Enterasys Networks 2200 - Manual (Page 154)

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)