1ATMTCP(8)                    Maintenance Commands                    ATMTCP(8)
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NAME

6       atmtcp - set up ATM over TCP connections
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SYNOPSIS

9       atmtcp [-d] [-v] command ...
10       atmtcp -V
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DESCRIPTION

13       The  main purpose of atmtcp is to establish TCP connections and to con‐
14       figure them as virtual ATM devices.   Such  pairs  of  "ATM  over  TCP"
15       devices  are  connected  as  if they were real ATM adapters linked by a
16       cable or fiber, i.e. SDUs sent on a given VPI/VCI are received  at  the
17       other end on the same VPI/VCI.
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19       Virtual  interfaces  and  ATM  over  TCP  connections are called links.
20       Other link types supported by atmtcp are  real  interfaces,  files  for
21       recording  and  playback of ATM traffic, and printing a hex dump of the
22       PDU content on standard output. Any pair of such links can be connected
23       with  atmtcp.   If  additional links are attached to such a connection,
24       they send to all other links, except to the first link and the  respec‐
25       tive sender, and they receive from all other links.
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27       atmtcp  can  operate with two types of virtual interfaces: ephemeral or
28       persistent. By default,  atmtcp  interfaces  are  ephemeral.  When  the
29       atmtcp  process  that  created an interface terminates, the virtual ATM
30       device is removed as soon all VCs are closed. However, if the interface
31       was  previously  created as a persistent interface, only the communica‐
32       tion stops, but the interface and all VCs on it remain intact. Attempts
33       to  send  data on an atmtcp interface in this state fail silently, i.e.
34       the interface behaves just like a real ATM interface without a wire.  A
35       new  atmtcp  process can then attach to the interface and resume opera‐
36       tion. Persistent interfaces need to be removed explicitly.
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38       If atmtcp has any readable links after processing the command line,  it
39       enters a loop to perform the data forwarding. If no readable links have
40       been specified, atmtcp terminates after processing the command line. If
41       any setup operation fails, atmtcp terminates at this point and does not
42       attempt to cancel  previous  operations  (e.g.  creation  of  permanent
43       interfaces).
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OPTIONS

46       -d     print detailed progress information on standard error.
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48       -v     print some progress information on standard error.
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50       -V     print version number of atmtcp on standard output and exit.
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COMMANDS

53       create [itf]
54              create  a persistent interface. If no interface number is speci‐
55              fied, atmtcp uses the default value 0.
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57       remove [itf]
58              remove a persistent interface. If the interface is still in use,
59              it is marked as ephemeral and will be removed as soon as all VCs
60              are closed. If no interface number is specified, atmtcp uses the
61              default value 0.
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63       virtual [itf]
64              link  to  the corresponding virtual (ATM over TCP) interface. If
65              no interface number is specified, the kernel assigns  the  first
66              available number.
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68       real [itf]
69              link  to the corresponding ATM interface. If no interface number
70              is specified, atmtcp uses  the  default  value  0.   If  a  link
71              requests  that  a VC be opened, atmtcp will attempt to open a VC
72              with the specified QoS parameters  on  that  interface.  If  the
73              operation  succeeds, data can be sent or received on that VC. If
74              the operation fails, an error code is returned to the requester.
75              Note  that  only  data  arriving on open VCs can be received and
76              that a real ATM interface never initiates a connection.   atmtcp
77              can share ATM interfaces with other applications.
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79       connect host [port]
80              connect  to an instance of atmtcp running on the specified host.
81              If the port argument is omitted, atmtcp uses  the  default  port
82              2812.
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84       switch host line [port]
85              like  connect,  but  connects  to  an  ATM over TCP "switch" and
86              selects the specified virtual line.
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88       listen [port]
89              listen for an incoming ATM over TCP  connection.   If  the  port
90              argument  is omitted, atmtcp uses the default port 2812.  atmtcp
91              waits until the connection is established. Only  one  connection
92              is accepted per listen command.
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94       listen-bg [port]
95              like listen, but run in background after beginning to listen.
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97       read file [stream]
98              play  back all streams from the specified file. If a stream num‐
99              ber is specified, only that stream is played back.
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101       write file
102              record the traffic of all links in the specified file. The  PDUs
103              from  each  link  are stored in a stream with the same number as
104              the link.
105
106       print  print a hex dump of the content of all received PDUs on standard
107              output.
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109       bg     continue to run in background (i.e. in a forked child process).
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111       wait [seconds]
112              wait  for  the specified number of seconds. If no time is speci‐
113              fied, atmtcp waits for a newline on standard input.
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RESTRICTIONS

116       Due to recent protocol changes, atmtcp is currently not compatible with
117       the ATM over TCP "switch".
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119       Only  AAL  SDUs  are  exchanged,  no segmentation or reassembly is per‐
120       formed.  That implies that using different AALs (e.g. AAL5 and AAL0) on
121       either side will reveal limitations of this emulation.
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123       The  atmtcp  process  needs to run during the the whole lifetime of the
124       connection.
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EXAMPLES

127       Create a pair of virtual ATM over TCP interfaces on the local host  and
128       connect them:
129
130         # session A
131         atmtcp virtual listen
132         # session B
133         atmtcp virtual connect localhost
134
135       Create  virtual  interface  1, connect it to real ATM interface 0, then
136       start atmsigd on the virtual interface, and log all the  traffic  in  a
137       file:
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139         atmtcp virtual 1 real 0 write /tmp/log
140         atmsigd 1.0.5
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142       Take the previously created file and examine the traffic sent from atm‐
143       sigd using saaldump:
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145         # session A
146         atmtcp virtual 1 read /tmp/log 0 wait
147         # session B
148         saaldump 1.0.5
149         # press [Enter] in session A
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AUTHOR

153       Werner Almesberger, EPFL ICA <Werner.Almesberger@epfl.ch>
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SEE ALSO

156       atmdiag(8)
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160Linux                           April 26, 2000                       ATMTCP(8)
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