[c-nsp] ibgp TTL

[David Freedman]

How about explicit path TE with no autoroute announce (and only statics
for these dedicated iBGP loopbacks?)


> 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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