mpcd (8) - Linux Manuals

mpcd: ATM MPOA (Multi-Protocol Over ATM) client daemon


mpcd - ATM MPOA (Multi-Protocol Over ATM) client daemon


mpcd [ -s Control ATM address ] [ -l Data ATM address ] [ -c MPS control ATM address ] [ -i Interface number ] [ -m MPS MAC address ] [ -L LEC address [ -n ELAN name ] [ -C LECS Address ]]


MPOA client (MPC) is responsible for creating and receiving internetwork layer shortcuts. Using these shortcuts MPCs forward unicast internetwork layer packets effectively over ATM without need for routing protocols.

MPC has two roles; ingress and egress. In ingress role MPC detects flows destined outside it's own subnet and tries to establish shortcuts to those destinations. In egress role MPC accepts shortcuts and packets arriving on those shortcuts. Maintaining shortcuts is done with the help of MPOA server (MPS).

Just as the Linux LAN Emulation client, MPOA client is also divided in two parts. The parts are kernel component and a daemon process. The daemon opens and receives data shortcuts and control connections with the kernel component. The kernel component tallies packets flowing out from the LANE device and makes the decision if a packet should be forwarded using LANE or MPOA shortcuts.

If the daemon is killed with SIGHUP it will close all the open connections, purge ingress and egress cache entries, query LECS if applicable and then restart itself.

Linux MPOA client only supports non-LLC-muxed shortcuts. The number of supported MPOA clients is unlimited.


-s Control ATM address
Local ATM address this MPC uses for MPOA control connections.
-l Data ATM address
Local ATM address from and to which MPOA shortcuts are established.
-c MPS control ATM address
ATM address of MPS. Only needed if MPS can not advertise it by itself.
-i Interface number
The interface number of LEC this MPC serves. E.g. 2 for "lec2".
-m MPS MAC address
MAC address of default router where MPS recides. Only useful if the MPOA server fails to advertise itself.
-L LEC address
Listen address of the LANE client zeppelin. mpcd uses this address as its own ATM address when it queries LECS for MPC configuration parameters. If this option is not present then mpcd will not use LECS to query for configuration parameters. This option is normally the same as zeppelin's -l option.
-n ELAN name
Name of the ELAN for which mpcd asks for parameters when it connects to LECS. If this option is not given, LECS should respond with parameters belonging to the default ELAN if one exists. This option is normally the same as zeppelin's -n option.
-C LECS address
ATM address of LECS mpcd asks for parameters. If this option is left empty and -L is given, mpcd uses ATM Forum assigned Well-Known LECS address. This option is normally the same as zeppelin's -c option.


This script snippet shows how to run LANE and MPOA. After UNI signalling and ILMI have been started LANE (zeppelin) and MPOA (mpcd) are started. The commented out line shows how to start mpcd so that it queries LECS for MPC parameters.

Arguments jaarli[1-3] are local ATM addresses listed in file /etc/hosts.atm.

case "$1" in
 cd $ATM
 if -x sigd/atmsigd then

  sigd/atmsigd -b 

 if -x ilmid/ilmid then

  ilmid/ilmid -b -x

 if -x led/zeppelin then

  led/zeppelin -2 -n sampo -i2 -l jaarli3 &
  ifconfig lec2 \

       netmask \

  ifconfig lec2 up
  route add default gw

 if -x mpoad/mpcd then

  mpoad/mpcd -i2 -s jaarli1 -l jaarli2 &
  #mpoad/mpcd -i2 -s jaarli1 -l jaarli2 \
              -L jaarli3 -n sampo 

exit 0


Supports only Ethernet type of ELANs. Probably others too.


Heikki Vatiainen <hessu [at]>, Sampo Saaristo <s156953 [at]>


zeppelin(8), atmsigd(8)