User's Manual

pulsAR radio Operator’s Manual
2-14
>show ethernet
2.5.2 Packet priorities
As packets arrive into a radio from any port, the bridging algorithm determines if the packets need to
be transmitted over RF. If so the radio queues the packets into one of several priority queues.
Starting with the highest priority the packets are classified as follows:
• Vital packets: These are UDP packets with a specific destination UDP port number. This port
number is part of the field programmable radio configuration (see command >udp).
• NetCrossing Gateways Serial packets: These are SNAP encapsulated packets containing
synchronous serial data generated by the Afar NetCrossing Gateway devices.
• High-Priority: These includes network management packets for “ECON” command sessions, and
also IP packets with a value in the “Type-Of-Service” indicating high priority. The radio
interprets the IP TOS field per the IETF differentiated services (DS) definition as shown below:
01234567
Codepoint Unused
When the codepoint field has the value xxx000, the three most significant bits are interpreted as
precedence bits. The radio gives high priority to packets with a precedence field of 6 or 7. In
hexadecimal notation this translates into TOS values of E0 and C0.
• Low-priority: All other packets
When the time to transmit over RF arrives, the software always takes packets from the higher priority
queues first.