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Re: iMPLS benefit

  • From: Yakov Rekhter
  • Date: Mon Mar 15 13:29:03 2004

Mark,

> Please see inline.

in-line...

> >>>>>>>>i heard there is a way to run MPLS for layer3 VPN(2547)
> >>>>>>>>service without needing to run label switching in the
> >>>>>>>>core(LDP/TDP/RSVP) but straight IP (aka iMPLS). 
> >>>>>>
> >>>>>>	ftp://ftp.ietf.org/internet-drafts/draft-townsley-l2tpv3-mpls-0
1.txt
> >>>>>>
> >>>>>>	See also Mark's talk from the last NANOG
> >>>>>>
> >>>>>>	http://nanog.org/mtg-0402/townsley.html
> >>>>>
> >>>>>That requires to run L2TP. An alternative is to run GRE (or even plain
> >>>>>IP). The latter (GRE) is implemented by quite a few vendors (and is
> >>>>>known to be interoperable among multiple vendors).
> >>
> >>The only multi-vendor interoperable mode of GRE that I am aware of requires
> >>manual provisioning of point-to-point GRE tunnels between MPLS networks and
> >>to each and every IP-only reachable PE.
> > 
> > 
> > I guess you are *not* aware of the Redback implementation of 2547
> > over GRE, as this implementation is (a) available today, (b)
> > interoperable with other implementations of 2547 over GRE, and (c)
> > does *not* require manual provisioning of point-to-point GRE tunnels
> > between MPLS networks and to each and every IP-only reachable PE.
> > 
> > And, just for the record, (stating the obvious) I don't work for Redback.
> 
> Are you referring to draft-raggarwa-ppvpn-tunnel-encap-sig-03.txt? (Just 
> guessing as the principal author used to work for Redback). Thanks for the 
> update, I was in fact not aware that companies other than Redback had 
> implemented it. You didn't name those companies, but I will happily stand 
> corrected here.

No, I was *not* referring to draft-raggarwa-ppvpn-tunnel-encap-sig-03.txt.
Redback's implementation that does not require manual provisioning of 
point-to-point GRE tunnels between MPLS networks and to each and every 
IP-only reachable PE is *purely* an implementation matter, and does *not*
require any new communities and/or attributes.

> In any case, the point I was trying to make was that there is more than 
> one way to do "MPLS over GRE" and that they are not all necessarily 
> interoperable as you seemed to imply in your message. You have helped 
> to make that quite clear.
> 
> >>The BGP extension defined in the draft below allows "iMPLS" for 2547 
> >>VPN support without requiring any manually provisioned tunnels (and 
> >>works for "mGRE" or L2TPv3).
> >>
> >>http://www.watersprings.org/pub/id/draft-nalawade-kapoor-tunnel-safi-01.txt
> > 
> > The question to ask is whether the extension you mentioned above is
> > truly necessary for supporting 2547 over GRE. The Redback implementation
> > I mentioned above is an existence proof that the extension is *not*
> > necessary for 2547 over GRE that does *not* involve manually provisioned
> > GRE tunnels.
> 
> Both draft-nalawade-kapoor-tunnel-safi-01.txt and 
> draft-raggarwa-ppvpn-tunnel-encap-sig-03.txt use BGP to advertise capabilities
> for carrying MPLS-labeled packets over various encapsulation types. Proof of 

And *neither* of these are requires in order to avoid manual provisioning 
of point-to-point GRE tunnels.

Yakov.




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