Interlogix GE-DS-242-PoE, User Manual

Page: 109 / 218

Chapter 4: Console Management
GE-DS-242-PoE Managed Ethernet Switch User Manual 105
Figure 4-57: QoS Configuration - Port-Based Priority
This page includes the following fields:
OBJECT DESCRIPTION
Port Number:
Indicate port 1 to port 26.
Port Priority:
Each port has 8 priority levels—0~7 or Disable to be chosen. 7 is
the highest priority.
TOS/DSCP
TOS/DSCP priority is obtained through a 6-bit Type-of-Service (TOS) or
Differentiated Service Code Point (DSCP) to 3-bit priority mapping.
The Type of Service (TOS) octet in the IPv4 header is divided into three parts;
Precedence (3 bits), TOS (4 bits), and MBZ (1 bit). The Precedence bits indicate
the importance of a packet, whereas the TOS bits indicate how the network
should make tradeoffs between throughput, delay, reliability, and cost (as defined
in RFC 1394). The MBZ bit (for "must be zero") is currently unused and is either
set to zero or just ignored.
0 1 2 3 4 5 6 7
Precedence TOS MBZ
Pv4 Packet Header Type of Service Octet
The four TOS bits provide 15 different priority values, however only five values
have a defined meaning.