Hi,

I have 7 numbers of 3750 Cisco Switch, they all are part of single stack. I found, there was flapping in the stack ports of Sw-3 (port-2) and Sw-4(port-1) which are directly connected with stack cable.

I have replaced the stack cable with new one, but now whole stack is flapping. Please help, I have attached the log below.

3730741: Jan  6 00:21:34.368: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 2 Switch3 has changed to state UP
3730742: Jan  6 00:21:35.291: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 1 Switch 4 has changed to state UP
3730743: Jan  6 00:21:36.382: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 2 Switch 3 has changed to state DOWN
3730744: Jan  6 00:21:37.304: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 1 Switch4 has changed to state DOWN
3730745: Jan  6 00:21:38.319: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 1 Switch 4 has changed to state UP

STACK#sh switch neighbor
  Switch #    Port 1       Port 2
  --------    ------       ------
      1        None          None
      2         1             3
      3         2            None
      4        None          None
      5         4             6
      6        None          None
      7        None           1

STACK#sh switch
Switch/Stack Mac Address : 0011.bbf1.4780
                                           H/W   Current
Switch#  Role   Mac Address     Priority Version  State
----------------------------------------------------------
*1       Master 0011.bbf1.4780     15     0       Ready
2       Member 0017.9409.4600     13     0       Ready
3       Member 0012.4347.0800     11     0       Ready
4       Member 0017.5ac4.2c00     9      0       Ready
5       Member 0017.95a9.5600     7      0       Ready
6       Member 000f.f749.5580     5      0       Ready
7       Member 0017.957f.5c00     3      0       Ready

STACK#sh swit stack-ring sp

Stack Ring Speed        : 16G
Stack Ring Configuration: Half
Stack Ring Protocol     : StackWise