On networks where you work, other, less common protocols may crop up, such as the following:
DLC (Data Link Control): A legacy protocol used to connect to a network-attached printer and some IBM mainframes. This protocol has been dropped from Microsoft's operating systems. It appeared with limited acclaim under Windows 2000, but it's gone gone gone from Windows XP and Windows 2003. If you need network-attached printer access, you'll probably use TCP/TP or some vendor proprietary protocol. Likewise, if you need to communicate with mainframes or other extreme legacy systems, you'll use TCP/IP, a gateway, or a vendor proprietary protocol. DLC can still be used on a Windows Server 2003 system, but you'll need to find a third-party vendor to provide an installation disk because Microsoft left it out of the goodie bag (that is, the distribution CD).
by Microsoft. NetBIOS, along with NetBEUI, formed the original networking components for LAN Manager and Windows NT.NetBIOS also works with IPX/SPX and TCP/IP, so don't assume that NetBIOS requires NetBEUI. (It doesn't.) If you're working on a network with only Windows 2000, Windows XP, and Windows 2003 systems, you can opt to not use NetBIOS at all!
NetBEUI (NetBIOS Enhanced User Interface): NetBEUI is a fast, efficient, but nonroutable local-area protocol developed by IBM and refined by Microsoft. NetBEUI and NetBIOS were the original networking components for LAN Manager and Windows NT. NetBEUI has gone the way of the dodo, at least according to Windows XP and Windows 2003. Out of sight, out of mind. NetBEUI can still be used on a Windows Server 2003 system, but you'll need to find a third-party vendor to provide an installation disk.
AppleTalk: The name of a set of protocols created by Apple Computer, whose Macintosh computer was one of the first mass-market computers to include built-in networking hardware and software. In most cases, where you have a Macintosh, you have some need for AppleTalk. To offer file and print access to Macintosh clients, Microsoft includes a networking component called Services for
Macintosh. This add-in module (which isn't installed during Windows Server 2003's initial setup) allows Mac users to access files, printers, and services on a Windows Server 2003.
ISO/OSI: A nifty palindrome that stands for the International Organization for Standardization Open Systems Interconnection protocol suite. OSI has never lived up to its original goal to succeed TCP/IP. Some OSI protocols are in broad use in Europe, where they have established a foothold. OSI is out there in industry, government, academia, and business because many governments, incluiding the U.S. government, require systems to be OSI-compliant.
Like TCP/IP, OSI is available for a broad range of systems, from PCs to supercomputers. Most protocol stacks resemble the OSI reference model for networking, and this model remains the most enduring legacy of the effort that went into OSI networking in the 1980s. Numerous third-party ISO/OSI implementations are available for Windows 2003, mostly from European companies, but Microsoft itself doesn't include these protocols with the operating system.
SNA: This refers to IBM's Systems Network Architecture, its basic protocol suite for large-scale networking and mainframe access. Because SNA was a pioneering protocol, companies that invested heavily in mainframe technology also usually invested in SNA. Many SNA networks are still in use, but the number is dropping because SNA is old, cumbersome, and expensive, and because TCP/IP is eating SNA's lunch — even on mainframes.
Connection types classify protocols
IP, IPX, and NetBEUI are connectionless protocols, and SPX and TCP are connection-oriented. What does this mean? Must you care?
All these protocols operate at lower levels. Earlier in this chapter, we told you that a lower-level protocol's most important jobs are to break up arbitrarily long messages into digestible chunks when sending data across a network and then put them back together upon receipt. These chunks (called packets) from the basic message units for data moving across a network. These packets are further divided and stuffed into their envelopes by the access method in use. Such envelopes are called frames. Look at it this way: Packets move up and down the protocol stack; frames dance across the wires.
Connectionless protocols work the same way as mailing letters through the postal service. You drop the letter into a mailbox and expect the post office to deliver it. You may never know whether or not the letter actually gets there — unless it's a bill! IP, IPX, and NetBEUI provide no guarantee of delivery, and frames can arrive in any order.
Connection-oriented protocols, on the other hand, use a handshake to start communications, where the would-be sender asks the receiver whether it can accept input before it starts sending. After transmission is underway, connection-oriented protocols treat each message like a registered letter, where you get a return card to verify its receipt. SPX and TCP packets are sequenced so that when they arrive, they can be reassembled in their original order, which makes them more reliable. Connection-oriented protocols can also request redelivery or send error
notices when packets are damaged or lost en route from sender to receiver.
IP and other connectionless protocols are typically fast and impose little overhead but are considered lightweight and unreliable. TCP and other connection-oriented protocols run more slowly than their connectionless
counterparts because they keep track of what has been sent and received and because they monitor the status of the connection between sender and receiver. More record-keeping and data-check information is built into each packet, which raises overhead requirements but also increases reliability.
The networking world includes hundreds of other protocol suites, each with its own collection of acronyms and special capabilities, but you don't need to know most of them. If you haven't seen a protocol that runs on your network in this chapter, you probably know more about it than we do anyway!