Enterprise QoS Solution Reference Network Design Guide

Catalyst 4500 Supervisor II+/III/IV/V—QoS Considerations and Design
show qos maps dscp tx-queue
show qos interface
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Enterprise QoS Solution Reference Network Design Guide
Chapter 2 Campus QoS Design
The Catalyst 4500 show qos maps dscp tx-queue verification command truncates the show qos maps
output to only report the DSCP-to-Queue mappings for egress queues. The output is shown in tabular
form, with the first digit of the decimal DSCP value in rows and the second digit in columns.
In the example below, only DSCP 0 is mapped to Q2; DSCP CS1 (8) and AF11/AF12/AF13 (10/12/14)
are mapped to Q1; DSCP CS2 (16) and AF22/AF22/AF23 (18/20/22) are mapped to Q4; DSCP CS3 (24)
and AF31 (26) are mapped to Q4, as is the non-standard DSCP 25. DSCP CS4 (32) and
AF41/AF42/AF43 (34/36/38) are mapped to Q4, as are DSCP CS6 (48) and CS7 (56). DSCP EF (46) is
mapped to Q3.
Example 2-44 Show QoS Maps DSCP Tx-Queue Verification for a Catalyst 4500 Switch
CAT4500-SUP4#show qos maps dscp tx-queue
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 ! DSCP 0 => Q2; DSCP CS1 => Q1
1 : 01 01 01 01 01 01 04 02 04 02 ! DSCP AF11/AF12/AF13 => Q1
! DSCP CS2 and AF21 => Q4
2 : 04 02 04 02 04 04 04 02 02 02 ! DSCP AF22/AF23 => Q4
! DSCP CS3, 25 and AF31 => Q4
3 : 02 02 04 03 04 03 04 03 04 03 ! DSCP CS4 and AF41/AF42/AF43 => Q4
4 : 03 03 03 03 03 03 03 03 04 04 ! DSCP EF => Q3; DSCP CS6 => Q4
5 : 04 04 04 04 04 04 04 04 04 04 ! DSCP CS7 => Q4
6 : 04 04 04 04
CAT4500-SUP4#
The Catalyst 4500 show qos interface verification command displays the global state of QoS (enabled
or not), the trust state of an interface, as well as any queuing/shaping parameters that have been defined
for the interface.
In the first example below, the show qos interface command is being applied on an access-edge
FastEthernet interface that has been configured to conditionally-trust Cisco IP Phones. Furthermore, the
output reports that Q3 has been enabled as the priority-queue on this interface and is shaped to 30 Mbps
(30%). Bandwidth cannot be assigned for non-priority queues on this interface, as is indicated by the
“N/A” entries under the bandwidth column.
In the second example below, the show qos interface command is being applied to a GigabitEthernet
uplink interface which as been configured to trust-DSCP. As before, Q3 has been enabled as the
priority-queue and has been shaped to 30%, which now translates to 300 Mbps. Bandwidth is assignable
on this interface and therefore Q1 is allocated 50 Mbps (5%), Q2 is allocated 250 Mbps (25%), Q3 is
allocated 300 Mbps (30%), and Q4 is allocated 400 Mbps (40%).
Example 2-45 Show QoS Interface Verification for a Catalyst 4500 Switch
CAT4500-SUP4#show qos interface FastEthernet2/1
QoS is enabled globally
Port QoS is enabled
Administrative Port Trust State: 'cos'
Operational Port Trust State: 'cos'
Trust device: cisco-phone
Default DSCP: 0 Default CoS: 0
Appliance trust: none
Tx-Queue Bandwidth ShapeRate Priority QueueSize
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