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-   -   DHCP Lease (http://support.avaya.com/forums/showthread.php?t=10353)

kirchenlo 08-25-2015 06:04 AM

DHCP Lease
Does anyone know how IP Office does handle the DHCP lease, when I use IP Office as DHCP server? It seems that the DHCP lease of IP Office is 3 days but I am not 100% shure.

I have a problem at a customer that the phones are rebooting regularly and I have the impression it is related to the DHCP lease, any idea?

This is what I found about the DHCP lease, so therefore I think my issue might related to the DHCP lease:

Option 51 - DHCP lease time.

If this option is not received, the DHCPOFFER is not be accepted. Avaya recommends a lease time of six weeks or greater. If this option has a value of FFFFFFFF hex, the IP Address lease is assumed to be infinite as per RFC 2131, Section 3.3, so that renewal and rebinding procedures are not necessary even if Options 58 and 59 are received. Expired leases cause Avaya IP Telephones to reboot. Avaya recommends providing enough leases so an IP Address for an IP telephone does not change if it is briefly taken offline.

Does anyone have an idea?

markgallagher 08-25-2015 06:41 AM

Just did a quick test and you are correct, the lease time when using the IP Office itself for DHCP is 3 days.

The phone will check its lease halfway through that period and if allowed (ie. the IP Office is still supporting DHCP and the address hasn't been assigned to any other device) will renew the lease. So effectively the lease is checked and extended every one and half days.

The frequent restarts would only be caused by DHCP if for some reason the DHCP signalling was being blocked. But if that were the case then the phone would keep cycling until you statically addressed it. My suspicion would be elsewhere (assuming the IP Office is the only server on the network doing DHCP?). [You can see and track the DHCP leases in IP Office Monitor, and the phone restarts to see if they coincide]

The obvious one with IP Office is that the phones will go through a restart each time the IP Office is restarted (and whilst it is improving a lot of IP Office config changes still require a system restart).

havel3 08-25-2015 10:25 AM

Most common cause of regular IP Phone reboot is a bad configured or congested network.
The reboot starts when the keep alive packets to/from the gatekeeper or phone are missed.

claud4 08-26-2015 06:00 AM

DHCP lease time decided by DHCP server , IP Phone has nothing to do with it .
Frequent restart problable reasons are
1- Network congestion - and phones cannot contact with IP Office
2- PoE Power output not enough from the switch . Try with lesser phones on same switch
3-Switch may be overheating
4- IP confict . Most probably some other device or PC taking same IP of IP-Office .

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