Questions on stacking switches

[Freak21]

At a new location and there are quite a few stacks of 2 3750's in different locations. Most seem to only have 1 stack cable installed from slot 1 of switch 1 to slot 2 of switch 2. I know this only gives you 16 Gbps on the back plane vs. 32 so I want to put the other stack cable in.

I was wondering, can you install a new stack cable with the switches being on or do you need to power them down first?

 

[ISPKing]

Are you even coming close to pushing 16bps? I have only seen a few rare deployments where that much data would be running over and access switch.


CCNP

 

[ISPKing]

16gpbs*

CCNP

 

[ADB100]

You can install the cable with them powered on.

 

[VinceWhirlwind]

Here's me removing the 2nd cable, stacking a 3rd switch to the 2nd, then closing the loop from switch 3 to switch 1 (bottom-up):

Notice 2733: 24w4d: %STACKMGR-5-SWITCH_READY: Switch 3 is READY
Warning 2732: 24w4d: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 2 Switch 3 has changed to state UP
Warning 2731: 24w4d: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 1 Switch 3 has changed to state UP
Notice 2730: 24w4d: %STACKMGR-5-SWITCH_READY: Switch 3 is READY
Warning 2728: 24w4d: %STACKMGR-4-SWITCH_ADDED: Switch 3 has been ADDED to the stack
Warning 2727: 24w4d: %STACKMGR-4-SWITCH_ADDED: Switch 3 has been ADDED to the stack
Warning 2726: 24w4d: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 1 Switch 1 has changed to state UP
Warning 2725: 24w4d: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 2 Switch 2 has changed to state UP
Warning 2724: 24w4d: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 1 Switch 1 has changed to state DOWN
Warning 2723: 24w4d: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 2 Switch 2 has changed to state DOWN

 

[VinceWhirlwind]

Incidentally - in my opinion the small effort of closing the stacking loop on 3750 stacks is worth it.
I have been called to incidents where dodgy stack cables have caused failures in stacks where the loop is not closed.
In stacks larger than 2 switches, closing the loop is necessary to guard the stack against individual switch failures, too.

 

[VinceWhirlwind]

Plus you get a free stacking cable with each 3750 anyway, so there is no reason to throw it away instead of just using it.

 

[Freak21]

RGR thanks for the info. Not sure if it will be needed but always figured better to have it installed and maybe not need it then need it and not have it. And since the IOS is pushed from the stack master to the rest it will probaly help with IOS upgrade time.

 

[ISPKing]

^^most definitely, cisco recommended a 16gpbs link for any ios bigger then 15MB, and 32gpbs for optimal transfer time............

CCNP