Extreme Networks ExtremeWare XOS Guide Manual page 301

Observing DiffServ information. When a packet arrives at the switch on an ingress port and this feature is
enabled, the switch examines the first six of eight TOS bits, called the DiffServ code point. The switch can
then assign the QoS profile used to subsequently transmit the packet based on the code point. The QoS
profile controls which queue is used when transmitting the packet out of the switch and determines the
forwarding characteristics of a particular code point. Examining DiffServ information can be enabled or
disabled; by default it is disabled. To enable DiffServ examination, use the following command:
enable diffserv examination port [<port_list> | all]
To disable DiffServ examination, use the following command:
disable diffserv examination port [<port_list> | all]
Because the DiffServ code point uses six bits, it has 64 possible values (2
are grouped and assigned to the default QoS profiles listed in
Table 45: Default DiffServ code point-to-QoS profile mapping
BlackDiamond 10K switch
Code point QoS profile
0-7 QP1
8-15 QP2
16-23 QP3
24-31 QP4
32-39 QP5
40-47 Q61
48-55 QP7
56-63 QP8
Changing the default DiffServ code point mapping . You can change the QoS profile assignment for each of
the 64 code points using the following command:
configure diffserv examination code-point <code-point> {qosprofile} <qosprofile>
Once assigned, the rest of the switches in the network prioritize the packet using the characteristics
specified by the QoS profile.
Replacing DiffServ code points. The switch can be configured to change the DiffServ code point in the
packet prior to the packet being transmitted by the switch. This is done with no impact on switch
performance.
The DiffServ code point value used in overwriting the original value in a packet is determined by the
QoS profile. You enter the QoS profile you want to use to determine the replacement DiffServ code
point value.
To replace DiffServ code points, you must enable DiffServ replacement using the following commands
enable diffserv replacement ports [<port_list> | all]
NOTE
The port in this command is the ingress port. This command affects only that traffic based on explicit packet class
of service information and physical/logical configuration.
ExtremeWare XOS 11.3 Concepts Guide
Table 45.
BlackDiamond 8800 family of switches and the Summit
X450 switch QoS profile
QP1
QP1
QP1
QP1
QP1
QP1
QP1
QP8
Traffic Groupings
6
= 64). By default, the values
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