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

2. 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??

3. Networking and Its Benefits
A CONVERGED NETWORK!!!

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

5. Networking and Its Benefits
Schools, Corporations
Internet

6. 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

7. 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

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

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

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

11. 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

12. 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

13. 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

14. 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

15. 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.

16. 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

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

18. Communication Protocols
PROTOCOLS = RULES TO FOLLOW

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

20. 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

21. 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

22. 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

23. 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

24. 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

25. 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

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

27. 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

28. 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?

29. 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

30. 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

31. 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

32. 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

33. 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.

34. 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!!!

35. 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

36. Routing Tables and ARP tables
Used by routers to store information

37. 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

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

39. Distribution Layer Devices and Communication Methods
Packet Tracer

40. 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

41. 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

42. 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

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

44. 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