Cos Mapping - Cisco 3845 - Security Bundle Router Software Manual
Software configuration guide
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Understanding QoS
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This display shows the available classification options:
Switch(config-cmap)# match ip dscp ?
<0-63>
af11
af12
af13
af21
af22
af23
af31
af32
af33
af41
af42
af43
cs1
cs2
cs3
cs4
cs5
cs6
cs7
default
ef
For more information on DSCP prioritization, see RFC-2597 (AF per-hop behavior), RFC-2598 (EF), or
RFC-2475 (DSCP).
CoS Mapping
The switch uses EVC and EFPs to support VLAN mapping from the customer VLAN-ID (C-VLAN) to
a service-provider VLAN-ID (S-VLAN). See the
Protocol Tunneling using EFPs" section on page
For QoS, you can set the service-provider CoS (S-CoS) from either the customer CoS (C-CoS) or the
customer DSCP (C-DSCP) value. You can map the inner CoS to the outer CoS for any traffic with
traditional 802.1Q tunneling (QinQ). This allows copying the customer CoS into the service provider
network.
By default, the switch supports C-CoS to S-CoS propagation for QinQ. When you configure QinQ, you
can also set the S-CoS from C-DSCP.
Configuring CoS matching on EFPs configured for tunneling:
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Cisco ME 3800X and 3600X Switch Software Configuration Guide
27-8
the binary form of the DSCP number. When congestion occurs, the drop precedence of a packet
determines the relative importance of the packet within the class. An AF41 class provides the
highest probability of a packet being forwarded from one end of the network to the other.
Entering Class Selector (CS) service values of 1 to 7, corresponding to IP precedence bits in the ToS
field of the packet.
Using Expedited Forwarding (EF) to specify a low-latency path. This corresponds to a DSCP value
of 46. EF services use priority queuing to preempt lower priority traffic classes.
Differentiated services codepoint value
Match packets with AF11 dscp (001010)
Match packets with AF12 dscp (001100)
Match packets with AF13 dscp (001110)
Match packets with AF21 dscp (010010)
Match packets with AF22 dscp (010100)
Match packets with AF23 dscp (010110)
Match packets with AF31 dscp (011010)
Match packets with AF32 dscp (011100)
Match packets with AF33 dscp (011110)
Match packets with AF41 dscp (100010)
Match packets with AF42 dscp (100100)
Match packets with AF43 dscp (100110)
Match packets with CS1(precedence 1) dscp (001000)
Match packets with CS2(precedence 2) dscp (010000)
Match packets with CS3(precedence 3) dscp (011000)
Match packets with CS4(precedence 4) dscp (100000)
Match packets with CS5(precedence 5) dscp (101000)
Match packets with CS6(precedence 6) dscp (110000)
Match packets with CS7(precedence 7) dscp (111000)
Match packets with default dscp (000000)
Match packets with EF dscp (101110)
On service instances configured for 802.1Q tunneling, the CoS value of the VLAN tag (inner VLAN
or C-VLAN) received on the interface (C-CoS) is automatically reflected in the tunnel VLAN tag
(outer VLAN or S-VLAN) by default.
The set cos policy-map class configuration commands always apply to the outer-most VLAN tag
after processing is complete, that is the S-VLAN-ID. For example, in 802.1Q tunnels, entering a set
cos command changes only the CoS value of the outer tag of the encapsulated packet.
"Configuring IEEE 802.1Q Tunneling and Layer 2
11-17.
Chapter 27
Configuring QoS
OL-23400-01
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