Re: MDT source interface ?

From: Petr Lapukhov (petr@internetworkexpert.com)
Date: Mon Nov 10 2008 - 17:59:44 ARST

Hi,
Under the respective vrf configuration do the following:
ip vrf TEST
bgp next-hop Loopback X

this will change the next-hop in MPBGP advertisemet and also affect the
source IP address of the MDT tunnel associated with the VRF. IOS does not
let you allow selecting the MDT source IP address and picks it up
automatically based on the configured MP-BGP peers (it seems to pick up to
first source interface used for MP-BGP peering).

In order for a PE router to accept the incoming MDT-encapsulated packet, the
tunnel source IP address must the the MPBGP next-hop address for the source
C-address of encapsulated packet. This is the VPN-based RPF check. Also you
must have a PIM neighbor on the MDT tunnel interface with the IP address
matching the MP-BGP peering address.

HTH 

-- 
Petr Lapukhov, CCIE #16379 (R&S/Security/SP/Voice)
petr@internetworkexpert.com

Internetwork Expert, Inc.
http://www.InternetworkExpert.com
Toll Free: 877-224-8987
Outside US: 775-826-4344
2008/11/9 backbone systems <backbone.systems@gmail.com>

> CUST A-1----PE1----P-----PE2-----CUST A -2--225.1.1.1
>
> I am trying to Ping from CUST A site 1 to site 2 and the reply is
> successful.
> But when try to ping the destination from my PE1 router i dont get replies,
>
> PE1------ping vrf ABC 225.1.1.1
>
> wen i do debug ip mpack... i can see on PE1 that the source of the
> packet is lo0 of PE1 bc mdt by default take the source interface as
> the MBGP interface used for connectivity.
>
> is there any way i can change this default behaviour? How can i make
> my ping successful sitting on  PE1
>
> Any gud references on this topic will be helpful.
>
>
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>
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