01introB - 01introB 18 Jan 2011 CSCD58S Computer Networks 1...

Info iconThis preview shows pages 1–9. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 01introB 18 Jan 2011 CSCD58S Computer Networks 1 01introB CSCD58S Computer Networks 1 CSCD58S CSCD58S Computer Networks Computer Networks Introduction, part B: network core, Internet structure, delay & loss, protocol layers, design principles, security 01introB 18 Jan 2011 CSCD58S Computer Networks 2 01introB CSCD58S Computer Networks 2 Chapter 1: roadmap Chapter 1: roadmap 1.1 What i s the Internet? 1.2 Network edge Network access and physical media 1.3 Network core Internet structure and ISPs 1.4 Delay & loss in packet-switched networks 1.5 Protocol layers, design principles 1.6 Security issues 1.7 History 01introB 18 Jan 2011 CSCD58S Computer Networks 3 01introB CSCD58S Computer Networks 3 The network core The network core b mesh of interconnected routers b t h e fundamental question: how is data transferred through net? c circuit switching: dedicated circuit per call: e.g. telephone network c packet-switching: data sent thru net in discrete chunks: e.g. Internet 01introB 18 Jan 2011 CSCD58S Computer Networks 4 01introB CSCD58S Computer Networks 5 Network core: circuit switching Network core: circuit switching end-end resources reserved for call b link bandwidth, switch capacity b dedicated resources: no sharing b the upside: circuit-like metered performance guarantees b the downsides: call setup required and capacity/usage limits. 01introB 18 Jan 2011 CSCD58S Computer Networks 5 01introB CSCD58S Computer Networks 6 Network core: circuit switching Network core: circuit switching network resources (e.g., bandwidth) divided into slices b slices allocated to calls (connections, users) b resource slice i d l e if not used by owning call ( n o s h a r i n g ) b dividing link bandwidth into slices c frequency division c time division FDMA frequency time TDMA frequency time 4 users Example: 01introB 18 Jan 2011 CSCD58S Computer Networks 6 01introB CSCD58S Computer Networks 7 Network core: packet switching Network core: packet switching each end-end data stream divided into p a c k e t s b user A, B packets s h a r e network resources b each packet uses full link bandwidth b resources used a s n e e d e d , resource contention: b aggregate resource demand can exceed amount available b congestion: packets queue, wait for link use b store and forward: packets move one hop at a time x Node receives complete packet before forwarding to next link Bandwidth division into pieces Dedicated allocation Resource reservation 01introB 18 Jan 2011 CSCD58S Computer Networks 7 01introB CSCD58S Computer Networks 8 Network core: packet switching Network core: packet switching b Sequence of A & B packets does not have fixed pattern, bandwidth shared o n d e m a n d B s t a t i s t i c a l m u l t i p l e x i n g b In TDM each host gets same slot in revolving TDM frame A B C 10 Mb/s Ethernet 1.5 Mb/s 45 Mb/s D E statistical multiplexing queue of packets waiting for output link 01introB 18 Jan 2011 CSCD58S Computer Networks 8 01introB CSCD58S Computer Networks...
View Full Document

Page1 / 51

01introB - 01introB 18 Jan 2011 CSCD58S Computer Networks 1...

This preview shows document pages 1 - 9. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online