Brocade Communications Systems Brocate Ethernet Access Switch 6910 - Manual (Page 851)

Brocade 6910 Ethernet Access Switch Configuration Guide 801
53-1002581-01
Chapter
39
Quality of Service
In this chapter
This chapter describes the following tasks required to apply QoS policies:
• Class Map – Creates a map which identifies a specific class of traffic.
• Policy Map – Sets the boundary parameters used for monitoring inbound traffic, and the action
to take for conforming and non-conforming traffic.
• Binding to a Port – Applies a policy map to an ingress port.
Overview
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, VLAN lists, CoS values or source ports. 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.
NOTE
You can configure up to 16 rules per class map. You can also include multiple classes in a policy
map.
You should create a class map before creating a policy map. Otherwise, you will not be able to select
a class map from the policy rule settings screen (see
page 805 ).