Prescription:NE200 Networks

Aim of Module	To enable students to describe and use the facilities and techniques available for the connection of local and remote computers and peripherals, concentrating mainly on asynchronous communications.
Credits	7
Suggested Time	70 student learning hours
Prescription Expiry Date	Nov 2002

Level and Assessment Schedule
Topics	Highest Skill Level	Suggested Assessment Percentage
1 Telephone Network as a medium	C	15
2 Terminal Networks	A	35
3 Physical Layer	A	25
4 Line Control	A	25
		100

The Student Will

1  Telephone Network as a medium

C		Describe the Telecom network and the facilities and equipment offered for digital communications, with reference to:
	1.1	Common carriers
		- sub-lease
		- VAN facilities - PACNET
		- packet switch networks (PSN), (ISDN), etc.
	1.2	Telephone network
		- operation exchanges, trunks
		- problems encountered for digital transmission
		- options as distance increases, including speeds, error rate and costs
		- direct dialled connection (dial-up)
		- private permanent connection (leased line)
		- direct connection between sites
		- packet switched network (PSN)

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2  Terminal Networks

A		Describe the facilities available to support local and remote terminal network; use and demonstrate these facilities:
	2.1	Terminal types
	2.2	Terminal Connections
		- local
		- remote
		- multiplexers
		- frequency division multiplexers (FDM's)
		- time division multiplexers (TDM's)
		- statistical multiplexers (STATMUX's)
	2.3	Data concentrators
	2.4	Message switches
	2.5	Front end Processors

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3  Physical Layer

A		Describe the concept of protocols and how these can be layered. Describe in detail and gain practical experience in the connection of RS232 devices.
	3.1	Describe the main signals used in RS232 and V24, including (as a minimum) TXD, RXD, CTS, RTS, DTR, DSR, GND, CD.
	3.2	Explain in detail the operation of these signals when communicating via a modem.
	3.3	Explain the following transmission delays incurred:
		- modem turnaround
		- modem delay
		- reaction time
		- propagation delay
	3.4	Show the timings for a typical transmission sequence.
	3.5	Explain and demonstrate the problems and solution of connecting RS232/V24 devices, including:
		- connection and use of a null modem cable
		- use of a break-out box (or similar) to connect devices including terminals and printer to computers

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4  Line Control

C	4.1	Describe briefly the operation of these protocols and where they are used in an Asynchronous environment (eg: XMODEM).
	4.1.1	Explain what quenching is and why it is necessary.
	4.1.2	Explain the XON/XOFF protocol.
	4.1.3	Describe the ASCII character-based protocols including the use of ACK, NAK, ENQ, ETB, ETX, EOT, SOH, STX, DLE, SYN)
	4.1.4	Explain the concept of polling and why it is needed. Describe methods used including roll call and hub polling.
	4.2	Simple line control protocols.
C	4.2.1	Describe in detail Binary Synchronous Communications (BSC), differentiating between synchronous/asynchronous transmission and synchronous/ asynchronous protocols.
C	4.2.2	Describe typical message formats.
A	4.2.3	Detail and apply the operation of the ten control characters mentioned in (4.1.3)
		- establish connection
		- transfer data
		- terminate transfer
		- indicate problems
		(e.g. check-sum error, time out etc.)

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Note
>	Access to modems and break out boxes (or similar) are essential for this subject.