BIRD ignored routes

Nat J net at alcifer.org
Thu Mar 12 18:08:11 CET 2015


Hmm, I did a quick tcpdump the day before but didn't spot any withdrawals.
Today, however , I do see both routes being accepted. The only difference
between before and now is that the next-hop is no longer the same as the IP
of the session where this was learned.


On Mar 11, 2015 5:06 AM, "Ondrej Zajicek" <santiago at crfreenet.org> wrote:

> On Tue, Mar 10, 2015 at 03:04:53PM -0400, Nat J wrote:
> > Hi All,
> >
> > I’m having an issue with bird ignoring some prefixes it’s receiving. I'm
> > new to bird and may be overlooking something simple. The config is
> > essentially this
> >
> > [1] Exabpg1:AS_X < — > BIRD:AS_Y (route-server)
> > [2] Exabgp2:AS_X < — > BIRD:AS_Y (route-server)
> >
> > [3] BIRD:AS_Y < — > BIRD:AS_Z
> >
> > [1] & [2] behave as expected, however when the route-server exports to
> the
> > 2nd BIRD instance the routes are ignored. The debug file unfortunately
> > makes no mention of the routes being ignored. Any suggestions on how I
> can
> > find the cause for those being ignored.
>
> Hi
>
> First thing to try would be to run just one Exabgp link, with disabled
> add-path, to see if something changes. Another good idea would be to try
> to catch the [3] with tcpdump, as the receiver (AS_Z) not only ignore
> these updates, but also consider them to be withdraws.
>
> --
> Elen sila lumenn' omentielvo
>
> Ondrej 'Santiago' Zajicek (email: santiago at crfreenet.org)
> OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net)
> "To err is human -- to blame it on a computer is even more so."
>
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bird> show protocols all
name     proto    table    state  since       info
device1  Device   master   up     12:04:01
  Preference:     240
  Input filter:   ACCEPT
  Output filter:  REJECT
  Routes:         0 imported, 0 exported, 0 preferred
  Route change stats:     received   rejected   filtered    ignored   accepted
    Import updates:              0          0          0          0          0
    Import withdraws:            0          0        ---          0          0
    Export updates:              0          0          0        ---          0
    Export withdraws:            0        ---        ---        ---          0

Exa1     BGP      master   up     12:05:27    Established
  Description:    Exa1
  Preference:     100
  Input filter:   ACCEPT
  Output filter:  ACCEPT
  Routes:         1 imported, 0 exported, 1 preferred
  Route change stats:     received   rejected   filtered    ignored   accepted
    Import updates:              1          0          0          0          1
    Import withdraws:            0          0        ---          0          0
    Export updates:              1          1          0        ---          0
    Export withdraws:            0        ---        ---        ---          0
  BGP state:          Established
    Neighbor address: 192.168.3.4
    Neighbor AS:      65010
    Neighbor ID:      192.168.3.4
    Neighbor caps:    AS4 add-path-rx add-path-tx
    Session:          external route-server AS4
    Source address:   192.168.3.3
    Hold timer:       145/180
    Keepalive timer:  28/60

Exa2     BGP      master   up     12:05:28    Established
  Description:    Exa2
  Preference:     100
  Input filter:   ACCEPT
  Output filter:  ACCEPT
  Routes:         1 imported, 1 exported, 0 preferred
  Route change stats:     received   rejected   filtered    ignored   accepted
    Import updates:              1          0          0          0          1
    Import withdraws:            0          0        ---          0          0
    Export updates:              1          0          0        ---          1
    Export withdraws:            0        ---        ---        ---          0
  BGP state:          Established
    Neighbor address: 192.168.4.4
    Neighbor AS:      65010
    Neighbor ID:      192.168.4.4
    Neighbor caps:    AS4 add-path-rx add-path-tx
    Session:          external route-server AS4
    Source address:   192.168.4.3
    Hold timer:       111/180
    Keepalive timer:  9/60

ExaOut   BGP      master   up     12:13:07    Established
  Description:    main exa
  Preference:     100
  Input filter:   ACCEPT
  Output filter:  ACCEPT
  Routes:         0 imported, 2 exported, 0 preferred
  Route change stats:     received   rejected   filtered    ignored   accepted
    Import updates:              0          0          0          0          0
    Import withdraws:            0          0        ---          0          0
    Export updates:              2          0          0        ---          2
    Export withdraws:            0        ---        ---        ---          0
  BGP state:          Established
    Neighbor address: 192.168.5.4
    Neighbor AS:      65011
    Neighbor ID:      192.168.5.4
    Neighbor caps:    refresh restart-aware AS4 add-path-rx add-path-tx
    Session:          external route-server AS4 add-path-rx add-path-tx
    Source address:   192.168.5.3
    Hold timer:       187/240
    Keepalive timer:  44/80

================

bird> show protocols all
name     proto    table    state  since       info
device1  Device   master   up     12:11:29
  Preference:     240
  Input filter:   ACCEPT
  Output filter:  REJECT
  Routes:         0 imported, 0 exported, 0 preferred
  Route change stats:     received   rejected   filtered    ignored   accepted
    Import updates:              0          0          0          0          0
    Import withdraws:            0          0        ---          0          0
    Export updates:              0          0          0        ---          0
    Export withdraws:            0        ---        ---        ---          0

EXT      BGP      master   up     12:13:07    Established
  Preference:     100
  Input filter:   ACCEPT
  Output filter:  ACCEPT
  Routes:         2 imported, 0 exported, 1 preferred
  Route change stats:     received   rejected   filtered    ignored   accepted
    Import updates:              2          0          0          0          2
    Import withdraws:            0          0        ---          0          0
    Export updates:              2          2          0        ---          0
    Export withdraws:            0        ---        ---        ---          0
  BGP state:          Established
    Neighbor address: 192.168.5.3
    Neighbor AS:      65012
    Neighbor ID:      192.168.5.3
    Neighbor caps:    refresh restart-aware AS4 add-path-rx add-path-tx
    Session:          external AS4 add-path-rx add-path-tx
    Source address:   192.168.5.4
    Hold timer:       182/240
    Keepalive timer:  47/80

bird> show route all
192.168.200.0/24   via 192.168.5.3 on eth1 [EXT 12:13:07] * (100) [AS65010i]
        Type: BGP unicast univ
        BGP.origin: IGP
        BGP.as_path: 65010
        BGP.next_hop: 192.168.10.4
        BGP.local_pref: 100
                   via 192.168.5.3 on eth1 [EXT 12:13:07] (100) [AS65010i]
        Type: BGP unicast univ
        BGP.origin: IGP
        BGP.as_path: 65010
        BGP.next_hop: 192.168.11.4
        BGP.local_pref: 100
bird>


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