Verify 3850 Stack Bandwidth Utilization

[robo764]

I'm in the process of replacing a number of access switches, and I'm trying to verify if I need to replace some 3850 stacks (2-3 switches, each) with 9300s or if 9200s would suffice.  As I understand it, the biggest difference in this situation is the available stack bandwidth.

I wanted to see how much of this we are currently using, but the only way I currently know to look is "sh controllers util".  Is there some other way?  They are all showing "0" for this, which could be accurate, but I also want to make sure I'm not missing anything. 

Here's what I get from one of the stacks, as an example:

Total Ports : 168
Total Ports Receive Bandwidth Percentage Utilization : 1
Total Ports Transmit Bandwidth Percentage Utilization : 1
Switch 1 Stack Ring Max Percentage Utilization : 0
Switch 2 Stack Ring Max Percentage Utilization : 0
Switch 3 Stack Ring Max Percentage Utilization : 0

[Devaa]

Check if below cmds help you.

show switch stack-ports detail
show switch stack-ports detail | i rate
show switch stack-ring speed
show switch stack-bandwidth

[robo764]

Those show me the capability but don't seem to provide utilization information:

Server-C3850-Stack#sh switch stack-ports ?
  summary  Show details of switch stack ports info
  |        Output modifiers
  <cr>

Server-C3850-Stack#sh switch stack-ports
Switch#   Port1     Port2
----------------------------
1         OK        OK
2         OK        OK
3         OK        OK

Server-C3850-Stack#sh switch stack-ports sum
Sw#/Port#  Port Status  Neighbor  Cable Length   Link OK   Link Active   Sync OK   #Changes to LinkOK  In Loopback
-------------------------------------------------------------------------------------------------------------------
1/1        OK           2         50cm           Yes       Yes           Yes       1                   No
1/2        OK           3         50cm           Yes       Yes           Yes       1                   No
2/1        OK           3         50cm           Yes       Yes           Yes       1                   No
2/2        OK           1         50cm           Yes       Yes           Yes       1                   No
3/1        OK           1         50cm           Yes       Yes           Yes       1                   No
3/2        OK           2         50cm           Yes       Yes           Yes       1                   No

Server-C3850-Stack#show switch stack-ring speed

Stack Ring Speed        : 480G
Stack Ring Configuration: Full
Stack Ring Protocol     : StackWise

Server-C3850-Stack#sh switch stack-bandwidth
                   Stack       Current
Switch#   Role     Bandwidth   State
------------------------------------------------------------
*1       Active    480G        Ready
 2       Standby   480G        Ready
 3       Member    480G        Ready

[Joseph W. Doherty]

As an aside, you would need a very, very busy dual or triple 3850 stack for stack ring bandwidth to be an issue.

[robo764]

Yeah, I'm trying to find some way to showing my leadership team that we didn't 3850s need at these locations, and so don't need a 9300 to replace them.  Everything else is pretty straight-forward, I just want to make sure I'm not misrepresenting anything when I point at the output of "show controllers util" and say that we're barely touching the stack bandwidth. 

[Joseph W. Doherty · Accepted solution]

Understood, although, laugh, with management, more often we need to justify the need to upgrade, not the converse.

Unsurprising ". . . say that we're barely touching the stack bandwidth." may be the case.