Re: [Idr] Fwd: I-D ACTION:draft-pmohapat-idr-acceptown-community-01.txt

Jeffrey Haas <> Tue, 06 May 2008 19:46 UTC

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Date: Tue, 6 May 2008 15:46:53 -0400
From: Jeffrey Haas <>
To: "Jim Guichard (jguichar)" <>
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Subject: Re: [Idr] Fwd: I-D ACTION:draft-pmohapat-idr-acceptown-community-01.txt
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[Note to John S. - I was definitely the confused one here.  The issue is
not that the routers in question can't be configured to handle the
leaking from one VRF to another internally without a BGP announcement.
The issue is that the users don't want the administrative overhead of
doing that at the configuration level for each VRF on each router.]

On Tue, May 06, 2008 at 02:07:09PM -0400, Jim Guichard (jguichar) wrote:
> Lets say VPN-a uses RT 100:1 and VPN-b uses RT 100:2. In order to create
> an extranet you need to import RT 100:2 into VPN-a and RT 100:1 into
> VPN-b. This is an additional import statement. However, if you change
> the VPN-b route RT values at the RR then VPN-a can import based on RT
> 100:1.

Ok, the typical configuration on the router is what I expected it to be.
The piece I didn't understand was the alteration of the RT via "BGP VPN
route server".

> > If it's across multiple PEs, this implies something along the lines of
> > RT A and RT B are distinct on a per VRF basis.  This seems somewhat
> > unlikely (at least on the completely distinct basis) since it wouldn't
> > scale well for many VRFs being in the same VPN.
> It is 100% likely and indeed necessary should you want different VPNs.

To clarify: This wasn't per-VPN.  My comment was effectively each box
was it's own VPN.  That's not what you had meant.

My apologies for the long message train to reach this conclusion.

I still recommend to the authors that they don't consider a well-known
standard community.  Please consider either using a new extended
community or adding a configuration knob for the existing route-target
community.  I think that would serve your requirements without otherwise
complicating existing non-VPN situations.

-- Jeff
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