Extreme Networks ExtremeWare XOS Guide Manual page 212

Quality of Service
Figure 11: IP packet header encapsulation
0 bits
Version IHL
Identification
Time-to-live
Observing DiffServ code points as a traffic grouping mechanism for defining QoS policies and
overwriting the Diffserv code point fields are supported.
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 36: Default DiffServ code point-to-QoS profile mapping
BlackDiamond 10K
Code Point Switch Qos Profile
0-7 QP1
8-15 QP2
16-23 QP3
24-31 QP4
32-39 QP5
40-47 QP6
48-55 QP7
56-63 QP8
ExtremeWare XOS 11.1 Concepts Guide
0 1 2 3
DiffServ code point
Type-of-service
Flags
Protocol Header checksum
Source address
Destination address
Options (+ padding)
Data (variable)
Aspen 8810
Switch QoS Profile
QP1
QP1
QP1
QP1
QP1
QP1
QP1
QP8
4 5 6 7
31
Total length
Fragment offset
EW_023
6
= 64). By default, the values
Table 36.
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