The MPLS WG Archive

[Ajay Simha <asimha@cisco.com>]

On Mon, 3 Sep 2001, Mareline Sheldon wrote:

> We can distribute label binding information by piggybacking this on top of
> the routing protocols. Why do OSPF and IS-IS make a rather poor match for
> what is required to distribute local binding information and why is BGP
> quite suitable for doing the same ? We can always extend the protocols to
> carry this information by adding new TLVs.
> Please can anybody explain.
> Regards,
> Mary

Mareline,

Reading RFC 3036 one can see the need for a separate protocol for carrying
labels.  It has additional things such as:

1. neighbor discovery
2. non-adjacent neighbors

I guess someone on the list can argue that all these things could be
incorporated into OSPF/ISIS or any other routing protocol.  Based on the sheer
quantity of new things in RFC 3036 it seems like adding all these new
capabilities to something like OSPF would not be appropriate.


BGP on the other had is not a link state protocol.  It has proved to be a
robust protocol to carry:

1st - unicast ip routes
2nd - mcast routes

BGP also seemed to the favorite protocol folks are are looking at to carry
voice routing tables etc..

Again BGP does not replace LDP.  It only serves for exchanging label bindings
for external routes - again BGP has been the choice of protocols for carrying
external routes.


-ajay

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-- 
Ajay Simha
MPLS Deployment Engineer
IOS Technology Division
(919) 392-3141

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 Live as if you were to die tomorrow"

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