SG500, Questions about QoS Settings

[StefanSab]

Hi all,
have here a SG500 with latest Firmware.

I would like to change "CoS/802.1p to Queue Map" default settings i want to use queque 8, but i get this warning.

Queue 8 is reserved for stack-control traffic. Using this queue for user traffic might disrupt stack stability. Do you want to continue?

Interestingly, queque 8 is specified in CLI_500 tutorial as a default value:

0. Default Configuration
   The default CoS value mapping to 8 queues is as follows:

   • CoS value 0 is mapped to queue 1.

   • CoS value 1 is mapped to queue 2.

   • CoS value 2 is mapped to queue 3.

   • CoS value 3 is mapped to queue 6.

   • CoS value 4 is mapped to queue 5.

   • CoS value 5 is mapped to queue 8.

   • CoS value 6 is mapped to queue 8

   • CoS value 7 is mapped to queue 7.

The same behavior with "DSCP to Queue Map"

Therefore the question, can i use the "queque 8" or is this critical ?

thx
Stefan

[Tom Watts]

Hi Stefan, it is not critical if you're not using the stack function.

If you remove the queue 8 or occupy it some other way in a stack environment it may have adverse effects for how the stack interops between units or how data relays between the units.

-Tom
Please mark answered for helpful posts

[StefanSab]

Hi Tom, thanks for fast answer.

hmm, i have 4 SG500 units with stack funktion then it is better do not use queque 8.

But why different default values (SG500 <-> Tutoeial) described in the cli_500 tutorial (CoS and DSCP) ?

Understanding question

Why is DSCP values 16 (why not queque 3 or 4), 24,40 the in the high queque 7, the same with DSCP values 48-63 ?

Stefan