NetWare is a Network Operating System Developed by Novell

8/6/2019 NetWare is a Network Operating System Developed by Novell

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Novel Netware

NetWare is a network operating system developed byNovell, Inc.It initially used cooperative multitasking to run various services onapersonal computer, with network protocols based on thearchetypal XeroxNetwork Systemsstack.

Novell superseded NetWare with Open Enterprise Server(OES) in2005. The latest version of NetWare is v6.5 Support Pack 8, whichis identical to OES 2 SP1, NetWare Kernel.

History

NetWare evolved from a very simple concept: file sharing insteadof disk sharing. In 1983 when the first versions of NetWareoriginated, all other competing products were based on the conceptof providing shared direct disk access. Novell's alternativeapproach was validated by IBM in 1984, which helped promote the

NetWare product.

Novell NetWare shared disk-space in the form of NetWare

volumes, comparable to DOS volumes. Clients running MS-DOSwould run a special terminate and stay resident (TSR) program thatallowed them to map a local drive letter to a NetWare volume.Clients had to log in to a server in order to be allowed to mapvolumes, and access could be restricted according to the login
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name. Similarly, they could connect to shared printers on thededicated server, and print as if the printer was connected locally.

At the end of the 1990s, with Internet connectivity booming, the

Internet's TCP/IP protocol became dominant on LANs. Novell hadintroduced limited TCP/IP support in NetWare v3.x (circa 1992)and v4.x (circa 1995), consisting mainly of FTP services andUNIX-style LPR/LPD printing (available in NetWare v3.x), and a

Novell-developed webserver (in NetWare v4.x). Native TCP/IPsupport for the client file and print services normally associatedwith NetWare was introduced in NetWare v5.0 (released in 1998).

During the early-to-mid 1980s Microsoft introduced their ownLAN system in LAN Manager, based on the competingNBF

protocol. Early attempts to muscle in on NetWare failed, but thischanged with the inclusion of improved networking support inWindows for Workgroups, and then the hugely successfulWindows NT and Windows 95. NT, in particular, offered servicessimilar to those offered by NetWare, but on a system that couldalso be used on a desktop, and connected directly to otherWindows desktops where NBF was now almost universal.

The rise of NetWare

The popular use and growth of Novell NetWare began in1985 with the simultaneous release of NetWare 286 2.0aand the Intel 80286 16-bit processor. The 80286 CPUfeatured a new 16-bit protected mode that provided accessto up to 16 MB RAM as well as new mechanisms to aidmulti-tasking. (Prior to the 80286, PC CPU servers used theIntel 8086/8088 8/16-bit processors, which were limited toan address space of 1MB with not more than 640 KB ofdirectly addressable RAM.)
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The combination of a higher 16 MB RAM limit, 80286processor feature utilization, and 256 MB NetWare volumesize limit (compared to the 32 MB that MS-DOS allowed at

that time) allowed the building of reliable, cost-effectiveserver-based local area networks for the first time. The 16MB RAM limit was especially important, since it madeenough RAM available for disk caching to significantlyimprove performance. This became the key to Novell'sperformance while also allowing larger networks to bebuilt.

In another significant innovation, NetWare 286 washardware-independent, unlike competing server systemsfrom 3Com. Novell servers could be assembled using anybrand system with an Intel 80286 or higher CPU, anyMFM, RLL, ESDI, orSCSI hard drive and any 8- or 16-bitnetwork adapter for which Netware drivers were available.

Novell also designed a compact and simple DOS-client

software program that allowed DOS stations to connect to aserver and access the shared-server hard drive. While theNetWare server file system introduced a new, proprietaryfile-system design, it looked like a standard DOS volume tothe workstation, ensuring compatibility with all existingDOS programs.
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Early years

NetWare originated from consulting work by SuperSetSoftware, a group founded by the friends Drew Major, DaleNeibaur, Kyle Powell and later Mark Hurst. This workstemmed from their classwork at Brigham YoungUniversity in Provo, Utah, starting in October1981.

In 1983, Raymond Noorda engaged[clarification needed] the workby the SuperSet team. The team was originally assigned tocreate a CP/Mdisk sharing system to help network the

CP/M hardware that Novell sold at the time. The team wasprivately convinced that CP/M was a doomed platform andinstead came up with a successful file-sharing system forthe newly introduced IBM-compatible PC. They also wrotean application called Snipes - a text-mode game - and usedit to test the new network and demonstrate its capabilities.Snipes was the first network application ever written for acommercial personal computer, and it is recognized as one

of the precursors of many popular multiplayer games suchasDoom and Quake.[1]

This network operating system (NOS) was later calledNovell NetWare. NetWare was based on theNetWare CoreProtocol (NCP), which is a packet-based protocol thatenables a client to send requests to and receive replies from

a NetWare server. Initially NCP was directly tied to theIPX/SPX protocol, and NetWare communicated nativelyusing only IPX/SPX.

The first product to bear the NetWare name was released in1983. It was called Netware 68 (aka S-Net); it ran on the
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Motorola68000 processor on a proprietary Novell-built fileserver and used a starnetwork topology. This was soonjoined by NetWare 86 V4.x, which was written for the Intel

8086. This was replaced in 1985 with Advanced NetWare86 version 1.0a which allowed more than one server on thesame network. In 1986, after the Intel 80286 processorbecame available, Novell released Advanced NetWare 286V1.0a and subsequently V2.0B (that used IPX routing toallow up to 4 network cards in a server). In 1989, with theIntel 80386 available, Novell released NetWare 386. LaterNovell consolidated the numbering of their NetWare

releases, with NetWare 386 becoming NetWare 3.x.

NetWare 286 2.x

NetWare version 2 had a reputation as notoriously difficult

to configure, since the operating system was provided as aset of compiled object modules that required configurationand linking. Compounding this inconvenience was that theprocess was designed to run from multiple diskettes, whichwas slow and unreliable. Any change to the operatingsystem required a re-linking of the kernel and a reboot ofthe system, requiring at least 20 diskette swaps. An

additional complication in early versions was that theinstallation contained a proprietary low-level formatprogram forMFM hard drives, which was runautomatically before the software could be loaded, calledCOMPSURF.
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NetWare was administered using text-based utilities suchas SYSCON. The file system used by NetWare 2 wasNetWare File System 286, or NWFS 286, supporting

volumes of up to 256 MB. NetWare 286 recognized 80286protected mode, extending NetWare's support of RAMfrom 1 MB to the full 16 MB addressable by the 80286. Aminimum of 2 MB was required to start up the operatingsystem; any additional RAM was used for FAT, DET andfile caching. Since 16-bit protected mode was implementedthe i80286 and every subsequent Intel x86 processor,NetWare 286 version 2.x would run on any 80286 or later

compatible processor.

NetWare 2 implemented a number of features inspired bymainframe and minicomputersystems that were notavailable in otheroperating systems of the day. The SystemFault Tolerance (SFT)features included standard read-after-write verification (SFT-I) with on-the-fly bad block

re-mapping (at the time, disks did not have that featurebuilt in) and software RAID1 (disk mirroring, SFT-II). TheTransaction Tracking System (TTS) optionally protectedfiles against incomplete updates. For single files, thisrequired only a file attribute to be set. Transactions overmultiple files and controlled roll-backs were possible byprogramming to the TTS API.

NetWare 286 2.x supported two modes of operation:dedicated and non-dedicated. In dedicated mode, the serverused DOS only as aboot loaderto execute the operatingsystem file net$os.exe. All memory was allocated toNetWare; no DOS ran on the server. For non-dedicated
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operation, DOS 3.3 or higher would remain in memory, andthe processor would time-slice between the DOS andNetWare programs, allowing the server computer to be

used simultaneously as a network file-server and as a userworkstation. All extended memory (RAM above 1 MB)was allocated to NetWare, so DOS was limited to only640kB; expanded memory managers that used the MMU of80386 and higher processors, such as EMM386, would notwork either, because NetWare 286 had control of protectedmode and the upper RAM, both of which were required forDOS to use this approach to expanded memory; 8086-style

expanded memory on dedicated plug-in cards was possiblehowever. Time slicing was accomplished using thekeyboard interrupt. This feature required strict compliancewith the IBM PC design model, otherwise performance wasaffected. Non-dedicated NetWare was popular on smallnetworks, although it was more susceptible to lockups dueto DOS program problems. In some implementations, users

would experience significant network slowdown whensomeone was using the console as a workstation. NetWare386 3.x and later supported only dedicated operation.

Server licensing on early versions of NetWare 286 wasaccomplished by using a key card. The key card wasdesigned for an 8-bit ISA bus, and had a serial numberencoded on a ROM chip. The serial number had to match

the serial number of the NetWare software running on theserver. To broaden the hardware base, particularly tomachines using the IBM MCA bus, later versions ofNetWare 2.x did not require the key card; serialised licensefloppy disks were used in place of the key cards.
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NetWare 3.x

Starting with NetWare 3.x, support for 32-bitprotectedmode was added, eliminating the 16 MB memory limit ofNetWare 286. This allowed larger hard drives to besupported, since NetWare 3.x cached (copied) the entirefile allocation table (FAT) and directory entry table (DET)into memory for improved performance.

By accident or design, the initial releases of the client TSR

programs modified the high 16 bits of the 32-bit 80386registers, making them unusable by any other program untilthis was fixed. Phil Katz noticed the problem and added aswitch to his PKZIP suite of programs to enable 32-bitregister use only when the Netware TSRs were not present.

NetWare version 3 eased development and administrationby modularization. Each functionality was controlled by asoftware module called aNetWare Loadable Module(NLM) loaded either at startup or when it was needed. Itwas then possible to add functionality such as anti-virussoftware, backup software, database and web servers, longname support (standard filenames were limited to 8characters plus a three letter extension, matching MS-DOS)orMacintosh style files.

NetWare continued to be administered using console-basedutilities. The file system introduced by NetWare 3.x andused by default until NetWare 5.x wasNetWare FileSystem 386, or NWFS 386, which significantly extendedvolume capacity (1 TB, 4 GB files) and could handle up to
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16 volume segments spanning multiple physical diskdrives. Volume segments could be added while the serverwas in use and the volume was mounted, allowing a server

to be expanded without interruption.Initially, NetWare usedBindery services for authentication.This was a stand-alone database system where all useraccess and security data resided individually on eachserver. When an infrastructure contained more than oneserver, users had to log-in to each of them individually, andeach server had to be configured with the list of all allowed

users.

The "NetWare Name Services" product allowed user datato be extended across multiple servers, and the Windows"Domain" concept is functionally equivalent to NetWarev3.x Bindery services with NetWare Name Services addedon (e.g. a 2-dimensional database, with a flat namespaceand a static schema).

For a while, Novell also marketed an OEM version ofNetWare 3, called Portable NetWare, together with OEMssuch as Hewlett-Packard, DEC and Data General, whoported Novell source code to run on top of their Unixoperating systems. Portable NetWare did not sell well.

While Netware 3.x was current, Novell introduced its first

high-availability clustering system, named NetWare SFT-III, which allowed a logical server to be completelymirrored to a separate physical machine. Implemented as ashared-nothing cluster, under SFT-III the OS was logicallysplit into an interrupt-drivenI/O engine and the event-
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driven OS core. The I/O engines serialized their interrupts(disk, network etc.) into a combined event stream that wasfed to two identical copies of the system engine through a

fast (typically 100 Mbit/s) inter-server link. Because of itsnon-preemptive nature, the OS core, stripped of non-deterministic I/O, behaves deterministically, like a largefinite state machine.

The outputs of the two system engines were compared toensure proper operation, and two copies fed back to the I/Oengines. Using the existing SFT-II software RAID

functionality present in the core, disks could be mirroredbetween the two machines without special hardware. Thetwo machines could be separated as far as the server-to-server link would permit. In case of a server or disk failure,the surviving server could take over client sessionstransparently after a short pause since it had full stateinformation and did not, for example, have to re-mount the

volumes - a process at which NetWare was notoriouslyslow. SFT-III was the first NetWare version able to makeuse ofSMP hardware - the I/O engine could optionally berun on its own CPU. The modern incarnation of NetWare'sclustering, Novell Cluster Services (introduced in NetWarev5.0), is very different from SFT-III. NetWare SFT-III,ahead of its time in several ways, was a mixed success.

Novell designed NetWare 386 3.x to run all applications onthe server at the same level of processormemoryprotection, known as "ring 0". While this provided the bestpossible performance, it sacrificed reliability. The resultwas that crashes (known as abends, short forabnormal
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ends) were possible and would result in stopping thesystem. Starting with NetWare 5.x, software modules(NetWare Loadable Modules or NLM's) could be assigned

to run in different processor protection rings, ensuring thata software error would not crash the system.


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NetWare 4.x

Version 4 in 1993 also introduced NetWare DirectoryServices, later re-branded asNovell Directory Services

(NDS), based on X.500, which replaced the Bindery with aglobal directory service, in which the infrastructure wasdescribed and managed in a single place. Additionally,NDS provided an extensible schema, allowing theintroduction of new object types. This allowed a single userauthentication to NDS to govern access to any server in thedirectory tree structure. Users could therefore access

network resources no matter on which server they resided,although user license counts were still tied to individualservers. (Large enterprises could opt for a license modelgiving them essentially unlimited per-server users if theylet Novell audit their total user count)

Version 4 also introduced a number of useful tools andfeatures, such as transparent compression at file system

level and RSA public/private encryption.

Another new feature was the NetWare AsynchronousServices Interface (NASI). It allowed network sharing ofmultiple serial devices, such as modems. Client portredirection occurred via an MS-DOS orMicrosoftWindows driver allowing companies to consolidatemodems and analog phone lines.[2]

The upgrade was not without its flaws- initially NetWare 4could not coexist with earlier versions on the same networkbecause of incompatibilities.[3]

[
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The Network Layer

The Network layer has the responsibility for dealing withrouting packets to the correct destination.

Services provided to the Transport layer

The network layer provides both packet oriented andconnection oriented services for the transport layer.

Services should be independent of subnet technology The transport layer should be shielded from the

number, type and topology of the subnets present The network addresses made avaialbele to the

transport layer should use a uniform numbering planeven across LANs and WANs

Connection vs packet

Issue Connection

Packet

---------------------------------------

----

Initial Required Not

possible

Setup

---------------------------------------

-------

Destination Only duringNeeded on

Address setup every

packet

-------------------------------------

-------------


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Packet Guaranteed not

guaranteed

Sequencing

-------------------------------------

----------

Error Done by Done

by

Control Network

Transport

-------------------------------------

------------

Flow Provided by Notprovided

Control Network

Network

-------------------------------------

------------

Option Yes No

Negotiation

-------------------------------------

------------

Connection Yes No

Identifiers

The services are provided by the network layer primitives.

Internal organization

1. Virtual Circuits: Connection oriented protocol.Analogous to the phone service.

2. Datagrams: Packet oriented protocol. Analogous to thepostal service.
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---------------------------------------

----

Issue Datagram

Circuit

---------------------------------------

----

Circuit Setup Not Possible

Required

---------------------------------------

----

Addressing Each packet

Only VC no requiredhas full address

---------------------------------------

----

State Info None in Subnet VC

requires table space

---------------------------------------

----

Routing Each packet

Only at VC setup

---------------------------------------

----

Node failure Only on packets

All VC's at node gone

at node

-------------------------------------------

Congestion Difficult

Easy if buffers


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Control

Preallocated for VC

---------------------------------------

----

Complexity In transport layer In

network layer

---------------------------------------

----

Suited for Connection

Connection oriented service

and Connectionless

-------------------------------------------

Routing

Routing can be based upon either adaptive algorithms ornon adaptive ones.

1. Shortest path routing: Dikjstra's algorithm2. Multipath Routing3. Centralized Routing.4. Isolated Routing:

1. Hot potato2. Backward Learning3. Flooding

5. Distributed routing: Periodic Exchange of routing

information between IMP's6. Optimal Routing7. Flow Based Routing8. Hierachical Routing9. BroadCast Routing


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Congestion

1. Preallocation of Buffers.2. Packet discarding

3. Isarithmic Congestion Control. (Tokens again).4. Flow Control5. Choke packets6. Deadlocks: This is real. It happened.

Internetworking

OSI and Internetworking. The Network layer can be

seen as split into three sublayers.1. subnet access layer2. subnet enhancement layer: uniformizes subnet

access layers.3. internet layer

Relay Devices1. Repeaters: Layer 1 devices, copy bits between

individula segments2. Bridges: Layer 2 devices, store and forward

frames between LAN's3. Gateways: Layer 3 devices, Store and forward

packages between dissimilar networks4. Protocol Converters: Layer 4 devices, provide

interfacing in higher layers.

The Network Layer is Layer 3 of the seven-layerOSImodel ofcomputer networking.
http://en.wikipedia.org/wiki/OSI_modelhttp://en.wikipedia.org/wiki/OSI_modelhttp://en.wikipedia.org/wiki/Computer_networkinghttp://en.wikipedia.org/wiki/OSI_modelhttp://en.wikipedia.org/wiki/OSI_modelhttp://en.wikipedia.org/wiki/Computer_networking


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The Network Layer is responsible for routing packetsdelivery including routing through intermediate routers,whereas the Data Link Layeris responsible for Media

Access Control, Flow Control and Error Checking.The Network Layer provides the functional and proceduralmeans of transferring variable length data sequences from asource to a destination host via one or more networks whilemaintaining the quality of service functions.

Functions of the Network Layer include:

Connection model: connectionless communication

For example, IP is connectionless, in that a frame cantravel from a sender to a recipient without therecipient having to send an acknowledgement.Connection-oriented protocols exist at other higherlayers of that model.

Host addressing

Every host in the network needs to have a uniqueaddress which determines where it is. This addresswill normally be assigned from a hierarchical system,so you can be "Fred Murphy" to people in your house,"Fred Murphy, Main Street 1" to Dubliners, or "Fred

Murphy, Main Street 1, Dublin" to people in Ireland,or "Fred Murphy, Main Street 1, Dublin, Ireland" topeople anywhere in the world. On the Internet,addresses are known as Internet Protocol (IP)addresses.
http://en.wikipedia.org/wiki/Packet_forwardinghttp://en.wikipedia.org/wiki/Routinghttp://en.wikipedia.org/wiki/Data_Link_Layerhttp://en.wikipedia.org/wiki/Datahttp://en.wikipedia.org/wiki/Quality_of_servicehttp://en.wikipedia.org/wiki/Connectionlesshttp://en.wikipedia.org/wiki/Internet_Protocolhttp://en.wikipedia.org/wiki/IP_addresshttp://en.wikipedia.org/wiki/IP_addresshttp://en.wikipedia.org/wiki/Packet_forwardinghttp://en.wikipedia.org/wiki/Routinghttp://en.wikipedia.org/wiki/Data_Link_Layerhttp://en.wikipedia.org/wiki/Datahttp://en.wikipedia.org/wiki/Quality_of_servicehttp://en.wikipedia.org/wiki/Connectionlesshttp://en.wikipedia.org/wiki/Internet_Protocolhttp://en.wikipedia.org/wiki/IP_addresshttp://en.wikipedia.org/wiki/IP_address


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Message forwarding

Since many networks are partitioned into subnetworksand connect to other networks for wide-area

communications, networks use specialized hosts,called gateways orrouters to forward packets betweennetworks. This is also of interestto mobileapplications, where a user may move from onelocation to another, and it must be arranged that hismessages follow him. Version 4 of the InternetProtocol (IPv4) was not designed with this feature in

mind, although mobility extensions exist. IPv6 has abetter designed solution.

Within the service layering semantics of the OSI networkarchitecture the Network Layer responds to service requestsfrom the Transport Layerand issues service requests to theData Link Layer.

Protocol

IPv4/IPv6, Internet Protocol

DVMRP, Distance Vector Multicast Routing Protocol ICMP, Internet Control Message Protocol IGMP, Internet Group Multicast Protocol PIM-SM, Protocol Independent Multicast Sparse Mode PIM-DM, Protocol Independent Multicast Dense Mode IPsec, Internet Protocol Security IPX, Internetwork Packet Exchange RIP, Routing Information Protocol DDP, Datagram Delivery Protocol
http://en.wikipedia.org/wiki/Routerhttp://en.wikipedia.org/wiki/Internet_Protocolhttp://en.wikipedia.org/wiki/Internet_Protocolhttp://en.wikipedia.org/wiki/IPv4http://en.wikipedia.org/wiki/IPv6http://en.wikipedia.org/wiki/Transport_Layerhttp://en.wikipedia.org/wiki/Data_Link_Layerhttp://en.wikipedia.org/wiki/Internet_Protocolhttp://en.wikipedia.org/wiki/DVMRPhttp://en.wikipedia.org/wiki/Internet_Control_Message_Protocolhttp://en.wikipedia.org/wiki/IGMPhttp://en.wikipedia.org/wiki/Protocol_Independent_Multicasthttp://en.wikipedia.org/wiki/Protocol_Independent_Multicasthttp://en.wikipedia.org/wiki/IPsechttp://en.wikipedia.org/wiki/IPXhttp://en.wikipedia.org/wiki/Routing_Information_Protocolhttp://en.wikipedia.org/wiki/Datagram_Delivery_Protocolhttp://en.wikipedia.org/wiki/Routerhttp://en.wikipedia.org/wiki/Internet_Protocolhttp://en.wikipedia.org/wiki/Internet_Protocolhttp://en.wikipedia.org/wiki/IPv4http://en.wikipedia.org/wiki/IPv6http://en.wikipedia.org/wiki/Transport_Layerhttp://en.wikipedia.org/wiki/Data_Link_Layerhttp://en.wikipedia.org/wiki/Internet_Protocolhttp://en.wikipedia.org/wiki/DVMRPhttp://en.wikipedia.org/wiki/Internet_Control_Message_Protocolhttp://en.wikipedia.org/wiki/IGMPhttp://en.wikipedia.org/wiki/Protocol_Independent_Multicasthttp://en.wikipedia.org/wiki/Protocol_Independent_Multicasthttp://en.wikipedia.org/wiki/IPsechttp://en.wikipedia.org/wiki/IPXhttp://en.wikipedia.org/wiki/Routing_Information_Protocolhttp://en.wikipedia.org/wiki/Datagram_Delivery_Protocol


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BGP, Border Gateway Protocol
http://en.wikipedia.org/wiki/Border_Gateway_Protocolhttp://en.wikipedia.org/wiki/Border_Gateway_Protocol


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Software myths

System Safety and Computers [Addison-Wesley, 1995],

Nancy Leveson lists seven myths regarding the safety ofsoftware:

The cost of computers is lower than that of analog orelectromechanical devices.

Software is easy to change.

Computers provide greater reliability than the devices

they replace.Increasing software reliability will increase safety.

Testing software and formal verification of softwarecan remove all the errors.

Reusing software increases safety.

Computer reduce risk over mechanical systems.

Divide into groups.1) Discuss each of the above statements with your groupand rate it as follows:A = AgreeB = Mostly agreeC = Mostly disagreeD = DisagreeGive a one or two sentence argument for your rating.

2) Write each group's results on the board.

3) Discuss as a class.


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What is the aim of softwareengineering?

To solve the software crisis where software isdelivered late, with faults, and over budget. Softwareengineering aims to deliver fault free software, ontime and within budget, meeting the requirementsand needs of the client. The software is developed

keeping in mind the future maintenance that isinvolved.

Documents

NetWare is a Network Operating System Developed by Novell