Re: Bgp update source loopback

Raghav,
it would be a logical one. Playing in the lab is one thing, having such
an inconsustency in a large environment would definitely cost you some
troubles when something goes wrong and your night-watch engineer will
have to troubleshot asking himself why on the Earth one peer uses
physical interface while the other goes from the loopback :-)
A nice approach is KISS, keep it simple stupid, as Occam would say
"entities must not be multiplied beyond necessity" :-)

HTH
A.

On 5/16/2010 3:37 PM, Raghav Bhargava wrote:
> Hi Alexei,
>
> I have tested this thing in a non MPLS environment. I think as long as
> you have NLRI reachibilty to the loopback it does not creates any
> inconsistency, but maybe i could be wrong.
>
> -Raghav
>
> On Sat, May 15, 2010 at 10:03 PM, Alexei Monastyrnyi
> <alexeim73_at_gmail.com <mailto:alexeim73_at_gmail.com>> wrote:
>
> Technically speaking sure, but that would introduce inconsistency
> and certain level of unpredictability of this peering behavior. As
> many folks have pointed out, peering from IP address of physical
> interface vs loopback involves peer IP address reachbility and in
> case of MPLS environments also proper labes assignments.
>
> The easiest way to understand is to play around with it on
> Dynamips, real quick setup of 2 to 4 routers would do.
>
> HTH
> A
>
>
> On 5/16/2010 2:28 PM, Raghav Bhargava wrote:
>> Since we all are talking about BGP update source loopback.
>>
>> Experts,
>>
>> Can we have below command on one Router and not on the other one and form
>> ibgp peering..:)
>>
>> neighbor x.x.x.x update-source-loopback x
>>
>>
>> Raghav
>>
>> On Sat, May 15, 2010 at 9:13 PM, Mustafa Yadav<mustafa.yadav_at_gmail.com> <mailto:mustafa.yadav_at_gmail.com>wrote:
>>
>>
>>> Good be a good troobleshooting question if it is not configured.
>>>
>>> On Sun, May 16, 2010 at 6:55 AM, Scott Morris<swm_at_emanon.com> <mailto:swm_at_emanon.com> wrote:
>>>
>>>
>>>> If you decide not to, there will be lots of extra work in order to get
>>>>
>>> your
>>>
>>>> next-hop information correlating with your label path information....
>>>>
>>>>
>>>>
>>>>
>>>> Mustafa Yadav wrote:
>>>>
>>>> Hi All,
>>>>
>>>> I see i-bgp configuration in all mpls labs done by using update-source
>>>> loopback.Why do we have to use loopback as a source?If we do not use I
>>>>
>>> think
>>>
>>>> ibgp also come up.Is not that right?
>>>>
>>>>
>>>> Blogs and organic groups athttp://www.ccie.net
>>>>
>>>>
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>
>
>
>
> --
> Warm Regards
> Raghav

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Received on Sun May 16 2010 - 16:02:42 ART