Hi, We had for a long time four stacks of 3550 and 3560 connected by Optic Fiber to a Layer 3 swtich 6500.Today we have chaged those stack by 3750 switches and the problem go on. This is the problem: Management IP of Vlan1 stop responding by a short time, meanwile, the PC's conected to those stacks go on working and all the stacks are shown by CDP protocol in the 6500. We have no events, no error on fiber, nothing at all. We have no control what are conected to those stack, the most are Dell computers but there is no control which device al conected to us stacks.
The management IP belong to the same subnet in a lonely vlan with all devices, PC's, printers, etc-