1. Ethernet

2. Ethernet  Ethernet is the standard communications protocol embedded in software and hardware devices, intended for building a local area network (LAN).  Contention based communication  Two signals at the same time is called a collision  If there is a signal on the wire the computer waits a random amount of time, then tries again

3. Ethernet  Uses Frames to communicate with all devices  Frame must have a source address and a destination address

4. Ethernet  Terms: Medium - Ethernet devices attach to a common medium that provides a path along which the electronic signals will travel. Historically, this medium has been coaxial copper cable, but today it is more commonly a twisted pair or fibre optic cabling. (UTP) Segment – Everyone in a LAN that is communicating on the same medium (This room, Library) Node - Devices that attach to that segment are stations or nodes. (Computer) Collision Domain - is a physical network segment where data packets can “collide”

5. Token Ring  Local area network (LAN) technology  It uses a special three-byte frame called a token that travels around the ring.  Token ring frames travel completely around the loop.

6. Network Architectures

7. Client Server  Communication between service providers (servers) and service requesters, called clients serversclientsserversclients  A server machine is a high-performance host that is running one or more server programs which share its resources with clients  A client does not share any of its resources, but requests a server's content or service function.  Types of Servers: – Print servers – DNS (Domain Name Servers) – File Storage Servers – Database Server – Internet Servers – Application Servers

8. Client Server  All data is stored on the servers, which generally have far greater security controls than most clients  With tens or hundreds of client PC`s, a server is the only way to manage complex and simultaneous operations  Dedicated Server – Servers only job is to server the other computers  Non Dedicated Server – Server is used as a desktop computer for everyday use

9. Client Server  Advantages – High security levels  Login into server  Different levels of access for files and options – Centralized resources – Easy to add computers to network (Scalable) – Easier to upgrade  Disadvantages – More expensive to setup and maintain (increased cost) – If server crashes the network is down – Server software (OS) is more expensive

10. Peer to Peer  Allows for two or more computers to pool their resources together  All clients provide resources, which may include files, printers, storage space  As nodes arrive and demand on the system increases, the total capacity of the system also increases

11. Peer to Peer  Many file sharing networks, including Gnutella, G2 and Limewire. Peer-to-peer file sharing popularized peer-to-peer technologies. As of 2009, it is the largest contributor of network traffic on the Internet.  Best used for small networks under 10 computers  Used where security is not a great concern

12. Peer to Peer  Advantages – No need for network administrator ($45 per hour) – Network is fast / inexpensive to set up – Each PC in the network can back up another PC for security – Easiest type of network to build – As clients increase so does the capacity  Disadvantages – Not centralized making administration difficult – Lack of security – No one computer is reliable – Demand on the network as computers are added – Depended on all computers to function – If one computer is used more often, then that computer becomes slower