This guide describes how to administer Wanware, a comprehensive hardware/software package used to provide X.25/LAPB, Frame Relay and raw synchronous protocol services. Wanware is designed to connect to 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 Wanware Installation Guide and keep it handy during installation.
Refer to Obtaining Technical Support when additional technical support is required.
As well as providing programmers with access to WAN protocol primitives (such as making calls, accepting calls, sending data, reading data, and so on), Wanware integrates with the operating system to provide:
RFC 1356 defines multi-protocol interconnect on X.25 networks. In other words, it specifies how to transfer IP datagrams over X.25 virtual circuits. In a similar fashion, RFC 1490 defines multi-protocol interconnect over Frame Relay. Since Wanware adheres to these standards, it can be used to connect to any other equipment implementing these standards.
Often in TCP/IP networks, a local IP address and IP network is assigned to each physical interface. This is done with an ifconfig command. However, with Wanware devices the IP address and the /etc/x25hosts and /etc/frelhosts files determine the board/link number used to send the data to that host, separate from the interface used. That is, the Wanware devices represent logical interfaces -- they are not directly associated with any physical connection. It is therefore possible to have several IP addresses (IP networks; i.e. several ifconfig statements) associated with one physical link. Likewise, it is possible to have one ifconfig statement that sets one IP address for several physical links.
The user can control the number of X.25 virtual circuits to be used for each IP connection. When packet and window sizes are limited (such as the 128/2 default in most public data networks), the ability to use more than one virtual circuit for each IP connection increases throughput considerably.
Wanware automatically maintains X.25 connections. It establishes new virtual circuits (to a user-specified limit) whenever it can't send IP packets because of X.25 flow control. It disconnects virtual circuits that have been idle for a period of time.
Wanware normally uses statically mapped X.121 addresses when connecting virtual circuits. The user can select between statically mapped and DDN-style X.121 address generation. With static mapping, X.121 addresses are user-specified and assigned by the packet switch manager. DDN-style addresses are generated automatically from the IP address of a host.
For the rest of this document, we refer to "X.121 addresses" by the more familiar term "X.25 addresses". X.121 is the CCITT's specification for the structure of addresses on a data network, and is the technically correct term for the address field. However, X.25 is a more familiar term, and so is used throughout the rest of this document.
Using large IP packets avoids spending CPU cycles and buffer space segmenting and reassembling packets. However, some network bridges and gateways may be unable to carry large IP packets. For example, RFC 1356 specifies a maximum IP packet size of 1500 bytes, which ensures compatibility with all gateways on the Internet.
The default maximum IP packet size for Wanware is 1500 bytes. You may change it to better suit your networking environment. Generally, the larger the better, subject to limits imposed by the streams buffer resources in your kernel, and the other equipment being used in your internet.
Note that IP segment length has an influence on response time. Using a large IP segment length, while reducing IP header overheads, can also cause perceptible delays. It can take appreciable time to assemble a large IP segment from a sequence of full packets/frames travelling over a slow link.
As installed, Wanware limits IP communications to hosts whose X.25 address is stored in its table of X.25/IP address equivalences. For added security, Wanware will not accept calls when the Incoming Call packet doesn't contain a Calling DNA field which is present in the table (or when the Calling DNA field is not present in the Incoming Call packet). For proper operation in a point-to-point or test environment, configure Wanware to supply a Calling DNA in Call Request packets.
In a public network X.32 environment where the Calling DNA is random (as a result of public dial ports being part of a telephone hunt group), a machine receiving a call won't recognize the Calling DNA, and thus won't accept an incoming call. The section "Identifying X.25 Hosts That Call Us: default_xinetN" describes how Wanware can be configured so as to avoid this problem.
Applications can obtain full control over X.25 virtual circuits and LAPB links 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.
Link Access Procedure-Balanced (LAPB) is a specific implementation protocol of HDLC, used for a single error-free data connection. LAPB is used on the data link layer (layer 2) of the OSI seven layer model of data communications. It functions the same as X.25 except there is no packet layer (no multiplexing of several virtual connections).
As well as sending TCP/IP data over Frame Relay lines, application can have direct access to the Frame Relay DLCIs using a C function library.
Some applications require a lower level control of the data that is sent and received on the wire. The raw synchronous API allows the user to send and receive frames with zero bit stuffing, CRCs and flags, but no other predefined protocol using a C function library.
Connections may be made by using either a Plain Old Telephone Service (POTS) dial-up network or a private (leased, dedicated) line. For dial-up connections, the software supports CCITT V.25bis to connect to a remote X.25 device, then treats the connection in much the same way as a dedicated X.25 link.
When Auto-dialer Control is used, the configured telephone number is automatically dialed whenever an X.25 virtual circuit needs to be established.
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 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 application to which they should be passed. Calls from the protocol stack are 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 for use with 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 Wanware package consists of:
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