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RE: A question on CE to PE route exchanges ...
From: Dave Israel <davei () biohazard demon digex net>
Date: Sun, 20 May 2001 19:55:13 -0400

Oops... I answered this privately, assuming NANOG at large would
not be interested.  The issue here is that Cisco will tend to
add IGP routes to the default table, not the VPN table.  Bad
things ensue.

I was actually referring to the CE interface address; peering
with the CE's loopback is, IMHO, more trouble than its worth
unless you have multiple connections on the same router.  But
as long as the address you are peering with is in the private
routing table, you're fine, regardless of whether or not it is
also in the default table.

I cannot speak to the "most common;" I think it is too early
to tell.  But we are tending towards static routes (nice and
stable, without the chance of the other guy breaking you)
and BGP (which is already designed to handle trans-border

I have not tried it, but I would assume the OSPF area "repair"
toys would work nicely over this, if you want an IGP running
across your CE routers.  (I'm more of an ISIS guy than an
OSPF guy... anybody know why this would blow up in your face?)


On 5/19/2001 at 21:14:40 -0700, Elwin Eliazer said:

Even i am interested in knowing the exact issue with
using IGPs? What is the most common CE-PE route
exchange behaviour now ... Static routes OR IGP OR

Dave, are you referring the CE loopback address also
to be local?


--- Alex Mondrus <alex.mondrus () ipoptical com> wrote:

I also like the RFC2547bis.

I would like to learn more about your painful
experience with IGP in this
context. Please elaborate a little bit more on this
subject -> Dave Israel
wrote "Besides, in at least one major current
implementation, your IGP
options are painfully limited."


Thanks in advance, Alex

-----Original Message-----
From: Dave Israel
[mailto:davei () biohazard demon digex net]
Sent: Friday, May 18, 2001 5:45 PM
To: Elwin Eliazer
Cc: nanog () merit edu
Subject: Re: A question on CE to PE route exchanges

On 5/18/2001 at 14:13:53 -0700, Elwin Eliazer said:


RFC2547bis suggests the use of EBGP between
CE and PE routers; Is this a preferable model for
service providers and enterprise customers, when
compared to using IGP?

Yes.  BGP is designed for network borders.  Besides,
in at least one
major current implementation, your IGP options are
painfully limited.
Are there anyone who have deployed this? If so,
how is the EBGP peering setup if the CE router
is with a local (VPN) IP address?

The BGP session lives in VPN space, the routes only
exist in VPN
routing tables.  Your CE having a VPN address is
really just the
natural solution.


Elwin Stelzer Eliazer
Corona Networks

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Dave Israel
Senior Manager, IP Backbone
Intermedia Business Internet

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