From: stephen skinner (stephenski@gmail.com)
Date: Thu Nov 06 2008 - 04:55:57 ARST
thats brillian and it does make sense , many thanks to you david and jason
cheers
On Thu, Nov 6, 2008 at 2:53 PM, David Lonnie <david.lonnie@gmail.com> wrote:
> 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
>>>> >
>>>> >
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>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>
>>
>> --
>> Only two things are infinite, the universe and human stupidity, and I'm
>> not sure about the former.
>>
>
>
-- 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
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