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Catalyst 3750 Switch Software Configuration Guide
OL-8550-09
Chapter 38 Configuring IP Unicast Routing
Configuring Protocol-Independent Features
• Policy-based routing based on packet length, TOS, set interface, set default next hop, or set default
interface are not supported. Policy maps with no valid set actions or with set action set to Don’t
Fragment are not supported.
• The switch supports quality of service (QoS) DSCP and IP precedence matching in PBR route maps,
with these limitations:
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You cannot apply QoS DSCP mutation maps and PBR route maps to the same interface.
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You cannot configure DSCP transparency and PBR DSCP route maps on the same switch.
–
When you configure PBR with QoS DSCP, you can set QoS to be enabled (by entering the mls
qos global configuration command) or disabled (by entering the no mls qos command). When
QoS is enabled, to ensure that the DSCP value of the traffic is unchanged, you should configure
a DSCP trust state on the port where traffic enters the switch by entering the mls qos trust dscp
interface configuration command. If the trust state is not DSCP, by default all nontrusted traffic
would have the DSCP value marked as 0.
Enabling PBR
By default, PBR is disabled on the switch. To enable PBR, you must create a route map that specifies
the match criteria and the resulting action if all of the match clauses are met. Then, you must enable PBR
for that route map on an interface. All packets arriving on the specified interface matching the match
clauses are subject to PBR.
PBR can be fast-switched or implemented at speeds that do not slow down the switch. Fast-switched
PBR supports most match and set commands. PBR must be enabled before you enable fast-switched
PBR. Fast-switched PBR is disabled by default.
Packets that are generated by the switch, or local packets, are not normally policy-routed. When you
globally enable local PBR on the switch, all packets that originate on the switch are subject to local PBR.
Local PBR is disabled by default.
Note To enable PBR, the stack master must be running the IP services image.