Owner manual

Priority Classification Configuration Screen
6-36 802.1 Configuration Menu Screens
6.7.2 About the IP Rewrite Function
The Type of Service (TOS) field [also known as the Differential Services (DF) field in RFC 2474]
is an 8-bit field. It is located in the IP packet and used by a device to indicate the precedence or
priority of a given frame (see Figure 6-8). The TOS layer-3 priority indicator enables the ability to
signal the frame priority from end to end as the frame makes its way through the network.
Figure 6-8 Datagram, Layer 2 and Layer 3
This IP TOS Rewrite feature enables a Network Administrator to assign Layer 3 TOS
characteristics to incoming frames and setting the switch to rewrite the 8-bit TOS value in the
Layer 3 information portion of incoming frames.
The SmartSwitch products enable you to configure the switch to:
• Insert a user-defined 8-bit value into the layer-3 TOS field.
• Write over an existing TOS value. This is useful when the Network Administrator wants to
enforce a specific priority policy in the network.
6.7.3 Displaying the Current PID/Classification Assignments
To see which ports are set to a particular PID/Classification (Classification Rule), the Protocol Port
Configuration screen must be displayed.
To access the Protocol Port Configuration screen, proceed as follows:
1. Use the arrow keys to step to the line with the Classification Rule of interest.
2. Press ENTER. The Protocol Port Configuration screen displays, showing a list of the current
ports and those associated with the Classification Rule selected in step 1. These ports are
identified on the screen by a YES setting. For more information about the Protocol Port
Configuration screen and how to use it, refer to Section 6.8.
Destination
Address
(DA)
Source
Address
(SA)
VLAN
Priority
Type of
Service
(8-bits)
3559_1
Layer 2
Layer 3
Addr
Length
Version
VLAN
Priority
Type of
Service
(8-bits)