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3750 Switch stack port flapping

Jagan1976
Beginner
Beginner

Hi guys,

Need some advice.

I keep getting link flaps on my stack. Not sure where is the issue.

Powered down and checked all cables and connectivity but issue still there.

  Switch #    Port 1       Port 2

  --------    ------       ------

    1           Ok           Ok

    2          Down          Ok

    3           Ok          Down

    4           Ok           Ok

    5           Ok           Ok

Here is the stack-port summary captured within few minutes.

Switch#/  Stack   Neighbor   Cable    Link   Link   Sync      #         In

Port#     Port              Length    OK   Active   OK    Changes   Loopback

          Status                                          To LinkOK

--------  ------  --------  --------  ----  ------  ----  ---------  --------

  1/1     OK         2      50 cm     Yes    Yes    Yes        1        No

  1/2     OK         5      1 m       Yes    Yes    Yes        3        No

  2/1     Down      None    50 cm     Yes    No     Yes     2367        No

  2/2     OK         1      50 cm     Yes    Yes    Yes        1        No

  3/1     OK         4      50 cm     Yes    Yes    Yes        1        No

  3/2     Down      None    50 cm     Yes    No     Yes        0        No

  4/1     OK         5      50 cm     Yes    Yes    Yes        2        No

  4/2     OK         3      50 cm     Yes    Yes    Yes        1        No

  5/1     OK         1      1 m       Yes    Yes    Yes        1        No

  5/2     OK         4      50 cm     Yes    Yes    Yes        1        No

Switch#/  Stack   Neighbor   Cable    Link   Link   Sync      #         In

Port#     Port              Length    OK   Active   OK    Changes   Loopback

          Status                                          To LinkOK

--------  ------  --------  --------  ----  ------  ----  ---------  --------

  1/1     OK         2      50 cm     Yes    Yes    Yes        1        No

  1/2     OK         5      1 m       Yes    Yes    Yes        3        No

  2/1     Down      None    50 cm     Yes    No     Yes     2367        No

  2/2     OK         1      50 cm     Yes    Yes    Yes        1        No

  3/1     OK         4      50 cm     Yes    Yes    Yes        1        No

  3/2     Down      None    50 cm     Yes    No     Yes        0        No

  4/1     OK         5      50 cm     Yes    Yes    Yes        2        No

  4/2     OK         3      50 cm     Yes    Yes    Yes        1        No

  5/1     OK        None    1 m       Yes    Yes    Yes        1        No

  5/2     OK        None    50 cm     Yes    Yes    Yes        1        No

Switch#/  Stack   Neighbor   Cable    Link   Link   Sync      #         In

Port#     Port              Length    OK   Active   OK    Changes   Loopback

          Status                                          To LinkOK

--------  ------  --------  --------  ----  ------  ----  ---------  --------

  1/1     OK        None    50 cm     Yes    Yes    Yes        1        No

  1/2     OK        None    1 m       Yes    Yes    Yes        3        No

  2/1     Down      None    50 cm     Yes    No     Yes     2367        No

  2/2     OK         1      50 cm     Yes    Yes    Yes        1        No

  3/1     OK         4      50 cm     Yes    Yes    Yes        1        No

  3/2     Down      None    50 cm     Yes    No     Yes        0        No

  4/1     OK         5      50 cm     Yes    Yes    Yes        2        No

  4/2     OK        None    50 cm     Yes    Yes    Yes        1        No

  5/1     OK        None    1 m       Yes    Yes    Yes        1        No

  5/2     OK        None    50 cm     Yes    Yes    Yes        1        No

Switch#/  Stack   Neighbor   Cable    Link   Link   Sync      #         In

Port#     Port              Length    OK   Active   OK    Changes   Loopback

          Status                                          To LinkOK

--------  ------  --------  --------  ----  ------  ----  ---------  --------

  1/1     OK         2      50 cm     Yes    Yes    Yes        1        No

  1/2     OK         5      1 m       Yes    Yes    Yes        3        No

  2/1     Down      None    50 cm     Yes    No     Yes     2367        No

  2/2     OK         1      50 cm     Yes    Yes    Yes        1        No

  3/1     OK         4      50 cm     Yes    Yes    Yes        1        No

  3/2     Down      None    50 cm     Yes    No     Yes        0        No

  4/1     OK         5      50 cm     Yes    Yes    Yes        2        No

  4/2     OK         3      50 cm     Yes    Yes    Yes        1        No

  5/1     OK         1      1 m       Yes    Yes    Yes        1        No

  5/2     OK         4      50 cm     Yes    Yes    Yes        1        No

9 Replies 9

Leo Laohoo
VIP Community Legend VIP Community Legend
VIP Community Legend

Can you post the output to the command "PID: WS-C3750"?

Command not accepted. You mean the sh inventory?

NAME: "1", DESCR: "WS-C3750-48P"

PID: WS-C3750-48PS-S   , VID: V06  , SN: xxxxxxx

NAME: "GigabitEthernet1/0/1", DESCR: "1000BaseSX SFP"

PID: Unspecified       , VID:      , SN: xxxxxxxx

NAME: "2", DESCR: "WS-C3750-48P"

PID: WS-C3750-48PS-S   , VID: V06  , SN: xxxxxxx

NAME: "3", DESCR: "WS-C3750-48P"

PID: WS-C3750-48PS-S   , VID: N/A  , SN: xxxxxxx

NAME: "4", DESCR: "WS-C3750-48P"

PID: WS-C3750-48PS-S   , VID: V06  , SN: xxxxxx

NAME: "5", DESCR: "WS-C3750V2-48PS"

PID: WS-C3750V2-48PS-S , VID: V06  , SN: xxxxx

NAME: "GigabitEthernet5/0/1", DESCR: "1000BaseSX SFP"

PID: Unspecified       , VID:      , SN: xxxxxx

Hi,

You may have a bad stacking cable or a bad interface on one of the switches.

Have a look at this doc for troubleshooting tips:

http://www.cisco.com/en/US/docs/switches/lan/catalyst3750/software/troubleshooting/switch_stacks.html#wp58952

HTH

Leo Laohoo
VIP Community Legend VIP Community Legend
VIP Community Legend

Very nice. 

How the heck am I suppose to help you if you block out the serial number????    The information I seek, whether or not your switch is part of the Field Notice, can be found in the first seven characters.

If you want to block them out, block out the last four characters. 

Jagan1976
Beginner
Beginner

Some more info:

Switch#/   Lost Sync   # times Link   # Changes

  Port#      Events        Not OK      To LinkOK

---------  -----------  ------------  ----------

  1/1               0             0           1

  1/2               0             2           3

  2/1               0          2367        2367

  2/2               0             0           1

  3/1               0             0           1

  3/2               0             0           0

  4/1               0             1           2

  4/2               0             0           1

  5/1               0             0           1

  5/2               0             0           1

Switch# sh switch stack-ring speed

Stack Ring Speed        : 16G

Stack Ring Configuration: Half

Stack Ring Protocol     : StackWise

Leo Laohoo
VIP Community Legend VIP Community Legend
VIP Community Legend

Field Notice attached.

Thanks Leo. I checked the document and my devices do not fall in those groups.

Jagan,

Kindly try changing the Cables now .

Whats the firmware its running?

Regards

Inayath

Thanks Inayath,

Tried changing the cable but still the same. In the end got the switch replaced and the stack is stable now.

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