© The JNT Association 1997 Networking for WebMasters John MacCulloch UKERNA ukerna.ac.uk

© The JNT Association 1997 Web Components Server Hypertext InformationBase HTML Client Display Hypertext Transfer Protocol HTTP Network

© The JNT Association 1997 Typical Networks Road Rail Telephone National Grid Canal Airline Old Boy / Old Girl Computer Postal Underground Radio / Television Mobile Telephone

© The JNT Association 1997 What is a Network Infrastructure which enables computer systems ( and people ) to inter communicate

© The JNT Association 1997 What is a Network Infrastructure which enables computer systems ( and people ) to inter communicate

© The JNT Association 1997 What is a Network Infrastructure which enables computer systems ( and people ) to inter communicate

© The JNT Association 1997 What is a Network Infrastructure which enables computer systems ( and people ) to inter communicate

© The JNT Association 1997 Network Performance BandwidthMBits / Sec How many bits/sec can be got across the network ( cars / hour over the mororway ) Latencym Secs How long from A to B Jitterm Secs Variation in Latency

© The JNT Association 1997 Network Classifications Size LANMANWAN Access PublicPrivate Protocol OpenProprietary Timing SynchronousAsynchronous Topology StarRingBusTreeMesh Switching PacketCircuit

© The JNT Association 1997 Network Size LANMANWAN LocalMetropolitanWide CampusCityCountry

© The JNT Association 1997 Network Timing Synchronous Data bits are timed by a clock pulse Asynchronous Data bits are transmitted as required

© The JNT Association 1997 Asynchronous Under Load Load Latency Jitter ZeroMax

© The JNT Association 1997 Network Topology Star Ring Bus TreeMesh

© The JNT Association 1997 Network Switching Circuit Switching dedicated connection established between end points which remains in place for the duration of the call Packet Switching information packets are individually routed through the network

© The JNT Association 1997 Network Functions Ping Traceroute File Transfer Terminal Access Electronic Mail Usenet News Video World Wide Web

© The JNT Association 1997 Example Page Raw Text 1 K HTML 2 K + graphic 40 K Postscript 100 K PS ( 300dpi )1,000 K

© The JNT Association 1997 Law’s Law A picture may be worth a thousand words but a JPEG file takes longer to transmit. Derek Law, Director of Information Services and Systems at Kings College

© The JNT Association 1997 Hints Look at your site through different eyes different clients distant location or simulate low bandwidth Promote UK based search engines Note Law’s Law Use right graphic type (.gif.jpeg ) Remember Web is Client Pull

© The JNT Association 1997 Questions

© The JNT Association 1997 Networking for WebMasters John MacCulloch UKERNA ukerna.ac.uk