Subject: Re: [Idr] WG adoption requested for draft-vandevelde-idr-remote-next-hop-06

From: Yakov Rekhter <[email-masked]>
Date: Mon, 28 Jul 2014 06:44:52 -0700

Hi,
 
> The authors have requested IDR adopt draft-vandevelde-idr-remote-next-
> hop-06 as a working group document.

>From section 5.3 of the draft:

   With usage of the BGP-remote-Next-Hop attribute the service provider
   can tunnel that packet towards an alternate BGP Remote-Next-Hop at
   the end-users alternate provider and restore the network connectivity
   even though the local link towards the end-user is broken.

Consider the following example:

  S--CE1---PE1---ISP1-----PE2---CE2----|
                  |                    |
                  |                    |
                 ISP2-----PE3---CE3----D

where site D is multihomed to ISP1 and ISP2.

Would PE2 attach the Remote Next Hop indicating PE3 as an alternative
next hop, and PE3 attach the Remote Next Hop indicating PE2 as
an alternative next hop ? If yes, then how does PE2 know that PE3
is an alternative next hop ? Ditto for PE2.

Furthermore, I am not sure why in the multi-homing scenario described
above there is a need for the Remote Next Hop attribute. E.g.,
take a look at rfc2260 or at draft-bonica-v6-multihome-03 - 
both can be used to provide multi-homing, and neither of these use 
the Remote Next Hop attribute.

Yakov.