Networks Terminology and Hardware

Network A network is a group of connected computers that can communicate with each other to share information and equipment, such as printers.

Advantages of a network Sharing Data Reliably – without passing physical volumes, easy backup Sharing Data Reliably – without passing physical volumes, easy backup Sharing Resources – reduces cost of buying hardware Sharing Resources – reduces cost of buying hardware Sharing Programs – programs can run centrally. Sharing Programs – programs can run centrally. Communication - people can communicate and exchange messages with each other easily, effectively, and instantly. Communication - people can communicate and exchange messages with each other easily, effectively, and instantly. Security Options – restricted access Security Options – restricted access

Networks are classified by their: Size Size Architecture Architecture Topology Topology

Size of Networks LAN – Local Area Network: Connects computers and devices in close proximity such as a small office or building like KRSS. LAN – Local Area Network: Connects computers and devices in close proximity such as a small office or building like KRSS. WAN – Wide Area Network: Connects a number of local area networks together over long distances (across cities, countries etc…) WAN – Wide Area Network: Connects a number of local area networks together over long distances (across cities, countries etc…)

Architecture Configurations Peer to Peer (p2p): Peer to Peer (p2p): People on a peer to peer network store their files on their own computers. Anyone may access files stored on any other computer. Before the advent of TCP/IP protocols, peer to peer provided a simple and inexpensive way to connect fewer than 10 computers. (provided in Windows 98, 2000, & XP Home)

Two Network Configurations Client/Server - Client/Server - all files stored on a central computer. Everyone connected to the network can access the files stored on the central server. A Client is a computer that can access information stored on a server.

Terminology Protocol – set of rules for communication Network Interface Card (NIC) – Every node is connected through an NIC – most use a 10/100 Mbps Ethernet card Node – Anything that is connected to the network (computers, printers, scanners etc…) Backbone – The main cabling of a network that all of the segments connect to. (usually faster than the connection to each NIC) Segment – Any portion of a network that is separated by a switch, bridge or router, from other parts of the network

The 4 Common Wired Topologies Topology – The configuration of nodes connected to the network. Bus – Each node is directly connected to a single central cable called a bus or backbone. Bus – Each node is directly connected to a single central cable called a bus or backbone. All information travels along the backbone until it reaches its destination node. All information travels along the backbone until it reaches its destination node. Each end must be terminated (resistor) to keep messages from bouncing back when it reaches the end of the cable. Each end must be terminated (resistor) to keep messages from bouncing back when it reaches the end of the cable.

1. Bus

2. Ring (Token Ring) Nodes are daisy-chained. The end of the network comes back around to the first node – completes a circuit. Nodes take turns sending and receiving info through use of a token. Only node with token can send info or receive info (developed by IBM).

3. Star Star – each node is connected to a central device called a hub. The hub/concentrator takes a signal that comes from any node and passes it to all other nodes on the network.

4. Tree (Star-Bus) The most common - combines star and bus topologies – nodes in areas are connected to hubs/concentrators (creating stars), hubs are connected together along network backbone – stars are often nested

Basics of Ethernet What it is: Currently, Ethernet is a type of wired network that connects computers and other devices. What it is: Currently, Ethernet is a type of wired network that connects computers and other devices. The cables are usually copper Nodes communicate with Packets or Frames of data The cables are usually copper Nodes communicate with Packets or Frames of data Where it came from: Where it came from: Originally, the material used to connect computers was ether. It was a good conductor, and it was thought that it would be less susceptible to interference. Originally, the material used to connect computers was ether. It was a good conductor, and it was thought that it would be less susceptible to interference. Problem: it was too expensive Problem: it was too expensive

Basics of Ethernet cont’d There are practical limits to the size of the network: concerns include: There are practical limits to the size of the network: concerns include: Distance limitations – electrical signals weaken as they travel. Distance limitations – electrical signals weaken as they travel. Electrical interference scrambles signals Electrical interference scrambles signals Practical number of devices as only one device can transmit at any given time. Practical number of devices as only one device can transmit at any given time.

Ethernet Network Standards 10BaseT 10BaseT 10 Mbps 10 Mbps Uses UTP or CAT 5 cables Uses UTP or CAT 5 cables Baseband transmission – only one signal allowed on a transmission wire Baseband transmission – only one signal allowed on a transmission wire 100BaseT 100BaseT 100 Mbps (fast ethernet) 100 Mbps (fast ethernet) Use CAT5 cables – fiber optic available Use CAT5 cables – fiber optic available Broadband – multiple signals on a single wire. Broadband – multiple signals on a single wire. 1000BaseT – Gigabit Ethernet 1000BaseT – Gigabit Ethernet 1000 Mbps - Broadband 1000 Mbps - Broadband Use CAT5e or CAT6 cables Use CAT5e or CAT6 cables

UTP - Unshielded Twisted Pair 10/100 BaseT – cheap, 100m max. STP - CAT5 – Shielded Twisted Pair – used to reduce electrical interference Coaxial Cable – must run in a ring. Fiber Optics –expensive – largest bandwidth Connecting Nodes

4 Types of Connectors AUI – D-shaped plug with 15 pins – common on routers and some hubs RJ45 – connectors look like big phone connectors – uses eight wires – used by most hubs and NICs BNC – small round barrel-like connectors – twist and lock together – used for coaxial Fiber Optic – usually for only one fiber optic strand

CSMA/CD CSMA/CD – Carrier Sense Multiple Access with Collision Detection Regulates communication among nodes Regulates communication among nodes Provides a “fair” set of rules for use of the line Provides a “fair” set of rules for use of the line

Hub (how hubs work) Receive data Receive data Broadcast out data on all lines Broadcast out data on all lines Receiving computers are responsible for listening to see if the data is for them Receiving computers are responsible for listening to see if the data is for them Problems: More computers  more collisions Can’t scale more than 10 computers (Scalability) Takes more time on average for information to reach the intended node (Latency)

Router (how routers work) Receive data Receive data Find out who the data is for Find out who the data is for Send out data on a port that can eventually reach the intended receiver without going through a high traffic area Send out data on a port that can eventually reach the intended receiver without going through a high traffic area Keeps a table inside the router to keep track of where the high traffic areas are Keeps a table inside the router to keep track of where the high traffic areas are

Switch/Bridge (how switch’s work) LAN Switches break hub networks into distinct segments - makes it possible for several users to send data over the network at the same time without slowing each other down creates a series of instant networks that contain only two devices communicating with each other at that particular moment. Nodes communicate only with the switch, so it creates a collision free environment

Wireless Bluetooth Bluetooth WiFi: Wireless Fidelity - Otherwise known as Wireless Networking WiFi: Wireless Fidelity - Otherwise known as Wireless Networking

IEEE Standards – Ethernet wired standard – Ethernet wired standard is the 10 Mbps standard is the 10 Mbps standard 802.3u is the 100 Mbps standard 802.3u is the 100 Mbps standard 802.3z is the 1000 Mbps standard 802.3z is the 1000 Mbps standard – Ethernet wireless standard – Ethernet wireless standard b is the 11 Mbps standard b is the 11 Mbps standard g is the 54 Mbps standard g is the 54 Mbps standard

IP Address A four part number assigned to every computer on a network A four part number assigned to every computer on a network ie ie Each part of the number can be between Each part of the number can be between A device can be manually configured to have the same address every time the device turns on A device can be manually configured to have the same address every time the device turns on A device can be set to take an assigned number from a server or router every time it is turned on A device can be set to take an assigned number from a server or router every time it is turned on

MAC Address A six part hexadecimal number that is unique to every network card A six part hexadecimal number that is unique to every network card Ie 00:02:3F:DC:75:C4 Ie 00:02:3F:DC:75:C4 No two network cards have the same MAC address. No two network cards have the same MAC address. The address is permanently put into the NIC at the manufacturer The address is permanently put into the NIC at the manufacturer

TCP/IP Transmission Control Protocol/Internet Protocol Uses IP addresses for communication (i.e ) Developed by ARPA (Advanced Research Projects Agency) at BB&N in Allows for Packet Switching Large pieces of data are broken into smaller pieces called packets Included with each data packet is the address of the sending node and receiving devices.

UDP/IP User Datagram Protocol (UDP) User Datagram Protocol (UDP) A connection-less, unreliable, transport protocol A connection-less, unreliable, transport protocol Perfect for real time communication Perfect for real time communication Internet radio Internet radio Voice over IP (internet telephone) Voice over IP (internet telephone) Music on demand Music on demand Video conferencing Video conferencing Video on demand Video on demand

Speeds

Security What can you do to stop someone from breaking into your system? What can you do to stop someone from breaking into your system?