Enterasys Networks 1G58x-09 - Manual (Page 442)

Port Priority and Classification Configuration Commands
Configuring Priority Classification
9-24 Matrix E1 Series (1G58x-09 and 1H582-xx) Configuration Guide
About ToS
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 header and used by a device to indicate the precedence or
priority of a given frame (see
Table 9-1 ). Together with the 802.1p priotity and IP, ToS fields enable
the ability to signal the frame priority from end to end as the frame makes its way through the
network. The set priority classification tosvalue command enables you to set the value for the
precedence or priority of a frame at both Layer 2 and Layer 3.
Figure 9-1 Datagram, Layer 2 and Layer 3
This IP ToS rewrite feature enables a Network Administrator to assign both Layer 2 Class of
Service (CoS0 and Layer 3 ToS characteristics to incoming frames by rewriting the 8-bit ToS value
in the IP header of incoming frames.
The Matrix E1 products enable you to configure the device to:
• Insert a user-defined 8-bit value into the IP ToS field.
• Overwrite an existing ToS value. This is useful when the Network Administrator wants to
enforce a specific priority policy in the network.
9.3.4.5 set priority classification tosvalue
Use this command to enter the ToS value. This value identifies to the various switch devices and
routers in the IP-based network those packets which should have preferential treatment on a Class
of Service (CoS) basis.
set priority classification tosvalue tos_value priority_value data_meaning
data_value [data_mask]
Destination
Address
(DA)
Source
Address
(SA)
VLAN
Priority
Type of
Service
(8-bits)
3559_2
Layer 2
Header
Length
Version
VLAN
Priority
Type of
Service
(8-bits)
Layer 3 - IP Packet