QoS stack ring bandwidth?

[samhopealpha]

Hi everybody, 

According to Cisco Doc
http://www.cisco.com/c/en/us/support/docs/switches/catalyst-3750-series-switches/91862-cat3750-qos-config.html

it said 
"Stack ring bandwidth depends on the stack cabling. If the stack is connected at full bandwidth, you receive 32Gbps bandwidth. This bandwidth is shared by all the switches in the stack."

in Switch config, stack ring should be refered to SRR (mls qos srr-queue input xxxxxx)

the question is: 

if there is only 1 x 3750 switch, what is the bandwidth of the ring ? 32Gbps? or the stack ring not existed?

or do I have any misunderstanding concept on the above?

Thanks 
Sam

[samhopealpha]

Nobody has idea?

[Terry Cheema]

A standalone 3750 is considered a switch stack with one member. Ring is still there but it operates at half speed 16Gbps unless both the stack cables are connected.

If you connect even both the stack ports on the same switch with a stack cable, it will complete the ring and ring will be again operating at 32Gbps.

On your switch record the output of the command: show switch stack-ring speed

with no stack cable connected  (it shoud be 16Gbps)

with stack cable looped from port 1 to port 2. (it will be 32Gbps)

I dont have a switch right now, but as far as I remember above is the xpected behavior.

-Terry

[Terry Cheema · Accepted solution]

Here is the output from one of the standalone 3750 switch in my lab:

SW01#sh switch
Switch/Stack Mac Address : 1111.1111.1111
                                           H/W   Current
Switch#  Role   Mac Address     Priority Version  State
----------------------------------------------------------
*1       Master 1111.1111.1111     1      3       Ready      
SW01#sh switch stack-ring s

Stack Ring Speed        : 16G           <<<<<<<<<<<<
Stack Ring Configuration: Half        <<<<<<<<<<<<
Stack Ring Protocol     : StackWisePlus

SW01#sh switch stack-ports
  Switch #    Port 1       Port 2
  --------    ------       ------
    1          Down         Down  

SW01#

-Terry