The match precedence command examines the higher-order three bits in the type of service (ToS) byte of
the IP header. Up to eight precedence values can be matched in one match statement. For example, match
precedence ipv4 0 1 2 3 4 5 6 7 returns matches for IP precedence values of 0, 1, 2, 3, 4, 5, 6, and 7. Only
one of the eight values is needed to yield a match (OR operation).
The precedence values are used as a matching criterion only. The value has no mathematical significance.
For instance, the precedence value 2 is not greater than 1. The value simply indicates that a packet marked
with the precedence value of 2 is different than a packet marked with the precedence value of 1. The treatment
of these different packets is defined by the user through the setting of QoS policies in policy map class
configuration mode.
The following table lists the IP precedence value number and associated name in descending order of
importance.
Table 3: IP Precedence Values and Names
NameValue
routine0
priority1
immediate2
flash3
flash-override4
critical5
internet6
network7
ipv4 precedenceipv4
ipv6 precedenceipv6
Task ID
OperationsTask ID
read, writeqos
Examples
The following example shows how to configure the service policy called policy1 and attach service policy
policy1 to an interface. In this example, class map ipprec5 evaluates all packets entering GigabitEthernet
interface 0/1/0/9 for a precedence value of 5. If the incoming packet has been marked with the precedence
value of 5, the packet is queued to the class queue with the bandwidth setting 300 kbps.
RP/0/RP0/CPU0:router# configure
Cisco IOS XR Modular Quality of Service Command Reference for the Cisco CRS Router, Release 4.0
OL-23235-03 51
Quality of Service Commands on the Cisco IOS XR Software
match precedence
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