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Bizarre problem with odd IP addresses

We have a remote site, fiber-connected with a single 24-port powered switch. I am getting alot of reports of phones spontaeously resetting. When I look at the CCM Syslog, I see the reason code as Keepalive timeouts. However, QoS is configured on this switch and the phone resets are happening one at a time, rather than several at once. Even more bizarre, when I started looking for patterns, I found that only phones that had pulled an odd DHCP IP address are having a problem. No phone with an even numbered IP address has had a problem and every phone with an odd numbered IP has, typically 3 or 4 times a day.

The switch is a 3560-24PS running IPBase 12.2(46). There are no ACL's or firewalls on the voice network. Has anyone seen anything like this before?

I am currently waiting on one of the network engineers to get on-site to manually switch one of the phones to an even address for one of the power users to verify.


Re: Bizarre problem with odd IP addresses

We seem to have found the solution. I don't know why, but the issue seems to have been very short lease times on the Cisco Router DHCP Server. We were using 1 hour leases, and the problem has disappeared now that we have increased those lease times to 12 hour leases.

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