Extreme Networks Summit 300-48, Руководство пользователя программного обеспечения

Страница: 128 / 198

128 Summit 300-48 Switch Software User Guide
Quality of Service (QoS)
Configuring DiffServ
Contained in the header of every IP packet is a field for IP Type of Service (TOS), now also called the
DiffServ field. The TOS field is used by the switch to determine the type of service provided to the
packet.
Observing DiffServ code points as a traffic grouping mechanism for defining QoS policies and
overwriting the Diffserv code point fields are supported in the Summit 300-48 switch.
Figure 14 shows the encapsulation of an IP packet header.
Figure 14: IP packet header encapsulation
Table 45 lists the commands used to configure DiffServ. Some of the commands are described in more
detail in the following paragraphs.
Table 45: DiffServ Configuration Commands
Command Description
disable diffserv examination ports [<portlist> |
all] Disables the examination of the diffserv field in
an IP packet.
enable diffserv examination ports [<portlist> |
all] Enables the diffserv field of an ingress IP packet
to be examined by the switch in order to select a
QoS profile. The default setting is disabled.
EW_023
Type-of-service
DiffServ code point
IHL
Data (variable)
0 bits 31
Options (+ padding)
Destination address
Source address
0 7 6 5 4 3 2 1
Total length Version
Protocol Time-to-live Header checksum
Flags Identification Fragment offset