PAD Services

Remote PAD Support (x29server)

Figure 6-3

Remote PAD Support
HP 9000 host

T

T

T

 

 

 

 

 

User Level

 

 

 

 

 

x29server

 

 

 

 

 

 

 

UNIX

 

 

 

 

 

 

 

 

 

 

Applications

 

PAD

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

BSD

 

Sockets

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

X.25

 

 

 

 

 

 

 

Pseudo-

 

 

 

 

 

 

 

 

 

 

terminal

 

 

 

Level III

 

Kernel

 

drivers

 

 

 

 

 

 

 

 

 

 

 

 

 

(PTYs)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Packet-Switching

Network

The x29server remote PAD support provides capabilities for:

Managing call acceptance.

Launching applications automatically.

Ensuring system security.

Monitoring access and data transfers.

When x29server begins execution, it examines the PAD support section (pad_spt) of the /etc/x25/x29hosts file. The PAD support section contains user-configurable parameters for all devices. See Appendix B, X.25 Configuration Files and Examples, for an example of the x29hosts file.

Call Acceptance Mechanism and System Security

The x29server process operates in conjunction with devices declared in the set of pad_spt (PAD support) entries contained in the x29hosts file. It continually “listens” to the network and initializes communications channels at the user level when a call request is received. x29server can handle a large number of calls because each communication channel is managed by an independent process.

Chapter 6

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