Allied Telesis AT-S62 - Manual (Page 224)

Chapter 14: Classifiers
Section II: Advanced Operations 224
Observe these guidelines when using this criterion:
❑ The Protocol variable must be left blank or set to IP.
❑ You cannot specify both an IP ToS value and an IP DSCP value in
the same classifier.
IP DSCP (DiffServ Code Point) (ToS) (Layer 3)
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 66 on page 223. Routers within
the network use this DSCP value to classify packets, and assign QoS
appropriately. When a packet leaves the DiffServ domain, the DSCP
value can be replaced with a value appropriate for the next DiffServ
domain.The range of the value is 0 to 63.
Observe these guidelines when using this criterion:
❑ The Protocol variable must be left blank or set to IP.
❑ You cannot specify both an IP ToS value and an IP DSCP value in
the same classifier.
IP Protocol (Layer 3)
You can define a traffic flow by the following Layer 3 protocols:
❑ TCP
❑ UDP
❑ ICMP
❑ IGMP
❑ IP protocol number
If you choose to specify a Layer 3 protocol by its number, you can enter
the value in decimal or hexadecimal format. It you choose the latter,
precede the number with the prefix “0x”.
Source IP Addresses (Layer 3)
Source IP Mask (Layer 3)
You can define a traffic flow by the source IP address contained in IP
packets. The address can be of a subnet or a specific end node.