Assigning DSCP policies to packets matching specified TCP and UDP port applications (Example)

Port Applications

DSCP Policies

 

DSCP

Priority

23-UDP

000111

7

80-TCP

000101

5

914-TCP

000010

1

1001-UDP

000010

1

Procedure
  1. Determine whether the DSCP codepoints that you want to use to mark matching packets already have an 802.1p priority assigned, which could indicate use by existing applications (show qos dscp-map command).
    NOTE:

    A DSCP codepoint must also have a priority configured before you can use it to mark matching packets.

    Viewing the current DSCP-map configuration
    switch(config)# show qos dscp-map
    
      DSCP -> 802.p priority mappings
      NOTE: ‘qos type-of-service diff-services’ must be configured 
             before DSCP is honored on inbound traffic.
    
      DSCP CodePoint DSCP Value 802.1p tag   DSCP Policy name
      -------------- ---------- -----------  ---------------------------
      000000         0          0            cs0
      000001         1          No-override
      000010         2          No-override
      000011         3          No-override
      000100         4          No-override
      000101         5          No-override
      000110         6          No-override
      000111         7          No-override
      001000         8          1            cs1
      001001         9          No-override
    
  2. Configure the DSCP policies for the codepoints you want to use.
    Figure 42: Assigning priorities to the selected DSCPs
  3. Assign the DSCP policies to the selected TCP/UDP port applications and display the result.
    Figure 43: Configuring a DSCP policy for global TCP/UDP port classifiers
  4. The switch applies the DSCP policies as shown in the preceding image to IP packets with the specified source and destination TCP/UDP port applications that are received in the switch. The switch manages the packets as follows:
    1. Overwrites the original DSCPs in the selected packets with the new DSCPs specified in the above policies.
    2. Assigns the 802.1p priorities in the above policies to the selected packets.