Quality of Service (QoS): Managing Bandwidth More Effectively

Using QoS Types To Configure QoS for Outbound Traffic

Notice that codepoints 000000 and 001001 are named as DSCP policies by other codepoints (000001 and 000110 respectively). This means they are not available for changing to a different 802.1p priority.

Outbound IP packets with a DSCP of 000110 will have a priority of 7.

Figure 6-6. Example of a Type-of-Service Configuration Enabling Both Direct 802.1p Priority Assignment and DSCP Policy Assignment

Assigning a DSCP Policy on the Basis of the DSCP in IPv4

Packets Received from Upstream Devices

The preceding section describes how to forward a policy set by an edge (or upstream) switch. This option changes a DSCP policy in an IPv4 packet by changing its IP ToS codepoint and applying the priority associated with the new codepoint. (A DSCP policy consists of a differentiated services codepoint and an associated 802.1p priority.) You can use this option concurrently with the diffserv 802.1p priority option (above), as long as the DSCPs specified in the two options do not match.

To use this option to configure a change in policy:

1.Identify a DSCP used to set a policy in packets received from an upstream or edge switch.

2.Create a new policy by using qos dscp-map < codepoint > priority < 0 - 7 > to configure an 802.1p priority for the codepoint you will use to overwrite the DSCP the packet carries from upstream. (For more on this topic, refer to “Differentiated Services Codepoint (DSCP) Mapping” on page 6-32.)

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