1 Introduction to Networking Dr. Mahdi Nasereddin PPU

2 Introduction  Web Browser, , streaming audio, etc..  The Web browser 17 messages!!! 6 messages to translate into an IP addresswww.google.com 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 TCPUDP SequencedNot sequenced ReliableNot reliable Virtual circuitLow overhead Windowing flow controlNo flow control

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 PortApplication 21ftp 23telnet 53DNS 69TFTP 110POP3 80HTTP

25 Internet Layer Protocols  Internet Protocol “IP”  IP Address: Like a home address for the post office  Network Address: /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 to The prefix length (/24), is the number of significant bits in a network

26 Addressing  Class A (N.H.H.H)  Class B (N.N.H.H)  Class C (N.N.N.H)

27 Practice Makes Perfect  What class does the following IPs belong to?

28 Reserved IPs  All 0s for the host address  Network address Example:  All 1s for the host address  Broadcast address Example:   local node  All 0s for the Network address  This network Example: (If I am on network then this is the same as my IP address )  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