KB.15.15

NOTE: Different applications may use the same DSCP in their IP packets. Also, the same

application may use multiple DSCPs if the application originates on different clients, servers, or

other devices. Using an edge switch enables you to select the desired packets and mark them with

predictable DSCPs that can be used by downstream switches to honor policies set in the edge

switch.

When enabled, the switch applies direct 802.1p prioritization to all packets having codepoints

that meet these prerequisites:

• The codepoint is configured with an 802.1p priority in the DSCP table. (Codepoints configured

with No-override are not used.)

• The codepoint is not configured for a new DSCP policy assignment.

Thus, the switch does not allow the same incoming codepoint (DSCP) to be used simultaneously

for directly assigning an 802.1p priority and also assigning a DSCP policy. For a given incoming

codepoint, if you configure one option and then the other, the second overwrites the first.

Assigning an 802.1p priority for a global IP-diffserv classifier 253