A question on CE to PE route exchanges ...

Dave Israel davei at biohazard.demon.digex.net
Sun May 20 23:55:13 UTC 2001


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
communication.)

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?)

-Dave

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
> BGP??
> 
> Dave, are you referring the CE loopback address also
> to be local?
> 
> cheers,
> Elwin.
> 
> --- Alex Mondrus <alex.mondrus at ipoptical.com> wrote:
> > Dave
> > 
> > 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."
> > 
> > http://www.ipoptical.com
> > 
> > Thanks in advance, Alex
> > 
> > 
> > 
> > -----Original Message-----
> > From: Dave Israel
> > [mailto:davei at biohazard.demon.digex.net]
> > Sent: Friday, May 18, 2001 5:45 PM
> > To: Elwin Eliazer
> > Cc: nanog at merit.edu
> > Subject: Re: A question on CE to PE route exchanges
> > ...
> > 
> > 
> > 
> > On 5/18/2001 at 14:13:53 -0700, Elwin Eliazer said:
> > > 
> > > Hi,
> > > 
> > > 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.
> > 
> > -Dave
> 
> 
> =====
> -------
> Elwin Stelzer Eliazer
> Corona Networks
> -------
> 
> __________________________________________________
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-- 
Dave Israel
Senior Manager, IP Backbone
Intermedia Business Internet





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