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Question on MP-BGP Session

Hi Sir,

I have the following BGP configuration of an RR and a PE in an MPLS VPN environment:

RR

--

!

router bgp 65000

neighbor 2.2.2.2 remote-as 65000

neighbor 2.2.2.2 update-source Loopback0

neighbor 2.2.2.2 route-reflector-client

!

address-family vpnv4

neighbor 2.2.2.2 activate

neighbor 2.2.2.2 send-community extended

neighbor 2.2.2.2 route-reflector-client

exit-address-family

!

!

PE1

---

!

router bgp 65000

no bgp default ipv4-unicast

neighbor 1.1.1.1 remote-as 65000

neighbor 1.1.1.1 update-source Loopback0

!

address-family vpnv4

neighbor 1.1.1.1 activate

neighbor 1.1.1.1 send-comunity both

neighbor 1.1.1.1 next-hop-self

exit-address-family

!

!

Theorectically, given the above config, can the two routers successfully peered?

(1) The RR is configured to exchange IPv4 and VPNv4 routes and exchanges only extended BGP communities.

(2) The PE router is configured to exchange only VPNv4 routes and exchanges both standard and extended BGP communities.

Please advise.

Thank you.

B.Rgds,

Lim TS

1 ACCEPTED SOLUTION

Accepted Solutions

Re: Question on MP-BGP Session

IF you have anymore queuries regaridng the same, pls respond.

Or we can close the thread, if have answered your query.

HTH-Cheers,

Swaroop

2 REPLIES

Re: Question on MP-BGP Session

In the above scenario what will happen is,

1) The RR will show a NoNeg state for normal IPV4 session. Assuming you have not activated the IPV4 address-family for the RR on PE1.

2) On PE1 side you will not see any neighbor when you want to see IPV4 neighbors.

3) For VPNV4 both sides agree upon and the peering happens, and they exchange VPNV4 updates.

Now, generally in a MPLS scenario, to avoid IPV4 peering, the default behaviour of BGP to form IPV4 peering is turned off on RR, and not on PE. So when ever a PE tries to peer on both IPV4 and VPNV4, all the PE's would see NoNeg state for IPV4 with the RR and VPNV4 will work as usual, and all the VPNS would be able to exchnage routes and other updates.

If you want to have IPV4 peering also, on a per neighbor basis, what you can do is where you have turned off default IPV4 peering, in that address-family you will have to specifically activate the neighbor for IPV4 as well. For Example: you have turned off IPV4 peering on PE1, so you will have to enter IPV4 address-family on PE1 and activate the RR neighbor IP. so they exahnge IPV4 and VPNV4.

HTH-Cheers,

Swaroop

Re: Question on MP-BGP Session

IF you have anymore queuries regaridng the same, pls respond.

Or we can close the thread, if have answered your query.

HTH-Cheers,

Swaroop

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