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3750 Stacking Speed - 16 Gbps vs 32 Gbps

I am configuring a stack of 3 3750's with the stackwise technology. I have noticed with CNA that it sometimes reports a 16 Gbps speed stack and sometimes a 32 Gbps stack. Right now it is reporting 16 Gbps. I assume it has something to do with the stacking ports.

Here is what the switch reports now:

ncrplan01#sh switch stack-ports

Switch # Port 1 Port 2

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

1 Ok Down

2 Ok Ok

3 Down Ok

All ports have stacking cables in a looped fashion. I don't see any commands for bringing up the "Down" stacking ports. What am I missing?

2 REPLIES
Hall of Fame Super Silver

Re: 3750 Stacking Speed - 16 Gbps vs 32 Gbps

Barry

Am I correct in assuming that there is a cable from stack port 2 on switch 1 to stack port 1 on switch 3? Is it possible that this cable connecting 1 to 3 is not quite fully connected? Or is it possible that the cable is faulty?

With both paths active you should get 32 Gbps and with only a single active path you would get 16. And the down stack ports on switch 1 and 3 mean that you have only a single path at this point.

HTH

Rick

New Member

Re: 3750 Stacking Speed - 16 Gbps vs 32 Gbps

OK! This is kinda weird. I disconnected the cable from 3 to 1 and then just pushed it back on. This brought the the link from 3 to 1. When I screwed it in, the link went down again. In order to get it back up, I have to back off the screws a few turns :-(

ncrplan01#

000051: Aug 21 17:25:33.540: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 1 Switch 3 has changed to state UP

000052: Aug 21 17:25:33.775: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 2 Switch 1 has changed to state UPsh switch stack-ports

Switch # Port 1 Port 2

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

1 Ok Ok

2 Ok Ok

3 Ok Ok

ncrplan01#sh switch stack-ports

Switch # Port 1 Port 2

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

1 Ok Ok

2 Ok Ok

3 Ok Ok

ncrplan01#

000053: Aug 21 17:26:22.865: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 1 Switch 3 has changed to state DOWN

000054: Aug 21 17:26:23.301: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 2 Switch 1 has changed to state DOWN

000055: Aug 21 17:26:29.341: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 2 Switch 1 has changed to state UP

000056: Aug 21 17:26:30.096: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 1 Switch 3 has changed to state UP

ncrplan01#

Anyhow, thanks for your help. I guess I will open a TAC Case.

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