Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Bronze

tx-queue 1 and tx-queue 2 on 4500: What's the difference?

Given a 4500 in an environment that isn't going to use Scavenger/CS1 and best practice which states:

DSCP-TxQueue Mapping Table (dscp = d1d2)

d1 : d2 0 1 2 3 4 5 6 7 8 9

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

0 : 02 01 01 01 01 01 01 01 01 01

1 : 01 01 01 01 01 01 04 02 04 02

2 : 04 02 04 02 04 04 04 02 02 02

3 : 02 02 04 03 04 03 04 03 04 03

4 : 03 03 03 03 03 03 03 03 04 04

5 : 04 04 04 04 04 04 04 04 04 04

6 : 04 04 04 04

Does anyone know a good reason for 0/Default existing in Q2 instead of Q1?

I can't seem to demonstrate a reason with the testing I'm doing. Granted, I'm going to put it in Q2 just in case they decide to use scavenger later on down the road, but I am curious if there's a real reason why other than Cisco says so.

As far as I can tell Q1 vs. Q2 is just another bit bucket with another bandwidth allocation, there's no documented different priority for the two within the switch itself except the output of this command:

Switch#show platform mapping tx-queue

Tx-Queue

CLI Hardware

1 3

2 2

3 0

4 1

But it's an undocumented command.

So what's the difference between the two?

-- -Mark Turpin
1 REPLY
Silver

Re: tx-queue 1 and tx-queue 2 on 4500: What's the difference?

The reason you are seeing this is because the configurations that you are not seeing in the configuration are already pre-configured by default. For example, DSCP 8, 10, 14 all map to TX-queue 1. So, only the non-standard/non-default configurations will show up on the configuration.

you can check the default mapping through

show qos map dscp tx-queue.

533
Views
0
Helpful
1
Replies
CreatePlease to create content