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Maybe RSVP and Q.2931, but not NHRP

  • From: fddi1-ncd@BayNetworks.com (Andrew Smith)
  • Date: Wed, 29 May 96 19:05:21 PDT
  • Cc: ion@nexen.com

> From owner-ion@nexen.com Wed May 29 15:11:41 1996
> Date: Wed, 29 May 1996 17:58:14 +0500
> From: jhalpern@us.Newbridge.com (Joel Halpern)
> To: ercm20@tattoo.ed.ac.uk, manfredi@engr05.comsys.rockwell.com
> Subject: Re: Maybe RSVP and Q.2931, but not NHRP
> Cc: ion@nexen.com

Joel wrote:
> 1) Router-Host and Host-Router communication
YES
> 2) Heirarchy.  In the presence of Heirarchy, we will abstract out the
>     ATM addresses of the lower level routers
YES
> 3) Virtual routers - the correct ATM destination for the traffic may not
>    actually be the router
Exploded routers actually need something a with a bit more oomph than plain
vanilla NHRP. In themselves, they are not a sufficient justification for 
why you still need NHRP when I-PNNI is around.

> 4) Other routing protocols.  Even if some of your routers run I-PNNI,
>     you want interoperability with other protocols (including OSPF and BGP.)

In the same routing domain as I-PNNI? I hope not. I think what you are saying is
you might want to run NHRP and OSPF in the same domain but that's nothing to do with
Sam's question.

> Also, even if the whole network is using BGP with the "Next-Hop" attribute,
> the same kinds of issues apply.
> 
> Neither PAR nor full I-PNNI get rid of NHRP.  These are complementary
> technologies.

Although there are (useful, non-trivial) *deployment* scenarios where you would 
not want the bother (and expense) of running both I-PNNI and NHRP so they are not
entirely complementary and there is some overlap. I distinguish between "complementary 
in a deployment" vs. "complementary in standards' development". 
[Distinguish this also from the debate over on the other channel about MPOA and 
I-PNNI: there I believe the answer is "they are complementary"].

> Thank you,
> Joel M. Halpern				jhalpern@newbridge.com
> Newbridge Networks Inc.


Andrew

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