BGP keepalive_time

[Arvin Gan]

Hi Ondrej,
    Thanks for your response. My test step as below:
1. create bgp1:   keepalive_time:80, hold_time:240
2. create bgp peer bgp2,  keepalive_time:80, hold_time:240
3. bgp1 connected to bgp2, BGP established, all work normally
4. configure bgp2 keepalive_time to 5, and hold_time to 20
5. use command : "show protocols all bgp1",  session state is not stable, sometime normal, sometime report error hold time expired.
    the negotiated  hold time on bgp1 is changed 20, but keepalive_time is 80

Thanks
Arvin

-----Original Message-----
From: Ondrej Zajicek <santiago at crfreenet.org> 
Sent: Tuesday, June 12, 2018 7:43 PM
To: Arvin Gan <AGan at advaoptical.com>
Cc: bird-users at network.cz
Subject: Re: BGP keepalive_time

On Tue, Jun 12, 2018 at 01:54:07AM +0000, Arvin Gan wrote:
> Hi all,
> 
>      When I used bird, found a question that BGP session received OPEN 
> message, hold_time is updated with min(config_hold_time, 
> peer_hold_time), but keepalive_time is not updated if keepalive_time 
> is not zero,  that maybe cause keepalive_time is more than  the 
> updated hold_time after received OPEN message.
> 
> Line 702 in packets.cc for bgp protocol :
>     conn->keepalive_time = p->cf->keepalive_time ? : conn->hold_time / 
> 3;

That is true, but the answer is just to not configure keepalive time to too short values (or better not configure it at all).

It is not clear what to do when user configured explicit keepalive time which is too short w.r.t. negotiated hold time.

--
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."