.TH PLAP 3.SH NAMEplap \- USR/3Com Edgeserver packet bus link access protocol.SH SYNOPSIS.B bind -a '#X' /net.PP.nf.B /net/plap/clone.BI /net/plap/ n /ctl.BI /net/plap/ n /data.BI /net/plap/ n /local.BI /net/plap/ n /remote.BI /net/plap/ n /status.BI /net/plap/ n /listen.SH DESCRIPTIONThe.I plapdriver serves a three-level directory giving access to the link levelprotocol used by an Edgeserver card to communicate withother cards in a USR/3Com chassis.On first.I attach(usually by a.IR bind (1)to.BR /net )the driver opens a connection to the packet bus device.B #Ydescribed in.IR pbus (3).It multiplexes that connection using a specialised member of the LAP familyof protocols..PPThe top level directory contains a single directory naming the protocol,.BR plap .It contains a.B clonefile and a set of conversation directories numbered from 0 to 127;only active conversation directories are present..PPOpening the.B clonefile allocates a new conversation directory.IR n .The file descriptor will point to the control file,.BR ctl ,of that directory.Reading the file returns a text string giving the conversation number..PPEach conversation directory contains six files.The connection is controlled by writing text strings to the.B ctlfile.Once a connection has been established, data is exchanged with theremote peer by reading and writing the.B datafile..PPA.I plapaddress has the form:.IP[.IB slot .].IB chan ! sap.PPwhere.I slotis a chassis slot number,.I chanis a logical channel (eg, a modem number),and.I sapis a number representing a `service access point'..PPThe following control messages are supported:.TP.BI connect " remoteaddr \fP\fR[\fP \fIlocaladdr\fP ]\fI "Make a connection to the givenremote address (of the form given above).If a local address is not specified, thesystem will assign an unused address dynamically(the local chassis slot number is of course fixed).Connect fails if the connection is already announced or connected,or.I localaddris already in use..TP.BI announce addressSet the local address to.I addressand accept incoming calls to that address.If no address is specified, all incoming calls to addresses not explicitly announcedwill be accepted by this connection.Announce fails if the connection is already announced or connected,or the local.I addressspecified is already in use..PPThe.B remoteand.B localfiles contain the remote and local addresses for the connectionin the full address form.IB slot . chan ! sap.The.B statusfile returns a line giving the directory name, number of active opens, and the stateof the connection..PPA process listens for incoming calls by opening the.B listenfile using.IR sys-open (2).The open will block until a call arrives, when it will return a file descriptoropen on the.B ctlfile of the newly accepted connection, which can be read to find the directorynumber and thus the other files..PPThe device follows the conventions that allow.BR dial ,.BR announceand.B listenof.IR sys-dial (2)to do the work needed to establish and manipulate network connections..SH SOURCE.B /os/pc/devplap.c.SH SEE ALSO.IR pbus (3).SH BUGSThe driver cannot be included in the public distribution.