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       radrelay -- Deprecated command.


       The  functions  of radrelay have been added to radiusd.  One benefit is
       that one instance of radiusd can  read  multiple  detail  files,  among

       The  rlm_sql_log  module  does  something similar, but for SQL queries.
       See it’s man page for details.


       Many sites run multiple radius servers; at least one  primary  and  one
       backup  server.  When the primary goes down, most NASes detect that and
       switch to the backup server.

       That will cause your accounting packets to go the the backup  server  -
       and  some  NASes  don’t  even switch back to the primary server when it
       comes back up.

       The  result  is  that  accounting  records  are  missed,   and/or   the
       administrator must jump through hoops in order to combine the different
       detail files from multiple servers. It  also  means  that  the  session
       database  ("radutmp",  used  for radwho and simultaneous use detection)
       gets out of sync.

       We solve this issue by "relaying" packets from one server  to  another,
       so they both have the same set of accounting data.

       See raddb/sites-available/buffered-sql for more information.


       If the RADIUS server suddenly receives a many accounting packets, there
       may be insufficient CPU power to process them all in a  timely  manner.
       This  problem  is  especially noticable when the accounting packets are
       going to a back-end database.

       Similarly, you may have one database that tracks "live"  sessions,  and
       another   that  tracks  historical  accounting  data.   In  that  case,
       accessing the first database is fast, as it is  small.   Accessing  the
       second database many be slower, as it may contain multiple gigabytes of
       data.  In addition, writing to the first database in a timely manner is
       important,  while data may be written to the second database with a few
       minutes delay, without any harm being done.

       See raddb/sites-available/copy-to-home-server for more information.


       radiusd(8), rlm_sql_log(5)


       The FreeRADIUS Server Project

                                23 October 2007