ATMTCP(8)                    Maintenance Commands                    ATMTCP(8)


       atmtcp - set up ATM over TCP connections


       atmtcp [-d] [-v] command ...
       atmtcp -V


       The  main purpose of atmtcp is to establish TCP connections and to con-
       figure them as virtual ATM devices.   Such  pairs  of  "ATM  over  TCP"
       devices  are  connected  as  if they were real ATM adapters linked by a
       cable or fiber, i.e. SDUs sent on a given VPI/VCI are received  at  the
       other end on the same VPI/VCI.

       Virtual  interfaces  and  ATM  over  TCP  connections are called links.
       Other link types supported by atmtcp are  real  interfaces,  files  for
       recording  and  playback of ATM traffic, and printing a hex dump of the
       PDU content on standard output. Any pair of such links can be connected
       with  atmtcp.   If  additional links are attached to such a connection,
       they send to all other links, except to the first link and the  respec-
       tive sender, and they receive from all other links.

       atmtcp  can  operate with two types of virtual interfaces: ephemeral or
       persistent. By default,  atmtcp  interfaces  are  ephemeral.  When  the
       atmtcp  process  that  created an interface terminates, the virtual ATM
       device is removed as soon all VCs are closed. However, if the interface
       was  previously  created as a persistent interface, only the communica-
       tion stops, but the interface and all VCs on it remain intact. Attempts
       to  send  data on an atmtcp interface in this state fail silently, i.e.
       the interface behaves just like a real ATM interface without a wire.  A
       new  atmtcp  process can then attach to the interface and resume opera-
       tion. Persistent interfaces need to be removed explicitly.

       If atmtcp has any readable links after processing the command line,  it
       enters a loop to perform the data forwarding. If no readable links have
       been specified, atmtcp terminates after processing the command line. If
       any setup operation fails, atmtcp terminates at this point and does not
       attempt to cancel  previous  operations  (e.g.  creation  of  permanent


       -d     print detailed progress information on standard error.

       -v     print some progress information on standard error.

       -V     print version number of atmtcp on standard output and exit.


       create [itf]
              create  a persistent interface. If no interface number is speci-
              fied, atmtcp uses the default value 0.

       remove [itf]
              remove a persistent interface. If the interface is still in use,
              it is marked as ephemeral and will be removed as soon as all VCs
              are closed. If no interface number is specified, atmtcp uses the
              default value 0.

       virtual [itf]
              link  to  the corresponding virtual (ATM over TCP) interface. If
              no interface number is specified, the kernel assigns  the  first
              available number.

       real [itf]
              link  to the corresponding ATM interface. If no interface number
              is specified, atmtcp uses  the  default  value  0.   If  a  link
              requests  that  a VC be opened, atmtcp will attempt to open a VC
              with the specified QoS parameters  on  that  interface.  If  the
              operation  succeeds, data can be sent or received on that VC. If
              the operation fails, an error code is returned to the requester.
              Note  that  only  data  arriving on open VCs can be received and
              that a real ATM interface never initiates a connection.   atmtcp
              can share ATM interfaces with other applications.

       connect host [port]
              connect  to an instance of atmtcp running on the specified host.
              If the port argument is omitted, atmtcp uses  the  default  port

       switch host line [port]
              like  connect,  but  connects  to  an  ATM over TCP "switch" and
              selects the specified virtual line.

       listen [port]
              listen for an incoming ATM over TCP  connection.   If  the  port
              argument  is omitted, atmtcp uses the default port 2812.  atmtcp
              waits until the connection is established. Only  one  connection
              is accepted per listen command.

       listen-bg [port]
              like listen, but run in background after beginning to listen.

       read file [stream]
              play  back all streams from the specified file. If a stream num-
              ber is specified, only that stream is played back.

       write file
              record the traffic of all links in the specified file. The  PDUs
              from  each  link  are stored in a stream with the same number as
              the link.

       print  print a hex dump of the content of all received PDUs on standard

       bg     continue  to run in background (i.e. in a forked child process).

       wait [seconds]
              wait for the specified number of seconds. If no time  is  speci-
              fied, atmtcp waits for a newline on standard input.


       Due to recent protocol changes, atmtcp is currently not compatible with
       the ATM over TCP "switch".

       Only AAL SDUs are exchanged, no  segmentation  or  reassembly  is  per-
       formed.  That implies that using different AALs (e.g. AAL5 and AAL0) on
       either side will reveal limitations of this emulation.

       The atmtcp process needs to run during the the whole  lifetime  of  the


       Create  a pair of virtual ATM over TCP interfaces on the local host and
       connect them:

         # session A
         atmtcp virtual listen
         # session B
         atmtcp virtual connect localhost

       Create virtual interface 1, connect it to real ATM  interface  0,  then
       start  atmsigd  on  the virtual interface, and log all the traffic in a

         atmtcp virtual 1 real 0 write /tmp/log
         atmsigd 1.0.5

       Take the previously created file and examine the traffic sent from atm-
       sigd using saaldump:

         # session A
         atmtcp virtual 1 read /tmp/log 0 wait
         # session B
         saaldump 1.0.5
         # press [Enter] in session A


       Werner Almesberger, EPFL ICA <>



Linux                           April 26, 2000                       ATMTCP(8)

Man(1) output converted with man2html