NAME

bsspclock - BSSP daemon task for managing scheduled events

SYNOPSIS

bsspclock

DESCRIPTION

bsspclock is a background "daemon" task that periodically performs scheduled BSSP activities. It is spawned automatically by bsspadmin in response to the 's' command that starts operation of the BSSP protocol, and it is terminated by bsspadmin in response to an 'x' (STOP) command.

Once per second, bsspclock takes the following action:

First it manages the current state of all links ("spans"). Specifically, it infers link state changes ("link cues") from data rate changes as noted in the RFX database by rfxclock:

If the rate of transmission to a neighbor was zero but is now non-zero, then transmission to that neighbor resumes. The applicable "buffer empty" semaphore is given (enabling start of a new transmission session) and the best-efforts and/or reliable "PDUs ready" semaphores are given if the corresponding outbound PDU queues are non-empty (enabling transmission of PDUs by the link service output task).

If the rate of transmission to a neighbor was non-zero but is now zero, then transmission to that neighbor is suspended -- i.e., the semaphores triggering transmission will no longer be given.

If the imputed rate of transmission from a neighbor was non-zero but is now zero, then all best-efforts transmission acknowledgment timers affecting transmission to that neighbor are suspended. This has the effect of extending the interval of each affected timer by the length of time that the timers remain suspended.

If the imputed rate of transmission from a neighbor was zero but is now non-zero, then all best-efforts transmission acknowledgment timers affecting transmission to that neighbor are resumed.

Then bsspclock enqueues for reliable transmission all blocks for which the best-efforts transmission acknowledgment timeout interval has now expired but no acknowledgment has yet been received.

EXIT STATUS

"0"

bsspclock terminated, for reasons noted in the ion.log file. If this termination was not commanded, investigate and solve the problem identified in the log file and use bsspadmin to restart bsspclock.
"1"

bsspclock was unable to attach to BSSP protocol operations, probably because bsspadmin has not yet been run.

FILES

No configuration files are needed.

ENVIRONMENT

No environment variables apply.

DIAGNOSTICS

The following diagnostics may be issued to the ion.log log file:

bsspclock can't initialize BSSP.

bsspadmin has not yet initialized BSSP protocol operations.
Can't dispatch events.

An unrecoverable database error was encountered. bsspclock terminates.
Can't manage links.

An unrecoverable database error was encountered. bsspclock terminates.

BUGS

Report bugs to <https://github.com/nasa-jpl/ION-DTN/issues>