A question on CE to PE route exchanges ...

Robert Raszuk raszuk at cisco.com
Mon May 21 21:18:15 UTC 2001



> 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.

What ... ? For protocols that have been vrf aware routes go into vrfs
and not global RIB. Those IGPs would be in shipping images: RIP, OSPF.
Very soon also EIGRP & ISIS. Just watch your CPU before using IGPs on a
wide scale with tons of customer routes flappoing :). 

Just not be understood that I recommend the above IGPs :) I am also
seeing worldwide the following set of protocols on the PE-CE in order or
preference: static, BGP & RIP.

R.

> Dave Israel wrote:
> 
> 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
> > -------
> >
> > __________________________________________________
> > Do You Yahoo!?
> > Yahoo! Auctions - buy the things you want at great prices
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> 
> --
> Dave Israel
> Senior Manager, IP Backbone
> Intermedia Business Internet




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