THE NETWORKS Theo Chakkapark

Open System Interconnection  The tower of power!  The source of this power comes from the model’s flexibility

Network Topologies  Ring

Network Topologies  Bus

Network Topologies  Star

TCP/IP protocol  Internet uses TCP/IP protocol

Internet Addressing  IP Address

Internet Addressing  Port

TCP/IP Protocol Suite: Encapsulation  It’s kinda like Tetris(TM)!

Domain Name System  Sorta like the yellow pages, but for the internet

Networking Equipment  Repeaters are like the Verizon Guy, they never shut up, but that’s a good thing in networking

Networking Equipment  Hubs

Networking Equipment  Switch

Networking Equipment  Router

END  NO MORE PAST THIS POINT

Serious stuff here  OSI Model  Highest level is the application layer, provides interface to allow applications to communicate with each other over network  Presentation layer ensures that data is presented to communication applications in a common format (ie delivers data in big/little endian format)  Session layer establishes/terminates communication sessions between host processes; maintains integrity of communication even if layers below lose data

Serious stuff here  OSI Model Continued  Transport layer ensure reliable transmission from the source to destination and creates communication resources so data is transferred quickly and effectively; provides error recovery  Network layer routes data through systems and subnetworks, which consists of a topology, or connectivity among network components  Data-link layer manages direct connections between components on the network  Physical layer ensures that the raw data is transmitted from a source to a destination over the physical medium; transmits and repeats signals across network boundaries

Serious stuff here  Topologies  Bus: Components connected through a single cable that runs the network + Each component can communicate directly with any other component on the bus, and easy to add new components - Length limit on cabling, breaks in cable can disrupt the network  Ring: Uses single cable, where the ends are jointed. Packets pass around the ring until they reach destination

Serious stuff here  Topologies Cont.  Star: Each component is connected to a central hub The hub receives data from one component and forwards it to all other components, leaving it to the individual components to determine whether or not they are the target + Most of the network service, troubleshooting, and wiring changes are done on the central hub - Problems with the hubs affects the entire network - Requires more cabling than a bus or ring

Serious stuff here  IP Addresses  IP addresses are like an apartment address  Ports are like the individual unit numbers in an apartment  Data has an IP address and a port, so it knows where to travel to  DNS = Domain Name System  Like a phone book: Domain names are looked up in DNS, and translated to an IP destination

Serious stuff here  TCP/IP Protocol  At the application layer, a process can exchange data with another process anywhere on the internet and treat the connection as if it were a file on the local system  The network layer deals with hop-by-hop communication  The transport layer deals with end-to-end communication; uses Transmission Control Protocol (TCP)  The link layer is responsible for getting frames of bits from one machine to another

Serious stuff here  TCP/IP Encapsulation  User data is sent from the application layer to the transport layer  The OS adds a TCP header that identify the source and destination ports, forming a TCP segment, and sends that to the network layer  In the network layer, an IP header identifying the source and destination systems are added, which gets sent to the link layer  The link layer appends information that allows this data to pass through a medium, such as ethernet, or ADSL

Serious stuff here  Repeaters regenerate or amplify electrical signals in the network  Hubs propagate data through the network without regard to the actual destination; it sends it through the ENTIRE network  Switches are an intelligent hub, where it can send data to an intended destination without sending it to other computers  Routers bridge networks together; differs from switch in that a switch forwards based on destination address, while a router forwards packets based on protocol