Cisco WS-C4507R Troubleshooting Manual page 55

Cat4500(config)#
r3_4507R_S4#sh qos maps cos dscp
CoS-DSCP Mapping Table
--------------------------------
DSCP:
RST-3508
9805_05_2004_c2
RST-3508
9805_05_2004_c2
© 2004 Cisco Systems, Inc. All rights reserved. Printed in USA.
Presentation_ID.scr
COS/DSCP Mapping
Check if COS to DSCP and DSCP to COS Mapping
Is Configured Properly
qos map cos 7 to dscp 40
CoS: 0 1 2 3 4 5 6
0 8 16 24 32 40 48
If a L2 trunk port is configured to "trust dscp",
•
If the packet is an IP packet, then it will use the DSCP from the IP header
If not, it will use the port default DSCP (configured via qos dscp <val>)
If a L2 trunk port is configured to "trust cos",
•
If the packet is tagged it will map the CoS to an internal DSCP (as per CoS-to-DSCP
mapping table) and then use the DSCP-to-TxQ mapping to determine queue and the
DSCP-to-CoS table to determine egress CoS
If the packet is untagged, it uses the port default CoS and then the
•
other mapping tables as explained above
http://www.cisco.com/en/US/products/hw/switches/ps4324/products_configuration_guide_chapter09186a00801cddc9.html#1223900
© 2004 Cisco Systems, Inc. All rights reserved.
Classification/TOS Re-Write Summary
Determine the "internal DSCP" value—this
•
depends on the policy-map and port trust
configuration
If a packet encounters both input and
•
output classification policy:
Output policy has precedence
If no output policy then input policy has
precedence
If no output/input policy then RX port trust
is used
© 2004 Cisco Systems, Inc. All rights reserved.
Cat4500(config)#qos map dscp 40 to cos 7
Cat4500#sh qos maps dscp cos( truncated)
DSCP-CoS Mapping Table (dscp = d1d2)
d1 : d2 0 1
-------------------------------------
7
4 : 07 05 05 05 05 05 05 05 06 06
5 : 06 06 06 06 06 06 07 07 07 07
40
2 3 4 5 6 7 8 9
109 109 109
110 110 110