chapter03 - Introduction Types of network Network...

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Unformatted text preview: Introduction Types of network Network principles Internet protocols Network case studies: Ethernet, wireless LAN and ATM Summary Chapter 3: Networking and Internetworking Why should we study network technology? Network is the basis of distributed system The performance, reliability, scalability, of the underlying networks impact the behavior of DS and therefore affect their design Some concepts transmission media : wire, cable, fiber and wireless channels hardware devices : router, switch, bridge, hub, repeater and network interface software components : protocol stacks, communication handler and driver communication subsystem : the collection of hardware and software components that provide the communication facilities for a distributed system. host : computers and devices that use the network for communication purpose node : computer or switching device attached to a network subnet : a unit of routing (delivering data from one part of Internet to another); its a collection of nodes that can be reached on the same physical network. Concepts Performance latency : the delay that occurs after a send operation is executed before data starts to arrive at the destination computer. It can be measured as the time the time to transfer an empty message. It forms a part of process-to-process latency . data transfer rate : the speed at which data can be transferred between two computers in the network once transmission has begun, bits/s Message transmission time = latency + length / data transfer rate data transfer rate is determined primarily by network physical characteristics, whereas the latency is determined primarily by software overheads, routing delays and delay of accessing to transmission channels In distributed systems, messages are always small in size, so the latency is more significant than data transfer rate total system bandwidth : the total volume of traffic that can be transferred across the network in a given time. Ethernet: system bandwidth is as same as data transfer rate WAN: multiple channels, deteriorates when there are too many messages Comparison of different communication channel local network a null message transmission time is under a millisecond local memory - 1000 or more times faster than local network local hard disk - 500 times slower than fast local network Internet - round-trip latencies are in 300-600ms due to switching and contention Networking issues for distributed systems Scalability WWW: world wide wait ? future Internet: several billion nodes and hundreds of millions of active hosts, new addressing and routing mechanisms Reliability Networks are highly reliable, whereas client and server computers and their software often aren't, so error detection and recovery is best performed end-to- end at the highest feasible level ....
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This note was uploaded on 06/12/2011 for the course CS 551 taught by Professor Staff during the Summer '08 term at Colorado State.

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chapter03 - Introduction Types of network Network...

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