Enterasys SmartSwitch 2H252 Supplemental User's Manual page 5

This supplement provides information concerning the IP TOS Rewrite feature added to the Priority
Classification Configuration screen. This information applies to the following:
• 2nd and 3rd generation devices with firmware revision 4.07.xx and higher
• SmartSwitch 9000 series 9x5xx devices with firmware revision 1.07.xx and higher
NOTE:
"2nd generation devices" refers to the 2x2xx standalone and 6x2xx module series
devices of the SmartSwitch 6000 family.
"3rd generation devices" refers to the 6x3xx series modules devices of the SmartSwitch
6000/Matrix E7 family.
This supplement supersedes the information in the Priority Classification Configuration section in
the following documents:
• SmartSwitch Series 2E253, 2H252, 2H253 and 2H258 Local Management User's Guide
(9033069)
• MATRIX E7 Series and SmartSwitch 6000 Series Modules (6x2xx and 6x3xx) Local
Management User's Guide (9034046-02)
• SmartSwitch 9000 9x5xx-Series Local Management User's Guide (9033130-05)
1.0 IP TOS REWRITE FEATURE
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
signal the frame priority from end to end as the frame makes its way through the network.
Figure 1 Datagram, Layer 2 and Layer 3
Figure 1). The TOS layer-3 priority indicator enables the ability to
Overview
1