Case Study:

Investigate Networking Media, Access Methods,

Topologies

Presented byNick Wallingford

Case Exercise …ABC Enterprises is a manufacturing company with two basic areas, office and manufacturing. The company is relocating its office and factory area. The previous tenants have left a coaxial cable in a bus physical topology from their Ethernet network which connected some of their offices.

The factory area is to house arc welders, drilling, milling and other heavy machining equipment involving high voltages and currents. Some additional office areas and the factory areas are to be wired for a LAN.

Recommend a cost effective solution for the media and topologies to be used for their LAN. You are to support your solution with reasons for the media, access method and the topology selected.

‘Mark Up’ to Identify Critical Elements …

ABC Enterprises is a manufacturing company with two basic areas, office and manufacturing. The company is relocating its office and factory area. The previous tenants have left a coaxial cable in a bus physical topology from their Ethernet network which connected some of their offices.

The factory area is to house arc welders, drilling, milling and other heavy machining equipment involving high voltages and currents. Some additional office areas and the factory areas are to be wired for a LAN.

Recommend a cost effective solution for the media and topologies to be used for their LAN. You are to support your solution with reasons for the media, access method and the topology selected.

Key Points and Commentary …

• Manufacturing company relocating office and factory – Two distinct areas with inherent differences– Assume reasonably close proximity

• Office area has existing coaxial cable– Need decision about re-use or scrap– Cost of testing vs cost of replacement

• Factory area has electromagetic interference– Media must not be susceptible or affected, so UTP (even if shielded)

would not be used– Wireless considered– Fiber optic ultimately selected

• Process control machinery in the factory?– Need for predetermined and predictable response times?– Must not be affected by high traffic/packet collisions in the network– Assume does not require deterministic response…

Case Exercise – Solution Arrived At …

ABC Enterprises at Auckland finally went in for this solution:

•Media - UTP for the additional office work positions connected using a hub. Fiber optic in the factory area using a hub

•Topology - Star for the additions in the factory and the offices with the older co-axial integrated using an Ethernet hub

•Access method - CSMA/CD

Case Exercise – Additional Narrative …

The solution worked only for a period of a year until some major changes took place. These included modernising the factory area with CNC machines, a two-fold increase in the office personnel at Auckland using computers and the opening of branch offices in Wellington, Hamilton and Gisborne which had their own LANs. The interim solution adopted using dial up networking to establish data communication between the branch offices’ LANs and the head office at Auckland seemed unsatisfactory most of the time.You have been selected as the Networks Manager and are expected to improve the existing situation along with future recommendations to cover future growth.

‘Mark Up’ to Identify Critical Elements …

The solution worked only for a period of a year until some major changes took place. These included modernising the factory area with CNC machines, a two-fold increase in the office personnel at Auckland using computers and the opening of branch offices in Wellington, Hamilton and Gisborne which had their own LANs. The interim solution adopted using dial up networking to establish data communication between the branch offices’ LANs and the head office at Auckland seemed unsatisfactory most of the time.You have been selected as the Networks Manager and are expected to improve the existing situation along with future recommendations to cover future growth.

Key Points and Commentary …

• CNC machines in factory – Probably require control and monitoring from office area– Electromagnetic interference still needs consideration

• PC users in office have risen dramatically– Probably requires some separation so collision frequency is

reduced– May well continue into future

• Three regional offices, each with own LAN– Hopefully developed using similar/same equipment and

software• Dial up networking with regional offices not

satisfactory – WAN requires re-development– Nature of traffic needs consideration– Dedicated line probably too expensive though workable

Key to Diagram …

Router

Switch

10/100 Mb Hub

Computer Numeric Control (CNC) machine

Server

PC/workstation

Frame Relay

Frame Relay Frame relay network

Process control workstation

Hamilton Gisborne Wellington

Main Office (Auckland)

100 Mb full duplex

over UTP

10 Mb/s UTP

Process Control

Workstation

Computer Numeric Control (CNC)

machinery

100 Mb full duplex over fiber

FactoryFiber optic cabling

Frame Relay

Frame Relay

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