Re: On BGP and VPLS

Hi Kireeti,

sorry for the late reply on this...

On Fri, 2003-05-09 at 19:18, Kireeti Kompella wrote:
> Hi Alex,
> 
> On Fri, 2 May 2003, Alex Zinin wrote:
[snip]
> >  2. Distribution of information
> >
> >    When used as an IP routing protocol, BGP distributes routes among
> >    all participating routers.
> 
> For 2547, you have the same issue: BGP distributes routes among *all*
> participating routers, whereas only a few are really interested in them.
> So why is this an issue for VPLS but not for 2547?  The distribution
> mechanisms are identical.

I'm not sure the issues are quite the same.

In 2547, as far as I understand it, a given labelled route announcement
from a PE must be sent to every other PE with a VRF matching the route
target for that announcement.

In VPLS a unique label is required by each other PE which is a member of
a given VPLS, so each label advertised is used by exactly one other PE.

So it's a question of degree I think?

Or to put it another way, with respect to the set of all PEs:

Distribution of IPv4 routes can be characterised as "broadcast".
Distribution of VPN-IPv4 labelled routes can be characterised as
"multicast".
Distribution of VPLS labels can be characterised as "unicast".

Why select a broadcast mechanism (BGP with RRs) to meet a unicast
requirement?

[rest snipped]

Giles

-- 
=================================================================
Giles Heron    Principal Network Architect    PacketExchange Ltd.
ph: +44 7880 506185              "if you build it they will yawn"
=================================================================