Re: Connection timeout

[Howard Chu <hyc@symas.com>]

Dave Horsfall wrote:
> On Wed, 18 Jul 2007, Aaron Richton wrote:
>
> > As of 2.3.28, libldap's connections use TCP keepalives. You should be 
> > able to configure your networking stack to get the desired behavior.
>
> But the connection has yet to be made, so keepalives don't enter into it.
>
> We're a homogenous FreeBSD shop, so I'd like to eliminate either FreeBSD 
> or OpenLDAP as a possibility before filing this as a bug with one or the 
> other.  Can someone please do:
>
> On client.example.net, set up ldap.conf with
>
> 	URI	ldap://server1.example.net ldap://server2.example.net
>
> Server1, although resolving, does not run an LDAP server (and may not 
> phyically exist).  If it's on the same subnet as the client, then so much 
> the better as that eliminates any router issues.
>
> What I am seeing is a timeout of a minute before switching to Server2.

That would be normal when trying to contact a nonexistent host, and depends 
entirely on your kernel's TCP stack/connection timeouts. As already noted, you 
can explicitly set a shorter timeout using LDAP_OPT_NETWORK_TIMEOUT.

> Revealingly, should the client attempt to contact itself first (where 
> there is no server) then the switch-over happens right away, but the 
> network guru swears up and down that there are no packet filters in the 
> way.

When a host is alive but simply has no server on the requested port, the TCP 
stack immediately sends a "connection refused" response to the client, so 
generally there should be no delay. Again, this is normal, and any "network 
guru" should know that.
--
  -- Howard Chu
  Chief Architect, Symas Corp.  http://www.symas.com
  Director, Highland Sun        http://highlandsun.com/hyc/
  Chief Architect, OpenLDAP     http://www.openldap.org/project/