[BFD] BFD is Not working after system reboot.

[seunghwan hwang]

Hello K.

Thanks for checking in this issue.
But, I can't understand.
If it was because of the iptables, it would have been a problem for BGP as
well.
And I'm not using iptables rules, So Any packets weren't dropped.

* iptables status
============================================================
# iptables -L
Chain INPUT (policy ACCEPT)
target     prot opt source               destination

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination
============================================================

* Port status
============================================================
# netstat -lnp | grep bird
tcp        0      0 0.0.0.0:179             0.0.0.0:*               LISTEN
     44890/bird
udp        0      0 0.0.0.0:3784            0.0.0.0:*
    44890/bird
udp        0      0 0.0.0.0:4784            0.0.0.0:*
    44890/bird
unix  2      [ ACC ]     STREAM     LISTENING     320049   44890/bird
    /run/bird/bird.ctl
unix  2      [ ACC ]     STREAM     LISTENING     398938   44893/bird6
     /run/bird/bird6.ctl
============================================================

* BIRD Status
============================================================
# birdc show bfd sessions
BIRD 1.6.8 ready.
bfd1:
IP address                Interface  State      Since       Interval
 Timeout
10.11.251.4               ---        Init       09:37:57      2.000    6.000
10.11.250.4               ---        Init       09:37:56      2.000    6.000

# birdc show protocols
BIRD 1.6.8 ready.
name     proto    table    state  since       info
kernel1  Kernel   master   up     09:37:52
direct1  Direct   master   up     09:37:52
device1  Device   master   up     09:37:52
static1  Static   master   up     09:37:52
bfd1     BFD      master   up     09:37:52
as1      BGP      master   up     09:37:56    Established
as2      BGP      master   up     09:37:57    Established
============================================================

Is it related to the increase in this value?
============================================================
# netstat -s
...
Udp:
    52759 packets received
    0 packets to unknown port received
    0 packet receive errors
    34365164 packets sent
    0 receive buffer errors
    0 send buffer errors
    IgnoredMulti: 3399
...
============================================================

Please check it.

Regards.

2020년 7월 16일 (목) 오후 8:05, Kees Meijs | Nefos <kees at nefos.nl>님이 작성:

> Hi Seunghwan,
>
> It might be your problem isn't BIRD but packet filter related.
>
> Please check the BFD packets are allowed in iptables c.q. netfilter using
> the correct ports and/or addresses.
>
> A possible reason why it starts working after a manual protocol restart is
> a ESTABLISHED, RELATED rule.
>
> References:
>
>    - https://tools.ietf.org/html/rfc5881 (Encapsulation, IANA
>    Considerations)
>    - https://tools.ietf.org/html/rfc5883 (IANA Considerations)
>
>
> K.
>
> On 16-07-2020 11:00, seunghwan hwang wrote:
>
> Hello.
> BFD is Not working normally.
> My configuration is shown below.
>
> OS: Ubuntu 18.04
> Kernel: 4.15.0-54-generic
> BIRD ver: 1.6.8
> ==================================
> protocol bfd {
>         multihop {
>             min rx interval 300 ms;
>             min tx interval 300 ms;
>             multiplier 3;
>         };
> }
>
> protocol bgp as1 {
>         import all;
>         export all;
>
>         local ~ as ~;
>         neighbor ~  as ~;
>         enable route refresh off;
>         hold time 90;
>         bfd on;
> }
>
> protocol bgp as2 {
>         import all;
>         export all;
>
>         local ~ as ~;
>         neighbor ~  as ~;
>         enable route refresh off;
>         hold time 90;
>         bfd on;
> }
> ==================================
>
> After system reboot(# shutdown -r now), BGP neighbor is established, But
> BFD sessions are stuck in 'INIT' status. And BIRD does not send BFD packets.
> BFD sessions have recovered after restart protocol bfd1(# birdc restart
> bfd1).
>
> Is it a normal situation?
> I think BFD has to start the mechanism after BGP neighbor is UP.
> Is there any missing part of my configurations?
> Please check it.
>
> Regards
>
>
>
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