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Table Of Contents  CertiGuide to Network+
 9  Chapter 0100:  Network Protocols

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Before examining the details of NetBEUI (NetBIOS Extended User Interface) and what it is, take a moment to be clear what it is not. NetBEUI is NOT NetBIOS!

NetBEUI is a transport protocol for carrying data, while NetBIOS is a session layer service that broadcasts computer names. The confusion comes from the fact that when IBM/Microsoft released the transport protocol, Net BEUI session layer NetBIOS was tightly bound to it. Add to this a popular book making this claim (which was not caught through technical editing) and a popular myth is created.

Continuing the car analogy, you may wish to think of NetBEUI as a Mazda Miata.

The fastest of all the protocols, the tradeoff is that NetBEUI cannot support a huge network load. Microsoft says that this protocol will work with up to 200 or so computers. In the real world a safe number to pick is between 20 and 60 computers, depending on traffic.

This is because the NetBIOS part of NetBEUI broadcasts computer names that all the other computers must listen to.

If you add too many computers to the network, the network will be too busy chatting about who is who, and have little bandwidth left for carrying data. NetBIOS uses a simple single name scheme that is limited to 15 characters.

There is actually a hidden 16th character that is used for control information. Since this is a simple scheme, each computer must have a unique name.


NetBIOS is limited to 15 characters

Can be found in LMHosts

Reason for existence of WINS (client server)

NetBIOS is the naming convention; NetBEUI is the transport.

Still for small networks, its low memory requirements and zero tuning parameters make this an excellent choice in many cases. Another important point of NetBEUI is the fact that it is not routable. Many consider this a bad feature. The reality is, it depends. Not being routable means it cannot carry data outside of the LAN. This could be a good thing in secure environments that also meet the limitations listed.

Another limitation of NetBEUI is its vendor-specific nature. Since NetBEUI is predominantly a Microsoft Windows protocol, you should carefully research support for this protocol on the other types of systems in your network if you plan to deploy it and want to communicate with non-Windows machines using it.


NetBEUI is NOT routable.

NetBEUI not! NetBIOS!

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CertiGuide for Network+ ( on
Version 1.0 - Version Date: November 7, 2004

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