DMC(4)                                                                  DMC(4)



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

SYNOPSIS
       device dmc0 at uba0 csr 167600 vector dmcrint dmcxint

DESCRIPTION
       The  _d_m_c  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 _d_m_c 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  infor‐
       mation see the adb script /usr/lib/adb/dmcstats, or the DMC11 technical
       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  _r_o_u_t_e(8)  command,  or  by  the  use  of the routing process
       _r_o_u_t_e_d(8) on each end of the link.

DIAGNOSTICS
       dmc%d: bad control %o.  A bad parameter was passed to the _d_m_c_l_o_a_d  rou‐
       tine.

       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.



4.2 Berkeley Distribution        May 21, 1986                           DMC(4)