[c-nsp] ibgp TTL

[Manu Chao]

Thank you Oli,

OSPF stub area or IS-IS Level 1 was the better option compared to ACL on the
non-MPLS router because routing control stay under MPLS backbone control

Increasing metric is useless because non MPLS path must NEVER be used

On Wed, Oct 14, 2009 at 6:44 PM, Oliver Boehmer (oboehmer) <
oboehmer at cisco.com> wrote:

> Manu,
>
> > More detail:
> >
> > I have a standard IP/MPLS backbone with MP-iBGP between PEs loopbacks
> with
> > IS-IS L2 or OSPF area 0 as IGP.
> >
> > This IGP is extended to some non MPLS routers X.
> >
> > In some backbone links failure, IGP allow MP-iBGP to stay UP via X links
> > (non MPLS).
> >
> > This specific IGP design introduce a L3VPN blackhole that can be solved
> by
> > IGP prefix filtering or by limiting TTL for MP-iBGP sessions, if possible
> :)
>
> Hmm, you could also cause iBGP session to fail if you just add an interface
> ACL not allowing iBGP between your PEs across the links not running MPLS.
>
> Not sure if there is any real solution to this, other than increasing the
> link metric towards the "non-MPLS-capble part" so much that MPLS packets
> will not cross these links (or turn this part of the network into a stub
> area to achieve the same).
>
>        oli
>
>
>
> > On Wed, Oct 14, 2009 at 2:10 PM, Oliver Boehmer (oboehmer)
> > <oboehmer at cisco.com> wrote:
> > yes, only supported for ebgp. Would be interested about the "very
> > specific design" and why Manu requires this functionality?
> >
> >        oli
> >
> > > AFAIK this command is for eBGP only, no?
> > >
> > > On Tue, Oct 13, 2009 at 10:07 PM, Matlock, Kenneth L
> > > <MatlockK at exempla.org>wrote:
> > >
> > > > Router bgp <AS>
> > > > Neighbor <AS> ttl-security hops <hops>
> > > >
> > > > ?
> > > >
> > > > Ken Matlock
> > > > Network Analyst
> > > > Exempla Healthcare
> > > > (303) 467-4671
> > > > matlockk at exempla.org
> > > >
> > > >
> > > >
> > > > -----Original Message-----
> > > > From: cisco-nsp-bounces at puck.nether.net
> > > > [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Manu Chao
> > > > Sent: Tuesday, October 13, 2009 4:52 AM
> > > > To: cisco-nsp at puck.nether.net
> > > > Subject: [c-nsp] ibgp TTL
> > > >
> > > > For a very specific design, i need to limit TTL value in
> > ibgp-multihop.
> > > >
> > > > Is it possible to limit iBGP TTL like we do with ebgp-multihop ttl
> > > > command?
> > > >
> > > > Any input appreciated.
> > > >
> > > > Manu
> > > >  _______________________________________________
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>