IPv6 packets are
forwarded by paths that are different from those for IPv4. QoS features
supported for IPv6 environments include packet classification, queueing,
traffic shaping, weighted random early detection (WRED), class-based packet
marking, and policing of IPv6 packets. These features are available at both the
process switching and Cisco Express Forwarding switching paths of IPv6.
All of the QoS
features available for IPv6 environments are managed from the modular QoS
command-line interface (MQC). The MQC allows you to define traffic classes,
create and configure traffic policies (policy maps), and then attach those
traffic policies to interfaces.
To implement QoS in
networks running IPv6, follow the same steps that you would follow to implement
QoS in networks running only IPv4. At a very high level, the basic steps for
implementing QoS are as follows:
-
Know which
applications in your network need QoS.
-
Understand the
characteristics of the applications so that you can make decisions about which
QoS features would be appropriate.
-
Know your network
topology so that you know how link layer header sizes are affected by changes
and forwarding.
-
Create classes
based on the criteria you establish for your network. In particular, if the
same network is also carrying IPv4 traffic along with IPv6, decide if you want
to treat both of them the same way or treat them separately and specify match
criteria accordingly. If you want to treat them the same, use match statements
such as
match
precedence ,
match
dscp . If you want to treat them separately,
add match criteria such as
match
protocol
ip and
match
protocol
ipv6 in a match-all class map.
-
Create a policy
to mark each class.
-
Work from the
edge toward the core in applying QoS features.
-
Build the policy
to treat the traffic.
-
Apply the policy.
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