Direct protocol affects BGP

Fabiano D'Agostino fabiano.dagostino96 at gmail.com
Tue Mar 24 22:49:47 CET 2020


There is no gateway because they are directly connected. However my network
topology is the following:
[pc-a - router1 ]=AS 1 ; [pc-b - router 2]=AS 2;
pc-a:
enp0s3
address 192.168.1.11
gw 192.168.1.1
router1:
enp0s3
address 192.168.1.1
enp0s8
192.168.2.2

router1 bgp configuration:
protocol bgp {
    ipv4 {
            import all;
            export all;
   }
local as 1;
neighbor 192.168.2.22 as 2


Il giorno mar 24 mar 2020 alle ore 22:40 Alexander Zubkov <green at qrator.net>
ha scritto:

> There is also no gateway in you "route" output on routes exported from
> bird. Maybe you have some filters that causing it? Could you show your
> config if it is not secret?
>
> On Tue, Mar 24, 2020 at 9:53 PM Fabiano D'Agostino
> <fabiano.dagostino96 at gmail.com> wrote:
> >
> > Yes, 'show route', is from Bird. I don't have route-reflector, but just
> two routers which have a bgp session. Anyway, yes when direct is disabled,
> the bgp session is established.
> >
> > Il giorno mar 24 mar 2020 alle ore 21:45 Alexander Zubkov <
> green at qrator.net> ha scritto:
> >>
> >> "show route" looks a little weird, is it from bird? There are also
> >> commonly a protocol and metric shown.
> >> Those are from your route-reflector? Do you have your bgp sessions up
> >> when direct is disabled?
> >>
> >> On Tue, Mar 24, 2020 at 9:33 PM Fabiano D'Agostino
> >> <fabiano.dagostino96 at gmail.com> wrote:
> >> >
> >> > Good evening Alexander,
> >> >
> >> > Direct protocol enabled:
> >> > 'route' command:
> >> > Destination Gateway Genmask            Flags Metric iface
> >> > 192.168.1.0      *        255.255.255.0       U       0         enp0s3
> >> > 192.168.1.0      *        255.255.255.0       U       32       enp0s3
> >> > 192.168.2.0      *        255.255.255.0       U       0         enp0s8
> >> > 192.168.2.0      *        255.255.255.0       U        32      enp0s8
> >> > 192.168.4.0      *        255.255.255.0       U        32      enp0s8
> >> > 'show route' command:
> >> > 192.168.1.0/24 enp0s3
> >> > 192.168.2.0/24  enp0s8 via 192.168.2.22 on enp0s8
> >> > 192.168.4.0/24 via 192.168.2.22 on enp0s8
> >> >
> >> > Direct protocol disabled:
> >> > 'route' command:
> >> > Destination Gateway Genmask            Flags Metric iface
> >> > 192.168.1.0      *        255.255.255.0       U       0         enp0s3
> >> > 192.168.2.0      *        255.255.255.0       U       0         enp0s8
> >> > 'show route' command:
> >> > empty
> >> >
> >> > Thanks,
> >> >
> >> > Fabiano
> >> >
> >> > Il giorno mar 24 mar 2020 alle ore 21:00 Alexander Zubkov <
> green at qrator.net> ha scritto:
> >> >>
> >> >> I think it would be easier if you showed your route tables in both
> cases.
> >> >>
> >> >> On Tue, Mar 24, 2020 at 8:57 AM Irene Lalioti <
> irene.lalioti at restena.lu> wrote:
> >> >> >
> >> >> > Hello guys!
> >> >> >
> >> >> > Just because today we encountered again the same issue with
> direct, I am very curious on this:
> >> >> >
> >> >> > I totally agree with what you guys explained about the need of the
> direct protocol. Once we set it then reachability works and all is ok.
> >> >> >
> >> >> > Our big question is why was it working before the moment it lost
> the BGP session?? In other words: the set up :
> >> >> >
> >> >> > RS - BGP session with the ROUTER - and behind the Router we have
> Caches.
> >> >> >
> >> >> > Before the router was announcing to the RS(BIRD v2.0.7) the caches
> and that they are reachable by the router. Without any direct.
> >> >> >
> >> >> > Until one day we lose the bgp session, and we can ping the caches
> from the RS but not reachable . Once we set it as direct on the bird then
> all is fine.
> >> >> >
> >> >> > Question is why was it working before without direct ?? :=)
> >> >> >
> >> >> > Many thanks for your time!
> >> >> >
> >> >> > Have a great day all!
> >> >> >
> >> >> > Irene.
> >> >> >
> >> >> > On 23/03/2020 17:07, Fabiano D'Agostino wrote:
> >> >> >
> >> >> > Hi Bernd,
> >> >> > no, the routing "from the kernel" doesn't come via 'learn yes',
> but via RIB, I mean if I do 'route' it shows the directly connected
> networks. The problem is that if I use the Direct protocol, the command
> 'route' shows me two same directly connected networks, one coming from RIB
> and the other one coming from Bird.
> >> >> > I tried protocol bgp { direct; }, but it doesn't change.
> >> >> >
> >> >> > Thanks,
> >> >> >
> >> >> > Fabiano
> >> >> >
> >> >> > Il giorno lun 23 mar 2020 alle ore 16:15 Bernd Naumann <
> bena at spreadshirt.net> ha scritto:
> >> >> >>
> >> >> >> On 23.03.20 16:01, Fabiano D'Agostino wrote:
> >> >> >> > Hi Benedikt,
> >> >> >> > I am just learning Bird and I didn't want to use the Direct
> protocol
> >> >> >> > because using it I have two same routes in the RIB for the
> directly
> >> >> >> > connected networks, one coming from the kernel and the second
> one coming
> >> >> >> > from the direct protocol.
> >> >> >>
> >> >> >>
> >> >> >> Is the routing "from the kernel" coming via `learn yes;`? If you
> have no
> >> >> >> need to import "alien" routes, you can disable `learn` and just
> use
> >> >> >> `direct` and `static` protocol. /* OR if you know that your
> neighbor is
> >> >> >> directly connected to you can also set 'direct' on the `protocol
> bgp`. */
> >> >> >>
> >> >> >> Bernd
> >> >> >>
> >> >> >>
> >> >> >
> >> >> > --
> >> >> > Irene Lalioti
> >> >> > Network Engineer
> >> >> > Fondation RESTENA
> >> >> > 2, avenue de l'Université
> >> >> > L-4365 Esch/Alzette
> >> >> >
> >> >> > Tel: +352 424409 1
> >> >> > Fax: +352 422473
>
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