BGP backdoor link

[muralikrishnan.chelakara]

Dear Team,

Can u explain how does bgp backdoor link will work , 

Scenario :

Two customer sites connected  different PE  

CE1>>>PE1(mpls core )PE2>>>CE2 this CE 1 and CE2 have back to back connectivity with Eigrp  , how does the loop avoidance happens here 

[Vasilii Mikhailovskii · Accepted solution]

Hello.

If you are running EIGRP between CE-PE, then loop avoidance mechanism should be the SOO.

PS: read following about BGP backdoor links

http://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/26634-bgp-toc.html#bgpbackdoor

https://supportforums.cisco.com/document/148471/what-bgp-backdoor-feature

[muralikrishnan.chelakara]

hi ,

i am using PE -CE as EBGP  and  both CE having backdoor link and using eigrp

[Vasilii Mikhailovskii · Accepted solution]

Hello.

If CE-PE protocol is eBGP., then ISP would be using SOO as loop-prevention mechanism.

Also, if you have same AS for both CE-PE links, then your CE would prevent the prefix to be learnt due to self AS been found in AS-path.

PS: I hope this answers your question about loop-prevention mechanism on ISP side; If you have a question about CE network, then additional information needed - what is advertised via each links, what is routing policy (active/active or active/backup), what link is primary (MPLS or backdoor) and etc.