[rbak-nsp] Inter-context routing

[David Freedman]

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> OK - I think I answered my own question:
>
> next-hop-self
> Purpose: Advertises the local peer address as the next-hop address for
> all external Border Gateway Protocol (eBGP) routes sent to the specified
> neighbor or peer group.
>
> Can you not use next-hop-self with iBGP?

what it means is that next-hop-self over an iBGP session will work but
only change the next hop of routes you learnt via eBGP but would pass on
to your iBGP peer.

There is no point changing the next hop of iBGP routes you would reflect
onward, if you really want to do this then I suspect you will need to do
it manually in a route-map.

Dave.



>
> Jim.
>
> jim at scusting.com wrote:
>> Thanks - that got the BGP up.  I have now setup the contexts as
>> route-reflector clients and I'm now having issues with the routes
>> which the context announces onto another device.
>>
>> ---------------------------------
>> context BLAH-L06
>>  interface loop0 loopback
>>  ip address 10.0.4.5/32
>>
>> router bgp 65100
>>  peer-group WBS internal
>>   next-hop-self
>>   address-family ipv4 unicast
>>    route-map Routes_to_WBS out
>>
>>  neighbor 10.0.3.83 internal
>>   peer-group WBS
>> ---------------------------------
>>
>> Now if I go to 10.0.3.83 and look at a route received from BLAH-L06
>> which originated in context BLAH-L05 I see:
>>
>> lon-gs1wbs#sh ip bgp 10.0.1.205
>> BGP routing table entry for 10.0.1.205/32, version 114
>> Paths: (1 available, no best path)
>> Flag: 0x820
>>  Not advertised to any peer
>>  Local
>>    10.0.4.5 (inaccessible) from 10.0.3.88 (10.0.4.6)
>>      Origin incomplete, metric 0, localpref 100, valid, internal
>>      Originator: 10.0.4.5, Cluster list: 10.0.4.6
>>
>> Why is context BLAH-L06 announcing this route with a next hop of
>> 10.0.4.5 which is in context  BLAH-L05?  The peer-group is setup with
>> 'next-hop-self' so should that not mean it should announce the route
>> with itself as the nexthop - ie 10.0.4.6 (or the physical IP 10.0.3.88) ?
>>
>> Thanks,.
>>
>> Jim.
>>
>>
>> David Freedman wrote:
>>>
>>> You should explicitly set the update-source for ibgp, ensure you have
>>> "update-source loop0" or somesuch in your bgp neighbor config
>>>
>>> ------------------------------------------------
>>> David Freedman
>>> Group Network Engineering
>>> Claranet Limited
>>> http://www.clara.net
>>>
>>>
>>>
>>> -----Original Message-----
>>> From: redback-nsp-bounces at puck.nether.net on behalf of Jim TEST
>>> Sent: Thu 1/7/2010 10:13
>>> To: redback-nsp at puck.nether.net
>>> Subject: [rbak-nsp] Inter-context routing
>>>
>>> Hi,
>>>
>>> I'm trying to setup some intercontext routing which seems to work with
>>> the statics but I'm unable to get BGP running between the 2 contexts,
>>> I'm sure I had this working like this before..
>>>
>>> Here is what I have:
>>>
>>> -------------------------------------------------------
>>> context BLAH-L05
>>>  interface loop0 loopback
>>>   ip address 10.0.4.5/32
>>>
>>>  router bgp 65100
>>>   router-id 10.0.4.5
>>>   address-family ipv4 unicast
>>>    redistribute connected
>>>    redistribute static
>>>
>>>   neighbor 10.0.4.6 internal
>>>    next-hop-self
>>>    address-family ipv4 unicast
>>>    ip route 10.0.4.6/32 context BLAH-L06
>>>
>>> -------------------------------------------------------
>>> context BLAH-L06
>>>  interface loop0 loopback
>>>   ip address 10.0.4.6/32
>>>
>>>  router bgp 65100
>>>   router-id 10.0.4.6
>>>   address-family ipv4 unicast
>>>    redistribute connected
>>>    redistribute static
>>>
>>>   neighbor 10.0.4.5 internal
>>>    next-hop-self
>>>    address-family ipv4 unicast
>>>     ip route 10.0.4.5/32 context BLAH-L05
>>>  -------------------------------------------------------
>>>
>>> Am I missing something obvious?  I can ping between contexts using the
>>> loopbacks so they can see each other, but BGP just sits in Idle or
>>> Connect in either context and I'm not seeing any errors.  Am I missing
>>> something silly here?  I had BGP working between contexts before and I'm
>>> sure it was a very simple setup like this?
>>>
>>> Thanks.
>>>
>>> Jim.
>>> _______________________________________________
>>> redback-nsp mailing list
>>> redback-nsp at puck.nether.net
>>> https://puck.nether.net/mailman/listinfo/redback-nsp
>>>
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