Subnet advertisement on Multiple Router with Redundancy

[samksam77in]

Hi All,

Need assistance in configuring this Multihome BGP scenario where i want to advertise 201.201.201.0/24 & 110.110.110.0/24 on both upstream for redundancy at POP site and priority for these two subnets should be upstream 2, in case upstream 2 fails traffic will be diverted from upstream 1.

As far as  my understanding I must be having an IBGP peering between IDC and POP routers for the redundancy however with my experiment traffic is getting affected and not able to meet the requirement.

Help on above is highly appreciated.

Have attached the diagram for the reference.

Sam.

[Spooster IT Services]

Hi,

Following link have the sample configuration.  Go to Load Sharing When Dual-Homed to One ISP Through Multiple Local Routers section in the link.

http://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/13762-40.html

If this is helpful. Please rate.

[samksam77in]

Hi,

Thanks for your valuable response however what i am looking for is to configure ibgp between two internal Routers (IDC and POP) which are located away from each other and have a P2P connectivity between them, currently upstream1 is connected to IDC Router and upstream2 is connected in POP router with 620MB & 45MB respectively.

Very few bunch of clients are connected to POP with ip subnet 201.201.201.0/24 & 110.110.110.0/24 which i want to advertised to IDC upstream1 for failover scenario (in case upstream2 fails both this subnets should get traffic (Bandwidth) via upstream1 without any config altercation)

I did not find the similar solution mentioned in the link provided by you.

Would appreciate if i can get much needed help with the above mentioned scenario.

Thanks 

Sam.

[Spooster IT Services · Accepted solution]

Hi samksam77in,

Following is the sample configuration:-

IDC configuration

hostname IDC

!
router bgp AS#
network 201.201.201.0 mask 255.255.255.0
network 110.110.110.0 mask 255.255.255.0
network 123.123.123.0 mask 255.255.255.0
network 125.125.125.0 mask 255.255.255.0
network 126.126.126.0 mask 255.255.255.0
neighbor <Upstream 1 IP> remote-as AS#
neighbor <Upstream 1 IP> route-map RMAP out
no auto-summary
!

!--- IBGP peering with POP
neighbor IP ADDRESS remote-as AS#
neighbor IP ADDRESS next-hop-self
!

!--- This line sets eBGP peering with Upstream1.

neighbor Upstream1 IP ADDRESS remote-as AS#

access-list 10 permit 201.201.201.0 0.0.0.255
access-list 10 permit 110.110.110.0 0.0.0.255
!
access-list 20 permit 123.123.123.0 0.0.0.255
access-list 20 permit 125.125.125.0 0.0.0.255
access-list 20 permit 126.126.126.00 0.0.0.255

!--- Here, the route map prepends AS# to BGP updates for networks
!--- that are permitted by access list 10.

route-map RMAP permit 10
match ip address 10
set as-path prepend AS# AS# AS# (local)
!

!--- This line announces the network that is permitted
!--- by access list 20 without any changes in BGP attributes.

route-map RMAP permit 20
match ip address 20
!

POP router configuration

hostname POP
!
router bgp AS#

!--- The next two lines announce the networks to BGP peers.

network 201.201.201.0 mask 255.255.255.0
network 110.110.110.0 mask 255.255.255.0

!--- The next line configures iBGP on IDC.

neighbor IP ADDRESS remote-as AS#
neighbor IP ADDRESS next-hop-self

!--- The next line configures eBGP with Upstream2.

neighbor Upstream2 IP ADDRESS remote-as AS#
no auto-summary