Home > General > From LAN Manager and SMB to CIFS: The Evolution of Prehistoric PC Network Protocols – @SFoskett – Stephen Foskett, Pack Rat

From LAN Manager and SMB to CIFS: The Evolution of Prehistoric PC Network Protocols – @SFoskett – Stephen Foskett, Pack Rat

This is a great article down memory lane. Thanks Stephen.

SMB and CIFS was born out of the wild pre-history of PC networking

Computers aren’t much good on their own. This simple fact was evident even at the dawn of the microcomputing age, and has never been more true today in the “post-PC” world. If the standard microcomputer is the “Wintel” box (Microsoft’s Windows, Intel’s CPUs, and all that implies) then the standard network services protocol is SMB. So let’s take a nice deep dive into SMB, past, present, and future!

Networking PCs

In the mid-1980′s, IBM and Microsoft came to dominate microcomputers with what became known generically as “the PC.” PCs ran DOS, and DOS had no native networking capability whatsoever. But the use of PCs in business was growing rapidly, and a client/server computing paradigm loomed on the horizon.

It is just at this moment when standards-based local area networks (LANs) appeared. 3COM’s Ethernet rapidly gained strength, even against IBM’s own token ring, DECnet, and many others besides.

IBM was strong out of the gate with “PC-Network”, a line of proprietary networking equipment for PCs. Sytek created a complete API, known as NetBIOS, for inter-PC communication, along with their own layer-3 protocol. IBM ported NetBIOS to token ring, with an API emulator known as the NetBIOS Enhanced User Interface or NetBEUI. This term was later appropriated by Microsoft to refer to NBF, a layer-3 protocol for NetBIOS on Ethernet, causing much confusion.

Now that a standard LAN API was available, it was time for a higher-layer protocol for file access. IBM developed server message block (SMB), which used NetBIOS session and datagram services for transport.

One of the curious aspects of the single-tasking DOS operating system is the way it handles file open/close operations. Batch files would open and close a file many, many times as they proceeded through their instructions. This was no problem for a local disk, but network latency caused performance issues. So SMB included a client-side caching mechanism with opportunistic locks to reduce network traffic while still allowing the client and server to stay in sync. OpLocks are a hallmark of the SMB protocol even today.

http://blog.fosketts.net/2012/03/22/lan-manager-smb-cifs-history/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+StephenFoskettPackRat+%28Stephen+Foskett%2C+Pack+Rat%29

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Categories: General Tags: , ,
  1. July 1, 2012 at 11:05 am

    Nice post which a line of proprietary networking equipment for PCs. Sytek created a complete API, known as NetBIOS, for inter-PC communication, along with their own layer-3 protocol. IBM ported NetBIOS to token ring, with an API emulator known as the NetBIOS Enhanced User Interface or NetBEUI. Thanks a lot for posting this article.

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