From: David Bombal (davidbombal@davidbombal.com)
Date: Mon Jun 19 2006 - 17:57:04 ART
Hi JBuzz,
The optional priority queue on a 3750 is queue 1 (the 2950 & 3550 use queue
4 as priority queue). It is enabled with the "priority-queue out" interface
command.
The default mapping of cos to queues is as follows:
Cos 0,1 - q 2
Cos 2,3 - q 3
Cos 4 - q 4
Cos 5 - q 1
Cos 6,7 - q 4
The default mapping of dscp to queues is as follows:
DSCP 0-15 - q 2
DSCP 16-31 - q 3
DSCP 32-39 - q 4
DSCP 40-47 - q 1
DSCP 48-63 - q 4
Autoqos will do the following:
3750(config)#mls qos map cos-dscp 0 8 16 26 32 46 48 56 !- this configures
the COS to dscp mapping which maps cos values in incoming packets to a DSCP
value
ON EGRESS:
3750(config)# no mls qos srr-queue output cos-map
3750(config)# mls qos srr-queue output cos-map queue 1 threshold 3 5 !-
This maps cos 5 (normally for voice) to q 1
3750(config)# mls qos srr-queue output cos-map queue 2 threshold 3 3 6 7 !-
This maps cos 3(normally for voice signaling), 6 & 7 to q 2
3750(config)# mls qos srr-queue output cos-map queue 3 threshold 3 2 4 !-
This maps cos 2, 4 to q 3
3750(config)# mls qos srr-queue output cos-map queue 4 threshold 2 1 !- This
maps cos 1 to q 4
3750(config)# mls qos srr-queue output cos-map queue 4 threshold 3 0 !- This
maps cos 0 to q 4
!- The switch also does something similar with DSCP
C2970(config)# no mls qos srr-queue output dscp-map
C2970(config)# mls qos srr-queue output dscp-map queue 1 threshold 3 40 41
42 43 44 45 46 47 !- DSCP values mapped to q1
C2970(config)# mls qos srr-queue output dscp-map queue 2 threshold 3 24 25
26 27 28 29 30 31
C2970(config)# mls qos srr-queue output dscp-map queue 2 threshold 3 48 49
50 51 52 53 54 55
C2970(config)# mls qos srr-queue output dscp-map queue 2 threshold 3 56 57
58 59 60 61 62 63
C2970(config)# mls qos srr-queue output dscp-map queue 3 threshold 3 16 17
18 19 20 21 22 23
C2970(config)# mls qos srr-queue output dscp-map queue 3 threshold 3 32 33
34 35 36 37 38 39
C2970(config)# mls qos srr-queue output dscp-map queue 4 threshold 1 8
C2970(config)# mls qos srr-queue output dscp-map queue 4 threshold 2 9 10 11
12 13 14 15
C2970(config)# mls qos srr-queue output dscp-map queue 4 threshold 3 0 1 2 3
4 5 6 7
I hope this helps.
David Bombal
CCIE, CCSI, CCIP, CCSP, CCDP
http://www.ConfigureTerminal.com
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of j
buss
Sent: 19 June 2006 18:20
To: ccielab@groupstudy.com
Subject: [Bulk] Egress queue on Cisco 3750
Hi guys,
The default egress queue's for DSCP 46 and other values are changed when
enabling AUTO-QOS Why does cisco do this?
Why is for example a DSCP value first mapped to queue-1 and after enabling
auto-qos, it's mapped to queue 4 or whatever..
Is there a new standard for mapping DSCP values to Queue's.
Regards,
JBuzz
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