3750 stack cable

[Jon Marshall]

Quick question - need to deploy a 3750G stack (two switches) and only have one stack cable at the moment. I know it will work (without redundancy) but when I add the second cable later is there any downtime or does the stack just see the alternate path ? 

Cheers 

Jon

[Leo Laohoo · Accepted solution]

No downtime.  

[Jon Marshall]

Leo 

Cheers, thought that might be case just wanted to confirm. 

Jon

[Joseph W. Doherty]

Jon, I recall (?), for the 3750 series, Cisco recommends when changing stack cable connections, one switch should be powered off.

That said, I understand having both switches, powered, you can (usually) make/break connections w/o an issue.

If you do the change, with one switch powered off, of course, you'll have downtime for devices connected to it unless they are dual homed, but the rest of the stack continues to function.

[Jon Marshall]

Hi Joe 

As I am not actually breaking the connection, just adding the second cable should be fine as Leo says.

Thanks

Jon

[Leo Laohoo]

Yup.  It is fine to add a second stacking cable as long as the first is already there. 

I do it all the time and do not require any outage(s).

[Joseph W. Doherty]

As I recall the recommendation is for making or breaking a stack cable connection.  Basically, insuring the cable isn't carrying current.

As Leo describes, he does it all the time, w/o issue.  Yet, think of it this way, a rope/chain, has a capacity limit.  If you adhere to it, rope/chain shouldn't break.  Go above it, rope/chain will break, but exactly at what limit is variable.