Re: BGP Multihoming & single Router, load sharing and automatic fail over

Mohammadullah Nazafat · ‎02-28-2018

Hi,

This is my first question on Cisco #Support forum,

I have two ISP connected to my single router R1, R1 is publishing two prefixes, I want to use prefix A use RCOM ISP and prefix B use Sify ISP and RCOM should be my Primary ISP for other networks and also configure fail over also.

So please tell me how will i configure same

please find attached screenshot for same.

Thanks in advance.

Georg Pauwen · ‎03-01-2018

Hello,

there a numerous ways to achieve this, AS path prepending is one of them. Post the config of your R1 router, so we can fill in he necessary bits and pieces...

Mohammadullah Nazafat · ‎03-02-2018

GTR#sh running-config
Building configuration...

Current configuration : 1771 bytes
!
! Last configuration change at 16:27:15 UTC Fri Mar 2 2018
!
version 15.2
service timestamps debug datetime msec
service timestamps log datetime msec
!
hostname GTR
!
boot-start-marker
boot-end-marker
!
!
!
no aaa new-model
no ip icmp rate-limit unreachable
!
!
!
!
!
!
no ip domain lookup
ip cef
no ipv6 cef
!
!
multilink bundle-name authenticated
!
!
!
!
!
!
!
!
!
!
!
!
ip tcp synwait-time 5
!
!
!
!
!
!
!
!
!
interface Loopback0
ip address 10.125.73.193 255.255.255.192
!
interface Loopback1
ip address 10.125.76.129 255.255.255.224
!
interface Loopback2
ip address 172.16.1.1 255.255.255.0
!
interface FastEthernet0/0
no ip address
shutdown
duplex full
!
interface FastEthernet1/0
ip address 191.191.191.41 255.255.255.252
duplex full
!
interface FastEthernet2/0
ip address 180.180.180.221 255.255.255.252
duplex full
!
interface FastEthernet3/0
no ip address
shutdown
duplex full
!
router bgp 65028
bgp log-neighbor-changes
network 10.125.73.192 mask 255.255.255.192
network 10.125.76.128 mask 255.255.255.224
network 172.16.1.0 mask 255.255.255.0
redistribute connected
neighbor 180.180.180.222 remote-as 9583
neighbor 180.180.180.222 distribute-list 10 out
neighbor 191.191.191.42 remote-as 18101
neighbor 191.191.191.42 weight 500
neighbor 191.191.191.42 distribute-list 10 out
!
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
!
no ip prefix-list sequence-number
access-list 10 permit 10.125.73.192 0.0.0.63
access-list 10 permit 10.125.76.128 0.0.0.31
access-list 10 permit 172.16.1.0 0.0.0.255
!
!
!
control-plane
!
!
line con 0
exec-timeout 0 0
privilege level 15
logging synchronous
stopbits 1
line aux 0
exec-timeout 0 0
privilege level 15
logging synchronous
stopbits 1
line vty 0 4
login
!
!
end

GTR#

Mohammadullah Nazafat · ‎03-08-2018

GTR#sh running-config
Building configuration...

Current configuration : 1771 bytes
!
! Last configuration change at 16:27:15 UTC Fri Mar 2 2018
!
version 15.2
service timestamps debug datetime msec
service timestamps log datetime msec
!
hostname GTR
!
boot-start-marker
boot-end-marker
!
!
!
no aaa new-model
no ip icmp rate-limit unreachable
!
!
!
!
!
!
no ip domain lookup
ip cef
no ipv6 cef
!
!
multilink bundle-name authenticated
!
!
!
!
!
!
!
!
!
!
!
!
ip tcp synwait-time 5
!
!
!
!
!
!
!
!
!
interface Loopback0
ip address 10.125.73.193 255.255.255.192
!
interface Loopback1
ip address 10.125.76.129 255.255.255.224
!
interface Loopback2
ip address 172.16.1.1 255.255.255.0
!
interface FastEthernet0/0
no ip address
shutdown
duplex full
!
interface FastEthernet1/0
ip address 191.191.191.41 255.255.255.252
duplex full
!
interface FastEthernet2/0
ip address 180.180.180.221 255.255.255.252
duplex full
!
interface FastEthernet3/0
no ip address
shutdown
duplex full
!
router bgp 65028
bgp log-neighbor-changes
network 10.125.73.192 mask 255.255.255.192
network 10.125.76.128 mask 255.255.255.224
network 172.16.1.0 mask 255.255.255.0
redistribute connected
neighbor 180.180.180.222 remote-as 9583
neighbor 180.180.180.222 distribute-list 10 out
neighbor 191.191.191.42 remote-as 18101
neighbor 191.191.191.42 weight 500
neighbor 191.191.191.42 distribute-list 10 out
!
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
!
no ip prefix-list sequence-number
access-list 10 permit 10.125.73.192 0.0.0.63
access-list 10 permit 10.125.76.128 0.0.0.31
access-list 10 permit 172.16.1.0 0.0.0.255
!
!
!
control-plane
!
!
line con 0
exec-timeout 0 0
privilege level 15
logging synchronous
stopbits 1
line aux 0
exec-timeout 0 0
privilege level 15
logging synchronous
stopbits 1
line vty 0 4
login
!
!
end

GTR#