 9.0.0.0 10.0.0.1 0 100 0 4 ?
* 10.0.0.0 10.0.0.1 0 100 0 4 ?
*> 0.0.0.0 0 32768 ?
r1#sh ip rou
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, * - candidate
default
       U - per-user static route, o - ODR

Gateway of last resort is not set

C 1.0.0.0/8 is directly connected, Loopback0
C 2.0.0.0/8 is directly connected, Loopback2
C 3.0.0.0/8 is directly connected, Serial1
B 4.0.0.0/8 [20/0] via 3.3.3.2, 00:03:05
B 5.0.0.0/8 [20/0] via 3.3.3.2, 00:03:05
B 6.0.0.0/8 [20/0] via 3.3.3.2, 00:03:05
B 7.0.0.0/8 [20/0] via 10.0.0.1, 00:01:31
B 8.0.0.0/8 [20/0] via 10.0.0.1, 00:01:31
B 9.0.0.0/8 [20/0] via 10.0.0.1, 00:01:31
C 10.0.0.0/8 is directly connected, Serial0.1
r1#

------------------
r2#sh run
!
interface Loopback1
 ip address 4.4.4.4 255.0.0.0
 no ip directed-broadcast
!
interface Serial1/0
 no ip address
 no ip directed-broadcast
 encapsulation frame-relay
 no ip mroute-cache
!
interface Serial1/0.1 point-to-point
 ip address 5.5.5.1 255.0.0.0
 no ip directed-broadcast
 frame-relay interface-dlci 105
!
interface Serial1/1
 ip address 3.3.3.2 255.0.0.0
 no ip directed-broadcast
 clockrate 56000
!
router bgp 2
 no synchronization
 redistribute connected
 neighbor 3.3.3.1 remote-as 1
 neighbor 3.3.3.1 send-community
 neighbor 3.3.3.1 route-map comm out
 neighbor 3.3.3.1 filter-list 10 out
 neighbor 5.5.5.2 remote-as 3
 no auto-summary
!
ip classless
ip as-path access-list 10 permit ^$
ip as-path access-list 10 permit ^3$
ip as-path access-list 20 permit _3_
!
route-map comm permit 10
 match as-path 20
 set community 340
!
route-map comm permit 20
!

r2#sh ip bgp
BGP table version is 39, local router ID is 4.4.4.4
Status codes: s suppressed, d damped, h history, * valid, > best, i -
internal
Origin codes: i - IGP, e - EGP, ? - incomplete

   Network Next Hop Metric LocPrf Weight Path
*> 1.0.0.0 3.3.3.1 0 0 1 ?
*> 2.0.0.0 3.3.3.1 0 0 1 ?
* 3.0.0.0 3.3.3.1 0 0 1 ?
*> 0.0.0.0 0 32768 ?
*> 4.0.0.0 0.0.0.0 0 32768 ?
* 5.0.0.0 5.5.5.2 0 0 3 ?
*> 0.0.0.0 0 32768 ?
*> 6.0.0.0 5.5.5.2 0 0 3 ?
* 7.0.0.0 3.3.3.1 0 1 4 ?
*> 5.5.5.2 0 0 3 ?
* 8.0.0.0 3.3.3.1 0 1 4 ?
*> 5.5.5.2 0 3 4 ?
* 9.0.0.0 3.3.3.1 0 1 4 ?
*> 5.5.5.2 0 3 4 ?
* 10.0.0.0 5.5.5.2 0 3 4 ?
*> 3.3.3.1 0 0 1 ?
r2#sh ip rou
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, * - candidate
default
       U - per-user static route, o - ODR

Gateway of last resort is not set

B 1.0.0.0/8 [20/0] via 3.3.3.1, 00:03:56
B 2.0.0.0/8 [20/0] via 3.3.3.1, 00:03:56
C 3.0.0.0/8 is directly connected, Serial1/1
C 4.0.0.0/8 is directly connected, Loopback1
C 5.0.0.0/8 is directly connected, Serial1/0.1
B 6.0.0.0/8 [20/0] via 5.5.5.2, 00:17:35

B 7.0.0.0/8 [20/0] via 5.5.5.2, 00:17:35
B 8.0.0.0/8 [20/0] via 5.5.5.2, 00:17:35
B 9.0.0.0/8 [20/0] via 5.5.5.2, 00:17:35
B 10.0.0.0/8 [20/0] via 3.3.3.1, 00:03:22
-------

r3#sh run
 !
 interface Loopback1
 ip address 6.6.6.6 255.0.0.0
!
interface Serial0
 no ip address
 encapsulation frame-relay
 no ip mroute-cache
!
interface Serial0.1 point-to-point
 ip address 5.5.5.2 255.0.0.0
 frame-relay interface-dlci 107
!
interface Serial1
 ip address 7.7.7.1 255.0.0.0
 clockrate 56000
!
router bgp 3
 no synchronization
 redistribute connected
 neighbor 5.5.5.1 remote-as 2
 neighbor 7.7.7.2 remote-as 4
 neighbor 7.7.7.2 send-community
 neighbor 7.7.7.2 route-map com out
 neighbor 7.7.7.2 filter-list 10 out
 no auto-summary
!
ip classless
ip as-path access-list 10 permit ^$
ip as-path access-list 10 permit ^2$
ip as-path access-list 20 permit _2_
!

route-map com permit 10
 match as-path 20
 set community 240
!
route-map com permit 20

r3# sh ip bgp
BGP table version is 57, local router ID is 6.6.6.6
Status codes: s suppressed, d damped, h history, * valid, > best, i -
internal
Origin codes: i - IGP, e - EGP, ? - incomplete

   Network Next Hop Metric LocPrf Weight Path
* 1.0.0.0 7.7.7.2 0 4 1 ?
*> 5.5.5.1 0 2 1 ?
* 2.0.0.0 7.7.7.2 0 4 1 ?
*> 5.5.5.1 0 2 1 ?
* 3.0.0.0 7.7.7.2 0 4 1 ?
*> 5.5.5.1 0 0 2 ?
* 4.0.0.0 7.7.7.2 0 4 1 2 ?
*> 5.5.5.1 0 0 2 ?
* 5.0.0.0 5.5.5.1 0 0 2 ?
*> 0.0.0.0 0 32768 ?
*> 6.0.0.0 0.0.0.0 0 32768 ?
* 7.0.0.0 7.7.7.2 0 0 4 ?
*> 0.0.0.0 0 32768 ?
*> 8.0.0.0 7.7.7.2 0 0 4 ?
*> 9.0.0.0 7.7.7.2 0 0 4 ?
*> 10.0.0.0 7.7.7.2 0 0 4 ?
* 5.5.5.1 0 2 1 ?
r3#sh ip rou
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, * - candidate
default
       U - per-user static route, o - ODR

Gateway of last resort is not set

B 1.0.0.0/8 [20/0] via 5.5.5.1, 00:04:43
B 2.0.0.0/8 [20/0] via 5.5.5.1, 00:04:43
B 3.0.0.0/8 [20/0] via 5.5.5.1, 00:05:36
B 4.0.0.0/8 [20/0] via 5.5.5.1, 00:18:23
C 5.0.0.0/8 is directly connected, Serial0.1
C 6.0.0.0/8 is directly connected, Loopback1
C 7.0.0.0/8 is directly connected, Serial1
B 8.0.0.0/8 [20/0] via 7.7.7.2, 00:29:58
B 9.0.0.0/8 [20/0] via 7.7.7.2, 00:29:58
B 10.0.0.0/8 [20/0] via 7.7.7.2, 00:04:05
r3#

----------

r4#sh run
 !
 interface Loopback1
 ip address 9.9.9.9 255.0.0.0
!
interface Loopback2
 ip address 8.8.8.8 255.0.0.0
!
interface Serial0
 no ip address
 encapsulation frame-relay
 no ip mroute-cache
!
interface Serial0.1 point-to-point
 ip address 10.0.0.1 255.0.0.0
 frame-relay interface-dlci 100
!
interface Serial1
 ip address 7.7.7.2 255.0.0.0
!
router bgp 4
 no synchronization
 redistribute connected
 neighbor 7.7.7.1 remote-as 3
 neighbor 7.7.7.1 route-map chkcom in
 neighbor 10.0.0.2 remote-as 1
 neighbor 10.0.0.2 send-community
 neighbor 10.0.0.2 route-map chkcom in
 neighbor 10.0.0.2 route-map com out
 no auto-summary
!
ip community-list 10 permit 240
ip community-list 20 permit 160
!
route-map chkcom permit 10
 match community 10
 set local-preference 40
!
route-map chkcom permit 20
 match as-path 20
 set local-preference 60
!

route-map chkcom permit 30
 set local-preference 100
!
route-map com permit 10
 set community 460
!
r4#
r4#sh ip bgp
BGP table version is 64, local router ID is 9.9.9.9
Status codes: s suppressed, d damped, h history, * valid, > best, i -
internal
Origin codes: i - IGP, e - EGP, ? - incomplete

   Network Next Hop Metric LocPrf Weight Path
*> 1.0.0.0 10.0.0.2 0 100 0 1 ?
*> 2.0.0.0 10.0.0.2 0 100 0 1 ?
*> 3.0.0.0 10.0.0.2 0 100 0 1 ?
* 7.7.7.1 40 0 3 2 ?
*> 4.0.0.0 10.0.0.2 100 0 1 2 ?

* 7.7.7.1 40 0 3 2 ?
* 5.0.0.0 10.0.0.2 100 0 1 2 ?
*> 7.7.7.1 0 100 0 3 ?
* 6.0.0.0 10.0.0.2 100 0 1 2 3 ?
*> 7.7.7.1 0 100 0 3 ?
*> 7.0.0.0 0.0.0.0 0 32768 ?
* 7.7.7.1 0 100 0 3 ?
*> 8.0.0.0 0.0.0.0 0 32768 ?
*> 9.0.0.0 0.0.0.0 0 32768 ?
* 10.0.0.0 10.0.0.2 0 100 0 1 ?
*> 0.0.0.0 0 32768 ?
r4#
r4#



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