3-1-1. Cisco dual BGP with Metric (Redundancy)

   April 9, 2008
BGP sample configuration 3-1-1

Cisco dual BGP with Metric (Redundancy)

   
  • ISPs : 1
  • WAN links : 2
  • CPE : 1
  • PE : 2
  • Device : Cisco router with LAN/WAN ports.
  • WAN1 / Serial IP : 12.1.3.0/30 (mask 255.255.255.252)
  • WAN2 / Serial IP : 12.1.4.0/30 (mask 255.255.255.252)
  • Destination IP : 100.100.100.100 
  • LAN / Ethernet IP : 10.1.0.1/24 and 10.1.0.129/25(Secondary)
  • Receiving Route : Default route + full route from ISP
  • Memory : Full route(recommend 512M), partial route
    (recommend 128-256M)
  • LAN : ISP (AS20) and Customer (AS10)

 

BGP sample configuration 3-1-1

[Traffic flow]

Outbound traffic on CPE
All outbound traffic will go out thru primary line(12.1.3.1) due to route-map shadow_inbound tag local-pref 80 on default route from bgp peer(12.1.4.2)
 
Inbound traffic  on CPE
All inbound traffic will come in thru primary line (12.1.3.1) due to route-map shadow_outbound tag metric 200 on announced IP route.

[CPE/Customer Cisco Router]

Current configuration:
!
version 12.x
!
hostname CPE
!
interface Ethernet0
description to Internal network
ip address 10.1.0.1 255.255.255.0
ip address 10.1.0.129 255.255.255.128 secondary
no ip directed-broadcast
no ip mroute-cache
!
interface Serial0
description to ISP A – WAN 1
ip address 12.1.3.1 255.255.255.252
no ip directed-broadcast
no ip mroute-cache
no fair-queue
!
interface Serial1
description to ISP A – WAN 2
ip address 12.1.4.1 255.255.255.252
no ip directed-broadcast
no ip mroute-cache
no fair-queue
!
router bgp 10
no auto-summary
network 10.1.0.0 mask 255.255.255.0
neighbor 12.1.3.2 remote-as 20
neighbor 12.1.3.2 version 4
neighbor 12.1.4.2 remote-as 20
neighbor 12.1.4.2 version 4
neighbor 12.1.4.2 prefix-list 1 out
neighbor 12.1.4.2 route-map shadow_inbound in
neighbor 12.1.4.2 route-map shadow_outbound out
!
ip classless
!
ip prefix-list 1 seq 5 permit 10.1.0.0/24 le 32
 

!
route-map shadow_inbound permit 10

 

set local-preference 80

 

!

 

route-map shadow_outbound permit 10

set metric 200
!
!
line con 0
line aux 0
line vty 0 4
login
!
end

[PE1 / ISP Cisco Router]

Current configuration:
!
version 12.x
!
hostname PE
!
!
interface Serial0
description to WAN 1
ip address 12.1.3.2 255.255.255.252
no ip directed-broadcast
no ip mroute-cache
no fair-queue
!
 

router bgp 20
no auto-summary
neighbor 12.1.3.1 remote-as 10
neighbor 12.1.3.1 version 4
neighbor 12.1.3.1 default-originate <—to send a default route

neighbor 12.1.3.1 distribute-list 2 out
!
ip classless
!
access-list 2 permit 100.100.100.0 0.0.0.255
! 
line con 0
line aux 0
line vty 0 4
login
!
end
[PE2 / ISP Cisco Router]
Current configuration:
!
version 12.x
!
hostname PE
!
!
interface Serial1
description to WAN 2
ip address 12.1.4.2 255.255.255.252
no ip mroute-cache
no ip directed-broadcast
no fair-queue
!
 

router bgp 20
no auto-summary
neighbor 12.1.4.1 remote-as 10
neighbor 12.1.4.1 version 4
neighbor 12.1.4.1 default-originate <—to send a default route

neighbor 12.1.4.1 distribute-list 2 out
!
ip classless
!
access-list 2 permit 100.100.100.0 0.0.0.255
!
line con 0
line aux 0
line vty 0 4
login
!
end

 

[Verifing output]

CPE# show ip bgp neighbors 12.1.3.2 ad
BGP table version is 4, local router ID is 1.1.1.1
Status codes: s suppressed, d damped, h history, * valid, > best, i – internal,
              r RIB-failure, S Stale
Origin codes: i – IGP, e – EGP, ? – incomplete

   Network          Next Hop            Metric LocPrf Weight Path
*> 10.1.0.0/24      0.0.0.0                  0         32768 i

Total number of prefixes 1
CPE#

CPE# show ip bgp neighbors 12.1.4.2 ad
BGP table version is 4, local router ID is 1.1.1.1
Status codes: s suppressed, d damped, h history, * valid, > best, i – internal,
              r RIB-failure, S Stale
Origin codes: i – IGP, e – EGP, ? – incomplete

   Network          Next Hop            Metric LocPrf Weight Path
*> 10.1.0.0/24      0.0.0.0                  0         32768 i

Total number of prefixes 1
CPE#

CPE# show ip bgp neighbors 12.1.3.2 ro
BGP table version is 4, local router ID is 1.1.1.1
Status codes: s suppressed, d damped, h history, * valid, > best, i – internal,
              r RIB-failure, S Stale
Origin codes: i – IGP, e – EGP, ? – incomplete

   Network          Next Hop            Metric LocPrf Weight Path
*> 0.0.0.0          12.1.3.2                 0             0 20 i
*> 100.100.100.0/24 12.1.3.2                               0 20 ?

Total number of prefixes 2
CPE#

CPE# show ip bgp neighbors 12.1.4.2 ro
BGP table version is 4, local router ID is 1.1.1.1
Status codes: s suppressed, d damped, h history, * valid, > best, i – internal,
              r RIB-failure, S Stale
Origin codes: i – IGP, e – EGP, ? – incomplete

   Network          Next Hop            Metric LocPrf Weight Path
*  0.0.0.0          12.1.4.2                 0     80      0 20 i
*  100.100.100.0/24 12.1.4.2                       80      0 20 ?

Total number of prefixes 2
CPE#

PE1#show ip bgp nei 12.1.3.1 ro
BGP table version is 33, local router ID is 3.3.3.3
Status codes: s suppressed, d damped, h history, * valid, > best, i – internal,
              r RIB-failure, S Stale
Origin codes: i – IGP, e – EGP, ? – incomplete

   Network          Next Hop            Metric LocPrf Weight Path
*> 10.1.0.0/24      12.1.3.1                 0             0 10 i

Total number of prefixes 1
PE1#

PE2#show ip bgp nei 12.1.4.1 ro
BGP table version is 44, local router ID is 4.4.4.4
Status codes: s suppressed, d damped, h history, * valid, > best, i – internal,
              r RIB-failure, S Stale
Origin codes: i – IGP, e – EGP, ? – incomplete

   Network          Next Hop            Metric LocPrf Weight Path
*> 10.1.0.0/24      12.1.4.1               200             0 10 i

Total number of prefixes 1
PE2#

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Author: Chris Yoon

IT professional