3750 stackable switches configuration.

Answered Question
Feb 15th, 2010

hi,

If we use 4 stackable 3750 switches ( connected in chain to form a single logical switch of 96 ports )  and configured the ports in different VLANs.  And if  any switch is turned off,  say stack switch member 2 is powered down. What happens to the port numbering scheme? Now there will be three devices insted of four. In this case configurtaion of  switch 3 and 4 will be wrong.  Or it still works fine if stack member switch 2 is off.

We plan to conneect server two ethernet cards (Redundancy-Team-up Eth interface ) to seperate switches and obviously both ports will be in same VLAN.

IF port numbering scheme gets changed due to one member is powdered down then this solution will not work.

Please share the experience.

Any link on cisco.com which tells about such situation ?

Thanks

Subodh

I have this problem too.
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Correct Answer by Reza Sharifi about 4 years 2 months ago

Hello Subodh,

In a stack environment nothing will happen if one of the switch member powered off. Of course if you have any device single homed to that specific switch it will loose connectivity.  As for your server connectivity, make sure you team up the NICs (NIC teaming) and connect each NIC to a different switch and as long as you use Etherchannel you will have NIC redundancy and also switch redundancy. For your Etherchannel protocol use LACP as that is commonly supported by most servers.

HTH

Reza

Correct Answer by Paolo Bevilacqua about 4 years 2 months ago

Nothing happens to numbering, obviously.

Once matched, switches retain their number (switch provision) until split and reset.

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Correct Answer
Paolo Bevilacqua Mon, 02/15/2010 - 16:34

Nothing happens to numbering, obviously.

Once matched, switches retain their number (switch provision) until split and reset.

Correct Answer
Reza Sharifi Mon, 02/15/2010 - 17:40

Hello Subodh,

In a stack environment nothing will happen if one of the switch member powered off. Of course if you have any device single homed to that specific switch it will loose connectivity.  As for your server connectivity, make sure you team up the NICs (NIC teaming) and connect each NIC to a different switch and as long as you use Etherchannel you will have NIC redundancy and also switch redundancy. For your Etherchannel protocol use LACP as that is commonly supported by most servers.

HTH

Reza

bapatsubodh Mon, 02/15/2010 - 17:55

Thanks a lot for sharing your experience.

I was wondering if we  ether_channel as in our earlier installations we have HSRP with non-stackable switches.

Mostlikely NIC are in "failover mode" , probably I need to get in touch with AIX sysadmin and check.

Thanks again

Subodh

Reza Sharifi Mon, 02/15/2010 - 18:22

I actually tested Etherchannel with our servers running LACP.  It works really well.  When one NIC fails, the server used the other NIC without any downtime.

Good Luck

Reza

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Posted February 15, 2010 at 4:32 PM
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