Subject: LC comments on considerations extranet section

From: Eric Rosen <[email-masked]>
Date: Fri, 12 Jun 2009 15:02:27 -0400

The section on extranet 3.3.6 is not accurate.

It suggests  that it  is not  known how extranet  could be  achieved without
using BGP-based C-multicast routing.  This is odd considering (a) a solution
providing this feature has been shipping  for years, and (b) the solution is
written up in draft-rosen-l3vpn-mvpn-mspmsi-02.txt.

It  also suggests  that all  it takes  to do  extranet with  BGP C-multicast
routing  is to  reuse the  "already defined  and well  understood  BGP route
target import/export  semantics".  In  fact, this is  not true.   To support
extranet you also  have to know which C-streams in which  PMSIs are the ones
you need to receive.  In the  PIM control plane, you make this determination
by associating each PMSI with a particular PIM interface.  I don't think the
corresponding functionality is specified for the BGP control plane.

I think it  is premature to make a recommendation  based upon which extranet
scheme  works best  until we  have  both extranet  schemes written  up in  a
standards track document.

---

From: Thomas Morin <[email-masked]>
Date: Fri, 19 Jun 2009 18:02:02 +0200

Hi Eric, folks,

> written up in draft-rosen-l3vpn-mvpn-mspmsi-02.txt.
One could point out that :
- the section you quote does not say "not known" just "not specified"
- that a feature shipping is not a spec (!)
- that draft-rosen-l3vpn-mvpn-mspmsi-02 is not a WG doc, and that the 
scope of the draft is only WG docs
- (also, that draft-rosen-l3vpn-mvpn-mspmsi was not even talking about 
extranet when the paragraph in question was written one year ago)

So, nothing "odd" really.

> corresponding functionality is specified for the BGP control plane.
With PIM, the fact that the dataplane and control plane are so tied, is 
a double-edged sword, which happens to impact how extranet can be done.

> standards track document.
The (not) funny thing is that, if there had been an agreement to include 
Extranet in the base specs, for both PIM and BGP, consistently with mVPN 
requirements (RFC4834), we would have an interesting comparison to do.

But I have to agree with you that, since draft-ietf-l3vpn-2547bis-mcast 
has unfortunately finally not included Extranet, this section 3.3.6 is 
in a delicate position.  I don't mind removing it.

And I hope further work will be done soon on the Extranet subject.

Cheers,

-Thomas