Chapter 11

How Converting IPX Networks to an Intranet Works

• How Converting IPX to an Intranet Works

It's rare that an entire intranet will be built completely from scratch. It is more likely that an existing network, such as a Novell NetWare network, will be converted to an intranet. At a corporation there can be many networks already in existence before an intranet comes in, often connected in a company-wide Wide Area Network (WAN). There may be a variety of different network technologies connected to the WAN. One way of converting a network to an intranet is to take it piece by piece and convert individual department LANs to an intranet, and then build from there.

Often, the single most important factor in convincing a corporation to start an intranet is that people within the company will gain access to the Internet and its resources. So the first step in creating the intranet will often be giving easy access to the Internet from an existing corporate network. It's much faster for people to get at the Internet over a network instead of having to dial in via modem-and it also saves money in the long run. But when that Internet access is provided, it's also important that all the existing network services be maintained as well.

A simple solution is to have people run software needed both for the existing network as well as for the Internet. Let's take a NetWare network as an example. In order to use NetWare and get access to its services such as electronic mail and others, computers on the network need to run the IPX (Internet Packet Exchange) protocol. Don't be confused about the name-IPX doesn't allow access to the Internet, but instead to a NetWare network's resources.

When people want access to the Internet as well, they can run a TCP/IP stack-software that will allow them to access the Internet. The TCP/IP stack and IPX will both be running simultaneously on their computers. When they need to access a NetWare resource, IPX allows them to do it. When they want to access the Internet, TCP/IP does the job. The problem with this is that it is not as simple as it sounds because the protocol stacks take up considerable memory and sometimes there is not enough memory left to start applications without unloading one of the protocols.

Internet requests go via TCP/IP to an intranet router, which is connected to an Internet Service Provider via a Channel Service Unit/Data Service Unit (CSU/DSU). Especially in large companies with many people on a network, this connection will be made via a leased high-speed digital line, such as a T1 line. There needs to be a CSU/DSU and a router on the other end, and the requests travel through them in reverse order, that is into the CSU/DSU and then to the router. The CSU/DSU units are used to assure quality digital signals over digital phone lines.

In this kind of setup, people can access an intranet as well as the Internet. In this way, a company can slowly build up an intranet while keeping an existing Novell network. People on the network will be able to access intranet resources since they're running TCP/IP stacks, and NetWare resources, since they're running IPX.

How Converting IPX to an Intranet Works

Most intranets aren't built from scratch-many are existing networks, such as Novell NetWare, that have to be converted into an intranet. Often, the first step in moving toward an intranet is to give Internet access to users on an existing network. At some later point, intranet technology can then be brought inside the network itself and it can be turned into an intranet. This illustration shows that first step: how an existing network, such as a NetWare-based one, can be given access to the Internet, yet still keep access to the NetWare architecture.

1. When a computer on the network wants to connect to the Internet and request information from it, a request is sent to a router on the intranet. This router will send the request to the proper Internet destination.
2. On a NetWare network, the NetWare operating system is used to handle network traffic and administration. As a way to route packets across the network, NetWare uses the IPX (Internet Packet Exchange) protocol. Note that although IPX is called Internet Packet Exchange, it doesn't actually provide Internet access or transport Internet information. Workstations attached to the NetWare network-and servers on the network-need to have IPX loaded in memory in order to use the network.
3. In order for workstations on the Novell network to gain access to the Internet or intranet, they need to run the TCP/IP protocols that form the basis of the Internet. To do that, a TCP/IP stack must be installed on each computer that will allow it to access the Internet. That means that each computer will have both IPX and a TCP/IP stack installed on it, to allow it to access the Internet as well as the Ethernet network. Basically, this results in "RAM cram" and is one of the biggest headaches for anyone trying to run both protocol stacks.
4. A Channel Service Unit/Data Service Unit (CSU/DSU) makes the physical connection between the intranet router and an Internet Service Provider (ISP). The ISP provides the actual Internet connection and services. A variety of digital lines can connect the CSU/DSU to the ISP, including a 56 Kbps leased line, a high-speed T1 line, or an even higher-speed T3 line.
5. The requested information is sent back through the CDU/DSU and router, and is then routed to the computer that requested the information.
6. If the information is instead located on an intranet inside the company, the router will send the request to the proper host, which will then send the information back to the requester.
7. Some products such as NetWare/IP will allow computers on a NetWare network to access both NetWare services and servers and the Internet. That means they don't have to run both the IPX and TCP/IP protocols, eliminating the memory problems resulting from the multiple stacks.