Quality of Service (QoS): Managing Bandwidth More Effectively
Preparation for Configuring QoS
How the Switch Uses Resources in DSCP Configurations. In the
default configuration, the DSCP map is configured with one DSCP policy
(Expedited Forwarding; 101110 with a “7” priority) but, because no ToS Diff-
Services options are configured, no rules are used. If ToS Diff-Services mode
is enabled, then one rule is immediately used for this codepoint. Adding a new
DSCP policy (for example, 001111 with a “5” priority) and then configuring
ToS Diff-Services to assign inbound packets with a codepoint of 001010 to the
001111 policy implements all policies configured in the DSCP map and, in this
case, uses three rules; that is, one rule for each codepoint invoked in the
switch’s current DSCP configuration (101110—the default, 001111, and
001010). Adding another Diff-Services assignment, such as assigning inbound
packets with a codepoint of 000111 to the Expedited Forwarding policy
(101110), would use one more rule on all ports.
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