01-30-2012 07:18 AM - edited 03-07-2019 04:37 AM
Currently I have two Cisco 3750 switches stacked. They are both
Model : WS-C3750G-12S
IOS: Version 12.2(55)SE4
The stack is working as the distribution layer of my network and is currently servicing a number of buildings each with 3 fibre interlinked Cisco switches and links back to the 3750 stack via the 1st and 3rd switch for full redundancy.
On the 3750 stack - Show interface description.
Gi1/0/1 up up
Gi1/0/2 up up Link to Block_1
Gi1/0/3 up up Link to Block_10
Gi1/0/4 up up Link to Block_20
Gi1/0/5 up up Link to Block_30
Gi1/0/6 up up Link to Block_40
Gi1/0/7 up up Link to Block_50
Gi1/0/8 up up Link to Block_60
Gi1/0/9 down down Link to Block_70
Gi1/0/10 up up Link to Block_80
Gi1/0/11 up up
Gi1/0/12 down down
Gi2/0/1 admin down down
Gi2/0/2 up up Link to Block_1
Gi2/0/3 up up Link to Block_10
Gi2/0/4 up up Link to Block_20
Gi2/0/5 up up Link to Block_30
Gi2/0/6 up up Link to Block_40
Gi2/0/7 up up Link to Block_50
Gi2/0/8 up up Link to Block_60
Gi2/0/9 up up Link to Block_70
Gi2/0/10 up up Link to Block_80
Gi2/0/11 up up Link to Block_90
Gi2/0/12 up up Link to Block_100
In the Logs I am seeing the following interfaces flap very regularly..
GigabitEthernet1/0/6 Block_40
GigabitEthernet1/0/5 Block_30
GigabitEthernet1/0/10 Block_80
GigabitEthernet2/0/5 Block_30
GigabitEthernet2/0/6 Block_40
GigabitEthernet2/0/9 Block_70
At first I thought it was the IOS version so upgraded it to the most current version and the ports still flap.
Now I am thinking it may be the edge devices/ SFP incomparability or even spanning tree.
01-30-2012 01:11 PM
These are SFP links. Define "flap"? Can you please post the output to the "sh log"?
01-31-2012 01:04 AM
Correct. There are 24 SFP links on the stack which are connected to each building via fibre which is presented at the other end as SC. The switches in each vary between Cisco 3550 24PWR and 3524tXL, therefore the switches in each building are connected to the patch panel using SC-SC MM fibre.
Here are the logs from the last two hours.
Jan 31 06:55:42 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/10, changed state to down
Jan 31 06:55:45 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/10, changed state to up
Jan 31 07:20:38 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet2/0/5, changed state to down
Jan 31 07:20:41 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet2/0/5, changed state to up
Jan 31 07:32:29 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet2/0/6, changed state to down
Jan 31 07:32:32 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet2/0/6, changed state to up
Jan 31 07:32:53 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet2/0/5, changed state to down
Jan 31 07:32:57 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet2/0/5, changed state to up
Jan 31 07:47:41 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet2/0/2, changed state to down
Jan 31 07:47:44 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet2/0/2, changed state to up
Jan 31 07:50:45 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet2/0/2, changed state to down
Jan 31 07:50:48 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet2/0/2, changed state to up
Jan 31 07:52:52 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet2/0/5, changed state to down
Jan 31 07:52:56 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet2/0/5, changed state to up
Jan 31 07:52:57 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet2/0/5, changed state to down
Jan 31 07:53:00 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet2/0/5, changed state to up
Jan 31 07:55:19 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet2/0/6, changed state to down
Jan 31 07:55:23 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet2/0/6, changed state to up
Jan 31 07:56:03 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet2/0/5, changed state to down
Jan 31 07:56:06 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet2/0/5, changed state to up
Jan 31 07:56:11 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet2/0/5, changed state to down
Jan 31 07:56:14 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet2/0/5, changed state to up
Jan 31 07:57:55 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet2/0/2, changed state to down
Jan 31 07:57:58 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet2/0/2, changed state to up
Jan 31 07:59:32 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/5, changed state to down
Jan 31 07:59:35 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/5, changed state to up
Jan 31 08:11:58 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/10, changed state to down
Jan 31 08:12:02 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/10, changed state to up
Jan 31 08:27:31 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet2/0/6, changed state to down
Jan 31 08:27:34 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet2/0/6, changed state to up
Jan 31 08:29:36 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet2/0/5, changed state to down
Jan 31 08:29:39 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet2/0/5, changed state to up
Jan 31 08:38:55 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet2/0/6, changed state to down
Jan 31 08:38:58 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet2/0/6, changed state to up
Jan 31 08:41:44 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet2/0/5, changed state to down
Jan 31 08:41:48 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet2/0/5, changed state to up
If you need anymore information, just ask. I will be more than happy to provide.
Thanks
01-31-2012 01:00 PM
Freak me! Now THAT is what I call "flapping"!
Here's how to fix this:
1. Change the patch cable at both sides;
If it's still flapping;
2. Change the SFP and GBIC at both sides;
If it's still flapping;
3. Get an OTDR and check the integrity of your fibre optic;
If it's still flapping;
4. Replace switch #2.
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