Allied Telesis AT-S101 - Manual (Page 189)

AT-S101 Management Software Features Guide
189
Observe the following guidelines when using this variable:
ˆ When selecting a Layer 4 variable, this variable must be left blank or
set to IP.
ˆ If you choose to specify a protocol by its number, you can enter the
value in decimal or hexadecimal format. If you choose the latter,
precede the number with the prefix “0x.”
ˆ The range for the protocol number is from 1536 (0x600) to 65535
(0xFFFF).
DSCP (DiffServ Code Point)
The Differentiated Services Code Point (DSCP) tag indicates the class of
service to which packets belong. The DSCP value is written into the ToS
field of the IP header, as shown in Figure 57. Routers within the network
use this DSCP value to classify packets and assign QoS appropriately.
The location of this value is shown in Figure 57.
Figure 57. DSCP value in an IP Header
Protocol
You can define a traffic flow by the following Layer 3 protocols:
ˆ TCP
ˆ UDP
ˆ ICMP
0
ver IHL
0
3 7
ToS total length
15 31
. . .
1 2 3 4 5 6 7
DSCP value
Precedence