I have what appears to be a reproducible test case where my SPA514G phones (with firmware 7.5.5) will reboot after every (about) 4.5 times the dhcp renewal interval with the reboot reason being "DHCP failed". The issue only occurs when running my isc dhcp servers is load-sharing/failover mode. If only one dhcp server is operating, the phones continue to operate indefinitely. It appears to be a dhcp client issue with the phone, possibly related to the issue resolved in CSCtu59498. Only phones (and I only have SPA514G phones) on this lan segment have the problem (other devices work fine). My WAG is there is a problem when multiple offers are received by the phone and only one is completed.
Steps I have taken to isolate/reproduce the issue.
* Setup ISC DHCP servers in load-sharing/failover configuration (on same lan segment as phones).
* Configure dhcp server to return the basic info (netmask, router, ntp, dns), with a renewal time of 180 seconds.
* Configure dhcp server to assign static IP to the phone.
* Start up either dhcp server alone
* Factory reset phone
* Phone comes up, gets address, stays alive indefinitely (or at least longer than I was willing to wait).
* Shutdown active dhcp server
* Start other dhcp server alone
* Factory reset phone
* Phone comes up, gets address, stays alive indefinitely.
* Shutdown active dhcp server
* Start both dhcp servers, make sure they come up in load-sharing mode.
* Factory reset phone
* Phone comes up, gets address, will reboot with "DHCP failed" reason after 13:40 uptime (and continues to reboot after every 13:40 uptime).
* Shutdown either dhcp server, and the phone will then reboot one last time, and then stays operational (just as in the previous tests with just one dhcp server running).
I have pcap files from a mirror port watching the phone port. From a quick look, there is nothing unusual about the dhcp conversations.
If I change the renewal time to 5 minutes (from 3 minutes), the phone will reboot with "DHCP failed" after about 22 minutes (exact time was not documented). This is also about 4.5 times the renewal time. I did not test with other renewal times (the original problem I started tracking was a reboot after a couple of days of operation, which is consistent with my original dhcp renewal time of 12 hours, but the exact reboot time was not documented).
I do not have a Cisco support contract for these phones (although they were recently purchased new, so in theory they are under warranty), so AFAIK I cannot open a direct TAC case. I can provide more details (specific servers, switches, dhcp server configuration) if needed.
Thanks for any assistance or ideas.
(My current workaround is to only run one dhcp server).
