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ATMSIGD(8) Maintenance Commands ATMSIGD(8)


atmsigd - ATM signaling demon


atmsigd [-b] [-c config_file] [-d] [-D dump_dir] [-l logfile] [-m mode] [-n] [-q qos] [-t trace_length] [-u uni_version] [[itf.]vpi.vci [input output]]
atmsigd -V


atmsigd implements the ATM UNI signaling protocol. Requests to establish, accept, or close ATM SVCs are sent from the kernel (using a comparably simple protocol) to the signaling demon, which then performs the dialog with the network.

Note that atmsigd is not able to accept or establish connections until the local ATM address of the interface is configured by ilmid or manually using atmaddr.

The default signaling VC (interface 0, VPI 0, VCI 5) can be overridden on the command line by specifying a different PVC address.

When overriding the default VC, optionally a pair of named pipes to use for communicating with the user of signaling can be specified. Normally, the kernel is the user of signaling and atmsigd opens a special socket for communication with it.

If atmsigd is killed, all system calls requiring interaction with it will return with an error and set errno to EUNATCH.


Run in background (i.e. in a forked child process) after initializing.
Use the specified configuration file instead of /etc/atmsigd.conf If an option is specified in the configuration file and on the command line, the command line has priority.
Enables (lots of) debugging output. By default, atmsigd is comparably quiet.
Specifies the directory to which atmsigd will write status and trace dumps. If -D is not specified, dumps are written to /var/tmp.
Write diagnostic messages to the specified file. The special name syslog is used to send diagnostics to the system logger, stderr is used to send diagnostics to standard error. If -l is absent, the setting in atmsigd.conf is used. If atmsigd doesn't specify a destination either, messages are written to standard error.
Set the mode of operation. The following modes are available: user for the user side (the default), network for the network side (useful if you have two PCs but no switch), and switch for operation with a signaling relay in a switch.
Prints addresses in numeric format only, i.e. no address to name translation is attempted.
Configures the signaling VC to use the specified quality of service (see qos(7) for the syntax). By default, UBR at link speed is used on the signaling VC.
Sets the number of entries that should be kept in the trace buffer. -t 0 disables tracing. If -t is not specified, atmsigd uses a default of 20 trace entries.
Sets the signaling mode. The following modes are supported: uni30 for UNI 3.0, uni31 for UNI 3.1, uni31+uni30 for UNI 3.1 with 3.0 compatibility, uni40 for UNI 4.0, and uni40+q.2963.1 for UNI 4.0 with Q.2963.1 peak cell rate renegotiation.
Prints the version number of atmsigd on standard output and exits.


default configuration file
default location of status dumps
default location of signaling trace dumps


When receiving a SIGUSR1 signal, atmsigd dumps the list of all internal socket descriptors. With SIGUSR2, it dumps the contents of the trace buffer. If a dump directory was set, dumps are written to files called and, respectively, with number starting at zero and being incremented for every dump. If no dump directory is set, dumps are written to standard error.

Dumps are also generated whenever atmsigd detects a fatal error and terminates. No attempt is made to catch signals like SIGSEGV.


The generation of traces is a comparably slow process which may already take several seconds for only 100 trace entries. To generate a trace dump, atmsigd therefore forks a child process that runs in parallel to the signaling demon.


Werner Almesberger, EPFL ICA <>


atmaddr(8), atmsigd.conf(4), ilmid(8), qos(7)

April 26, 2000 Linux