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Hi Roberto:

Please open a launchpad bug documenting this issue in os-ken.

Thanks!

On Wed, Nov 16, 2022 at 3:41 PM Roberto Bartzen Acosta <
roberto.acosta at luizalabs.com> wrote:

> Thanks Sean.
>
>  I believe that the os-ken driver is not coded to honor this premise
> because the below function can learn new paths from peer update messages.
>
> https://opendev.org/openstack/os-ken/src/branch/master/os_ken/services/protocols/bgp/peer.py#L1544
>
> Em qua., 16 de nov. de 2022 às 09:14, Sean Mooney <smooney at redhat.com>
> escreveu:
>
>> On Wed, 2022-11-16 at 09:05 -0300, Roberto Bartzen Acosta wrote:
>> > Sorry for the mistake, I meant, the bgpspeaker should only
>> "*advertise*!"
>> > and not "learn" the AS_PATHs via BGP.
>> yes that used to be the scope of that project to advertise only and not
>> learn
>> so i would geuss either that has change recently and they broke backward
>> compaitbly
>> or they have refactord it to use an external bgp speaker like frr and it
>> learns by default
>>
>> i dont really see anything here
>> https://github.com/openstack/neutron-dynamic-routing/commits/master
>> im not really familar with the internals of the project but i dont see
>> any code to learn routs form
>>
>>
>> https://github.com/openstack/neutron-dynamic-routing/blob/master/neutron_dynamic_routing/services/bgp/agent/driver/os_ken/driver.py
>>
>> it just has code for advertizing and withdrawing routes.
>>
>>
>>
>> >
>> > Em qua., 16 de nov. de 2022 às 08:57, Sean Mooney <smooney at redhat.com>
>> > escreveu:
>> >
>> > > On Wed, 2022-11-16 at 08:43 -0300, Roberto Bartzen Acosta wrote:
>> > > > Hey folks,
>> > > >
>> > > > Please, I have a question here, the bgpspeaker should only "learn"
>> and
>> > > not
>> > > > "advertise" the AS_PATHs via BGP, right?
>> > >
>> > > its been a while since i looked at it but in the past it did not
>> supprot
>> > > learning at all
>> > >
>> > > it just advertised the routes for the neutron netowrks
>> > >
>> > > >
>> > > > In my tests, I can see that it is learning routes from BGP
>> neighbors.
>> > > This
>> > > > behavior can cause an AS_PATH loop because the bgpspeaker learns
>> back its
>> > > > own advertised routes, and I see a message like this in the logs:
>> > > >
>> > > > 2022-11-11 19:45:41.967 7220 ERROR bgpspeaker.peer [-] AS_PATH on
>> UPDATE
>> > > > message has loops. Ignoring this message:
>> > > >
>> > >
>> BGPUpdate(len=91,nlri=[],path_attributes=[BGPPathAttributeMpReachNLRI(afi=2,flags=144,length=46,next_hop='2001:db7:1::1',nlri=[IP6AddrPrefix(addr='2001:db9:1234::',length=64)],safi=1,type=14),
>> > > > BGPPathAttributeOrigin(flags=64,length=1,type=1,value=0),
>> > > > BGPPathAttributeAsPath(flags=80,length=10,type=2,value=[[65001,
>> > > >
>> > >
>> 65000]])],total_path_attribute_len=68,type=2,withdrawn_routes=[],withdrawn_routes_len=0)
>> > > >
>> > > > This can be fixed by suppressing the neighbor route advertisement
>> (using
>> > > > route-map export), but have I misunderstood how
>> neutron-dymanic-routing
>> > > > works or do we have a possible bug here?
>> > > >
>> > > > Regards
>> > > >
>> > >
>> > >
>> >
>>
>>
>
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