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1997

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CHAPTER 11

Inter-Networking and Packet Routing



Inter-Networking

Inter-Networking is the term for connecting two or more networks. NetSoft LAN can inter-network any combination of hardware, using any cabling schemes. This chapter explains a number of ways to inter-network your machines.

The basic procedure for inter-networking is simple. You merely assign a machine as a routing machine, (sometimes termed a gate-way), then load the network as normal, for whatever hardware you are using.

The routing machine will be using two or more network cards. On this machine, you must load the appropriate drivers for each network card used.

There is no limit to the number of routing machines used on the network. This gives you complete freedom in how you inter-connect your machines.

This chapter assumes that you are familiar with the general installation process (i.e. loading drivers and changing the DOSNET.INI file parameters).

Connecting a Parallel network to Serial network

Below is a diagram showing three machines connected using two cables. Machine 1 is connected to Machine 2 using the parallel cable. Machine 2 is connected to machine 3 using the serial cable.

router


The table below shows which drivers are loaded on each of the above machines.


  Machine 1      Machine 2       Machine 3

  DOSNET.COM     DOSNET.COM     DOSNET.COM
 PARALLEL.COM   PARALLEL.COM    SERIAL.COM
                 SERIAL.COM

Machine 1 loads DOSNET.COM and PARALLEL.COM, Machine 3 loads DOSNET.COM and SERIAL.COM. Machine 2 is connected by both parallel and serial, so it loads DOSNET.COM, PARALLEL.COM and SERIAL.COM.

On this network, all of the machines have access to one other. For example, machine 1 may use the hard disk or printer on machine 3. Machine 3 may use resources on machines 1 and 2 simultaneously (and so on).

Machine 2 is known as a Routing Machine, as it is using two standards (parallel and serial), whereas machines 1 and 3 are using only one standard (parallel or serial).

Machine 2 acts as a go-between for machines 1 and 3. This process means translating incoming parallel packets (destined for machine 3) to outgoing serial packets, and visa versa.

Connecting a laptop to an Ethernet or Arcnet based network

To connect a laptop to your Ethernet or Arcnet card-based network, install the card-based network as normal, then select any machine to be a laptop Routing Machine. The laptop's parallel or serial cable is connected to the Routing Machine's parallel or serial port, as shown below:

router


In this example, machine 4 is the laptop, and is connected to machine 3 (machine 3 has a network card installed). The laptop may use resources on machines 1, 2 or 3 (through machine 3). Machines 1,2 and 3 may also use the resources on the laptop machine (4).

The drivers required by the above machines are as follows:


  Machine 1      Machine 2       Machine 3      Machine 4

  DOSNET.COM     DOSNET.COM     DOSNET.COM      DOSNET.COM
 ETHERNET.COM   ETHERNET.COM   ETHERNET.COM    PARALLEL.COM
                               PARALLEL.COM


This example uses Ethernet and Parallel. If you wish to use Serial or Arcnet instead, substitute SERIAL.COM for PARALLEL.COM, and ARCNET.COM for ETHERNET.COM.
NOTE The UserCount= parameter under the heading [setup], in the DOSNET.INI file, must be set to the total number of machines (including laptops) on the network.

Connecting Arcnet to Ethernet

You can inter-network an Arcnet based network with an Ethernet based network. To do this, assign one machine as a Routing Machine. This machine must have both an Ethernet and Arcnet card installed, as shown below:

router


In this example, machine 3 is the routing machine and has both Arcnet and Ethernet cards installed. All machines may use the resources available on all of the other machines.

The drivers required by the above machines are as follows:


  Machine 1      Machine 2       Machine 3      Machine 4

  DOSNET.COM     DOSNET.COM     DOSNET.COM      DOSNET.COM
 ETHERNET.COM   ETHERNET.COM   ETHERNET.COM     ARCNET.COM
                                ARCNET.COM

  Machine 5
 DOSNET.COM
 ARCNET.COM


On machine number 3, you must set the parameters under the headings [Arcnet-1] and [Ethernet-1], as that machine is using two standards.

In this example, machines 1, 2 and 3 are using the NetSoft LAN NE1000/2000 ETHERNET.COM driver. You may inter-mix any of the Ethernet standards on these machines.

Star topology Serial and Parallel networks

NetSoft LAN allows up to four drivers of each kind to be loaded on each machine. This means that it is possible to connect five machines using 4 serial or parallel cables, creating a star topology network, as shown below:
router


In the above example, machine 5 loads the serial port driver 4 times (once for each connection). Again, all machines have full access to each other, through machine 5.

The drivers required by the above example would be similar to the following:


  Machine 1      Machine 2       Machine 3      Machine 4

  DOSNET.COM     DOSNET.COM     DOSNET.COM      DOSNET.COM
  SERIAL.COM     SERIAL.COM     SERIAL.COM      SERIAL.COM

  Machine 5
  DOSNET.COM
  SERIAL.COM
  SERIAL.COM
  SERIAL.COM
  SERIAL.COM

On machine 5, you must configure the parameters in the DOSNET.INI file under the following headings:
  Machine 5
 [Serial-1]
 [Serial-2]
 [Serial-3]
 [Serial-4]

The settings include the IRQ=, Port= and Speed= parameters for each port used.
NOTE If parallel is used instead of serial, change the settings under the heading [Parallel-x].

The packet router

The packet router program (ROUTER.COM) is neither a client nor a server configuration. Its purpose is to act as a software bridge only. This means that machine number 5 below simply loads the ROUTER.COM program (instead of DOSNET.COM), and then loads the SERIAL.COM driver 4 times (once for each connection).
router


Machines 1 through 4 may use each other's resources through machine 5. Machine 5 is not available to network users because it has been configured as a software bridge only.

The advantage of the router configuration is that it only requires about 5k of memory. In addition, it is non-dedicated. This means that the routing machine may be assigned to a non-network dedicated task (e.g. monitoring a telephone system), while performing all of the network routing in the background.


NOTE Because a sole routing machine (a machine using ROUTER.COM) is not part of the network, do not include that machine in the count for the UserCount= parameter in the DOSNET.INI file.

Routing Technology

The Routing Technology built into all NetSoft LAN configurations is very intelligent, it does not require setting up a hardware path showing how information is transferred from one machine to another.

This means that you can move machines around, without concern about the hardware connection details. For example, a laptop machine may be connected to machine number 3 today, but may be moved to machine number 1 another day. The routing process is completely automatic.

Routing fault tolerance

One of the most important features of NetSoft LAN's Routing Technology, is its ability to remember all connections if a machine is powered off. This means that if you connect to a server, and that server is powered off, you will still be connected when the server is powered back on.

If you are accessing the server machine at the moment it was powered off, you may receive a DOS error message, similar to the following:

General failure writing device ETH-NET1
Abort, Retry, Ignore, Fail.

This message is normal. When the server is back on-line, press R for Retry, and the Routing Technology will automatically re-connect you to the server.


[Chapter 12] [Chapter 10]
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