NAME

     atm_send, atm_sendto, atm_send_null  -  send  data  over  an
     established ATM connection

SYNOPSIS

     #include <fore_atm/fore_atm_user.h>

     atm_send(fd, buf, len)
     int fd;
     caddr_t buf;
     int len;

     atm_sendto(fd, buf, len, vpvc)
     int fd;
     caddr_t buf;
     int len;
     Vpvc vpvc;

     atm_send_null(fd, buf, len, hdr)
     int fd;
     caddr_t buf;
     int len;
     Atm_hdr hdr;

DESCRIPTION

     The atm_send() family of functions  attempts  to  write  len
     bytes  of  data  from  the  buffer pointed to by buf over an
     established ATM connection referenced by the file descriptor
     fd.   atm_send()  is  used  with  switched  virtual circuits
     (SVCs) and may  be  used  with  permanent  virtual  circuits
     (PVCs)  only  if  fd  is  associated  with a single PVC (see
     atm_connect_pvc(4N)).

     When fd is associated with multiple  PVCs,  atm_sendto()  is
     used  to transmit the data over the connection identified by
     the VPI/VCI pair vpvc.  The identifier vpvc must  correspond
     to  an  outgoing PVC actively connected from a previous call
     to atm_connect_pvc(4N).  atm_sendto() may not be  used  with
     SVCs.

     When sending data on a 100 series adapter  over  connections
     with  an  AAL  type of aal_null, atm_send() and atm_sendto()
     must be used.  buf specifies a sequence of cells  in  FORE's
     intermediate  cell  format (see atm_intro(4N) for details on
     cell formats).  len must correspond to a number of  complete
     cells, so it must be a multiple of 56.

     When sending data on a 200 series adapter  over  connections
     with  an AAL type of aal_null, atm_send_null() must be used.
     The first four bytes of the ATM header are specified in hdr,
     while  the HEC is automatically computed and inserted by the
     hardware.   buf  specifies  a  sequence  of  48  byte   cell
     payloads,  each to be transmitted with the specified header.
     len must correspond to a number of complete payloads, so  it
     must be a multiple of 48.  Note that atm_send_null() is used
     when fd is associated with an SVC as well as  with  multiple
     PVCs.   When  fd  references  an  SVC,  the VPI/VCI pair, as
     specified in the ATM cell header hdr, must be zero.  When fd
     references a PVC, the VPI/VCI must correspond to an outgoing
     PVC   actively   connected   from   a   previous   call   to
     atm_connect_pvc(4N).

     The number of bytes to send as specified  by  len  must  not
     exceed  the size of buf, nor must the number of bytes exceed
     the maximum transmission unit (MTU) for the connection.  See
     atm_open(4N)  for details on the MTU.  In addition, for con-
     nections using an AAL type of aal_null, len must follow  the
     restrictions outlined above.

RETURN VALUES

     The atm_send() family returns the number of bytes  transmit-
     ted  on  success.   On  failure,  they  return  -1  and  set
     atm_errno to indicate the error. atm_error(4N) can  be  used
     to print a text description of errors.

ERRORS

     The atm_send() family can also  fail  with  errors  returned
     from the write(2) and writev(2) system calls.

     On ULTRIX platforms, calling atm_send() or atm_sendto() on a
     closed  connection  may cause a SIGPIPE signal to be sent to
     the calling process.  Unless caught or  ignored,  this  ter-
     minates the process.

SEE ALSO

     atm_intro(4N),  atm_open(4N),  atm_pvc(4N),  write(2),  wri-
     tev(2)