Home BGP Configurations Cisco 2-1-1. Cisco Single BGP with Multi-hop (load-balancing)

Cisco Single BGP with Multi-hop (load-balancing)

   
  • ISPs : 1
  • WAN links : 2
  • CPE : 1
  • PE : 1
  • Device : Cisco router with LAN/WAN ports.
  • WAN1 / Serial IP : 12.1.3.0/30 (mask 255.255.255.252)
  • WAN2 / Serial IP : 12.1.3.4/30 (mask 255.255.255.252)

  • LAN / Ethernet IP : 10.1.0.0/24 (mask 255.255.255.0)
  • 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 2-1-1

 

 

[Traffic flow]

Outbound traffic on CPE perspective
Both circuits are sharing outbound traffic. It wouldn't be exact 50/50% of traffic due to traffic will be routed per destination, but not per packets. However, if you want to share links by packet, you can apply command "ip load-sharing" on participant interfaces.
Inbound traffic  on CPE perspective
Same concept as outbound traffic flow

 

[CPE/Customer Cisco Router]
Current configuration:
!
version 12.x
!
hostname CPE
!
interface Loopback0
description to Loopback for BGP
ip address 1.1.1.1 255.255.255.255
no ip directed-broadcast
no ip mroute-cache
!
interface Ethernet0
description to Internal network
ip address 10.1.0.1 255.255.255.0
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 12.1.3.5 255.255.255.252
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 3.3.3.3 remote-as 20
neighbor 3.3.3.3 version 4
neighbor 3.3.3.3 ebgp-multihop 2
neighbor 3.3.3.3 update-source loopback0
neighbor 3.3.3.3 prefix-list 1 out

!
ip classless
!
ip route 3.3.3.3 255.255.255.255 Serial0
ip route 3.3.3.3 255.255.255.255 Serial1
!
ip prefix-list 1 description to ISP
ip prefix-list 1 seq 5 permit 10.1.0.0/24 le 32
!
line con 0
line aux 0
line vty 0 4
login
!
end

 

[PE / ISP Cisco Router]
Current configuration:
!
version 12.x
!
hostname PE
!
interface Loopback0
description to Loopback for BGP
ip address 3.3.3.3 255.255.255.255
no ip directed-broadcast
no ip mroute-cache
!
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
!
interface Serial1
description to WAN 2
ip address 12.1.3.6 255.255.255.252
no ip mroute-cache
no ip directed-broadcast
no fair-queue
!
router bgp 20
no auto-summary
neighbor 1.1.1.1 remote-as 10
neighbor 1.1.1.1 version 4
neighbor
1.1.1.1 ebgp-multihop 2
neighbor
1.1.1.1 update-source loopback0
neighbor
1.1.1.1 default-originate <---to send a default route
!
ip classless
ip route 1.1.1.1 255.255.255.255 Serial0
ip route
1.1.1.1 255.255.255.255 Serial1
!
line con 0
line aux 0
line vty 0 4
login
!
end

[Verifing output]

CPE# show ip bgp neighbors 3.3.3.3 ad
BGP table version is 17, 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#
 

PE#show ip bgp nei 1.1.1.1 ro
BGP table version is 2, 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      1.1.1.1                  0             0 10 i

Total number of prefixes 1
PE#
CPE#show ip bgp neighbors 3.3.3.3 ro
BGP table version is 17, 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          3.3.3.3                  0             0 20 i

Total number of prefixes 1
CPE#

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