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Re: Re: Layer 2 MPLS VPN

  • From: Per Ole Klemetsrud <perole@kirurg.org>
  • Date: Mon, 10 Jan 2005 17:12:55 +0100 (CET)
  • cc: Puddinhead Wilson <puddinghead_wilson007@yahoo.co.uk>, mpls-ops@mplsrc.com
  • Resent-Date: Mon, 10 Jan 2005 11:33:40 -0500
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  • X-X-Sender: perole@galaga.local

>>I dont know about the "label block" schemes, I never
>>did really understand it. could someone clarify it?
>It refers to BGP based solution - all is explained in draft :)

It.s not that tricky, an example is the best way to explain it (please 
forgive incorrect terminology, this is from the top of my head).

Four PE.s in a given VPLS, with site-id 1,2,3 and 4.

Site 1 announces base 1000 for this VPLS via BGP
Site 2 announces base 2000
Site 3 announces base 3000
Site 4 announces base 4000

The inner label will be remote base + local site-id.  The inner label for 
the pseudowire from site 4 to site 2 will be 2000+4=2004 (possibly -1, I.m 
not 100% into the details).

This is why you have the site-range parameter, so the PE can choose 
appropriate blocks of label space.  In my opinion, this is way much 
simpler than the LDP scheme where targeted sessions for each PW has to be 
initiated.

=) Per

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