Digital Communication II

Lecturers: Dr S.M. Hand and Dr I.A. Pratt
(smh22@cl.cam.ac.uk and iap10@cl.cam.ac.uk)

No. of lectures: 12

Prerequisite course: Digital Communication I

This course is a prerequisite for Security (Part II).

Aims

This course aims to provide a detailed understanding of how (wide area) computer networks operate, and to present the issues which are involved in building such systems. It also hopes to cover a selection of topics which relate to recent trends in digital communications systems.

Lectures

• Introduction. [IAP] Course overview. Abstraction, layering. OSI reference model.

• The Internet: IP, UDP, RPC. [SMH] IP overview/review. Networking in Unix: structures, buffering, sockets, network interfaces. IP addresses and (simple) routing. Subnetting. IP checksum. Fragmentation. UDP, RPC, NFS. [2 lectures]

• The Internet: TCP and multicast. [SMH] TCP operation, state transitions. Handling loss: acks and retransmissions. Estimating RTT. Basic congestion control. Improving things: TCP vegas, SACKs, ECN. Other TCP details. Internet multicast model. Applications. Basic implementation. Refinements. [2 lectures]

• The Internet: routing. [SMH] ROADS and CIDR. Terminology: AS, IGP, EGP. Routing protocols: distance vector versus link state. Examples: RIP, OSPF. AS routing: I-BGP/E-BGP, metrics. The future.

• The Internet: IPv6. [RJB] Concepts. Internet multicast model. Applications. Basic implementation. Refinements. Congestion control.

• ATM case study [IAP] Multiplexing and virtual circuits. Signalling. ATM Adaption Layers. Quality of Service CBR, VBR, ABR.

• Wide Area Networks. [IAP] Fibre Technology. Long-haul link design. Dense Wave Division Multiplexing. Sonet/SDH. MPLS. Packet over SONET. Optical switching.

• Access Networks. [IAP] Cable Modems. xDSL. Fixed wireless. Satellite. Firewalls and Network Address Translation.

• Local Area Networks and System Area Networks. [IAP] Fast/Gigabit Ethernet. Optimising latency. Host interface design. User-space protocol processing.

• Congestion Pricing. [DM] Model and motivation. Practical considerations. The future.

Objectives

At the end of the course students should be able to

• enumerate and explain the layers of the OSI reference model

• describe how TCP attempts to handle congestion in the network

• compare and contrast connectionless and connection-oriented networks

• explain how IP routing works

• understand the motivation behind and operation of admission control algorithms

Recommended books

Comer, D. & Stevens, D. (1995). Internetworking with TCP-IP, vol. 1 and 2. Prentice-Hall (3rd ed.).
Halsall, F. (1992). Data Communications, Computer Networks and Open Systems. Addison-Wesley (3rd ed.).
Schwartz, M. (1987). Telecommunication Networks: Protocols, Modeling and Analysis. Addison-Wesley.