I am here 3rd time for same problem.
I have 2 site one is IPPL(core switch) and 2nd one is IPGCL(working on ring tropology ) .IPGCL is connect to IPPL by trunk port. Under IPGCL i have 16 L2 switch that are used ring tropology with IPGCL. now the problem is some time interface VLAN4 goes down for 1 or 2 minute then it automatically goes up.
Could you help me about this problem.