BFD sessions with FFR (VyOS) won't establish

[Lukas Haase]

Hi Alexander,

Thanks. I have tried

sysctl -w net.ipv4.ip_local_port_range="49152 65535"

but unfortunately no change.
What I do not understand is that Interval and Timeout is wrong on the non-working peer:

# birdc show bfd sess
BIRD 2.0.8 ready.
bfd1:
IP address                Interface  State      Since         Interval  Timeout
172.20.215.130            ---        Up         2024-01-16      0.100    0.500
172.20.215.131            ---        Init       2024-01-16      1.000   10.000

Do these parameters need to be identical among peers, similar as with OSPF? Note, they are identical to my knowledge but could there be any implicit setting that causes discrepancy between the peers and would cause a connection being stuck in "Up"? For example, in bird I have "idle tx interval 500 ms" but I could not find a corresponding option in VyOS/FFR.

Could you think of any tcpdump/netcat debug?

Thanks,
Luke



> Gesendet: Mittwoch, 17. Januar 2024 um 00:35 Uhr
> Von: "Alexander Zubkov" <green at qrator.net>
> An: "Lukas Haase" <lukashaase at gmx.at>
> Cc: bird-users at network.cz
> Betreff: Re: BFD sessions with FFR (VyOS) won't establish
>
> Hi,
> 
> There were reports here in the list that some BFD peers do not allow
> connections from non-standard ports and bird do not choose source port
> specifically. So you might need to tune your sysctl like that:
> 
> net.ipv4.ip_local_port_range = 49152 65535
> 
> Not sure if this is the case, but I would try that first.
> 
> Regards,
> Alexander
> 
> On Tue, Jan 16, 2024 at 9:15 AM Lukas Haase via Bird-users
> <bird-users at network.cz> wrote:
> >
> > Hello,
> >
> > My BFD session between bird work fine but the ones but the ones to VyOS (which uses FFR) just won't connect:
> >
> > # birdc show bfd sess
> > BIRD 2.0.8 ready.
> > bfd1:
> > IP address Interface State Since Interval Timeout
> > 172.20.215.131 --- Init 10:39:14.183 1.000 10.000
> > 172.20.215.130 --- Up 10:42:03.901 0.100 0.500
> >
> > 172.20.215.131 is here a VyOS box and its FFR config looks like:
> >
> > !
> > bfd
> > peer 172.20.215.129 multihop local-address 172.20.215.131
> > detect-multiplier 10
> > transmit-interval 100
> > receive-interval 100
> > exit
> > !
> > exit
> > !
> > end
> >
> >
> > For reference, my bird config is trivially:
> >
> > protocol bfd
> > {
> > interface "local-ibgp" {
> > min rx interval 100 ms;
> > min tx interval 100 ms;
> > idle tx interval 500 ms;
> > multiplier 10;
> > };
> > neighbor 172.20.215.130 local 172.20.215.129 multihop;
> > neighbor 172.20.215.131 local 172.20.215.129 multihop;
> > }
> >
> >
> > I have turned off firewall. What else could go wrong?
> >
> >
> > Thanks,
> > Luke
>