Initial Prioritization

For most switches, the local-priority has eight levels (0-7). Zero is the lowest priority. The allowed maximum will vary per product family. Local priority is used to determine which queue a packet will use. There are multiple options to configure the local priority:

  • qos cos-map: Maps Class of Services (CoS) values from VLAN tags in incoming packets to specific local priorities
  • qos dscp-map: Maps the DSCP from incoming packets to specific local priorities
  • qos trust: Assumes incoming packets are marked correctly, and takes the local-priority from either the CoS or Differentiated Service Code-Points (DSCP) field of the packet, or ignores any values set on incoming packets and places the packets into the default local priority queue if the none option is given

Configuration commands

Map incoming 802.1p values to a local priority:

switch(config)# qos cos-map <0-7> local-priority VALUE [color COLOR] [name NAME]

Map incoming DSCP to a local priority:

switch(config)# qos dscp-map <0-63> local-priority VALUE [color COLOR] [name NAME]

Configure QoS trust:

switch(config)# qos trust [none|cos|dscp]
switch(config-if)# qos trust [none|cos|dscp]

Show commands to validate functionality:

show qos [cos-map|dscp-map|trust]

Expected results

  1. Administrators can enable QoS trust to CoS on an interface
  2. Administrators can map incoming 802.1p values to local priorities
  3. The output of all show commands is correct

Example output

switch(config)# qos dscp-map 46 local-priority 7 color green name VOICE
switch # show qos cos-map
code_point local_priority color   name
---------- -------------- ------- ----
0          1              green   Best_Effort
1          0              green   Background
2          2              green   Excellent_Effort
3          3              green   Critical_Applications
4          4              green   Video
5          5              green   Voice
6          6              green   Internetwork_Control
7          7              green   Network_Control

Back to Index