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Re: Advertising Routes learnt from PE to PE

  • From: Aamer Akhter <aakhter@cisco.com>
  • Date: Wed, 14 May 2003 11:39:15 -0400
  • CC: <mpls@uu.net>
  • Resent-Date: Wed, 14 May 2003 12:34:03 -0400
  • To: <ferit@isocore.com>, "'Sugar, Sylvia'" <truesylvia@yahoo.co.uk>, <mpls-ops@mplsrc.com>
  • User-Agent: Microsoft-Entourage/10.1.1.2418

On 5/14/03 10:51 AM, "Ferit Yegenoglu" <ferit@isocore.com> wrote:

> 
> Sylvia,
> 
> One possible scenario where this could happen is the hub-spoke BGP/MPLS
> VPN. In this case the spoke PEs advertise their routes with a Route
> Target value "Hub". The hub PE imports these routes and advertises them
> to the CE router in the hub site. These routes are advertised across the
> hub site and eventually back to the PE hub router via a different
> interface. The PE hub router then readvertises these routes to the spoke
> PEs with a Route Target value "Spoke" and a different VPN label.

But to BGP, these "readvertised" prefixes are not the same. The rd will have
changed.

> 
> Ferit
> 
> 
> 
>> -----Original Message-----
>> From: owner-mpls@UU.NET [mailto:owner-mpls@UU.NET] On Behalf Of Sugar,
>> Sylvia
>> Sent: Wednesday, May 14, 2003 10:07 AM
>> To: mpls-ops@mplsrc.com
>> Cc: mpls@UU.NET
>> Subject: Advertising Routes learnt from PE to PE
>> 
>> Hi,
>> WIll a PE router ever advertise a route it learns from another PE
> router
>> to some other PE router.
>> I dont think it will ever do that as all the PE routers are IBGP peers
> and
>> would generally be in
>> full mesh.
>> 
>> Is there any case when this might happen .. i.e. a PE router
> advertises a
>> Route learnt from one PE
>> to another PE. How can one do that .. because IMHO the label that will
> be
>> advertised by the former
>> PE router will be for the PE router to which he sends the UPDATE. How
> can
>> this PE router advertise
>> another PE router the same label?
>> 
>> Moreover, if for some reason he has to .. does he assign a new label
> and
>> then advertise?
>> 
>> ANy comments on this would be very helpful!
>> 
>> Silviya Sugar
>> 
>> __________________________________________________
>> Yahoo! Plus
>> For a better Internet experience
>> http://www.yahoo.co.uk/btoffer
> 

-- 
Aamer Akhter / aa@cisco.com
NSITE - cisco Systems


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