On Mon, 20 Jan 1997 m.hampson@??? wrote:
> On Friday (17th Jan) we noticed that the main incoming exim mail relay
> at Imperial started to reject connections - well what actually happened
> was that the connection was made but we never got the smtp transactions
> starting.
>
> After a while I rebuild exim, increasing the number of SMTP listens from 5
> to 20. This kind of solved the problem, it still happened, but much less
Rebuild? It seems that you could just put the "smtp_connect_backlog"
param in the config file, right?
> often. With this number of listens it also became clear what was going
> on - lots of connections where hanging in SYS_RECV state. Tracerouting
> those connections pointed them all to a part of the US backbone that was
> having routing problems.
Common cause of this kind of problem.
> It may be a good idea to increasing the number of listens from 5. I agree
> that this cannot solve such a problem in all cases, but it certainly seemed
> to help a lot in this case.
The backlog param has different limits on different systems. 5 used to
be the old limit on many system. New systems are generally higher,
sometimes 128 or 256.
> Views anybody?
Document it. Put into a troubleshooting guide, so if it breaks for
someone, they know to increase "smtp_connect_backlog".
> Martyn
> --
> +--------------------------------------------------------------------+
> | Martyn Hampson | Tel: 0171 594 6973 |
> | Imperial College | Fax: 0171 594 6958 |
> | Computer Centre | E-Mail: M.Hampson@??? |
> | London SW7 2BP, ENGLAND | "Don't just do something, sit there!" |
> +--------------------------------------------------------------------+
Tom
