Networks Basics C Viven Rajendra firstname.lastname@example.org
Contents• What is a network?• How does it work?• HUB, Switch, Router.• Classifying network.• Proxy, IP, Subnet, DNS.• WiFi, netmon, simple applications.
Computer Network• A computer network is a group of interconnected “network capable devices”.• Components : Network Interface Cards, Hubs, Switches, Routers and galvanic cable.
How does it work?• What is communicated?• When is it communicated?• How is it communicated?• Example : Talking, torch light communication.• We need a protocol : Set of rules governing data communication.• TCP/IP is such a protocol.
Network Interface Card• Allows a network capable device access to a computer network such as the internet.• The MAC address identifies the vendor and the serial number of the NIC which is unique to the card.
Hub• A network hub or repeater hub is a device for connecting multiple twisted pair or fiber optic Ethernet devices together.• When a packet arrives at one port, it is copied to all the ports of the hub for transmission
Switch• A switch is a device that performs switching.• It forwards and filters datagrams (chunk of data communication) between ports based on the Mac-Addresses in the packets.
Router• Forward data packets between networks using headers and forwarding tables to determine the best path to forward the packets.• Processor, OS, memory.
Cables• Category 5 cable, known as Cat 5 or "Cable and Telephone", is a twisted pair cable.(100 Mbps)• An optical fiber is a glass or plastic fiber that carries light along its length.(40 Gbps)
Classifying Networks• On the basis of scale or extent of reach of network : LAN, MAN, WAN.• On the basis of connection method : hardware technology : Optical fibre, Ethernet, Wireless LAN.• Functional relationship: Client-Server, Peer-to-peer.• On the basis of network topology, Physical layout: Mesh, Star, Bus, Ring, Hybrid
Local Area Network (LAN)• Most current LANs run on Ethernet and use the IEEE 802.3 protocol for communication.• IITB LAN is a very good example.
Metropolitan Area Network• Large computer networks usually spanning a city.
IP address• An Internet Protocol (IP) address is a numerical identification that is assigned to devices participating in a computer network utilizing the Internet Protocol for communication between its nodes.• The format of an IP address is a 32-bit numeric address written as four numbers separated by periods. Each number can be zero to 255.• Mine is 10.2.201.72
Subnet mask• A portion of the networks computers and network devices that have a common, designated IP address routing prefix.• A mask used to determine what subnet an IP address belongs to.• An IP address has two components, the network address and the host address• Hostel-2 subnet is 255.255.0.0, so allowed ip-addresses are 10.2.xxx.xxx
Default gateway• A node (a router) on a computer network that serves as an access point to another network.• Viewed simply as an entry point and an exit point in a network.• A default gateway is used by a host when an IP packets destination address belongs to someplace outside the local subnet.• Hostel-2 has a computer : 10.2.250.1
Domain Name System (DNS)• Associates various information with domain names;• It serves as the "phone book" for the Internet by translating human-readable computer hostnames, e.g. www.google.com, into IP addresses, e.g. 18.104.22.168, which networking equipment needs to deliver information