Planning an SX.25 host configuration involves identifying the communications ports on the system and deciding on the services that each port will provide (see Chapter 1 for an explanation of available SX.25 services). It is also necessary to collect information that must be provided during the configuration process. This chapter contains these sections to help you with configuration planning:
When the SX.25 application starts, it requests a hardware inventory (see the hinv(1M) reference page) of the number of communications ports that are installed on the system. SX.25 automatically assigns a name to each port that the inventory reports.
The maximum number of serial ports on a Silicon Graphics system varies with the bus architecture used on different system models. Table 2-1 lists the bus type and model of each Silicon Graphics system, the maximum number of communication ports that each model can contain, and the name that SX.25 software assigns to each port:
Table 2-1. Port Numbering on Silicon Graphics Systems
Bus Type | Model | Maximum Ports | Distribution of Ports | Port Name |
|---|---|---|---|---|
GIO | Indy
Indigo CHALLENGE S | 4
4 4 | Slot 1, 2 ports
Slot 2, 2 ports
Same as Indy Same as Indy | wan00 wan01 wan10 wan11 Same as Indy Same as Indy |
EISA | Indigo 2
CHALLENGE M | 8
8 | Slot 1, 2 ports
Slot 2, 2 ports
Slot 3, 2 ports
Slot 4, 2 ports
Same as Indigo2 | wan00 wan01 wan10 wan11 wan20 wan21 wan30 wan31 Same as Indigo2 |
VME | CHALLENGE L | 16 | Slot 1, 4ports
Slot 2, 4ports
Slot 3, 4 ports
Slot 4, 4 ports | wan00 wan01 wan02 wan03 wan10 wan11 wan12 wan13 wan20 wan21 wan22 wan23 wan30 wan31 wan32 wan33 |
| CHALLENGE XL | 16 | Same as CHALLENGE L | Same as CHALLENGE L |
SX.25 software includes a collection of files that set parameters for link-level and packet-level protocols to values used by the vast majority of PDNs. In most cases, these values are appropriate for your port connections, and you can establish X.25 WAN and LAN connections using SX.25 parameter files. However, if you are using SX.25 for the first time, it is important to evaluate the suitability of the as-shipped files for connecting to your particular network and to identify any adjustments that might be needed. You can check factory-shipped parameter settings by opening the files with gx25adm (see “The Open Button” in Chapter 4).
If you are unsure of the operating requirements for a network to which you are connecting, discuss your questions with your network service provider.
If you plan to use SX.25 protocol parameter files, be prepared to supply this information during the configuration procedure:
A subnet ID for the port. This ID identifies the protocol stack to the SX.25 daemon.
A DTE address for the port. Ask your network service provider to supply addresses. See “X.121 Addresses” in Appendix A if you need detailed information.
The names of the ports to be configured. See Table 2-1 for the list of SX.25 port names.
Whether ports will operate as a DTE or DCE and the X.25 recommendation to which the port must conform (1980, 1984, or 1988).
The link procedure to be used on each port: LAP, LAPB, or LAPB with extended addressing for WAN ports; LLC1 or LLC2 for LAN ports.
If you plan to create custom parameter files, be prepared to substitute settings in the X.25 parameter files for settings that are required by your network service.
You might need to reset one or several of the packet-level parameters listed below to operate on the network to which you subscribe:
The extended address for any ports on which you plan to use OSI NSAP or other extended addressing.
The modulo number (8 or 128) used for packet sequencing
The type of logical channels that you will use and their numbers. (See “Logical Channels” in Chapter 1 and Figure 7-3.) Include PVCs if you plan to use them.
The default maximum size of packets and windows on local and remote DTEs, and the maximum size of the network service data unit (NSDU). (See Figure 7-4.)
Settings for packet-level timers, counters, and delays. (See Figure 7-5, Figure 7-6, and Figure 7-7.)
Throughput class boundaries. (See Figure 7-8.)
The types of negotiation that are supported: packet size, window size, and throughput class
If you belong to a closed user group (CUG), the conventions that are followed. (See Figure 7-9.)
The optional facilities to which you subscribe. (See Figure 7-10.)
Conventions for handling international calls, priority requests, addresses in outgoing calls, and diagnostic packets. (See Figure 7-11.)
Conventions for handling D-bits. (See Figure 7-12.)
You might need to reset one or several of the link-level parameters listed below to operate on the network to which you subscribe:
Frame and window specifications. (See Figure 7-14 and Figure 7-17.)
Link-level timers. (See Figure 7-15 and Figure 7-18.)
Link-level error handling and state indicators. (See Figure 7-16.)
XID parameters for LANs. (See Figure 7-19.)
If you plan to configure IP on any connections (see “IP Network Connections” in Chapter 1), plan to supply this information during the configuration procedure (also see Figure 5-1):
For each network to which the SX.25 host is connecting, a local Internet address for the SX.25 host, the subnetwork mask of the network, the version of X.25 run on the network, and the addressing scheme that the network uses (CCITT or DDN)
Whether to allow broadcast packets
The high-water mark for data concatenation (if higher than 576 octets)
Maximum idle and minimum connection time for virtual circuits
Mode of operation, CCITT or DDN
How to handle reset and expedited data requests
PVC channel ranges, if you plan to use PVCs
Listen information for applications using the connection
If you plan to create an IP/IXE map, which allows users to designate hosts by their name rather than by their address, you need to supply this information:
The address or name of the IP hosts to which the SX.25 host will connect. If you plan to use a hostname, it must be listed in SX.25 hosts file (/etc/hosts).
The maximum packet and window size to be used in connections
If you plan to use the PAD map (see “PAD and PADD Connections” in Chapter 1), plan to supply this information:
The name of the X.25 hosts to which local users will connect and any aliases by which these hosts are known (see Figure 5-6 and Figure 5-9)
The address of the X.25 hosts to which users will connect for PAD sessions. For WAN connections, the address is an X.121 address; for LAN connections, it is an LSAP address. Address information must include an extension for any host that is using extended addressing.
The X.29 version used on the remote host and any call user data (CUD) that is required in a connection request
The incoming and outgoing packet and window sizes on the remote host, whether it uses fast select, and whether it accepts reverse call charges (see Figure 5-7)
The closed user group (CUG) number and whether the CUG is bilateral or multilateral. If calls are routed by means of a recognized private operating agency (RPOA), the RPOA numbers (Figure 5-8).
If you plan to offer PADD services (see “PAD and PADD Connections” in Chapter 1), plan to supply this information:
Any CDU that is required in incoming calls
The addresses of hosts from which calls will be accepted
Whether CDU and address data must match exactly or in part
Whether the addresses are X.25 DTE (WAN connections) or X.25 NSAP (LAN connections)