A User's Guide to Local Area Network Connectivity, Study notes of Local Area Network (LAN)

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DISCLAIMER

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- REPORT NUMBER 86-0365 (^) "

TITLE A USERS GUIDE TO LOCAL AREA NETWORK CONNECTIVITY

AUTHOR(S) (^) MAJOR STEPHEN V. BROWN, USAF (^) i

FACULTY ADVISOR MAJOR CHARLES E. WILLIAMS, ACSC/EDOWC

DTIC

Submitted to^ the^ faculty^ in^ partial^ fulfillment^ of^ AP^.

requirements for graduation.

AIR COMMAND AND (^) STAFF COLLEGE AIR UNIVERSITY (^) :-

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MAXWELL AFB, AL 36112 AC W

SPONSOR (^) A--CO. A/DMTCM:DT (^) C

Subitte to the pproved (^) to public relel

requiemens frguation. Bie AIRCOMAN (^) AND:,.,STAFF, COLLEGE

AI-UIVRST

MAX EL (^) AF,"L.

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____"_____PREFACE i

I first became interested in the functional aspects of communication networks during my recent assignment to HO Air Force Manpower and Personnel Center. During my tour there I was involved in developing an office automation system i designed to support the existing base level personnel system. The functional definition of the future (^) personnel system *. included (^) a requirement to interface with every base level

. functional organization requiring (^) personnel information. My subsequent work with the existing base (^) level personnel system also exposed me to the functional (^) impacts a supporting communications network can have on an operation. Many (^) of the base level automated (^) data systems (ADSs) are currently in a position to redesign their systems to take advantage of (^) the new base level Sperry 1100/60 computers (Phase IV program). Much of the new design work will (^) involve shared data applications requiring communications access to various functional systems. (^) The move towards in-system processing is also being driven by Air (^) Force efforts to get out of the

punched card business. The single most cost effective

communications networking configuration (^) available to support these new requirements is the Local Area Network (^) (LAN). Unfortunately, LANs do not exist at most Air Force bases (^) and, although (^) cost effective to operate, they can be quite expensive to install, especially if the base cable plant already exists.

This handbook (^) is intended for the functional manager who *' is (^) confronted with the prospects of LAN connectivity. Although LANs are not currently installed at Air Force bases,

. they are being designed, and (^) planning for future installations is being done. An organizational structure has been established within the Air Force Communications Command (^) (AFCC) to develop (^) and maintain future Air Force %tandard LANs. As such, many, if not all, functional systems will (^) eventually be tied together through base (^) level LANs. This handbook will assist the relatively uninitiated (sysfems (^) wise) functional r manager in determining what a LAN can do and who (^) on the base is responsible for (^) LAN operations. It also provides some - details needed (^) to justify connectivity to a LAN.

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SCONTINUED________

I greatly (^) appreciate the (^) assistance provided (^) by many people in developing (^) this handbook. (^) In particular, Major (^) Ed Williams, my (^) advisor; Mrs. Joan (^) Bowden, my sponsor; (^) and other members of (^) the staff of the Air (^) Force Small Computer/Office Automation (^) Service Organization, (^) Gunter AFS, (^) AL.

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.. TABLE OF CONTENTS,""__.,...

Preface .................................... iii About the Author v ""........ List of Illustrations ................... ........... viii

CHAPTER What ONE--INTRODUCTIONis a LA N? ........................................... TO LOCAL AREA NETWORKS I

Network Topologies.. .. a. .. .. .. (^) .. .. .. ................ *.

Muing i-o................ ............................ 3****.

Star .............. s........................... Te ................................... 4

Al ternatives *...... m...... .............. P............. 5

CHAPTER TWO--INTRODUCTION TO AF LANS AND ALTERNATIVE

COMMUN I CAT IONS

Current Communications Networks at Base Level ............ 7

Air Force LA s........................................... 7

Systems Best Suited for (^) LANs ............................. 9

CHAPTER THREE--AIR FORCE LAN OPERATIONS

Air Force LAN Operations ..... ......... 11 HO AFCC .............................................. it^ - - H O ESD ........... o .. .. .. ... .. .. .. .. BIDDSP ..., ......... ....... ,..................... 11

Ele c tronic Installat ion Division. .................... 11

Standard Information System Center ................. 12 Base Level LAN Players .... .................... (^) ......... 12 IPC ..... .. .... ....... e........ a......... ......... 12 LAN Manager ................................... (^13)

CHAPTER FOUR--CRITERIA ESSENTIAL FOR CONNECTIVITY TO A LAN

Standards and Protocols ........................... (^) .... 14

Hardware Considerations........ o ....... ....... ....

Security Considerations .......... .. .. ....... ...... (^16) Maintenance ..... 16 1............................ Installation/Connect ion .............. .......... (^17)

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* ~~CONTINUED________

CHAPTER FIVE--REQUIREMENTS JUSTIFICATION

Functional Requirement.................................... 18

Justification Process ................................... 19

SBIBLIOGRAPHY (^) ...................... ..................... 21

INDEX ....................... .............* * ............... 23

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Chapter One

INTRODUCTION TO LOCAL AREA NETWORKS

One of the most challenging concerns for (^) many functional organizations in today's Air Force is computerization. (^) There currently exist over forty separate (^) automated data systems (ADS) that support functional applications running on (^) the standard (^) base level computer. The tremendous growth in microcomputer (^) technology in recent years has allowed many (^) of the base level functional organizations (^) such as personnel, accounting & finance (^) and maintenance to pursue development of office automation programs. The new functionally (^) automated systems are (^) being built with a wide range of different commercially (^) procured hardware and software. The one requirement (^) that these systems all have in common is the need for communications (^) access to shared information. That means they have to be able to communicate with (^) one another. There are numerous communications networking (^) schemes available today; the (^) one which the Air Force is moving toward to more efficiently cope with the problems of a multi-source (^) systems environment is a (^) Local Area Network.

What is a LAN?

A local area network (^) is a communication facility that covers a limited topology (physical configuration), (^) and interconnects (^) in an effective manner different types of servers (host or mainframe (^) computers) and workstations (distributed terminals), (^) more particularly personal and professional computers. In width it varies from (^) 100 meters to 10 km depending (^) on the architecture. Simply put, local network is (^) a term referring to the total communications environment which connects dissimilar computers or data systems in (^) a specifically constrained area. You can see the application for LANs at any Air Force

".C" (^) Base. The installation of a single communications network

that links the base (^) level computers (hosts) to the numerous functionally designed office (^) automation systems (workstations)

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hasis cheapermany advantages. than point-to-point First, a commonarchitecture communications (^) and much morenetwork

efficiently maintained. (^) Secondly, it provides a facility for WK more efficient office operation through reduced data (^) entry and keystroking. Finally, data system storage and retrieval problems are reduced through access to shared information. The following generalized (^) characteristics help to better define LANs:

- High data transfer rates - Limited geographic scope - Equal access by all user devices - Ease of reconfiguration and maintenance - Good reliability (^) and error characteristics - Stability (^) under high load - Compatibility with a variety of (^) equipment - Relatively low cost

Now that you have a feel for what a LAN is, we need (^) to describe network configuration or topologies, since (^) that's the part of a (^) LAN that makes it unique from other networks.

Network Topologies

The arrangement of computer resources and (^) communication facilities is known as network topology. (^) Unlike a long-haul network which is designed to support an unconstrained topology, LANs are designed to support a specific (^) topology, i.e., a typical (^) Air Force base. An additional feature that makes LANs unique to other networks is its (^) use of a *broadcasting' versus (^) point-to-point or multi-point topology. Most networks use a central (^) facility to determine where information (^) is to be routed and only the intended receiver gets the message. LANs are designed to "broadcast" information to all users (^) on the network and they in turn determine if the information is addressed (^) to them. The most i common LAN configurations in use (^) today are the ring, the star,

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Figure 1.2. Star Topology

The tree network (also (^) called bus) arranges the nodes like leaves (^) on a tree. See Figure 1.3. (^) The originating node transmits (^) the message along the communications (^) link (bus) and

each node reads the address (^) as it goes by. The tree network is probably the most (^) commonly used LAN topology and (^) best serves a large number of (^) nodes over a relatively short distance. (^) One of the major advantages (^) of this configuration is that single (^) node failures have no affect (^) on the overall

operation of the network.

Figure 1.3. Tree (Bus) Topology

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,N Mesh The mesh (^) network is basically an unconstrained hybrid or

nonspecific network. The nodes (^) are connected by patterns which are most economical (^) and can be redundant if required. See Figure 1.4. Mesh networks are not normally (^) used in LANs and are more commonly found in long-haul (^) networks.

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Figure 1.4. Mesh Topology

Alternatives

The trend toward local area (^) networking seems to be driven by two major concerns: (^) (1) interconnectability, and (2) cost. It's relatively (^) easy to see that these two features (^) of LANs are interdependent. (^) The proliferation of computer technology throughout the Air Force is (^) continuing to increase at an exponential (^) rate and requirements for shared information are common place. If all users (^) need access to one anothers data, then using a single common communications (^) line would provide for interconnectability (^) at a reduced cost. However, there are other (^) network configuration that, deiending on the

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Chapter Two

INTRODUCTION TO AF LANS AND ALTERNATIVE COMMUNICATIONS

Current (^) Communications Networks at Base Level

The Base Communications (^) Transmission and Distribution System (BCTDS), commonly referred (^) to as the Base Cable Plant, is the (^) collection of all base wire communications media. (^) It handles (^) the operation, maintenance and bookkeeping (^) of base communications wire resources. (^) Most base level communication requirements are met by (^) direct cable link or point-to-point networking schemes. There are also some (^) multi-point networking schemes in (^) use. The concept of a local area network (^) has evolved due to the proliferation of ADP equipment requiring (^) connectivity to numerous other information processing (^) system equipment. Can you imagine (^) the networking nightmare involved with point-to-point (^) communications for every piece of equipment (^) currently being installed to support functional systems?

You may have heard the term DON (Defense Data Network) (^) at your base. This is a (^) dedicated long-haul communication network providing (^) service from base to base, not intrabase communications. (^) You may have a requirement for interbase communications which will be satisfied (^) by a LAN hook-up to DDN.

Air Force LANs

HO AFCC and HQ ESD have jointly formed the Air (^) Force Mission Effective Information (^) Transmission System (MEITS), formally known as the Air Force (^) LAN Systems Program Office (AFLANSPO), which has been tasked (^) to develop a unified LAN architecture (ULANA) for the Air (^) Force. In essence what this group is doing is developing a standard family (^) of LAN products for Air Force use. (^) The network will have a broadband (ie. coaxial (^) cable) distribution system, a family of standard network interface (^) units and a separate network management system. See (^) Figure 2.1.

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Figure 2.1. View of ULANA LAN

ULANA will provide all the hardware/software (^) required to connect a variety of heterogeneous (^) data, voice and video devices, satisfying (^) most Air Force requirements. (^) Because full ULN development will (^) probably take several years, (^) plans have been established to procure (^) a standard interim LAN. These interim LAJs should (^) be available in 1986 and will provide off-the-shelf network interface units (^) (NIU) for use with existing (^) broadband distribution systems.

The first Air Force operational LAN (^) has recently been installed at Mather AFB. (^) This LAN is scheduled to be

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