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Introduction to Networking

Introduction to Networking. Dr. Mahdi Nasereddin PPU. Introduction. Web Browser, e-mail, streaming audio, etc.. The Web browser http://www.google.com 17 messages!!! 6 messages to translate www.google.com into an IP address 3 messages to establish a TCP connection

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Introduction to Networking

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  1. Introduction to Networking Dr. Mahdi Nasereddin PPU

  2. Introduction • Web Browser, e-mail, streaming audio, etc.. • The Web browser • http://www.google.com • 17 messages!!! • 6 messages to translate www.google.com into an IP address • 3 messages to establish a TCP connection • 4 messages used by HTTP to send a get request • 4 messages to tear down the TCP connection

  3. The Basics • Internetworking: • Communication between two or more networks via a router or gateway. • Hub? • Switches? • Routers?

  4. Hubs, Switches, and Routers • Routers • They are used to separate different networks • Main function: to route packets across networks • Deal with global addresses “IP addresses” • Hubs • Multi-port repeaters • Switches • Used within a network • Smarter than hubs • Deal with local addresses “Hardware or Mac Addresses”

  5. Media • 10Base2 • 10Base5 • 10BaseT • 100BaseTX • 1000BaseT • 1000BaseSX • 1000BaseLX

  6. Ethernet Cabling (Straight-Through Cable) • Recommended use: • Switch to router • Switch/Hub to Computer

  7. Ethernet Cabling (Crossover Cable) • Recommended use • Switch/hub to Switch/hub • Router to router • PC to PC • Router to PC

  8. Ethernet Cabling (Rolled Cable) • Recommended use: • Computer to console port of a switch or router

  9. Network Architecture • Peer to Peer • Server based

  10. Typical Networks 12

  11. Topologies • Bus • Ring • Star • Mesh • Star-Bus

  12. Bus Topology 18

  13. Simple Star Network 24

  14. Simple Ring Network 25

  15. Mesh Topology 27

  16. Star-Bus Topology 29

  17. Performance • How do we measure network performance? • Bandwidth (Throughput) • Number of bits that can be transmitted over a certain period of time (Ex. 10 Mbps) • Latency (Delay) • How long it takes a message to travel from one end of the network to the other (Measured is Seconds) • RTT • Latency = Propagation + Transmit + Queue • Propagation = Distance/Speed of light • Transmit = Size/Bandwidth

  18. Beyond the basics:The Layered Approach • Makes complex systems easier to understand • In networking, there are two approaches: • OSI • The TCP/IP model

  19. The TCP/IP Model

  20. Process/Application Layer Protocols • Telnet “Virtual terminal” • File Transfer Protocol “FTP” • Trivial File Transfer Protocol “TFTP” • Network File System “NFS” • Simple Mail Transfer Protocol “SMTP” • Line Printer Daemon “LPD” • X Windows • Simple Network Management Protocol “SNMP” • Domain Name Service “DNS” • Dynamic Host Configuration Protocol “DHCP”

  21. Host to Host Layer Protocols • Transmission Control Protocol “TCP” • User Datagram Protocol “UDP”

  22. TCP versus UDP

  23. Port Numbers • Used by TCP and UDP to communicate with upper layers keep track if different conversations crossing the network simultaneously • Sender port number start at 1024

  24. Port Numbers to remember

  25. Internet Layer Protocols • Internet Protocol “IP” • IP Address: 192.168.0.1 • Like a home address for the post office • Network Address: 192.168.0.0/24 • Like a ZIP/Postal code for the post office • Denotes a range of addresses • Format • ‘Dotted-Quad’ notation: xxx.yyy.zzz.aaa • Each dotted component is an 8-bit number • Range is 0.0.0.0 to 255.255.255.255 • The prefix length (/24), is the number of significant bits in a network

  26. Addressing • Class A (N.H.H.H) • 1-126 • Class B (N.N.H.H) • 128-191 • Class C (N.N.N.H) • 192-223

  27. Practice Makes Perfect • What class does the following IPs belong to? • 132.25.23.12 • 13.25.1.1 • 200.20.3.6 • 254.23.1.14

  28. Reserved IPs • All 0s for the host address Network address • Example: 132.12.0.0 • All 1s for the host address  Broadcast address • Example: 132.12.255.255 • 127.0.0.1  local node • All 0s for the Network address This network • Example: 0.0.12.1 (If I am on network 169.23.0.0 then this is the same as my IP address 169.23.12.1) • All 1s for the Network address All networks with this host address

  29. Subnet Mask • Subnet Mask tells you what bits belong to host id and what bits belong to network id • Why were they created?

  30. NAT and PAT? • Network Address Translation • Port Address Translation

  31. Protocol: IPv6 • Internet Protocol, Version 6 • RFC 2460 • Advantages over IPv4 • More native security • Increases available address space from 32 bits to 128 bits • Easily extensible • Disadvantages • IPv4 is everywhere (cannot be replaced overnight) • More protocol overhead (addresses are now 16 bytes instead of 4) • IP routing protocols must be reworked to support it

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