Removing a Switch from a Stack

[Matthew Martin]

Hello All,

In one of our locations we are running the following switch stack as shown below. We would like to remove one of the switches from the stack. I was originally thinking this was going to be a fairly simple process without causing any downtime, since we were able to already remove all the devices off one of the switches. But, it sounds like a reconfiguration might be needed from what I read.

3 Switch Stack:

NAME: "c92xx Stack", DESCR: "c92xx Stack"
PID: C9200-24T-E       , VID: V01  , SN: JAD23******

NAME: "Switch 1", DESCR: "C9200-48P-E"
PID: C9200-48P-E       , VID: V01  , SN: JAD23******

NAME: "Switch 2", DESCR: "C9200-48P-E"
PID: C9200-48P-E       , VID: V01  , SN: JAD23******

NAME: "Switch 3", DESCR: "C9200-24T-E"
PID: C9200-24T-E       , VID: V01  , SN: JAD23******

We were able to remove all devices connected to what we have labeled as Switch 1 (*except for the uplink port). However, I'd like to confirm for sure that what we have physically labeled as switch 1, is indeed Switch 1 logically in the config.

These 3 switches connect back to our Cisco 9500 core switch. Running 'sh cdp nei' on the 9500 core shows the 9200 connected to 3 ports on the core. The person who set this up is no longer with the company, so I'm not 100% sure on this... It appears that Switch 1 (*Te 1/1/1) and Switch 2 (*Te 2/1/1) connect back to the Core as trunk ports (*and they're part of a port-channel).

However, Switch 3 has an odd configuration and I'm not sure why it was setup this way. But, the Core side is configured with a Vlan we use for our BYOD Wi-Fi and the Switch 3 side shows "switchport access vlan 900", which is what we use when we connect an ISP connection to our switches.

*BTW, I'm not physically located where these switches are to visually confirm.

Show switch detail:

92000-Access#sh switch detail
Switch/Stack Mac Address : 683b.7826.4800 - Local Mac Address
Mac persistency wait time: Indefinite
                                             H/W   Current
Switch#   Role    Mac Address     Priority Version  State
-------------------------------------------------------------------------------------
 1       Member   683b.7826.4800     15     V01     Ready
 2       Standby  683b.7826.0080     14     V01     Ready
*3       Active   dc8c.3777.bf00     13     V01     Ready

         Stack Port Status             Neighbors
Switch#  Port 1     Port 2           Port 1   Port 2
--------------------------------------------------------
  1         OK         OK               2        3
  2         OK         OK               3        1
  3         OK         OK               1        2

So is there any possible way to get one of these switches removed without causing downtime? Of these 3 switches, Switch #3 which is the 24-port switch is the most important, as it has multiple ISP's connected to it, as well as an EPL link.

Any help would be greatly appreciated!

Thanks in Advance,
Matt

[David Ruess]

Hello,

I believe a reconfiguration is necessary to renumber the switches to reflect the accurate port slots. I am not aware of any command or process that renumbers/resets a switch stack to recalculate the stack.

-David

[Flavio Miranda]

@Matthew Martin 

 I would not do this during bussines hours, that´s for sure.  But, it should not be that critical either.

Take a close look on this guide and it should be enough.

https://www.cisco.com/c/en/us/products/collateral/switches/catalyst-9200-series-switches/nb-06-stackwise-architecture-cte-en.html#_Toc13521197

[Giuseppe Larosa]

Hello @Matthew Martin ,

looking at the output in your post we can see:

Switch#   Role    Mac Address     Priority Version  State
-------------------------------------------------------------------------------------
 1       Member   683b.7826.4800     15     V01     Ready
 2       Standby  683b.7826.0080     14     V01     Ready
*3       Active   dc8c.3777.bf00     13     V01     Ready

we can note that the Active switch is the one with the lowest priority , the standby switch member 2 has lower priority then switch 1.

A possible explanation for this is that switch-3 has the highest uptime and switch-1 has the lowest uptime.

from document provided by @Flavio Miranda 

>> All member switches participate in the election of an ACTIVE stack switch if they all boot up within the election window (120 seconds).

about switch numbering there is an option to renumber them

>> Switch numbering does not reflect the physical location of the switch. However, the numbering can be changed to match the physical location using the command “switch current-stack-member-number renumber new-stack-member-number” from the enable mode.

A reload is then needed.

You ask how to identify the swiches.  The active switch should have a MAST Led light on. For the other two switches probably you need someone on site to make a test connecting a laptop to an unused port and to see in the log what port ie. gex/0/y has became up/up.

>> vices connected to what we have labeled as Switch 1 (*except for the uplink port). However, I'd like to confirm for sure that what we have physically labeled as switch 1, is indeed Switch 1 logically in the config

The above method of connecting something to an unused port and to check the logs should work for you to be able to identify the switch logical number and the label number :

or even simpler to take a picture in front of the switches , the one with less number of ports with green LEDs should be your switch 1.

You need also to migrate the uplink of the switch you would like to remove to have again the second link in the port-channel to core switch.

Hope to help

Giuseppe

[Matthew Martin]

Hey, thanks for the reply.

Ahh ok. If if I understand correctly, then Switch 1, Switch 2 & Switch 3 are able to be determined by the port numbers, i.e. Gi 1/0/xx, 2/0/xx, 3/0/xx. If that's correct, then I know that the switch I want to remove is the one labeled as a "Member".

JWP-9200ATL-Access#show switch stack-mode
Switch#  Role    Mac Address     Version   Mode  Configured  State
--------------------------------------------------------------------------------------------------------------------
 1      Member   683b.7826.4800    V01     N+1     None       Ready
 2      Standby  683b.7826.0080    V01     N+1     None       Ready
*3      Active   dc8c.3777.bf00    V01     N+1     None       Ready

If the numbers in Column 1 represent in the port numbers, then Switch 1 is the one we want to remove...

So I want to keep the 2 Switches with the ports Gi 2/0/xx and Gi 3/0/xx.

Thanks Again,
Matt

[Giuseppe Larosa]

Hello @Matthew Martin ,

>> Ahh ok. If if I understand correctly, then Switch 1, Switch 2 & Switch 3 are able to be determined by the port numbers, i.e. Gi 1/0/xx, 2/0/xx, 3/0/xx. If that's correct, then I know that the switch I want to remove is the one labeled as a "Member".

your undestanding is correct you just have to identify it and connecting something to an unused port and seeing the port gi1/0/x coming up in the log buffer will tell you that is the right switch.

Because as you have noted your physical label may provide a different number for member 1 switch.

Hope to help

Giuseppe

[shambhu.kumar]

Hello Matthew

Press mode button of switch 1, then disconnect the power supply and power stack cable of switch 1 and then data stack cable and remove the switch, then reconnect data and stack cables and complete the stack ring.

you remove switch 1 from the switch stack, the configuration associated with the removed stack member remains in the running configuration as provisioned information. your interface naming will not be changed. You can use services without reloading but, and provisioned information of switch 1 you have to reload.

To change interface naming

config t
no switch 1 provision
config t
switch 3 renumber 1
switch 2 renumber 2

switch 1 priority 15
switch 2 priority 14

write
mem
reload

Hope this will help

[Matthew Martin]

Thanks for the reply. What does pressing the mode button do on the Switch? Just curious, I always thought the mode button just shows you different status lights when you click through the modes... Maybe the 9200 is different? I'm not on location there, so I don't have a 9200 on hand to look at.

Thank you for the steps you provided. Since we now know some downtime is going to need to occur, we're going to have to schedule some downtime, most likely over a weekend to complete the task.

***FYI***
If this is correct. In order to physically matchup what the logical Switch 1, 2 and 3 are. The output of the show license udi command combined with the output of show inventory seems to point to which is which.

9200-Access#sh lic udi
UDI: PID:C9200-24T,SN:JAD23xxxxxx

HA UDI List:
    Active:PID:C9200-24T,SN:JAD23130XXX
    Standby:PID:C9200-48P,SN:JAD23230YYY
    Member:PID:C9200-48P,SN:JAD23230ZZZ

9200-Access#
9200-Access#show inv                      (***output snipped***)
NAME: "c92xx Stack", DESCR: "c92xx Stack"
PID: C9200-24T-E       , VID: V01  , SN: JAD23xxxxxx

NAME: "Switch 1", DESCR: "C9200-48P-E"
PID: C9200-48P-E       , VID: V01  , SN: JAD23230ZZZ

NAME: "Switch 2", DESCR: "C9200-48P-E"
PID: C9200-48P-E       , VID: V01  , SN: JAD23230YYY

NAME: "Switch 3", DESCR: "C9200-24T-E"
PID: C9200-24T-E       , VID: V01  , SN: JAD23130XXX

Usually these serial numbers are printed on the chassis too, so can verify that way as well.

 -Matt

[Matthew Martin]

So I'm pretty sure I understand the process of removing a switch from the stack now. Thanks all who replied!

One other thing I'm curious about that I didn't see in any links I found. Once the switch is removed and the stack reloads and comes back up. I assume the port numbers will change depending on which switch becomes Switch 1 and which becomes Switch 2?

For example, if I make the 24-port switch = Switch 1... Will those ports go from Gi 3/0/1 <--to--> Gi 1/0/1  ?

If this is the case. Will whatever was configured on those ports, stay configured? Wondering how much reconfiguration will need to be done... If the IP Address I currently ssh to reach the switch remains, I assume I won't have a problem getting ssh'ed back into the stack.

Since I'm not in this location it would be difficult getting a console connection done since the ISPs are connected to this switch stack.

Thanks Again,
Matt

[Giuseppe Larosa]

Hello @Matthew Martin ,

>> Once the switch is removed and the stack reloads and comes back up. I assume the port numbers will change depending on which switch becomes Switch 1 and which becomes Switch 2?

No, switch renumbering is not automatic you need to configure it explictly as noted :

>>

However, the numbering can be changed to match the physical location using the command “switch current-stack-member-number renumber new-stack-member-number” from the enable mode.

A reload is then needed.

See also @shambhu.kumar 's  configuration example:

>>

config t
no switch 1 provision
config t
switch 3 renumber 1
switch 2 renumber 2

switch 1 priority 15
switch 2 priority 14

wr mem

reload

You need also to accomodate that uplink moving it to current switch 3.

Hope to help

Giuseppe

[paul driver]

Hello
SW1 which is just a member switch, but its connected to SW2/SW3 via two stacking cables.
Sw1-port1 <> SW2 port2
Sw1-port2<>SW3 port1

Pressing the mode button on the front panel of the switch(s) will identify the switch stack number and stacking role , There should be a solid green led light on the front panel of the master switch indicating its role.

As long as you have migrated any important links off SW1 before you power it down you should be good to remove it successfully without any downtime

So as/when you power down SW1 and disconnect the stack cables then that switch be isolated, however at this point the stack ring will not be closed, so to do that you will need to reconnect one of the removed stack cables between SW3 port1 <> SW2 port2  then you will be done.

Personally and only if its required id leave the renumbering for another time.