HSRP in a multihomed BGP network

6/24/2013

 
Multihomed Border Gateway Protocol (BGP) network where you have connections to more then one separate Internet service providers (ISPs). In the event of a failure of connectivity toward one ISP, the traffic is rerouted dynamically through the other ISP with the Hot Standby Router Protocol (HSRP).
Picture
Requirements:
  • Configure IP Addresses on physical and vlan interfaces as per diagram
  • Configure HSRP on MLS1 and MLS2 so that MLS1 become HSRP Active and MLS2 will act as standby. MLS2 should take Active role if MLS one gets down or Interface between MLS1 and ISP goes down..
  • Configure EBGP neighbor relationship as required
  • Redistribute connected interfaces via BGP. MLS1 and MLS2 should not redistribute their connected interface
  • Send routing information of 100.10.10.0 network to all network routers via BGP.
  • Find result by pinging all interfaces and by finding traceroute of all interfaces
! MLS1HSRP1active Configuration
interface FastEthernet0/0
ip address 1.1.1.1 255.255.255.252
no shut

interface Vlan1
ip address 100.10.10.1 255.255.255.0
standby 10 ip 100.10.10.100
standby 10 priority 90
standby 10 preempt
standby 10 track FastEthernet0/0

router bgp 65222
network 100.10.10.0 mask 255.255.255.0
neighbor 1.1.1.2 remote-as 10

! ISP Configuration
interface FastEthernet0/0
ip address 1.1.1.2 255.255.255.252
no shut

interface Serial0/0
ip address 11.1.1.1 255.255.255.252
no shut

router bgp 10
redistribute connected
neighbor 1.1.1.1 remote-as 65222
neighbor 11.1.1.2 remote-as 20

! R8 Configuration
interface Serial0/0
ip address 11.1.1.2 255.255.255.252
no shut

interface Serial0/1
ip address 150.1.1.1 255.255.255.252
no shut

router bgp 20
redistribute connected
neighbor 11.1.1.1 remote-as 10
neighbor 150.1.1.2 remote-as 333

! R10 Configuration
interface Serial0/0
ip address 150.1.1.2 255.255.255.252
no shut

interface Serial0/1
ip address 170.1.1.1 255.255.255.252
no shut

interface Serial0/2
ip address 12.1.1.1 255.255.255.252
no shut

router bgp 333
redistribute connected
neighbor 12.1.1.2 remote-as 440
neighbor 150.1.1.1 remote-as 20
neighbor 170.1.1.2 remote-as 200
! MLS2HSRP2standby Configuration
interface FastEthernet0/0
ip address 2.2.2.1 255.255.255.252
no shut

interface Vlan1
ip address 100.10.10.2 255.255.255.0
standby 10 ip 100.10.10.100
standby 10 priority 50
standby 10 preempt
standby 10 track FastEthernet0/0

router bgp 65222
network 100.10.10.0 mask 255.255.255.0
neighbor 2.2.2.2 remote-as 100

! ISP2 Configuration
interface FastEthernet0/0
ip address 2.2.2.2 255.255.255.252
no shut

interface Serial0/0
ip address 22.1.1.1 255.255.255.252
no shut

router bgp 100
redistribute connected
neighbor 2.2.2.1 remote-as 65222
neighbor 22.1.1.2 remote-as 200

! R9 Configuration
interface Serial0/0
ip address 22.1.1.2 255.255.255.252
no shut

interface Serial0/1
ip address 170.1.1.2 255.255.255.252
no shut

router bgp 200
redistribute connected
neighbor 22.1.1.1 remote-as 100
neighbor 170.1.1.1 remote-as 333

! Internet Configuration
interface Loopback0
ip address 44.44.44.44 255.255.255.255

interface Serial0/0
ip address 12.1.1.2 255.255.255.252
no shut

router bgp 440
redistribute connected
neighbor 12.1.1.1 remote-as 333

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