This guide describes how to administer Netcom II, a comprehensive hardware/software package used to provide X.25 protocol services to a PC. Netcom II is designed to connect to packet-switched data networks. It can operate as either a DCE (i.e. network switch) or DTE (i.e. customer-provided equipment), allowing direct connection to another computer without an intervening network.
If you are installing this product for the first time you should read the Netcom II Installation Guide and keep it handy during installation.
While we have made every effort to make this guide complete and intelligible, we recognize that some things may not be obvious to a new user. If you have suggestions for improvements, please contact us. We will be glad to hear from you.
If you require technical support, there are a few items that you can provide to help us solve your problem quickly. See Obtaining Technical Support.
As well as providing programmers with access to WAN protocol primitives (such as making calls, accepting calls, sending data, reading data, and so on), Netcom II integrates with the operating system to provide:
UNIX can treat X.25 Switched Virtual Circuits (SVCs) as pseudo-ttys connected to dial-up modems. Although incoming connections arrive from asynchronous terminals connected to CCITT X.3/X.28/X.29 PADs, to UNIX they appear as pseudo-ttys. Any program that interacts with a standard UNIX serial port can interact with X.25 SVCs.
Much of the expense associated with connecting remote terminals over dial-up asynchronous communications can be avoided by using X.25 network trunks instead of long distance telephone connections. Host site wiring is simpler, as a single modem and associated connection to the UNIX PC carries traffic for all X.25 users.
A PAD application is included for connecting terminal users to remote hosts over an X.25 link. The PAD (xpad) program supports the CCITT PAD protocols for asynchronous terminal connection to public packet-switched networks: X.3, X.28, and X.29. Using the PAD, terminal users establish connections with any host or hosts connected to an X.25 network, including but not limited to, other systems incorporating Netcom II.
The xfft utility provides a mechanism for downloading files quickly with another system that is also equipped with Netcom II software. An X.25 SVC is reliable, which means that xfft requires less overhead. xfft also uses full X.25 data packets to transfer data.
Applications can obtain full control over X.25 virtual circuits using a C function library.
This application interface allows processes to control all aspects of X.25 virtual circuit operation: per-call facilities on setup and clearing, Interrupt and Reset packets, and control of Q, D, and M bits in data packets. Contact us if you would like to see a sample application.
When Auto-dialer Control is used, the configured telephone number is automatically dialed whenever an X.25 virtual circuit needs to be established , either for an application, or for an add-on such as NetcomRouter .
The supplied incoming call control daemon, (x25daemon) is a table-driven utility giving the system administrator full control over SVC calls arriving at your computer.
By manipulating the table, it is possible to screen calls by various criteria: address, call user data, higher-level protocol type, and per-call facilities. Based on the table entries, calls may be routed to particular applications or protocol handlers , accepted for login, or cleared. The x25daemon maintains a log of its activities for use in determining network activity.
Incoming calls are tested against tables to determine the UNIX facility to which they should be routed. Calls from the STREAMS protocol stack are first tested by the table in x25incalls and if a match occurs, the calls are handled according to the directions in the table entry. For more information, see Incoming Call Control.
Users can use the call accounting facilities to collect information on SVC calls. The account utility translates call accounting records to ASCII, allowing later use for billing services or traffic studies.
As well as collecting statistics for traffic studies, the software keeps track of protocol events at all levels. tsgstat displays statistics on link and network performance to make troubleshooting easier.
The tsgstat utility also has mechanisms for determining link parameters and the link state. For a running trace of the protocol, the tsgtrace utility can be used. It interprets frame and packet level protocols, so you don't need to know the protocol syntax to understand what is happening.
The Netcom II package consists of:
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