The MPLS-OPS Archive

[Puddinhead Wilson <puddinghead_wilson007@yahoo.co.uk>]

Hi,
 
--- Muhammad Tahir <muhammadtahir2000@yahoo.com>
wrote: 
> According to figure: (what I understand is)
> 
> There will be only TWO labels in a label stack at
> one time, one for IGP: to travel the
> packet within the domain and the second for BGP
> label at the boundary of the domain to
> transfer the packet towards next domain. 
>

I do not think the IGP label is needed eitherways. The
only purpose it may serve is neighbour discovery. (I
think there are some extensions for RSVP for
autodiscovery but have not kept up with drafts)
 
> (BUT, according to RFC 3031(section 3.27.3), if
> there are two or more tunnels in ONE
> domain, then there will be 3 or more labels in one
> label stack at the inner most tunnel.)
> 
> so for me this is a little bit confusing!!!!
> 

I think the RFC goes with the design of nesting LSPs
for intercarrier scenarios etc. Whereas another
pragmatic approach could be to split customers across
routers. (The Virtual router approach, where BGP gives
a label pointing to the VRF). Somehow this does not
seem to be the popular demand though I always found it
a better approach.... :( ......

i think if you look a label as a "demux" which is used
to uniquely identify end point associations it does
become simpler.


> Tahir
> 
> 
> 
> --- Puddinhead Wilson
> <puddinghead_wilson007@yahoo.co.uk> wrote:
> 
> >  
> > > Hi,
> > > please clear the situation:
> > > 
> > > reference:(framework for mpls, draft, page 51)
> > >
> >
>
http://www.ietf.org/internet-drafts/draft-ietf-mpls-framework-05.txt
> > > 
> > > 1:
> > > Is it necessary that we MUST make level only at
> > > IGP(OSPF etc) and BGP based?
> > > It means that there will be ONLY two levels in
> each
> > > domain???
> > 
> > If you just run BGP all over, there is just one
> level
> > :)
> > 
> > 
> > > If yes, then there will be only two labels in
> each
> > > domain (at maximum) one is OSPF label and other
> will
> > > be BGP label??
> > 
> > What BGP label are you referring to?
> > 
> > 
> > 
> > 
> > 
> > 	
> > 	
> > 		
> >
>
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