1. Review on Networking Technologies Linda Wu (CMPT 471 2003-3)

2. Notes-2 CMPT 471  2003-3 2 Content  Network & network categories  Protocol  TCP/IP internet protocol suite  Ethernet technology References: chapter 1 & 2

3. Notes-2 CMPT 471  2003-3 3 Network & Network Categories  A network is a group of connected, communicating devices such as computers, routers and printers  An internet is two or more networks that communicate with each other Most notable internet: Internet

4. Notes-2 CMPT 471  2003-3 4 Network & Network Categories (cont.)  Network categories Connection-oriented (circuit-switched)  Dedicated connection between 2 points  Guaranteed network capacity  Circuit costs are independent of use e.g. telephone system Connectionless (packet-switched)  Data are divided into small pieces (packet)  Concurrent communication  Packet is sent only when the network is idle: delay, bandwidth cannot be guaranteed

5. Notes-2 CMPT 471  2003-3 5 Network & Network Categories (cont.)  Packet-Switched Technology WAN (wide area network)  Long distance, low speed connection  A series of packet switches, connected by long-distance communication lines  User computer attached to packet switches  Network is expanded by adding packet switch & communication line LAN (local area network)  High speed connection, short distance  Computer connects to the network by Network Interface card (NIC)

6. Notes-2 CMPT 471  2003-3 6 Protocol  Protocol is a set of rules that governs data communication Syntax: the structure or format of data Semantics: the meaning of each section of bits Timing: when should data be sent and how fast can it be sent  A protocol specifies: The details of message formats How a source sends a message How a destination responses when message arrives How a computer handles errors or other abnormal conditions

7. Notes-2 CMPT 471  2003-3 7 TCP/IP Internet Protocol Suite  Resulted from research funded by US ARPA TCP: Transmission Control Protocol IP: Internet Protocol  5 layers Application layer: user applications Transport layer: end-to-end delivery of data (TCP, UDP) Network layer: data transmission across multiple networks (IP) Data link layer: organize bits into frames Physical layer: transmit bits over a medium

8. Notes-2 CMPT 471  2003-3 8 TCP/IP Internet Protocol Suite (cont.)  ISO/OSI model OSI: Open System Interconnect Introduced by ISO (International Standards organizations) in late 1970s TCP/IP protocol suiteOSI model Dominant network architecture currently Dominated data communication before 1990 ProtocolsNot protocol; a model for designing network architecture Intensively used and tested in Internet Never fully implemented 5 layers7 layers

9. Notes-2 CMPT 471  2003-3 9 TCP/IP Internet Protocol Suite (cont.)  TCP/IP addressing Physical address  defined by WAN or LAN  Ethernet uses 48-bit physical address Internet (IP) address : 32-bit (IPv4)  Different address formats in different networks Port address : 16-bit  End objective of internet communication is a process communicating with another process  Port address: the label assigned to a process

10. Notes-2 CMPT 471  2003-3 10 TCP/IP Internet Protocol Suite (cont.)  Relationship of layers & addresses Processes TCP IP & other protocols Underlying physical networks Transport layer Application layer Network layer Data link layer Physical layer UDP Port address IP address Physical address

11. Notes-2 CMPT 471  2003-3 11 TCP/IP Internet Protocol Suite (cont.)  Features Network technology independence  Independent of any vendor’s hardware Universal interconnection  Every computer is assigned a universally unique address End-to-end acknowledgement  Provide acknowledgement between original source and final destination Application protocol standards  Include standards for many applications, e.g., email, file transfer, remote login

12. Notes-2 CMPT 471  2003-3 12 TCP/IP Internet Services  Application-level services World Wide Web Email File transfer Remote login  Network-level services Connectionless packet delivery Reliable stream transport

13. Notes-2 CMPT 471  2003-3 13 Underlying Physical Technologies  LAN Ethernet LAN: most widely used Token Ring LAN Wireless LAN Fiber Distributed Data Interconnect (FDDI) LAN  WAN ARPANET NSFNET ANSNET  ATM (asynchronous transfer mode)

14. Notes-2 CMPT 471  2003-3 14 Ethernet Evolution  10Base5 (Thick Ethernet) 10 Mbps, cable < 500m  10Base2 (Thin-wire Ethernet) 10 Mbps, cable < 200m  10Base-T (Twisted pair Ethernet) 10 Mbps, connection between a hub and a computer < 100m  100Base-T (Fast Ethernet) 100 Mbps  Gigabit Ethernet 1 Gbps

15. Notes-2 CMPT 471  2003-3 15 Thick Ethernet  Coaxial cable: ½ inch diameter  Host interface card: plug into computer bus  Transceiver: translate analog electrical signals to / from digital form  AUI (attachment unit interface) cable: control transceiver operation transceiver Ethernet cable AUI cable Host interface

16. Notes-2 CMPT 471  2003-3 16 Thin-Wire Ethernet  Coaxial cable: thinner, less expensive, more flexible (thinnet cable)  Replace costly transceiver with high speed digital circuit  Direct connection from computer to network Computer contains both host interface and circuit that connects to the cable Thinnet cable

17. Notes-2 CMPT 471  2003-3 17 Twisted Pair Ethernet  Reduce cost by replacing coaxial cable with unshielded copper wire  Connect computer to hub using four pairs of wires

18. Notes-2 CMPT 471  2003-3 18 Ethernet Properties  Shared bus All stations connect to a single, shared communication channel  Support broadcast All stations receive every transmission  Best-effort delivery No error checking or tracking  Distributed access control No central authority to grant access

19. Notes-2 CMPT 471  2003-3 19 Ethernet Hardware Address  Ethernet address: a 48-bit number  Fixed on Ethernet interface hardware Also called: hardware address, physical address, media access (MAC) address  Address assigning Ethernet hardware manufactures purchase blocks of Ethernet addresses, and then, Assign the addresses in sequence to the Ethernet interface hardware  No two hardware interfaces have the same Ethernet address: universally unique  Host interface filters incoming packets based on their destination addresses

20. Notes-2 CMPT 471  2003-3 20 Ethernet Frame Format  Ethernet Frame: packet that is transmitted on Ethernet  Format Preamble Dest. Addr Src. Addr Frame Type Frame Data CRC 866246~15004 Unit: octet (byte) Preamble: for synchronization CRC: Cyclic Redundancy Check, for error detection