[c-nsp] Small Issue With next-hop-self for VPNv4

[Tantsura, Jeff]

It is not cisco that dictates that it's RFC1966 - 
  In some implementations, modification of the BGP path attribute,
   NEXT_HOP is possible. For example, there could be a need for a RR to
   modify NEXT_HOP for EBGP learned routes sent to its internal peers.
   However, it must not be possible for an RR to set on reflected IBGP
   routes as this breaks the basic principle of Route Reflection and
   will result in potential black holeing of traffic.

It's also that you are not allowed to alter BGP attributes outbound (from
Cisco), if I recall correctly not the case for Juniper

CCO:
Using set clauses in outbound route maps modifies attributes, possibly
creating routing loops. To avoid this, set clauses of outbound route maps
are ignored for routes reflected to IBGP peers.

Personally, I don't think you should change default behaviour, unless you
really must too.


--
Jeff Tantsura  CCIE# 11416
Senior IP Network Engineer


-----Original Message-----
From: Piotr Marecki [mailto:peter at mareccy.org] 
Sent: 26 July 2005 15:00
To: cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] Small Issue With next-hop-self for VPNv4

This is standard Cisco IOS behavior - RR router won't change NEXT_HOP
attribute during iBGP route reflection - it will only change eBGP reflected
routes. To change NEXT_HOP attribute you have to use outbound route-map
with set ip next-hop.
Moreover , in similiar setup ( though diffrent IOS/Boxes ) i had also to
change MP-BGP NEXT_HOP on PE.

best regards

Piotr Marecki

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