From: David Lonnie (david.lonnie@gmail.com)
Date: Thu Nov 06 2008 - 04:53:25 ARST
Hi,
BGP router only advertises the best bgp routes to neighbors.on R2,the best
bgp routes are coming from R3 after weight manipulation.R2 and R3 are ibgp
neighbor.
IBGP learned routes will never advertise to other IBGP neighbors.So R2 will
no longer advertise the bgp routes (coming from R3) to all other IBGP
neighbors (which is R4 in this case). This is a normal behaviour.
wish my explanation can make you sense.
David
David
On Thu, Nov 6, 2008 at 2:37 PM, stephen skinner <stephenski@gmail.com>wrote:
> thanks for your responce david ,
>
> So let me just confirm ,
>
> because the routes that would be advertised to R4 after the weight
> manipulation would be IBGP routes ( from R3) , instead on EBGP routes from
> R1
> R2 will no longer advertise them to R4
>
> Yes ?
>
> On Thu, Nov 6, 2008 at 1:53 PM, David Lonnie <david.lonnie@gmail.com>wrote:
>
>> Hi,
>> I think A would be better.
>> Because R2 receives these routes from 2 paths. One is from R1 with weight
>> set 100, and another is from R3 with weight set 200.
>> So the best bgp routes on R2 are learned from R3.
>> According to ibgp learned routes will never advertise to other BGP
>> neighbors, R2 will never advertise these routes to R4.
>> That's why R4 can't receive routes from R2.
>>
>>
>>
>> David
>>
>>
>> On Thu, Nov 6, 2008 at 1:29 PM, Jason Madsen <madsen.jason@gmail.com>wrote:
>>
>>> I'm not exactly sure what you're trying to do in this scenario. Weight
>>> is
>>> locally significant only. It seems as though if you want to choose
>>> routes
>>> from one path over another by means of using Weight in AS2 you'd want to
>>> apply your weight values on R4. A numerically higher weight (more
>>> preferred) for the routes learned via either R2 or R3.
>>>
>>> Jason
>>>
>>> On Wed, Nov 5, 2008 at 10:08 PM, stephen skinner <stephenski@gmail.com
>>> >wrote:
>>>
>>> > Hello ,
>>> > can i ask a quick question please
>>> >
>>> > My topology
>>> >
>>> > R1
>>> > | |
>>> > R2 R3
>>> > | |
>>> > R4
>>> >
>>> > R1 is in AS1
>>> > R2,R3,R4 are in AS2
>>> >
>>> > R1 peers to R2 and R3
>>> > R2 and R3 peer to R4
>>> >
>>> > router-id are 1.1.1.1 - 2.2.2.3 - 3.3.3.3 - 4.4.4.4
>>> >
>>> > R2 is setting all incoming routes from AS 1 with a weight of 100
>>> > R3 is setting all incoming routes from AS1 with a weight of 200
>>> >
>>> > by default R4 sees routes in its BGP table from both R2 and R3
>>> >
>>> > Question
>>> > when i set on R2 the weight of 200 to all incoming routes from R3.
>>> > R4 no longer sees any routes in its BGP table from R2.
>>> > is this because :-
>>> >
>>> > A R2 is no longer advetising them because the bgp routing process says
>>> not
>>> > to advertise them to R4
>>> >
>>> > B R4 , the BGP proccess is seeing these routes from R2 with a lower
>>> weight
>>> > and decides no tto use them.
>>> >
>>> > TIA
>>> >
>>> > stephen
>>> > --
>>> > Only two things are infinite, the universe and human stupidity, and I'm
>>> not
>>> > sure about the former.
>>> >
>>> >
>>> > Blogs and organic groups at http://www.ccie.net
>>> >
>>> > _______________________________________________________________________
>>> > Subscription information may be found at:
>>> > http://www.groupstudy.com/list/CCIELab.html
>>>
>>>
>>> Blogs and organic groups at http://www.ccie.net
>>>
>>> _______________________________________________________________________
>>> Subscription information may be found at:
>>> http://www.groupstudy.com/list/CCIELab.html
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>
>
>
> --
> Only two things are infinite, the universe and human stupidity, and I'm not
> sure about the former.
Blogs and organic groups at http://www.ccie.net
This archive was generated by hypermail 2.1.4 : Mon Dec 01 2008 - 08:18:29 ARST