Quality of Service
ExtremeWare XOS 11.3 Concepts Guide
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● Physical/logical groupings
■ Source port
■ VLAN
NOTE
The source port and VLAN QoS apply only to untagged packets, and 802.1p QoS applies only to tagged packets. If
you use 802.1p or DiffServ QoS in conjunction with ACLs, you must configure the 802.1p or DiffServ action within
the ACL itself.
In general, the more specific traffic grouping takes precedence. Those groupings listed at the top of the
table are evaluated first. By default, all traffic groupings are placed in the QoS profile QP1. The
groupings are listed in order of precedence (highest to lowest). The three types of traffic groupings are
described in detail on the following pages.
NOTE
On the BlackDiamond 8800 family of switches and the Summit X450 switch, the precedence of IP ACL or MAC
ACL depends on specifications in the ACL file itself. Refer to Chapter 13 for more information on ACLs.
ACL-Based Traffic Groupings
ACL-based traffic groupings are based on any combination of the following items:
● IP source or destination address
● IP protocol
● TCP flag
● TCP/UDP or other Layer 4 protocol
● TCP/UDP port information
● IP fragmentation
● MAC source or destination address
● Ethertype
ACL-based traffic groupings are defined using access lists. Access lists are discussed in detail in
Chapter 13. By supplying a named QoS profile on an ACL rule, you can prescribe the bandwidth
management and priority handling for that traffic grouping. This level of packet filtering has no impact
on performance.
Explicit Class of Service (802.1p and DiffServ) Traffic Groupings
This category of traffic groupings describes what is sometimes referred to as explicit packet marking, and
refers to information contained within a packet intended to explicitly determine a class of service. That
information includes:
● Prioritization bits used in IEEE 802.1p packets
● IP Differentiated Services (DiffServ) code points, formerly known as IP Type of Service (TOS) bits
An advantage of explicit packet marking is that the class of service information can be carried
throughout the network infrastructure, without repeating what can be complex traffic grouping policies
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