Basic Communications Systems Class 5 2

Today’s Class Topics LAN Software LAN Operations and Services Network Operating Systems LAN Servers Comparisons Novell NetWare Windows NT Windows 2000 2

Introduction Data Communications and Computer Networks Chapter 9 Introduction Proper support of a local area network requires hardware, software, and miscellaneous support devices. A network operating system is the most important software component. Application programs are also required to support users on a LAN. Support devices such as hubs, switches, routers, servers, modems, power supplies, and more are also necessary.

Network Operating Systems Data Communications and Computer Networks Chapter 9 Network Operating Systems An operating system manages all applications and resources in a computer. A multitasking operating system supports the execution of multiple processes at one time. A network operating system is a large, complex program than manages the resources common on most local area networks. Besides performing standard operating system functions, a network operating system is called upon for additional functions.

Data Communications and Computer Networks Chapter 9

Client/Server Systems Data Communications and Computer Networks Chapter 9 Client/Server Systems A distributed computing system consisting of a server and one or more clients which request information from the server. Common examples of client/server systems include the file server found in a LAN network operating system and a database server found in many businesses. A two-tier client/server architecture supports clients directly connected to server. A three-tier client/server architecture has clients connected to a transaction processing monitor which is connected to the server.

Data Communications and Computer Networks Chapter 9

Network Operating Systems Data Communications and Computer Networks Chapter 9 Network Operating Systems Several popular network operating systems currently exist: Novell NetWare versions 3, 4 and 5 Windows NT and 2000 Unix Linux IBM OS/2

Novell NetWare Data Communications and Computer Networks Chapter 9 Novell NetWare Version 3 - Popular but older version of Novell NetWare. May no longer be supported by Novell by the end of 2000. User logs onto a particular server. Bindery maintains file system. Version 4 - Unlike version 3 this version allows single network login. Bindery replaced by powerful NDS database. Version 5 - Allows administrator to use IP protocol instead of Novell’s proprietary IPX/SPX protocols.

Novell NDS Data Communications and Computer Networks Chapter 9 Novell NDS A database that maintains information on, and access to, every resource on the network, including users, groups of users, printers, data sets and servers. Network administrator creates a hierarchical tree structure that represents the layout of the organization. Tree structure is composed of organizational units which are composed of further objects, and leaf objects which are not composed of further objects.

Data Communications and Computer Networks Chapter 9

Windows NT version 4 Data Communications and Computer Networks Chapter 9 Windows NT version 4 User interface based on popular Windows operating system, but is NOT the same as Windows 98 or Windows Me. Full service multi-tasking operating system capable of supporting multiple servers. NT systems work very well with other Microsoft products. Questionable if NT can support large systems. Blue screen of death (BSOD) plagues NT systems.

Windows 2000 Data Communications and Computer Networks Chapter 9 Windows 2000 Newest version of Windows NT network operating system. Specific versions of 2000 designed to support large enterprise systems. Directory service is called Active Directory and is similar in function to Novell’s NDS.

Data Communications and Computer Networks Chapter 9

Unix Data Communications and Computer Networks Chapter 9 Unix Older but very popular multitasking operating system capable of supporting network operations. First operating system written in the language C. Very stable system capable of supporting large operations. Numerous versions available from different vendors.

Linux Data Communications and Computer Networks Chapter 9 Linux Operating system based on the principles of Unix. Most versions available for free or very small price. Very stable multitasking system. When incorporated with other free software products, such as the Apache Web Server and Atipa’s BlueBird network management software, this system becomes extremely cost effective.

OS/2 Data Communications and Computer Networks Chapter 9 OS/2 Multitasking operating system available from IBM. Small but loyal following of supporters. Losing ground quickly to Novell and Windows and may soon RIP.

Data Communications and Computer Networks Chapter 9

NOS Marketplace UNIX is installed on more servers than any other operating system. Novell NetWare was the top selling LAN operating system between 1986 and 1997. NT and Linux are now outselling NetWare. NetWare still has more installed base than NT or Linux, but NT is expected to surpass NetWare by 2002.

Installed LAN Servers 1998 Source: Dataquest

Server O.S. Shipments (in millions) Source: IDC

File Servers A File Server provides shared files and directories that may be accessed by Client machines. All services provided through messages: Client sends Request message to Server Server performs action and sends Response message to Client Note that message sizes are limited (max. 1500 bytes of data in any Ethernet message, for example), so in some cases one Request may result in multiple Response messages.

File Servers Clients send requests : Open File, Close File, Read File, Write File, etc. File Server receives request, performs action, sends response.

Example: Get File Open File File Opened Read Data Data Close File File Closed

Client / Server Compatibility In order for a Client machine and a Server to be able to talk to each other, they must both implement the same File Services Protocol. A File Services Protocol defines a particular set of request and response messages a server understands: Novell Netware servers use NetWare Core Protocol (NCP). Microsoft servers use Server Message Blocks (SMB) protocol. UNIX servers often use Network File System (NFS) protocol.

Network Drives For DOS/Windows, unused drive letters can be mapped to directory on Server. These Network Drives can be used identically to local drives (like A:), but cause file actions to be done on Server.

Security Users must log on (with user name & password) to a server before accessing shared resources. Network Manager controls access rights for each user to each resource.

File Access Permissions Administrator can allow/disallow for any user : See any server View names of shared directories on any server View any file name(s) Read contents of file(s) Execute file(s) Modify file(s) Delete files Change file names Set access permissions for other users

Other Services / Servers A File Server only uploads/downloads files. Many other types of services are commonly used on LANs. For each service, you must have: Appropriate software running on a LAN server to implement this service (many services can be run on one physical server through multitasking) Matching client software running on your desktop Each service typically defines its own protocol (set of request and response messages).

Other Services / Servers Print Service (via file/print services protocol) Provide shared access to printer. Database Service (i.e. SQL protocol) Structured query access to shared database files. Remote Access Service (i.e. RAS protocol) Shared access to modems for connectivity in/out of LAN.

Other Servers Directory/Name Service (i.e. DNS protocol) Keeps track of names and relationships among all LAN users, devices and services IP Address Service (i.e. DHCP protocol) Assign IP addresses and routing information to LAN workstations. Network Management Service (i.e. SNMP protocol) Gather performance and configuration information from other LAN workstations and servers

Other Servers Gateway Services (various protocols) Access and Protocol translation to another computing environment (ex: IBM mainframe) FAX Services (via file/print protocol) Access to shared FAX machine/services. Application Services (i.e. WTS or Citrix protocols) Allows clients to run some application programs on the server rather than locally.

Other Servers Web/Intranet Services (HTTP protocol) Receive and process HTTP web commands E-Commerce Services (via HTTP (and other) protocols) Provide Web-based transaction services with high performance, reliability and security required. GroupWare Services (i.e. SMTP, IMAP) Provide office services based on common e-mail/groupware platform.

LAN Server Components 2

Server Hardware Speed is King Processor Disk Memory NIC

CPU Will improve the performance of servers that are compute bound Diminishing returns because of interaction with other subsystems System architecture Bus Memory subsystem Disk storage subsystem

Multiprocessing Symmetric multiprocessing (SMP) Multiple CPUs controlled by the SMP compatible OS Individual threads of application processes are assigned to CPUs on a first-available basis Load balancing occurs Share memory and disk controllers Most popular (close to 90%)

Multiprocessing Asymmetric multiprocessing (AMP) Entire application process assigned to single CPU (rather than threads) Loads can become unbalanced Each CPU is assigned own memory and other subsystems Can extend beyond single computer

Multitasking Multiple Processes on Single-CPU Implemented via Time-Slicing Two Types of MultiTasking: Pre-emptive Multitasking Cooperative Multitasking

Storage Systems Early NOS used disk mirroring/duplexing RAID - redundant array of inexpensive (independent) disks A series of standards that physically and logically link numerous storage devices to appear as one large device In a system of RAID disks, any one disk can fail with no loss of data.

Mirroring Duplexing

UPS (Uninterruptible Power Supply) Two purposes Sufficient backup power in event of power failure to allow for normal shut down Line conditioning during normal operations protecting from surges, brownouts, and static spikes

Novell NetWare 2

NetWare Applications Applications run on NetWare servers are NetWare Loadable Modules (NLMs) GroupWise (e-mail/groupware) Novell Storage Services (database) BorderManager (firewall/cache) Publisher (Intranet/E-Commerce) Host Integration / SAA (Gateway) ManageWise/ZENWorks (Management)

NetWare File System Structure

File System Rights Changes contents W (Write) Open and Execute Changes the Attribs See the F or D in a list Sets Trustees, IRF Makes a new F or D Deletes the F or D All of the Above W (Write) R (Read) M (Modify) F (File Scan) A (Access Control) C (Create) E (Erase) S (Supervisory)

Inheritance

Novell Directory Services NDS Composed of Objects, Properties and Values Extends the X.500 Specification for Directory Services Is extensible (can add objects and properties) Is integrated with Email apps, DB apps so it can be used for complete Enterprise resource management

NDS Tree

Sample Leaf Objects

NDS Cloud Logical Physical

NDS Object Rights

Object Rights B (Browse) C (Create) D (Delete) R (Rename) S (Supervisory) Lets you see the object Make a new object Remove an object Assign a new name All of the above PLUS S “All Property” rights

Microsoft Windows 200 / NT Servers

Microsoft Applications A variety of LAN services can be executed on Microsoft Servers Exchange Server (e-mail) SQL Server (database) Proxy Server (firewall/cache) Site Server (Intranet/E-Commerce) SNA Server (Gateway) SMS Server (Management)

NT/2000 System Security Object Oriented Security Each user, group, file, etc. is an object Each user, and group is assigned a unique Security Identifier (SID) 32 bit random character All objects have a security descriptor containing:

System Security SID of the owner of the object Discretionary ACL controlled by owner System ACL controlled by Administrator Access Control List (ACL) is associated with each object, indicating what rights other objects have to this object

System Security OS associates a security Access Token for each running process. Token determines what access rights the process has. Token contains SID of the user executing the process SIDs of all groups user belongs to Possibly SIDs of other (more privileged) users is the process is designed for impersonation

NT Domains Domain is: Collection of computers and related resources At least 1 NT server First NT server is established as the Primary Domain Controller (PDC) at install Others will be either Backup Domain Controller (BDC) or Server PDC holds the database of resource information – BDCs hold backup copies

Domain Security A Domain Administrator can Add new resources (Servers, Workstations, Users, Printers, etc.) to the Domain. Determine access rights of each User to every other resource in the Domain.

Windows 2000 Active Directory Windows 2000 uses the Active Directory system to provide a hierarchical resource organizational tree similar to Novell’s NetWare Directory System (NDS). Domains organized into Trees Domains named using Internet naming system (Domain Name System)

Two-Way Authentication Trees and Forest Forest japan. nwtraders.com china. Tree Two-Way Authentication contoso.com (root) japan. contoso.com china. Tree

Windows 2000 Active Directory Servers within each domain can act as Domain Controllers Information can be replicated between servers in various ways (no PDC and BDC) Within each Domain, can break resources up into different Organizational Units (OUs)

Active Directory Logical Structure Domain Tree Forest OU Domains Organizational Units Trees and Forests

Organizational Units Arrange OUs According to: Delegate Administrative Control at OU Level OUs Enable Single Domain Model Organizational Structure Sales Paris Repair Users Computers Network Administrative Model

Microsoft FS Permissions

WinNT Share

Directory Share Permissions

Network Software: Utilities, Tools, and Applications Data Communications and Computer Networks Chapter 9 Network Software: Utilities, Tools, and Applications In order to support a network operating system, may also need: Utilities Internet software Programming tools Applications

Utilities Data Communications and Computer Networks Chapter 9 Utilities Five of the more common groups of network utility software include: Anti-virus software Backup software Crash protection software Remote access software Uninstall software

Internet Server Software Data Communications and Computer Networks Chapter 9 Internet Server Software Software necessary to support the server side of Internet connections. Retrieves web pages and other documents when asked to by a client workstation. Can interface with a database program allowing users to store and retrieve data via the Internet. Necessary with commercial Internet applications.

Programming Tools Data Communications and Computer Networks Chapter 9 Programming Tools Software environments that allow programmers to create programs. Includes software tools such as compilers and interpreters. Software also allows individuals to edit, debug and test programs.

Application Software Data Communications and Computer Networks Chapter 9 Application Software Software programs that allow a user to perform common computer-based functions: Database software Desktop publishing software Office suites, which integrate a collection of office productivity tools. Standalone spreadsheet, word processing, and presentation software.

Software Licensing Agreements Data Communications and Computer Networks Chapter 9 Software Licensing Agreements Virtually every commercial software program comes with a specific license agreement. Most licensing agreements specify the following conditions: Software installation and use Network installation Back-up copies Decompilation

Software Licensing Agreements Data Communications and Computer Networks Chapter 9 Software Licensing Agreements Most licensing agreements also specify the following conditions: Rental statement Upgrade availabilities Copyright restrictions Maintenance agreements

Software Licensing Agreements Data Communications and Computer Networks Chapter 9 Software Licensing Agreements Most licensing agreements come in one of the following forms: Single user single station license Single user multiple station license Interactive user license Network server license Site license Corporate license

LAN Support Devices Data Communications and Computer Networks Chapter 9 LAN Support Devices Other devices necessary for the proper support of a LAN: Uninterruptable power supplies (UPS) Tape drives Printers Media converters Workstations (including thin client workstations)

LAN Software In Action: A University Makes a Choice Data Communications and Computer Networks Chapter 9 LAN Software In Action: A University Makes a Choice Primary uses of current network include Internet access, e-mail transfers, word processing, and student program compilation. Network operating system is currently older version of Novell NetWare. If university switched to Windows NT, the network operating system might better support the Microsoft applications. Unfortunately, switching to NT would require network support staff training, and potentially higher costs.