Stacking Cisco 2960-S switches

| Saturday, March 23rd, 2013 | 22 Comments »

brandontek-cisco-2960S

Back in January 2012, I went over the steps on stacking Cisco 3750 switches. You can view that article here. (Stacking Cisco 3750 switches)

The steps to stack Cisco’s 2960-S switches are generally the same so I won’t go into too much detail, but I wanted to shed some light on it just to provide some coverage for anyone that is looking to do this on their network. We will be going with three Cisco 2960-S switches.

The main components that you will need are: switches, stack modules and stack cables

Once you remove the stack module cover on the rear of the switch, you will of course have gaping holes that you will need to insert the modules into!

brandontek-cisco-2960S-before-after

 

 

You can go ahead and plug in the stack cables and allow the switches to select the MASTER through an election process, or you can define which switch you’d like to be the MASTER by setting the priority to the highest level which is 15.

switch(config)# switch 1 priority 15

My switches are in order from top to bottom: 1, 2 and 3. (MASTER, MEMBER, MEMBER)

I’ve provided how the stack cables actually look when stacked based on Cisco’s diagram. This provides full duplex stacking.

brandontek-cisco-2960S-stacked-cables

cisco-stack

 

*Notice the white/gray tabs on the stack cables. If the cables are on the top position, the tabs are on top. If they are connected on the bottom, the tabs are on the bottom!

 

If everything is done right, you can visually tell which switch is the MASTER by looking at the front display LED lights. Take a look at it below.

brandontek-cisco-2960S-master-LED

 

Stacking Benefits

  • 20Gbps Bandwidth – Just as I mentioned before, I don’t like the way the stacking speeds are advertised. As mentioned before in my Cisco Stacking 3750 switch blog, the displayed speeds is actually 10Gbps, but because it is full duplex, that’s how they arrived with 20Gbps.
  • Management – When stacked, all your switches are logically one switch. One management IP address to manage all three switches.
  • Cabling – Cleaner cabling since they stack from behind and would not interfere with any other cables you may have. So it is aesthetically pleasing.
  • 4 Member Switch capacity – You can stack up to four switches in your Flexstack switching fabric. This gives you much room for growth and 192 Ethernet 10/100/1000 ports with 16 optional modules.
  • Hot pluggable switches – You can remove and add switches while the stack is running. A working stack can accept new members or delete old ones without service interruption.
  • FlexStack – Hardware drop table.

 

Stacking Rules

  • Make sure your IOS versions are the same, if not, update each switch with the same IOS version before proceeding.
  • All switches out of the box (if not stacked, meaning they are standalone) defaults to being their own MASTER.
  • If you manually change the stack member number, you need to RELOAD that member switch in order for it to take effect. (hint: use the RELOAD SLOT command)
  • Priorities range from 1 through 15. The higher the priority, the higher the chances of the member switch becoming the MASTER.

 

Stack Commands

If you want to see the status of your stack ports.

brandontek-show-stack-ports

Verify that your stack is connected at full duplex.

brandontek-show-stack-ring-speed

 

Verify that you have access to all your interfaces. (I’ve cut the output for brevity)

brandontek-show-ip-b

Verify all your switches are part of the stack and who your MASTER switch is.

brandontek-cisco-2960S-show-switch

 

FlexStack vs StackWise Plus

So what is the difference between the two “stacking” technologies from Cisco? Have a look at the chart below!

brandontek-cisco-flexstack-stackwise

 

 

Conclusion

Whether you are stacking the 3750 or 2960 series switches, you will gain performance benefits. At the end of the day, you will have to decide if there is a business need for this type of technology for your network. As always, if you need more in depth information, you will have to visit Cisco’s website for the latest on their stackwise technology! Happy stacking!

 

 

 

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  • Chandra

    Thanks! good One!

  • murthasa

    Will you please tell me what configuration should we do in core switch in order to support stacking in access layer ?

  • brandontek

    Murthasa,

    There’s no configuration needed. Out of the box if you stack the switches they will automatically stack themselves. If you want to further provide granular control on the stacking, my above article covers those options.

  • emma

    thank you for share, I know a good cisco distributor, who sells the C2960S-STACK:
    http://www.3anetwork.com/cisco-c2960s-stack-price_p21.html

  • GlennRunciter

    What strategy should I pursue in this scenario : I have a standalone 2960s fully configured in production. I want to make it redundant by buying a second 2960s and stacking it.
    I’d prefer not to lose the running config on the first one. Can I turn my 2960 in a stack with a single member while retaining the current vlanconfig/routes, and the ADD a member to it ?

    thx

  • brandontek

    Hey Glenn:

    Yes you can do this with ZERO interruption. I’ve done this myself. You have to prep the primary switch, make sure that it is the MASTER so statically define the role.

    Once you do this, connect the second switch with all the cables and then power it on, it will come up as member.

    If you want to further make sure you don’t lose configurations ( I did this as well ), you will want to power up the second switch, define it’s role NOT as MASTER. Then power it off, connect it and power it on.

    Everything will be seamless.

  • GlennRunciter

    Thank you !

  • http://www.amcsquare.in/ Amc square learning | Reviews

    Thanks for info! Very Helpful.

  • Chris

    Hi
    What is the configuration commands required to do the above? would it be

    switch 1 priority 15
    switch 2 priority 1

  • brandontek

    Hi Chris,

    That would be correct. Switch 1 would be master.

  • Aidan Christopher
  • brandontek

    Thanks for finding this Aidan. Probably not much I can do, seems like a pretty large supplier too so that is pretty disappointing. =/

  • Dragos Birdu

    Would it be possible to stack a 24port 2960x with a 48port 2960x?

  • brandontek

    Hey Dragos,
    To my knowledge that should work just fine, as long as the firmware are the same on both.

  • Conny Molin

    Sorry for lifting an old thread but I have one small question regarding this though it’s a ws-c3750g-48ts in my case. I know the procedure is the same in general but there’s one thing I’m curious about.

    My production switch already has priority 15 today and both switches are running the same IOS. My new switch is configured for priority 1.

    Doing this is possible “live” without interruption or downtime but,
    do you also have to issue the “switch 2 provision ws-c3750g-48ts” from
    the switch that currently is no 1 and in production BEFORE adding and
    powering on the new switch member?
    If I’ve understood everything correctly it’s not needed but what is considered best practice and what is the difference between issuing the provision command vs not doing it?

  • brandontek

    Hi Conny:

    No worries, I do not mind revisiting old topics as truthfully, they are still fully in use today and the overall technology and methods haven’t changed much.

    Are you trying to make your “new” switch the master and in doing so, push “down” your current master to become switch#2 without any interruption/downtime?

  • Conny Molin

    No, the other way around. I want to make sure my current in production standalone switch takes the master role and retaining stack member id 1 as I don’t want changes to the naming of the current interfaces in use.

    The reason why I’m a bit insecure doing this is because it is currenty a core switch and I really can’t afford to take any chances.

    Oh, dont know wether it matters or not for this operation but were running MST spanningtree in it instead of the default PVST/RSTP.

  • brandontek

    Understood Conny, glad to see you’re taking precautions it would be a serious issue if you lost everything.

    So basically what you can do is make sure 10000% that your production switch is PRIORITY 15 and should naturally be SWITCH#1.

    For the second switch, before you connect it, log into it, renumber it so it is SWITCH#2 and make it PRIORITY 10 or anything lower than 15.

    Reboot it a couple times to make sure everything is set. Do show status on the switch to confirm it knows it is SWITCH#2 and priority is lower than 15.

    Once you do this, shut down the switch, connect it to your production switch (via stack cables) and power up the switch.

    Of course make a backup of everything first as a fail safe.

    I know it can be scary, I have done it in production many times but I have measured 100 times and cut once!

    Good luck, I hope you will at least have a maintenance window!

  • Conny Molin

    Allright, thanks!
    Yeah I’ll most likely set a window for it even though it shouldn’t be any problems. So, the ‘switch x provision type’ command is essentially not needed for this type of operation?

  • brandontek

    Technically since your master switch is already master and also has the longest uptime, the stack election would naturally make the second switch as #2 but for my own sanity I would rather define everything myself. Also, I did a write up specifically for the 3750 switches, not sure if you’ve seen it.

    http://www.brandontek.com/cisco/stacking-cisco-3750-switches/

  • http://xajuan.wordpress.com Xajuan

    this has helped me out I plan on condensing a switch stack from 4 to 2.