DHCP don't acknowledges more than 80 users??

Martin Hochreiter linuxbox at wavenet.at
Fri Dec 5 17:43:39 UTC 2008

> In communication interrupted state, the server will be serving roughly 
> half the unused addresses in the pool.
> If you want that to be sufficient for your needs during an outage, you 
> can put enough addresses in the pool
> so that half is sufficient for your needs (if you have that many 
> addresses).  If you want a server to take over the other
> server's work, you can put it in partner down state.  If you want it 
> to take over automatically, you can script up whatever
> tests you think are sufficient to assure you that the other server 
> truly is down (e.g., 30 minute wait, ping, info from a 3rd server that 
> monitors, etc) and have the script put dhcpd in partner down state.  
> Basically, dhcpd does nothing on its own that
> could start allocating duplicate addresses, a potential disaster, 
> simply because of a lack of network connectivity
> between the two dhcp servers.  The other server could be running even 
> if the servers can't talk IP, e.g. a wrongly
> installed acl in a router, and in such a case, the two servers are 
> designed to continue functioning without stepping on
> each other's toes.  The decision to assume the other server truly is 
> out of service is with you, or whatever scripted testing
> you've decided sufficiently mitigates the risk for your needs.
> If the server doesn't seem to be actually serving half the unused 
> addresses in the pool, you could inspect
> the lease file to see what state the unused ips are in both before you 
> kill the other server and after.
> John Wobus
John, thank you for your detailed expanation  - what I don't understand 
is that infact the real primary
server is servering all the clients without any interaction of me.

I did the tests last wednesday by setting shutting down both (3.0.3 and 
3.0.5) makeing the
3.0.5 that was secondary the primary one (by simply coping the config of 
the primary 3.0.3
and changing the IP address)  and start only this dhcpd in the night to 
see if
it works alone next day - what did not succeed.
Now I shuted down the 3.0.5 and started the formerly primary (3.0.3) 
again (with the
same configuration that had the 3.0.5 for testing before) ... and it 
works - without any
partner down setting and without seeing the 3.0.5 any time.

Is there a difference in the behaviour between 3.0.3 and 3.0.5 or is the 
Suse Linux Enterprise dhcpd 3.0.3
patched somehow that it really could do a failover without manual 
"partner down"?


More information about the dhcp-users mailing list