Aprs-is server requirements

These are collected server requirements for APRS-IS type core server

Requirements

Performance

APRS messages observed at APRS-IS core systems have following statistics:

• Hourly message rate is 120-150 thousand
• every exact 5 minutes there is a high burst of CWOP data, system must be able to handle 10 000 clients logging in and sending their messages within 5 seconds
• about 25% of all are CWOP messages
• Message lengths vary greatly:
  • 98.0% of all messages are shorter than 130 bytes long
  • reminder can be up to 300 bytes long

Communication

Core-internal communication:

• All arrived messages are sent to all core peers via TCP or SCTP streams
• Communication protocol with core peers carries a short prefix tag flagging which core nodes have already seen the message
• Average flow is 2-3 Mbit/s, CWOP bursts considerably higher

Duplicate filter:

...

Core-Client communication:

• Majority is write-only, not receiving anything (CWOP bursts, especially)
• Complex filters make system to need pre-process each arrived packet for: message type, lat/lon coordinates if any, source callsign