Adding c3850 to middle of stack

[pwilliams86]

Hi,

We have a 6 switch stack that is split between two cabinets, switches 1-3 in the left cabinet, 4-6 in the right. We need to add a new switch to each cabinet. I am confident adding a switch to the bottom of a stack and know the do's and dont's but adding a switch in the middle I am unsure. Would this work?

1. Add to the stack config "switch 7 provision ws-c3850-48p, switch 8 provision ws-c3850-48p"
2. Renumber switches 4-6 to 5-7
3. Provision two new switches as switch 4 and switch 8

The above shouldn't cause any downtime and can be done in preparation. Then

1. Power down switches 5-7 and remove stacking cables
2. Then add switch 4, then 5, then 6, then 7 and then 8.

Is this the correct way of doing it? If it is do I have to wait for each new switch to load fully before adding the next one?

The current stack looks like this

* 1 56 WS-C3850-48P 03.06.05E cat3k_caa-universalk9 INSTALL
2 56 WS-C3850-48P 03.06.05E cat3k_caa-universalk9 INSTALL
3 56 WS-C3850-48P 03.06.05E cat3k_caa-universalk9 INSTALL
4 56 WS-C3850-48P 03.06.05E cat3k_caa-universalk9 INSTALL
5 56 WS-C3850-48P 03.06.05E cat3k_caa-universalk9 INSTALL
6 56 WS-C3850-48P 03.06.05E cat3k_caa-universalk9 INSTALL

We will be updating the software to 03.07.05E

Many thanks,

Paddy

[paul driver]

Hello

Got to ask why not just add it to the bottom of the stack?

[pwilliams86]

We could but there are about 300 ports in each cabinet, any one of them may need to be patched in, we want to avoid there being a big run of cables going from one cabinet to the next.

[paul driver]

Hello

Must be missing something - the switches are connected via stackwise cables correct?

[pwilliams86]

Correct, we are using longer 2m stackwise cables to join the switches in seperate cabinets.

[paul driver]

Hello

Sorry I still dont understand why you cannot just add the switch to the bottom of the current stack, Surely it wouldn't matter if the switch was in the middle or on the end as far for any cable run would it?

[pwilliams86]

What we want to avoid having is network cables start being strung across between cabinets. There are just over 600 ports in the comms room, so each cab has slightly more than 300 ports in its patch panels. As much as we can we want to have a port patch from one cab going to a switch in the same cabinet, running up to 96 cables between the two cabinets soon becomes a mess.

[pieterh]

make sure the new switch has the same software version running as the existing stack members and clear the config

the process is very simple,  the stack with stackwise cables forms a ring, you can split the ring anywhere as long as the other path remains available. and so, you can add a new stack member anywhere in the ring

and if you add two new members you need to do the physical connection one-by-one to keep one path of the ring available

When the new members config is empty it wil automatically get the next free member-number on power-on

so the stack numbering may end up as 1-2-3-7-4-5-6-8,

until you use the "switch <x> renumber <y>" command (for all members) and do a reload !!!

[pwilliams86]

Hi,

Thank you for that information, I will try that out.

Paddy

[pieterh]

your procedure would change a little

1. Renumber switches 4-6 to 5-7
   this needs restart to activate -> maintenance window, rest can be done "on-line"
   reload whole stack or individual members "reload slot stack-member-number" (order 6,5,4)
2. Provision two new switches as switch 4 and switch 8
   Add to the stack config "switch 4 provision ws-c3850-48p, switch 8 provision ws-c3850-48p"
   at this point you are allready able to configure the ports of the new switches
3. remove stacking cables between 3 and 5 (was 4)
4. add (new) switch 4 and power on
5. remove stacking cables between 6 and 1
6. add switch 8 and power on