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5-19
Quality of Service (QoS): Managing Bandwidth More Effectively
Using QoS Classifiers to Configure Quality of Service for Outbound Traffic
For example, an edge switch “A” in an untagged VLAN assigns a DSCP of
000110 on IP packets it receives on port A6, and handles the packets with high
priority (7). When these packets reach interior switch “B” you want the switch
to handle them with the same high priority. To enable this operation you would
configure an 802.1p priority of 7 for packets received with a DSCP of 000110,
and then enable diff-services:
Figure 5-5. Example Showing Codepoints Available for Direct 802.1p Priority
Assignments
Disables direct 802.1p priority assignment to packets carry-
ing the < codepoint > by reconfiguring the codepoint priority
assignment in the DSCP table to
No-override. Note that if this
codepoint is in use as a DSCP policy for another diffserv
codepoint, you must disable or redirect the other diffserv
codepoint’s DSCP policy before you can disable or change the
codepoint. For example, in figure 5-5 you cannot change the
priority for the 000000 codepoint until you redirect the
DSCP policy for 000001 away from using 000000 as a policy.
(Refer to “Notes on Changing a Priority Setting” on page
5-36. Refer also to “Differentiated Services Codepoint
(DSCP) Mapping” on page 5-33.)
show qos type-of-service
Displays current Type-of-Service configuration. In diffserv
mode it also shows the current direct 802.1p assignments
and the current DSCP assignments covered later in this
section.
Executing this command
displays the current ToS
configuration and shows that the
selected DSCP is not currently in
The 000110 codepoint is unused,
and thus available for directly
assigning an 802.1p priority
without changing the packet’s
DSCP.
Note: All codepoints without a
“DSCP Policy” entry are
available for direct 802.1p priority
assignment.