Hi, I have intermitant problems with 3750 switch. Cisco TAC has not been able to find the problem. 1 CCIE consultant tried but failed also.
1.intermitant loss of voice quality on IPphone(7911 and 7940).
2.STP TC comming FROM stackport(The root change for 1 second causing network and voice outage).
4 3750G-12S (L2 aggregation and STP root)
12 wiring closet with anywhere from 1 to 8 stackets 3750 switch.
2 wiring closet made with legacy 3500XL (will be replace in the next few weeks)
Link between L2aggregation and wiring closet are all cross-stack etherchannel
(2 link with 1 blocking for 3500XL)
STP mode is PVST+ , vlan can span multiple wiring closet.
What was done...
Replaced all switch,cable,gbic
QOS configuration is perfect(validated by TAC and our SE)
There is no link flapping
debug output show one switch(never the same) in the wiring closet stack declare itself the STP root.
Conclusion...need fresh idea on this