Symptom
Interface speed transitions to 100Mbps automatically. It can effect random ports at random time.
Conditions
-Auto negotiation enabled on switch.
-Issue only observed for IP Phone model 8851.
Workaround
-Bouncing the port in any way resolves the issue.
-Apply 'speed 1000' on port.
Further Problem Description
-IP phones negotiate a speed of 1GB initially.
-Suddenly any random IP phone will move to 100Mb speed.
-Bouncing the port resolves the issue for some time(could be hours or days).
-Issue may be seen again on same or other ports on the switch.
-There is no identified trigger as of now.
-Issue is also isolated to only IP phones model 8851.
-Laptops connecting directly to the switchport are not exhibiting this problem.
