COMP1321
Digital Infrastructure
Richard Henson
February 2013
Week 12: Overview of
Important Network
Operating Systems
• Objective:
 Name significant network operating systems in
developments towards today’s organisational
networks
 Briefly explain features of proprietary products that
fulfil particular requirements of a network
operating system
 Explain a (network) operating system architecture
in terms of a multi-layered model
Operating Systems for PC
Ethernet Networks
• Original Topology (1980s, early 90s):
bus, coaxial cable & BNC connectors (!)
• DOS?
No way! not designed for:
• server end stuff
• distributed communications
• security…
Operating Systems for PC
Ethernet Networks
two popular client-server operating
systems emerged:
• Novell Netware


IPX/SPX protocol
not OSI compliant - proprietary & code secret
• DEC (Digital) PCSA


DECnet protocol
OSI & TCP/IP compliant - code open source
Netware - late 1980s
• Novell’s proprietary IPX/SPX network
protocol
network naming based on MAC address
• hardwired into network card during
manufacture
• Also, MHS protocol for messagehandling and email within the LAN
Novell Netware
• Cool Server stuff…
secure file system based on user, groups,
rights & inherited rights
supported mirroring, duplexing, RAID
TTS to reverse incomplete transactions
network resource names, etc. stored as a
separate bindery on each server
Other Features of Netware
• I/O optimisation:
disk caching
elevator seeking (disk accesses ordered
according to position on disk)
directory hashing
Strengths of Netware
Fast
• MAC address not IP, fewer headers, less
processing of packets
Secure
• awarded US gov Server Fault Tolerance
(SFT) grade III

when used with server duplexing
Enduring Problems
with Netware
• Only ran on Intel Platform
• Reliant on DOS/Windows at the client end
• NDS (Directory Structure) not X500 compliant
• Not directly compatible with TCP/IP
 interprocess communication based on IPX/SPX
 used MAC addresses (fixed on network card) as
unique identifiers, rather than IP addresses
• Not suitable for peer-peer networking
• Not pre-emptive in handling processes
What happened to Netware?
• V.successful in early 1990s
better sales than DEC PCSA architecture,
even though the latter was OSI compliant
(!!)
• SPX/IPX faster than TCP/IP…
70% of the PC network market
What happened to Netware
• Didn’t see what was coming (Microsoft!)…
 DEC mini computers lost market share
• everyone wanted a PC network
• main LAN rival DEC was being sold off and “asset
stripped”
• future looked bright
 BUT…
• by 1998, Novell Netware sales were sunk
• by 2000, even Oracle stopped supporting them
• only kept in business by merging with Red Hat Linux
More on DEC
(Digital Equipment)
• World’s most innovative computer
company for many years…
as already stated - first minicomputer:
• PDP-1 (Programmable Data Processor)
first UNIX/C implementation
• On PDP-5
DEC continued…
• Most successful minicomputer:
 VAX (Virtual Address eXtension)
• First virtual memory operating system
 VMS (virtual memory system) for VAX
• First commercially successful RISC chip
 alpha
• First commercial Internet domain & website
• First successful search engine: AltaVista
Organisational Networks
in 1990
• Business/finance companies:
usually IBM networks
• Science/Technology/Engineering
companies:
usually DEC networks
• Smaller companies (SME size...)
couldn’t justify/afford networks!
Where did DEC go?
• Second biggest computer company in the
world in 1990!
 over 100000 employees!
 with early 90s recession, went into decline…
• New MD in 1992, only accelerated the decline
 assets sold one by one…
• unkindest cut – alpha chip to Intel in 1997
 what was left (VMS) went to Compaq in 1998
• sold on to HP…
What happened?
• As with the downfall of IBM, Netscape
and Novell…
out-manoeuvred in business
perhaps the name Microsoft might help…
Microsoft and VMS…
• Now long enough ago to be of historical
interest…
Dave Cutler, brains behind DEC’s VMS;
• http://en.wikipedia.org/wiki/Dave_Cutler
went to work at Microsoft in 1988
• to develop “a new operating system” (NT)…
• DEC watching their mini-computers
become “dinosaurs” (1990-93)
pinned hopes on new RISC chip (alpha)
keen to get their alpha chip onto the original
Windows NT…
A tale of intellectual copyright
(and smart business)
• DEC saw NT as their big opportunity to get
into the PC server business
 expected Alpha chip platform/Windows NT to be
popular
 signed away rights to Cutler & co’s code – code
used in creating windows NT
•
• Microsoft effectively got the technologies behind VMS that
they used for NT… for free!!!!
• final insult… Intel platform preferred for servers (!)
Thanks to HP, and enthusiastic users, VMS lives (!)
 available for download at:
• http://www.openvms.compaq.com/openvms/freeware
Microsoft
& Network Operating Systems
• Whilst the US government was being defeated
in the courts by IBM…
 a deal that almost put them out of business was
pulled off by the young Bill Gates!
 story about IBM negotiations with Bill Gates
(regarding his mate Tim Paterson’s os):
• http://inventors.about.com/library/weekly/aa033099.htm
 and the tragedy of Gary Kildall (creator of CP/M,
main rival to DOS & one time business partner of
Steve Jobs)…
• http://www.businessweek.com/magazine/content/04_43/b3
905109_mz063.htm
DOS (Desktop Operating System)
• As was to be expected from a back-street
deal…
 DOS was an awful operating system…
 no way it could be satisfactorily used for even
multi-tasking, let alone networking…
 no way of
• logging in as an authenticated user…
• restricting access to resources…
 to the new (misguided?) computer generation…
• none of this mattered
 by the late 1980s Gates was the 4th richest person
in the world!
OS2, Windows,
and Windows NT
• By late 1980s, PCs being used for serious
business purposes
 IBM needed a serious operating system for the
PC…
 Microsoft worked them on OS2
 still didn’t see Gates as a rival!
• At about the same time…
 Cutler left DEC… joined Microsoft
 scope for a virtual memory operating system…
• (Windows)
Windows
• On the one hand
Microsoft were working with IBM on OS2
• One the other hand:
they were working on developing Windows
• and working with software developers to provide
applications for Windows…

users want apps, not operating systems!
• Guess which one won???
you’ve got it… Microsoft now bigger than IBM
Windows NT
• Windows… based on DOS
 virtual memory enabled multitasking
 but architecture fundamentally flawed…
• Stopgap while new “serious” operating
system being developed…
• using DEC technology…
 “New Technology” operating system quietly
released in 1993
 as a disguised front end enhancement to Windows
3.1
 known as Windows 3.11 (for workgroups)
NT Architecture
• Industry experts soon noticed that many
features were surprisingly similar to VMS…
 oddity… VMS + 1 = WNT (!!)
• But Microsoft’s customers were from a new
generation. The commercial desktop product
was still basically DOS, but Gates now
offered
 peer-peer networking and a simple network
protocol (NETBEUI)
 user-friendly graphical interface
 sharing resources on apps
 even TCP/IP compatibility…
Flexibility of Windows NT
(followed the Unix pattern)
Applications
Operating system functions & interface
Operating system kernel
hardware
Windows NT v Unix v Netware
• By 1994, three possible network
platforms:
Novell: fast, proven, scalable, well
established, but proprietary (NDS &
IPX/SPX)
Unix: robust, scalable, open source &
Internet ready but complex, & limited apps
Windows NT: neither robust nor scalable
• but Gates by now a past master at exploiting
weakness... (!)
Progressive Development of
Windows NT
Applications (Windows apps -> NT apps)
Operating system functions & interface (Windows)
os kernel (diff versions of NT available for diff CPUs)
range of CPUs, motherboards
NT version 4
• Released late 1996
Windows 95 interface & registry
many www features, incl. IIS (web server)
• Server end:
designed to support server applications
• no theoretical limit to number of users
now became a major challenge to Netware
(not TCP/IP compatible) & Unix (still not
enough apps)
main problem: not scalable
The 32-bit Windows NT
architecture
• Secure 32-bit kernel based on VMS
remains intact to present day
now enhanced to 64-bit
• (but this was supposed to happen originally
with “Windows 5”, to support DECs 64-bit
alpha-chip
• Separated kernel provided the
capability for NT, like Unix, to run on
multiple platforms
guess who didn’t like that idea!
Windows NT Architecture
• Supports pre-emptive multitasking &
multithreading
good for centralised control
• Secure file system (NTFS)
• Applications have separate address
spaces (unlike DOS/Windows… crash!)
up to 4 Gb of memory
up to 16 Eb of disk space (1Eb = 260 bytes)
NT architecture (continued)
• Server products have scope for
huge additional functionality…
offered as services
• Problems:
much code outside the kernel was
new; bugs had to be ironed out
each server had its own security
database; considerable problems for
scalability
Windows 2000
• The big one!!!
Designed to merge:
• peer-peer networking capabilities of Windows
• client-server requirements of LANs
• Microsoft technologies with Internet
technologies
Yet could still work with “DOS-based” i.e.
Windows 3.x/95/98 clients
• Microsoft’s own “history of Windows” (clientend/desktop versions):

http://www.microsoft.com/windows/winhistorydesktop
.mspx
Windows 2000
• Scalable
Active Directory
•
•
•
•
X500 compliant directory service
even developed with aid of RFCs
multiple domains
enterprise-wide security & resource-sharing
arguably much better than NDS
• finished off Novell Netware…
Windows 2000
• Secure… (!)
secure remote authentication
• with help from Active Directory…
Kerberos (IETF, RFCs)
PKI-ready (IETF, RFCs)
terminal services
• remote log on with minimal computing
resources
More Recent OS
Developments
• Novell survived (as a company) by:
 merging with developers of Linux
 continuing to support “legacy” Netware systems
• HP kept VMS customer base…
 once DEC alpha chip was history, developed
new Intel-based hardware platform (Integrity) to
interface with VMS kernel
• Linux (very) slowly gaining popularity…
Windows Server
Developments since 2000
• 2003 Server
 more improvements to active directory
 64-bit version available!
• 2008 Server
 file system enhancements
 active directory:
•
• directory tree extended
• better management tools (larger networks)
Although Bill Gates may have retired, Steve Cutler is
still with them (helped with “Azure” and now…Xbox)
 http://www.amd.com/usen/assets/content_type/DownloadableAssets/Micr
osoft_Video_Statement.wmv
Client-side Developments…
• Microsoft Domination…
 XP: finished off the evolution from Windows 95/98
 Vista: mainly a desktop change
• not universally appreciated!
• mobile devices started to have:


CPUs & operating systems (!)
user interfaces & use apps…
• Reaction to Vista…
 Apple became popular
 other “mobile” desktops became popular
• Windows 7 stopped the rot…
• Windows Mobile: good platform for apps
 but Windows client-end dominance lost for
good…
So, which Server operating
system would the larger
company use today?
•
•
•
IBM, or other “mainframe”?
 why not?
Windows 2008 very popular with finance
industry & previous IBM customers!
Unix (incl Linux) popular with previous
DEC customers
 still cheaper than Windows
 still more complicated, but suits
companies that value and develop
technologies
And the small business?
• Lot of contradictory advice
use Linux!
use Windows
Don’t bother?
• use virtualisation
• outsource
• use The Cloud
• Who should they listen to? Why?
And tomorrow?
• Important for people involved in
procurement for and management of
networks
Windows 2012 due (much change?)
Unix/Linux?
others?
• Time to do a little research...