1ATMTCP(8) Maintenance Commands ATMTCP(8)
2
6 atmtcp - set up ATM over TCP connections
7
9 atmtcp [-d] [-v] command ...
10 atmtcp -V
11
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.
18 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.
26 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.
37 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).
44
46 -d print detailed progress information on standard error.
47 -v print some progress information on standard error.
49 -V print version number of atmtcp on standard output and exit.
51
53 create [itf]
54 create a persistent interface. If no interface number is speci‐
55 fied, atmtcp uses the default value 0.
56 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.
62 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.
67 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.
78 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.
83 switch host line [port]
85 like connect, but connects to an ATM over TCP "switch" and
86 selects the specified virtual line.
87 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.
93 listen-bg [port]
95 like listen, but run in background after beginning to listen.
96 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.
100 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 print print a hex dump of the content of all received PDUs on standard
107 output.
108 bg continue to run in background (i.e. in a forked child process).
110 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.
114
116 Due to recent protocol changes, atmtcp is currently not compatible with
117 the ATM over TCP "switch".
118 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.
122 The atmtcp process needs to run during the the whole lifetime of the
124 connection.
125
127 Create a pair of virtual ATM over TCP interfaces on the local host and
128 connect them:
129 # session A
131 atmtcp virtual listen
132 # session B
133 atmtcp virtual connect localhost
134 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:
138 atmtcp virtual 1 real 0 write /tmp/log
140 atmsigd 1.0.5
141 Take the previously created file and examine the traffic sent from atm‐
143 sigd using saaldump:
144 # 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
150
153 Werner Almesberger, EPFL ICA <Werner.Almesberger@epfl.ch>
154
156 atmdiag(8)
157Linux April 26, 2000 ATMTCP(8)