PPPOE-RELAY(8)						      System Manager's Manual						    PPPOE-RELAY(8)

NAME

       pppoe-relay - user-space PPPoE relay agent.

SYNOPSIS

       pppoe-relay [options]

DESCRIPTION

       pppoe-relay is a user-space relay agent for PPPoE (Point-to-Point Protocol over Ethernet) for Linux.  pppoe-relay works in concert with the
       pppoe client and pppoe-server server.  See the OPERATION section later in this manual for details on how pppoe-relay works.

OPTIONS

       -S interface
	      Adds the Ethernet interface interface to the list of interfaces managed by pppoe-relay.  Only PPPoE servers may be connected to this
	      interface.

       -C interface
	      Adds the Ethernet interface interface to the list of interfaces managed by pppoe-relay.  Only PPPoE clients may be connected to this
	      interface.

       -B interface
	      Adds the Ethernet interface interface to the list of interfaces managed by pppoe-relay.  Both PPPoE clients and servers may be  con-
	      nected to this interface.

       -n num Allows at most num concurrent PPPoE sessions.  If not specified, the default is 5000.  num can range from 1 to 65534.

       -i timeout
	      Specifies  the  session idle timeout.  If both peers in a session are idle for more than timeout seconds, the session is terminated.
	      If timeout is specified as zero, sessions will never be terminated because of idleness.

	      Note that the idle-session expiry routine is never run more frequently than every 30 seconds, so the timeout  is	approximate.   The
	      default value for timeout is 600 seconds (10 minutes.)

       -F     The -F option causes pppoe-relay not to fork into the background; instead, it remains in the foreground.

       -h     The -h option prints a brief usage message and exits.

OPERATION

       pppoe-relay  listens  for  incoming PPPoE PADI frames on all interfaces specified with -B or -C options.  When a PADI frame appears, pppoe-
       relay adds a Relay-Session-ID tag and broadcasts the PADI on all interfaces specified with -B or -S options (except the interface on  which
       the frame arrived.)

       Any PADO frames received are relayed back to the client which sent the PADI (assuming they contain valid Relay-Session-ID tags.)  Likewise,
       PADR frames from clients are relayed back to the matching access concentrator.

       When a PADS frame is received, pppoe-relay enters the two peers' MAC addresses and session-ID's into a hash table.  (The session-ID seen by
       the  access  concentrator  may  be  different  from that seen by the client; pppoe-relay must renumber sessions to avoid the possibility of
       duplicate session-ID's.)  Whenever either peer sends a session frame, pppoe-relay looks up the session entry in the hash table  and  relays
       the frame to the correct peer.

       When a PADT frame is received, pppoe-relay relays it to the peer and deletes the session entry from its hash table.

       If  a client and server crash (or frames are lost), PADT frames may never be sent, and pppoe-relay's hash table can fill up with stale ses-
       sions.  Therefore, a session-cleaning routine runs periodically, and removes old sessions from the hash table.	A  session  is	considered
       "old"  if  no  traffic  has been seen within timeout seconds.  When a session is deleted because of a timeout, a PADT frame is sent to each
       peer to make certain that they are aware the session has been killed.

EXAMPLE INVOCATIONS

       pppoe-relay -C eth0 -S eth1

       The example above relays frames between PPPoE clients on the eth0 network and PPPoE servers on the eth1 network.

       pppoe-relay -B eth0 -B eth1

       This example is a transparent relay -- frames are relayed between any mix of clients and servers on the eth0 and eth1 networks.

       pppoe-relay -S eth0 -C eth1 -C eth2 -C eth3

       This example relays frames between servers on the eth0 network and clients on the eth1, eth2 and eth3 networks.

AUTHORS

       pppoe-relay was written by David F. Skoll <dfs@roaringpenguin.com>.

       The pppoe home page is http://www.roaringpenguin.com/pppoe/.

SEE ALSO

       pppoe-start(8), pppoe-stop(8), pppoe-connect(8), pppd(8), pppoe.conf(5), pppoe(8), pppoe-setup(8), pppoe-status(8), pppoe-sniff(8),  pppoe-
       server(8)

4th Berkeley Distribution					  26 January 2001						    PPPOE-RELAY(8)