Creating a stack of 2960s from a single live switch

[Martin Foglia]

I hope this to be a fairly simple question --

I have a live 28port Catalyst 2960S switch. By live I mean that there is an essential piece of equipment plugged into this switch that can suffer little to no downtime. Over the course of time the number of devices patched into this location has increased to exceed the 24 ports available and we have had to resort to adding unmanaged switches to fill the need. We have acquired an additional 2960 & stacking modules that I would like to stack together, keeping the existing switch as the master. It is my understanding that the stacking modules are hot-swappable and that this member switch can be added without bringing the master switch down, thus creating zero down time for the financial server that is connected.

The steps I believe that need to be followed are as such:

1. write mem to existing switch and backup to our TFTP server
   
2. install the stack module in the existing (while powered up) and new (while powered down)
   
3. place the 2 redundant FlexStack link cables on both switches
   
4. then simply power the member switch on
   

After boot the member switch will get it's OS and configuration from the master and I can begin moving CAT5 cables from the unmanaged switches to the stack.

Please let me know if I am missing anything.

Martin

[Arumugam Muthaiah]

Hi Martin,

Yes, you are steps looks good. At the same time, i am sharing the best pratice to add new member to stack.

Cisco Catalyst 2960-S switches do not need to be powered off to join a stack. However, when a new member joins
an existing stack, the new member will be rebooted anyway to clear its configuration . The new member is
automatically rebooted by the stack. A reboot is operationally equivalent to powering a switch off and then on again.
Thus, it is a better practice to add new stack members to an existing FlexStack powered off

The following are steps for adding a new member to an existing stack, and it is desired that the new member not
become the master

1. Place the new switch in its final location. Do not insert the power cord. To minimize downtime, complete all
   cabling that would be required of any switch placed into production at this time.
   
2. Insert the FlexStack module in the back of the new member.
   
3. Disconnect the FlexStack cable from the existing member just above to the new member. This would be the
   cable that is connecting the bottom member with the top member. You will need this to connect the new
   member located at the bottom of the stack to the member at the top.
   a.  When the FlexStack cable is disconnected, this is when the stack enters into a nonredundant mode.
   
4. Connect the new member with a FlexStack cable to the member just above. The FlexStack port used to connect
   one member to another is not important. Stack members should be connected to each other any way that
   makes cable management easiser for the network administrator.
   
5. Connect another FlexStack cable to the member at the top. Make sure that all cables are connected properly. A
   light tug on the FlexStack cable will make sure that it is properly seated.
   
6. Connect the AC power cord to the new member. It will power on. It will take a few minutes for the new member
   to complete the boot process.
   
7. The new member will join the existing stack. 
   a.  When the new member completes the boot process, this is when the stack enters into a fully redundant
   mode once again.
   
8. All the FlexStack links will be operational if all the connections were made properly
   

Refer:

http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps6406/white_paper_c11-578928.pdf

Regards,

Aru

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[cfuller]

I currently have 2 Cisco 2960S switches, however, on the back there is no area to add the FlexStack modules in order to stack the two. I am here to figure out if there is a way to stack the two switches without the flexstack module and if so, how to go about doing that. I have researched vlans, trunking, but I am still not sure how to make this happen. Thank you!

[Giuseppe Larosa]

Hello Martin,

in addition to Arumugan's good post the C2960 configuration guide recommends to configure an higher switch priority on the master

see

http://www.cisco.com/en/US/docs/switches/lan/catalyst2960/software/release/12.2_58_se/configuration/guide/swstack.html#wp1234264

>> We recommend you assign the highest priority value  to the switch that you want to be the master. The switch is then  re-elected as master if a re-election occurs.

This will provide benefits over time ensuring master identity.

Hope to help

Giuseppe