Stackwise on 3850's

[GarethGann]

Hi - Still finding my feet in the cisco world so please bear with me.

Just got four 3850s in the office and I'm having a go at configuring them. I have a base config running securing the various lines and services but I cannot get the switches to stack.

I originally plugged all the stackwise cables in but it did not set active switch to the one I desired. I then followed this documentation to configure the priority of each switch. I ran these commands on each switch after unplugging the stackwise cables:

switch01# switch 1 renumber 9

switch02# switch 2 renumber 7

switch03# switch 3 renumber 5

switch04# switch 4 renumber 3     (those numbers might not be exact but the end result is)

So with that I reloaded each switch for re-election but now each switch is detecting no neighbors.

SWITCH01#show switch

Switch/Stack Mac Address : dca5.f4d3.2080 - Local Mac Address

Mac persistency wait time: Indefinite

                                             H/W   Current

Switch#   Role    Mac Address     Priority Version  State

------------------------------------------------------------

*9       Active   dca5.f4d3.2080     1      V02     Ready

SWITCH01#show sw neighbors

  Switch #    Port 1       Port 2

  --------    ------       ------

      9        None          None

So SWITCH01 has the highest number so should get elected as the active in an election as I understand it but it is not detecting any neighbors. Nor are the other 3 switches. I have also double checked all cables are seated correctly.

Can anyone point me in the right direction to get this working? As you may have guessed, I'm not familiar with stacking switches so I apologise if I have made a mess of this.

Thanks,
Gareth

[Seb Rupik]

Hi Gareth,

If you want a switch to win the election after all the switches have rebooted you need to set its priority value to 15.

However, your issue appears to be linked the stacking cables.

Have you connected them in a cross pattern, so that they make a continuous ring?

What port status do the other switches report?

cheers,

Seb.

[Leo Laohoo]

Let's do this the EASY way ...

Renumber all your switches to 1.

1.  Remove all stacking cable.

2.  Power OFF all the switches.

3.  Power up the switch you want to be the master.

4.  Only the master switch.  The rest is POWER OFF.

5.  Cable up ONE stacking cable to the master.

6.  Power up the second switch.

7.  Do the next.

8.  And the next.

Done.

[Karan Puri]

Leo thats the most easiest way... make sure u check cisco doc for cabling properly...

[Richard Primm · Accepted solution]

Two things:

1. triple check that the stack cables are tightly and securely in each switch. I see this all the time, especially on the 3850

2. run "show switch stack-ports summary" and post output

As noted above - SET the PRIORITY of your desired "Active" (we used to call this Master)  to 15 and boot first, number the switch you would like to be the "Standby" 14 and reload him.  The rest of the switches will become "Members"  "renumbering" is great, but you want to set priority if you want to dictate who becomes Active/Standby

Also, are you cabling the stack cables from SW1 stack port 1 ----> Sw2 stack port 2 ///// Sw2 stack port 1 ----> SW3 stack port 2...... and so on (don't forget to loop the last cable back up to switch 1 to complete the ring)

[GarethGann]

Thanks for the infomation. Where I had gone wrong is not understanding that there are two seperate values for the switch numbers and their respective priorities. Running the correct command "switch 1 priority 15" was the ticket. show switch now returns the following:

STACK01#show switch
Switch/Stack Mac Address : dca5.f4d3.2080 - Local Mac Address
Mac persistency wait time: Indefinite
                                             H/W   Current
Switch#   Role    Mac Address     Priority Version  State
------------------------------------------------------------
*1       Active   dca5.f4d3.2080     15     V02     Ready
 2       Standby  7c95.f32e.8680     14     V02     Ready
 3       Member   7c95.f32e.ad80     13     V02     Ready
 4       Member   7c95.f380.4100     12     V02     Ready

Also I reseated all cables.

Thank you to all for your help. Greatly appreciated.

[GarethGann]

It turned out to be a combination of both the priorities and the cabling.

Thanking you greatly for your help.

Gareth