5-46
Quality of Service: Managing Bandwidth More Effectively
Globally-Configured QoS
.
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:
Syntax: qos type-of-service diff-services < codepoint >
Causes the switch to read the < codepoint > (DSCP) of an
incoming IP packet and, when a match occurs, assign the
associated 802.1p priority in the DSCP Policy table (see
Table 5-11).
no qos type-of-service
Disables all ToS classifier operation.
no qos dscp-map < codepoint >
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 5-16 you cannot change
the priority for the 000000 codepoint until you redirect the
DSCP policy for 000001 from using 000000 as a policy. (See
“Notes on Changing a Priority Setting” on page 5-93 and
“Differentiated Services Codepoint (DSCP) Mapping” on
page 5-90.)
show qos type-of-service
Displays the current Type-of-Service configuration. In IP-
diffserv mode it also shows the current direct 802.1p assign-
ments and the current DSCP assignments covered later in
this section.
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