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Platform Notes: SPARCstation Voyager Software Guide

Chapter 4 Using a Networked SPARCstation Voyager Disconnected From the Network

Your SPARCstation Voyager is designed to be easily transportable. Unlike a deskbound machine, the SPARCstation Voyager can be suspended and disconnected from the network, to resume and operate as a standalone system without rebooting. It can be suspended again, transported, and resumed back on the network.

To use your SPARCstation Voyager in nomadic mode, you must first perform a few procedures to configure the system.

Preparing the System

Using the SPARCstation Voyager in Nomadic Mode

Once you have configured it, you can disconnect your SPARCstation Voyager by simply unplugging the Ethernet cable. You can avoid reconfiguring and rebooting, as you would in a deskbound system, by configuring the Solaris 2, Edition II (or later) operating system environment in nomadic mode. Refer to Chapter 6, Configuring for Point-to-Point Protocol Connections for a detailed discussion of the procedures you need to perform after you install the operating system.

The nomadic operating mode allows SPARCstation Voyager to be connected to an IP network that provides ONC+ (NFS, NIS, NIS+, etc.) and Internet services (mail, ftp, rlogin, etc.), and also to be disconnected from the network and operated for extended periods of time with no network connection.

It is not possible to achieve this kind of connection flexibility without some constraints, but they are minimal.

Basic Considerations for Disconnected Operation

After you have made your SPARCstation Voyager disconnectable, you have to use it a little differently.

Creating and using a local home directory on your SPARCstation Voyager can make using your system in nomadic mode easier. Refer to "Creating a Local Home Environment" of Chapter 5, Configuring for Disconnected Operation for instructions.

Always start OpenWindows from a shell whose current working directory is contained on the local SPARCstation Voyager file system, such as your local home directory. Otherwise, when SPARCstation Voyager is disconnected, OpenWindows stops functioning.

When you operate a SPARCstation Voyager disconnected from the network, remote services are not available. NIS and NIS+ databases, such as hosts, and NFS mounted directories cannot be accessed. Refer to "Name Service Configuration" in Chapter 5, Configuring for Disconnected Operation for a complete list.

Before you disconnect the system from the network:

  1. cd out of all NFS mounted directories.

  2. Terminate any remote login sessions such as rlogin, telnet, or ftp.

  3. Terminate any remote clients that display windows on the local Xsun (X11) server.

  4. Wait about five minutes for the automounter to unmount all directories you cd'd out of in Step 1. Or, as root, type unmountall -F nfs.

If you cannot follow the above disconnection guidelines (you are late for a meeting and you want to pull the plug, for example), the system will continue to operate. Minor inconveniences may occur.

For example, it is possible to be in a working directory that is contained on a remote file system or to execute a command, such as ls or cd, that accesses a remote file system. If this happens, the command you executed will appear to stop and not return, and probably the shell that you executed it in will not process further commands.

If you do not want to wait for the system to notice the error and recover by itself (it could take a long time), you can terminate the command (by typing Control-c, for example) or change the working directory back to the home directory. If necessary, quit the window in which the command or shell is running.

Any client/server application with a remote component will not continue to work when the network is disconnected. Those that are stopped may fail when the network is reconnected, or if they are "touched," although it is usually safe to iconize them.

Any remote login sessions in effect at the time of disconnection will stop processing commands. You can leave them alone or terminate them. Few sessions will persist over long periods of disconnection.

While all OpenWindows deskset applications will survive across network transitions from connected to disconnected states, some of them may not operate as well while disconnected.

Occasionally, other problems occur if the Ethernet interface (le0) is not left UP at disconnection. If the interface is DOWN, you cannot open Calendar Manager, nor can you invoke admintool. The solution to these problems is to bring the interface UP using ifconfig. See the man page for information on how to manipulate the state of the interface.

Modem Connections

You can attach a PCMCIA or an external modem to SPARCstation Voyager and use it to create a data connection to another computer that can be accessed through a terminal emulator program such as tip or cu, or by using the PPP serial line networking facility.

Point-to-Point Protocol (PPP)

The Point-to-Point Protocol (PPP) provides IP networking capability over serial line interfaces like those provided by modems.

You can think of PPP as a slow speed analog of Ethernet. Just as two computers can be networked by an Ethernet cable, they can be networked by modems and PPP.

In both cases the machines communicate with each other using peer-to-peer or client/server applications that run over high-level protocols such as TCP/IP. PPP and high-speed, full-duplex modems allow sophisticated services and applications, such as NFS, rlogin, ftp, and remote X11 clients, to run over public switched telephone networks (PSTN).

You activate a PPP connection when you execute any command that causes a message to be put onto the network. Typically this happens when you change to a remote directory in an NFS file system, rlogin to a remote machine, copy a remote file (either by rcp or ftp), or do any other operation that involves a remote system.

Refer to Chapter 6, Configuring for Point-to-Point Protocol Connections for more information about PPP configuration.

Terminal Emulators

A terminal emulator is a software representation of a physical terminal, such as a Wyse or Televideo terminal, that allows the SPARCstation Voyager to connect to a remote machine in the same way as a real terminal connects. As with a real terminal, you will only be able to log in to a remote computer and interact with it through a (typically) 25 line by 80 character interface, and you won't be able to display graphics or use any of the OpenWindows graphical user interface tools. Solaris 7 includes two terminal emulators, tip and cu. See the respective man pages for further information on how to use these emulators. There are also public domain and third party terminal emulators that will work on Solaris. Some of these have more features than tip and cu and may be easier for novice Solaris users to operate.

Tip and the Sun PCMCIA Fax/Data Modem

The tip protocol has been configured to work with the optional Sun PCMCIA modem. To use tip with your Sun PCMCIA modem, you can connect to the modem by typing the device name.

For a modem in Slot 1: 

% tip pm1

For a modem in Slot 2: 

% tip pm2

After you type one of these commands, you are connected to your modem.

After you connect, you can type atcommands. Refer to thePCMCIA 2.0 Fax/Data Modem User's Manual for detailed at commands.