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Walkthrough Wednesdays

Cisco 7900[8.0.3] phones resetting randomly -Callmanager 4.1.3sr5d

I  have phones connected to 6500 series switches , 7912G phones keeps resetting randomly.

There are 796X phones which works fine.

I tried increasing the Keepalive in callmanager to 45 secs but still the issue persists.

I can see the below logs in 6500.

2011 Jan 02 16:28:26 IST +05:30 %SYS-3-PORT_DEVICENOLINK:Device on port 3/2 powered but no
link up
2011 Jan 02 16:28:26 IST +05:30 %SYS-3-PORT_DEVICENOLINK:Device on port 5/2 powered but no
link up
2011 Jan 02 16:28:26 IST +05:30 %SYS-3-PORT_DEVICENOLINK:Device on port 5/44 powered but
no link up


If this error message comes frequently, the problem could be with Ip phone or cable which exceeds the max. distance of 100 meters.

1. Try plugging 7912G into a known good port if u suspect the ip phone

2. Try plugging a known good Ip phone into the port if u think port or cable might be bad

3. Check config. and make sure the switch is in Auto mode, also make sure sufficient power is available for the Ip phone.

Try this and come up with good result....

All these basic steps are already done.

Still the 7912G phones alone resets randomly.

This may happen due to phones operating in LAN with lot of broadcast or multicast traffic. Under heavy broadcast or multicast traffic, the phone's interrupt stack can grow more than 64 bytes to 128 bytes.

The main problem behind IP phones getting reset is that the Interrupt Request (IRQ) stack overflows in the phone. The fix below is an increase of the IRQ stack size to 128 to prevent the stack from overflowing. The problem is that the IRQ buffer is not large enough, and can overflow causing the phone to go dead. By increasing its size, the overflow is prevented from stepping on another part of the phone's memory space and the phone does not go dead.

The resolution for this issue is to upgrade the firmware of the phone to a different load which has this bug fixed.

I have upgraded the firmware in Phones 7912G to 8.0.4 but still I am

facing the same issue.

Could be a new defect. Moreover Cisco is gonna announce End of Support for 7912 phones.

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