PVCs can be used for machines that are either connected back to back or
via a switch. In the latter case, the cell forwarding has to be manually
set up at the switch.
aread/awrite and
br/bw are simple programs
to access the ATM API. awrite sends the text string
passed as its second argument in an AAL5 PDU. aread
receives one AAL5 PDU and
displays it in hex. Both programs also display the return values of the
corresponding system calls and the current values of
errno.
bw either sends its standard input or a stream of
blocks containing
arbitrary data (if a number is passed as its fourth argument) in 8 kB
AAL5 PDUs. br receives AAL5 PDUs and writes them
to standard output.
The first argument of aread,
awrite, br and
bw is always the PVC address,
i.e. the ATM interface number, the VPI and the VCI number, with a dot
between elements. The interface number can be omitted if it is zero.
Example:
Note that some adapters only support VPI == 0. Also, the VCI range may be
limited, e.g 0 to 1023.
The interface number can be obtained from the initialization
message the driver printed during startup. atm0
is interface 0, atm1 is interface 1, etc. If the
system is equipped with a real
ATM adapter (e.g. not only atmtcp),
that adapter is normally at atm0.
aping receives and sends small AAL5 PDUs on a PVC.
It expects that
messages it sends are either echoed back or that a similar program on the
other side generates a stream of messages. aping
reports an error if no messages are received for too long.
aping is invoked by
specifying the PVC, like aread.
For "real" tests, you should use the modified version of
ttcp that
comes with this package. The original is available at
ftp://ftp.sgi.com/sgi/src/ttcp/.
The following options have been added:
- -a
use native ATM instead of UDP/TCP. The address must be in
the format
[itf.]vpi.vci
for PVCs, or a
valid ATM end system address for SVCs.
- -P num
use a CBR connection with a peak cell rate of
num cells per second. Default is to use UBR.
- -C
disable (UDP) checksums
Example:
Take our 
