Chapter 16 – Configuring Traffic Prioritization
TOS Prio ritization
The priority of an IP packet can be derived from its Type of Service field. The TOS
field has the following format:
7 6 5 4 3 2 1 0
+---+---+---+---+---+---+---+---+
| | TOS Bits | |
|PRECEDENCE |MD MT MR MMC| 0 |
| | | |
+---+---+---+---+---+---+---+---+
The four TOS bits (the 'TOS field') are defined as:
•MD - Mi nimize Delay,
•MT - Mi nimize Throughp ut,
•MR - Ma ximize Reliabi lity,
•MMC - Minimize Monetary Cost
As any (or all) of these bits may be set in a packet at a time, there are 16 possible
combinations. The router maps these combinations into the high, normal and low
priority queues as shown in the following table:
MD MT MR MMC Descriptions Priority Queue
0 0 0 0 Normal Service Normal
0 0 0 1 Minimize Monetary Cost Low
0 0 1 0 Maximize Reliability Normal
0 0 1 1 MR+MMC Normal
0 1 0 0 Maximize Throughput Low
0 1 0 1 MT+MMC Low
0 1 1 0 MT+MR Low
0 1 1 1 MT+MR+MMC Low
1 0 0 0 Minimize Delay High
1 0 0 1 MD+MMC High
1 0 1 0 MD+MR High
1 0 1 1 MD+MR+MMC High
1 1 0 0 MD+MT Normal
1 1 0 1 MD+MT+MMC Normal
1 1 1 0 MD+MT+MR Normal
1 1 1 1 MD+MT+MR+MMC Normal
Included With Traf fic Priorit ization
Your RuggedRouter software includes the priostats command line utility, which can be used to show
cummulative and one second interval statistics in a format similar to those of the GUI.
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