Odd network performance - 2960-S - Unplug and re-plug network cable

[adam.crutchley]

Hi Guys,

I have a bit of an odd issue which I hoped somebody may shed some light on.

I have a 2960-S switch which is used by an engineer to build laptops; we have noticed a few issues with network performance degrading over time to the laptops once they have been connected for a while.

The switch is connected to our company LAN, when we initially connect a laptop and ping across to the build server or next hop switch the ping result is under 3ms. But after about an hour the ping rate drops to > 200ms (no building going on just the laptop sat doing nothing throughout this time).

However, if I unplug the laptops Ethernet cable and plug it back in the ping response returns to < 3ms.

This is causing issues with the laptop build process as it starts to interfere with the laptop imaging process.

The switch is running IOS - 15.2(2)E9

The laptops are Windows 10

Any thoughts would be appreciated 

Adam

#2960-S

[Georg Pauwen]

Hello,

can you post the output of:

show process cpu history

sho proc cpu sorted | e 0.0

Also, there is always a chance that the laptop NICs and/or the cables you are using are causing this. Check if the behavior is consistent for all laptops, and try and change the cable (you might want to try a Category 6 or higher cable)...

[adam.crutchley]

Hi Georg,

Thanks for getting in touch, please find the CPU outputs below:

I have tried changing cables  (all are CAT 6), I will try a different model of laptop this weekend as we get them in batches so only have 1 model at the moment.

Rm6-Cab11#show processes cpu history

      111111111111111112222211111333331111111111111111111111111111

      555555566666999991111166666111116666666666777779999977777666

  100

   90

   80

   70

   60

   50

   40

   30                            *****

   20 **********************************************************

   10 **********************************************************

     0....5....1....1....2....2....3....3....4....4....5....5....6

               0    5    0    5    0    5    0    5    0    5    0

               CPU% per second (last 60 seconds)

      321222222222222222222222222222222222222222222222222222222222

      159444455455414145525775734443559554335245555545155455588575

  100

   90

   80

   70

   60

   50

   40

   30 **     ** **     ** *****     *****   *  ***** * ** ******

   20 ##########################################################

   10 ##########################################################

     0....5....1....1....2....2....3....3....4....4....5....5....6

               0    5    0    5    0    5    0    5    0    5    0

               CPU% per minute (last 60 minutes)

              * = maximum CPU%   # = average CPU%

      323333323333432334323432322333332333333233333222333234333233233333333323

      090000172000109001092069098000007003000600002999008821502800902061000892

  100

   90

   80

   70

   60

   50

   40             *    *   **                           *  **         *    *

   30 **********************************************************************

   20 ########################*##############**#############################

   10 ######################################################################

     0....5....1....1....2....2....3....3....4....4....5....5....6....6....7..

               0    5    0    5    0    5    0    5    0    5    0    5    0

                   CPU% per hour (last 72 hours)

                  * = maximum CPU%   # = average CPU%

Rm6-Cab11#show processes cpu sorted | e 0.0

CPU utilization for five seconds: 18%/0%; one minute: 17%; five minutes: 17%

PID Runtime(ms)     Invoked      uSecs   5Sec   1Min   5Min TTY Process

155   188275396    38496028       4890  9.99% 11.07% 11.43%   0 Hulc LED Process

   4    15592503      877159      17776  2.79%  0.84%  0.90%   0 Check heaps

161        1077         293       3675  0.19%  0.31%  0.22%   1 SSH Process

[Leo Laohoo]

15.2(2)E9 is a very, very stable firmware. The place where I work has this version as a standard and we have not seen anything "funny" with this version.
Can you post the complete output to the command "sh interface <PORT> controll"?
Another thing, if it is used to build laptops, what is the Ethernet NIC make and model? What firmware version is it running on?