3: Connecting to the Network Networking for Home & Small Business

What’s a Network? Make a phone call, watching TV, radio, Internet, Gaming –All depend on a reliable network Group of connected devices able to communicate with each other

Networks

Basic Network Components 4 categories of components –Hosts –Shared peripherals –Networking devices –Networking media

Hosts –They send & receive data –Have an IP Address

Shared Peripherals –Shared devices that ARE connected to a host –Print Sharing

Networking devices Interconnect hosts Move & control traffic

Networking media Connects Devices

Activity

Handout Complete

Client-Server Hosts have an IP Address Can act as a client or server –Server provides services to other hosts –One server can provide many services –Clients request & display info from servers

Popular Client-Server Network World of Warcraft Players from all over the world connect & play

Peer-to-Peer Networks One computer can sometimes act as the server & the client Simplest: 2 connected devices –Uses a crossover cable Multiple PC’s connect with a hub

Peer-to-Peer Networks Large businesses have lots of traffic –Dedicated servers to handle requests

Famous Peer-to-Peer LimeWire –Exchanging MP3’s with another device

Client, Server, or Both

Physical Topology Layout/Map of network Shows where each host is located, wiring, network devices

Logical Topology Groups hosts by how they use the network –Not physical location Host names, addresses, group info & applications can be recorded

Lab Building a Peer-to-Peer Network

End of Part 1 Review What does SOHO stand for? –Small office home office What interconnects hosts & controls traffic? –Network devices Which cable connects 2 PC’s together? –Crossover cable Hosts are devices that have what? –IP Addresses Describe client-server.

Principles of Communication The Message Source or Sender Destination or Receiver Channel or Pathway Protocol or Rules

Human Communication What are our rules of communication?

Protocols Rules of Communication over a medium Protocols define the details of how the message is transmitted, and delivered. This includes issues of:

Message Encoding Encoding Thoughts into words Proper encoding for that medium Light, electricity, or radio waves Destination will decode the message

Encapsulation Putting a letter in an envelope Encapsulated in a frame before sent over the network –The frame acts as the envelope –Has addresses of source and destination If not formatted correctly, they will not be delivered!

Handout Complete

Review What 4 things do you need for communication? –Source, destination, channel, protocol Describe encoding. –Bits into electricity, light, or radio waves A message is encapsulated in what? –Frame Which 2 address are in the frame? –Source & destination MAC address

Message Size You talk in sentences. –Length will vary depending on what can be processed or understood by the listener Messages sent across networks are broken into smaller pieces –Size of a frame

Message Timing People use timing to determine when to speak, how fast or slow to talk, and how long to wait for a response. These are the rules of engagement. Access Method Flow Control Response Timeout

Message Timing Access Method –When to begin sending & how to respond to errors –Collision if two talk at same time Flow Control –Sender can transmit messages faster than the destination can receive & process –Use flow control to negotiate correct timing for successful communication Response Timeout –How long to wait for responses & what to do

Unicast Message Pattern Unicast –1 to 1 single message

Multicast Message Pattern Multicast –1 to a group message

Broadcast Message Pattern Broadcast –1 to all

Activity

Review What is it called when one message format is placed in another message format? –Encapsulation Bob is talking to Sally. Which type of message pattern is this? –Unicast Which address is used in a frame? –MAC address (source & destination)

Review Which message is one to all? –Broadcast

Importance of Protocols Computers need rules to communicate Local network devices MUST speak same language Most common wired protocol is ETHERNET

Early Days of Computing Each vendor had their own rules Standards had to be created

Standardizing IEEE maintains standards approvals –Assigned a # –802.3 is Ethernet –100Base-T 100 megabit Ethernet Baseband Transmission Twisted Pair Cabling

Physical Addressing Remember encapsulating frames? –Source & destination address needed Each host on Ethernet has a physical address (MAC Address) –Burned into NIC NIC encapsulates source & dest. MAC Host that receives frame reads dest. MAC –If it contains its own MAC, it will process it –If not, it ignores it

Example

Lab Determine the Mac Address Ipconfig /all

Ethernet Frame Structure Frames are also called PDU’s –Protocol Data Units

Activity

Hierarchical Design Structure MAC Address is like your name –Doesn’t tell where you are on the network –Not efficient by itself –Imagine if all hosts on Internet could only be identified by a MAC address Ethernet is a broadcast technology –Sent to all in a network –Too much traffic & collisions Separate into smaller networks

Hierarchical in Life

Hierarchical Design in Networks Dividing your network into smaller groups or layers –Keeps local traffic local –Only data intended for other networks will move on to other layers Access Layer –Provides connections to hosts in a local Ethernet network. Distribution Layer –Interconnects the smaller local networks. Core Layer –A high-speed connection between distribution layer devices.

3 Layer Model

IP Addressing Your name doesn’t change but where you live might –MAC stays on NIC –Doesn’t change no matter where you move IP Address is like your address –It is logical, not physical Needed to go beyond your network –Stay local or go elsewhere???

IP Addressing 2 parts –Identify the network –Identify the host Network portion is same for all devices on a local network

IP Network Example

Lab Determine the IP Address of the Computer Let’s do this together How do we find the IP Address through the command prompt? –Ipconfig /all Why is an IP address important?

Handout 3 Layer Model & Addressing Activity

Review 1.What is the process of placing one format into another (like a letter into an envelope to be sent in the mail)? –Encapsulation 2.Which device is typically at the Distribution Layer? –Router 3.When a PC receives a message, which address is used to determine if it for that PC? –Destination MAC

Review 1.Which organization creates & maintains the standards? –IEEE –Why? 2.A frame contains which 2 addresses? –Source & Destination MAC 3.What does FCS stand for & what does it do? –Frame Check Sequence, checks for errors

Hubs At Access Layer Simple Device (DUMB) –Message in one port, out all others –Does not send to specific device –Sends one message at a time Collisions can occur They wait for silence, & then resend randomly Too many collisions slow the network Keep these collision domains SMALL

Pictures of Hubs

Hub Example

Hub & Collision Domain

Handout Hubs

Switches Access Layer Connects multiple hosts like a hub –Forwards a message to a specific host! –Reads the destination MAC Has a MAC address table –Ports & MAC addresses on them Creates a virtual circuit to destination No bandwidth sharing between hosts No collisions!

How a switch works

More about Switches… What if destination MAC is NOT in the table? –Floods message out all ports, except one it came in on –Compare the destination MAC in frame –Correct one processes the message

Switch Table How does the switch add the MAC address to its table? –It examines the source MAC & port it came in on –When it responds to a message, it adds it Updates table for every message

Example Go to Slide Look at example

What else about Switches? Hub attached to switch port scenario Separate collision domains for each switch port

Switch Handout

Review 1.Hubs & Switches are at which design layer? –Access Layer 2.Which device creates a virtual circuit from the source to destination? –Switch 3.Which device sends data in one port & out all ports regardless of the destination? –Hub

Review 1.Which address does a NIC read when deciding if the message is for itself? –Destination MAC 2.In 100Base-T, what does the 100 mean? –100Mbps –How about the T? Twisted Pair Cabling 3.If a switch receives a frame & doesn’t have the dest. MAC in its table, what happens? –Floods it out all ports, except one it came in on

Broadcasts One host can send messages to all other LOCAL hosts –Find info from others –Tell others something One destination MAC in a frame only –There’s a special MAC address that all hosts will receive & process –48 bits, all binary 1’s –In hexadecimal, FF:FF:FF:FF:FF:FF Look at 3.4.4

Broadcast Domain Too many hosts in a domain, causes traffic backup –This is why you divide into smaller LAN’s

Let’s Practice Together Slide 3.4.5

MAC & IP What if you want to send data, but only know their IP address and not their MAC? –ARP (Address Resolution Protocol)

ARP Host sends out a broadcast frame w/ the IP address of the destination host –FF:FF:FF:FF:FF:FF Each host receives & compares the IP address to see if it is their own Matching host sends its MAC address back to source Source then adds it to its ARP table Then it can send the message

ARP Example

Review 1.A broadcast frame contains which MAC address? –All F’s 2.How many bits is a MAC address? –48 3.Describe a broadcast 4.What separates broadcasts?

Distribution Layer Separates & connects your small networks –Connects your Access Layer networks –Can filter traffic & provide security

Routers Distribution Layer Connects different local networks Reads the packet encaps. in frame –Destination IP Address (network portion) –Subnet Mask Finds best path to that destination network

Routers- The Path… Each port connects a different local network Rips open to find destination IP Looks in Routing Table –In the table: Encapsulates in new frame Sends it out port towards or connected to that destination Routers DO NOT forward broadcasts!

Path Example- H1 to H4

Default Gateway When sending a message on your local network you use ARP to find dest. MAC When sending a message on another network –You encapsulate: Source IP Source MAC Destination IP You don’t know the destination MAC! So you include the MAC of the router port! Router will receive & process this MAC, BUT NOT THE ARP MAC broadcast!

Default Gateway This IP is set in TCP/IP settings Router port that your host connects to- same local network –If the host knows the IP, it will use ARP to find out the MAC address on router port –Example on next slide

Default Gateway

Lab Complete

Routing Tables Networks & best path to reach them Knows this info by: –Dynamically learned from other routers –Manually entered by admin No route in table? –Drop it OR –Default Route is set by admin

Routing Tables

Where does data go? Directly to the network destined for To another router When router forwards the frame, it MUST include a destination MAC –If it is connected, it will use the dest MAC from its ARP table –If not, it will sub MAC address of connected router’s port ARP table for each port/local network

Look at… activity

LAN Network over a small area –Under one administration –Router will separate

How many local networks?

Adding hosts to a LAN Advantages/Disadvantages?

Adding hosts to a LAN Advantages/Disadvantages?

Planning a Network Ethernet is most popular Planning is key! First, gather this info: –The number & type of hosts to be connected –The applications to be used –Sharing & Internet connectivity requirements –Security & privacy considerations –Reliability & uptime expectations –Connectivity requirements including, wired and wireless

Plan & Document Maps of topology Physical environment –Temperature –Power Physical configuration –Location of network devices –Length of cables –Hardware config Logical Configuration –Broadcast & collision domains –IP & Naming Scheme

Physical Topology How many broadcast, collision & networks?

Review 1.Describe a default gateway. 2.Each router port has an _______ table that hold the MAC addresses of devices connected to each port. –ARP 3.Which one device will separate or segment a network? –Router 4.Describe a routing table.

Multifunction Devices Integrated Routers –Usually for SOHO –Switch/router/access point in one –Single point of failure Cisco ISR –Separate components to add/replace

Linksys

Connecting the Linksys All connected to switch ports MUST be in same IP network to communicate Display IP configuration settings –Ipconfig –Ipconfig /all

Lab 3.6.4

Sharing Resources XP has simple file sharing –You can set more specific –Full Control –Modify –Read & Execute –List Folder Contents –Read –Write Look at 3.6.5

3: Connecting to the Network Networking for Home & Small Business