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CLI – The following example globally enables DSCP Priority service on the switch,
maps DSCP value 0 to CoS value 1 (on port 1), and then displays the DSCP Priority
settings.
* Mapping specific values for IP DSCP is implemented as an interface configuration
command, but any changes will apply to the all interfaces on the switch.
Quality of Service
The commands described in this section are used to configure Quality of Service
(QoS) classification criteria and service policies. Differentiated Services (DiffServ)
provides policy-based management mechanisms used for prioritizing network
resources to meet the requirements of specific traffic types on a per hop basis.
Each packet is classified upon entry into the network based on access lists, IP
Precedence, DSCP values, or VLAN lists. Using access lists allows you select traffic
based on Layer 2, Layer 3, or Layer 4 information contained in each packet. Based
on configured network policies, different kinds of traffic can be marked for different
kinds of forwarding.
All switches or routers that access the Internet rely on class information to provide
the same forwarding treatment to packets in the same class. Class information can
be assigned by end hosts, or switches or routers along the path. Priority can then be
assigned based on a general policy, or a detailed examination of the packet.
However, note that detailed examination of packets should take place close to the
network edge so that core switches and routers are not overloaded.
Switches and routers along the path can use class information to prioritize the
resources allocated to different traffic classes. The manner in which an individual
device handles traffic in the DiffServ architecture is called per-hop behavior. All
devices along a path should be configured in a consistent manner to construct a
consistent end-to-end QoS solution.
Notes: 1.
You can configure up to 16 rules per Class Map. You can also include
multiple classes in a Policy Map.
Console(config)#map ip dscp 4-269
Console(config)#interface ethernet 1/1 4-166
Console(config-if)#map ip dscp 1 cos 0 4-270
Console(config-if)#end
Console#show map ip dscp ethernet 1/1 4-271
DSCP mapping status: disabled
Port DSCP COS
--------- ---- ---
Eth 1/ 1 0 0
Eth 1/ 1 1 0
Eth 1/ 1 2 0
Eth 1/ 1 3 0
.
.
.
Eth 1/ 1 61 0
Eth 1/ 1 62 0
Eth 1/ 1 63 0
Console#