BGP with ECMP and weight control

[Maria Matějka]

Hello!

Would it be feasible for you to have a special route attribute to be set in filters that would control the nexthop weight? That seems to be probably a most simple solution. 

Maria

On November 19, 2020 5:42:38 PM GMT+01:00, Nigel Kukard <nkukard at LBSD.net> wrote:
>On 11/19/20 4:06 PM, Alexander Demenshin wrote:
>> Hi,
>>
>> I have two uplinks (different AS), and one is more stable/preferred,
>> but when "merge paths" is set to on, all routes are generated with
>> weight 1:
>>
>> 5.21.41.0/24 proto bird
>>         nexthop via 10.16.0.1 dev uplink1 weight 1
>>         nexthop via 10.17.0.1 dev uplink2 weight 1
>>
>> Is there any way to adjust weight for ECMP generated from BGP
>sessions?
>>
>> I could not find any option/attribute when it is related to BGP or
>kernel
>> protocol, while it is possible for OSPF and static protocols (to a
>> degree).
>>
>> Adjusting local preference or med (in BGP) does not really help -
>weight
>> is unchanged, though of course I could force routes from specific AS
>> to be preferred, but then I lose ECMP and if preferred session is
>dropped
>> it takes time to restore connectivity.
>>
>> Thank you! 
>
>
>I'd just like to say I'm very interested in this aswell, it would be an
>amazing feature to have.
>
>
>-N

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