Connecting to the Network Networking for Home and Small Businesses – Chapter 3

What is a network? The ability to connect people and equipment no matter where they are in the world. telephone computers television How does your body work as a network??

Networking and Its Benefits A CONVERGED NETWORK!!!

Networking and Its Benefits SOHO Network Small Office/Home Office sharing of resources Internet Printer

Networking and Its Benefits Schools, Corporations Internet

Networking and Its Benefits Define the components of an Information network Hosts PCs send and receive information across the network connected to a network device Peripherals not directly connected to the network, but connected to hosts Network devices hub, switch, router Network media used to connect hosts/devices

Networking and Its Benefits Clients and servers software installed determines the role of a client or a server Server software enables the server to provide information to other hosts Client software enables the client to request and display information from the server Example: Internet Explorer

Networking and Its Benefits Build computer peer-to-peer network and verify The ability to act as both a client and server

Network Topologies Physical topology created to record where each host is on the network shows how each host is connected (media, devices, etc)

Network Topologies Logical topology how the host uses the network host names, addresses, groups, applications

Communication Protocols Primary purpose of a network – to communicate Elements of communication Sender (source) has a need to communicate Receiver (destination) receives message and interprets it Channel pathway for information to travel

Successful delivery of the message Rules (protocols) must be followed: Identification of the sender and/or receiver Channel in which to communicate (face-to-face) Mode of communication (written or spoken) Language Grammar Speed or timing

Communication Protocols Encoding vs. Decoding Encoding Humans converting thoughts into language, symbols, or sounds Computers messages converted into bits by sending host each bit encoded into sound, light, or electrical impulses destination host then decodes the signal Decoding reverse of encoding

Communication Protocols Message formatting and encapsulation Message needs a specific format Compare to parts of a letter Identifier (recipient) Salutation Message Closing Identifier (sender) Encapsulation placing the letter into the envelope De encapsulation letter removed from the envelope

Communication Protocols Messages have size restrictions depending on the channel used If the message is broken into smaller pieces, it is easier to understand If the message is too long or too short, will be considered undeliverable.

Communication Protocols Timing when to speak; how fast or how slow how long to wait for a response Access Method determines when someone is able to send a message can speak when no one else is talking, otherwise a COLLISON occurs Flow Control timing for negotiations sender might transmit messages faster than the user can handle Response Timeout how long should you wait for a response and what action to take Acknowledgment may be required to ensure message was delivered

Communication Protocols Message Patterns Unicast – single destination Multicast – same message to a group Broadcast – all hosts need to receive the message

Communication Protocols PROTOCOLS = RULES TO FOLLOW

Communication Across a Local Ethernet Network Computers must speak the same language in order to communicate!!

Standards in technology Standards – rules by which equipment from different vendors operate Benefits of standards: Facilitate design Simplify product development Promote competition Provide consistency Facilitate training More vendor choices for customers

Communication Across a Local Ethernet Network IEEE (Institute of Electrical and Electronic Engineers) maintains networking standards 802.3 – Ethernet standard A breakdown of terminology 100 Base-T 100 = Speed in Mbps Base = Baseband transmission T = Twisted Pair

Communication Across a Local Ethernet Network Physical addressing MAC address (Media Access Control) Ethernet communication each interface has a MAC address each device may look at the data, but only the interface that matches the destination MAC will respond

The Ethernet Frame Preamble – beginning of the timing SFD (Start Frame Delimiter) – marks the end of the timing, but beginning of the frame Destination MAC Source MAC Length/Type Length – tells which protocol receives the data Type – number of bytes of data Encapsulation – packet of information FCS (Frame Check Sequence) – checks for damaged frames

The Hierarchical Design Structure Smaller, more manageable groups allow traffic to remain local on the networks Divided into three layers Access Layer connection to the hosts Distribution Layer interconnects smaller networks Core Layer high speed connection between distribution devices

Logical Addressing MAC vs. IP IP Address (Logical Address) assigned based on where the host is located assigned by the administrator Parts of an IP address Network – same for all hosts connected to the LAN Host – unique to each host on the network

Access Layer Devices Most basic level Made up of: host devices first line of networking devices hub, switch, workstations

Access Layer Device – A HUB Accepts data signal from one port and sends it (regenerates) out all ports multiport repeater Collisions results in message being garbled and unreadable occur when two or more hosts send a message at the same time (undesirable in a network) NOT VERY SMART a hub will not recognize there is a collision and send it all ports

Hubs And Collision Domains Collision domain – area where the collision has occurred. More collision domains = better performance How many collision domains exist in the graphic shown?

Access Layer Device – A SWITCH SMARTER THAN A HUB dedicated bandwidth out each port no need to share with other ports (unlike a hub) Can forward messages to a specific host by looking in its MAC table If destination MAC is not in its MAC table, floods the network out all ports looking for a response Only the host with the correct MAC address will respond

More Stuff on Switches How does the MAC table get built? keeps track of frames being sent between hosts records the information when there is a response Collision Domains each port on a switch is its own collision domain 8 port switch = 8 collision domains Online Activity 3.4.3

Broadcasts If there is only one destination MAC in a message, how can you contact everyone else? send a broadcast MAC hexidecimal digits FFFF.FFFF.FFFF Useful when hosts need to send information but don’t know what hosts are to receive it Switches and hubs send the broadcast out to everyone on their network. (Broadcast Domain) ONLINE ACTIVITY 3.4.5

ARP Request Sent when the sending host knows the destination IP, but not the MAC Will discover the MAC address of any local host on the network

Distribution Layer Devices and Communication Methods Responsible for making sure local traffic stays local on the network Traffic destined for other networks will be passed on.

Distribution Layer Devices—The Router Routers – directs traffic based on the destination IP address Routers build routing tables; switches build MAC tables Routers decode packets, switches decode frames Look only the network portion of the IP address finds the best path to take to get to the destination Routers do not forward broadcasts!!!

Default Gateway Used when a host wants to send data to a host on a different network. Must be set on the workstation connected to the routing device – the router interface connected to the PC Activity 3.5.3

Routing Tables and ARP tables Used by routers to store information

Types of Routing Dynamic Static information is obtained from neighboring routers Static manually entered by the network administrator What happen to a message that is not in the routing table? It is dropped unless . . . A default route is set “last resort” type of router will send it to the router it thinks may be have the destination IP ONLINE ACTIVITY 3.5.4

Distribution Layer Devices and Communication Methods LAN – Local Area Network Under the same administrative control

Distribution Layer Devices and Communication Methods Packet Tracer

Plan, Implement and Verify a Local Network Consider the following before beginning: Number and type of hosts Applications to be run on the network Data and devices to be shared Speed requirements (bandwidth) Level of security Reliability of the network Connectivity requirements

Building the Network Physical environment Physical configuration temperature control availability/placement of outlets Physical configuration location of devices how are devices connected location/length of cable runs hardware configurations (hosts, servers) Logical configuration size of broadcast & collision domains IP addressing scheme Naming Permissions Sharing

Multifunction Devices Integrated routers Linksys wireless router problem = single point of failure Cisco Integrated Services Router (ISR) performs services of three different devices router switch wireless access point

Implement and Document the Network Develop a prototype tests network design PACKET TRACER – ACTIVITY 3.6.2

Sharing Resources Main reason for networking – sharing resources File sharing Print sharing Consider this before sharing: security issues permissions granted Windows XP users use Simple File Sharing