Computers work best with numbers while humans work best with names. We created DNS in order to remember host names instead of IP addresses. Dictionaries are used in the same manner so we can remember AVP names instead of type numbers. Dictionaries are consulted when FreeRADIUS parses requests or generates responses.
However, dictionaries differ from DNS as the RADIUS client has no knowledge of these 'friendly' names used by FreeRADIUS. The AVP names are never exchanged between a RADIUS client and a RADIUS server. The AVP names are used solely by the server. The radclient and radtest programs are special clients that use the same dictionaries as the server because they are part of the FreeRADIUS suite of programs. The dictionaries are solely for the local administrator's convenience and vary depending on the version of FreeRADIUS. The JRadius Simulator in contrast has its own set of dictionaries that is independent from the dictionaries used by...
