DMC(4)							     Kernel Interfaces Manual							    DMC(4)

NAME

       dmc - DEC DMC-11/DMR-11 point-to-point communications device

SYNOPSIS

       /sys/conf/SYSTEM:
	    NDMC dmc_controllers     # DMC11

DESCRIPTION

       The  dmc  interface provides access to a point-to-point communications device which runs at either 1 Mb/s or 56 Kb/s.  DMC-11's communicate
       using the DEC DDCMP link layer protocol.

       The dmc interface driver also supports a DEC DMR-11 providing point-to-point communication running at data rates from 2.4 Kb/s to  1  Mb/s.
       DMR-11's  are  a more recent design and thus are preferred over DMC-11's.  The NXMT and NRCV constants in the driver should be increased in
       this case, as the DMR can accept up to 64 transmit and receive buffers, as opposed to 7 for the DMC.

       The configuration flags specify how to set up the device,
       0 -- full duplex DDCMP (normal mode)
       1 -- DDCMP Maintence mode (generally useless)
       2 -- DDCMP Half Duplex, primary station
       3 -- DDCMP Half Duplex, secondary station

       Several device error counters are available via "adb", for more information see the adb script /usr/share/adb/dmcstats, or the DMC11  tech-
       nical manual.

       The  host's  address must be specified with an SIOCSIFADDR ioctl, and the destination address specified with a SIOCSIFDSTADDR ioctl, before
       the interface will transmit or receive any packets.

ROUTING

       The driver places a HOST entry in the kernel routing tables for the address given in the SIOCSIFDSTADDR ioctl.  To use the DMC  as  a  link
       between	local  nets,  the  route  to the remote net must be added manually with the route(8) command, or by the use of the routing process
       routed(8) on each end of the link.

DIAGNOSTICS

       dmc%d: bad control %o.  A bad parameter was passed to the dmcload routine.

       dmc%d: unknown address type %d.	An input packet was received which contained a type of address unknown to the driver.

       DMC fatal error 0%o.  A fatal error in DDMCP occurred, causing the device to be restarted.

       DMC soft error 0%o.  A non-fatal error in DDMCP has occurred.

       dmc%d: af%d not supported.  The interface was handed a message which has addresses formatted in an unsuitable address family.

SEE ALSO

       intro(4N), inet(4F)

BUGS

       The current version of the driver uses a link-level encapsulation so that multiple protocol types may be used.	It  is	thus  incompatible
       with earlier drivers, including the 4.2BSD version.

3rd Berkeley Distribution					 October 22, 1996							    DMC(4)