First XOs have arrived!

First step: Open the box...

much more difficult than it sounds as it was apparently found necessary to put multiple layers of varying types of tape on the box

Second step: Ensure they are in fact fully updated.

Now the important part: BUBBLE WRAP.

Sure enough they are fully updated and are running properly.

Next step: establish a server for the OLPCs to run on.

Chapter 4: Ethernet Basics pg 98-end

Crossover Cables:
- way in which hubs can connect to each other
- reverses the sending and receiving pairs on one end of the cale
- connects to a regular port on each hub
- never connect two hubs by their uplink ports with a straight-through cable

Bridges:
- acts like a repeater or hub to connect two ethernet segments
- filters and forwards traffic between those segments based on the MAC addresses of  the computers on those segments
- initially behaves exactly like a repeater
- however it monitors and records the network traffic
- mainly used in wireless networks

Switched Ethernet:

Trouble With Hubs:
- can only have one message on the wire at any time

Switches to the Rescue:
- create point-to-point connections between two computers
- copies the source MAC addresses and quickly creates a table of MAC addresses of each connected computer (Source Address Table)
- switch acts like a telephone operator
- can buffer incoming crames
- also known as a broadcast domain

Spanning Tree Protocol:
- switching loops: redundant connections in a network
- created to determine things like the distances between them

Troubleshooting Hubs and Switches:
- problems fall into three categories
           - Obvious physical damage
           - Dead ports
           - general flakiness

Network+ Chapter 4: Ethernet Basics Pg 93-97

10BaseT Limits and Specifications:
- cable connecting hub and computer cannot exceed 100 meters in length
- cannot connect more than 1024 computers
- Speed: 10 Mbps
  Signal Type: baseband
  Distance: 100 meters between the hub and the node
  Node Limit: No more than 1024 nodes per hub
  Topology: star-bus topology; physical star, logical bus
  Cable type: CAT 3 or better UTP cabling with RJ-45 connectors

10BaseFL Summary:
- Speed: 10Mbps
  Signal Type: Baseband
  Distance: 2000 Meters between the hub and the node
  Node Limit: No more than 1024 nodes per hub
  Topology: star-bus topology: physical star, logical bus
  Cable Type: Multimode fiber-optic cabling with ST or SC connectors

- Can use a media converter to interconnect different Ethernet types

Extending and Enhancing Ethernet Networks

Connecting Ethernet Segments 

You can connect hubs in two ways:
      - uplink port or a crossover cable
    

Uplink Ports 

- Enable you to connect two hubs using a straight-through cable
- you cannot use a single central hub and connect multiple hubs to that hub
- When connecting hubs:
         - only daisy-chain hubs
         - take time to figure out the uplink ports
        

Network+ Chapter 4: Ethernet Basics Page 85-92

Node (NIC): A member of a network or a point where one or more functional units interconnect transmission lines

            - Must have a unique identifying address
            - Identified using 48-bit binary addresses known as Mac Addresses

Mac Address: Unique 48-bit address assigned to each network card. IEEE assigns blocks of possible addresses to various NIC manufacturers to help ensure that each address is unique. The Data Link layer of the OSI seven-layer model uses MAC addresses for locating machines.

           - give each NIC a unique address
           - computers on the network listen to the wire to see if it contains their MAC address
           - if a machine sees it's address it opens the frame to process data

Sniffers: Diagnostic program that can order a NIC to run in a promiscuous mode.
           - Ethernet provides no protection against sniffers
Promiscuous Mode: A mode for a NIC in which the NIC processes all frames that it sees on the cable.

Frame: A defined series of binary data that is the basic container for container for a discrete amount of data moving across a network. Frames are created at Layer 2 of the OSI model.
           - computers can determine what type of data (IPv4 or IPv6)
           - type field does not tell you if the fram carries an email or web page

Data:
           - contains whatever payload the frame carries
         
Pad:
           - minimum Ethernet frame is 64 bytes (but not all has to be data)
           - if fewer than 64 bytes in size, the sending relay will automatically add extra data

Frame Check Sequence:
           - Ethernet's term for the cyclic redundancy check
           - Enables Ethernet nodes to recognize when bad things happen to good data
           - machines must be able to detect when data has been damaged
       
CSMA/CD:
           - Carrier sense multiple access/collision detection
           - determines which computer should use a shared cable
           - means that each node using the network examines the cable before sending data
           - network access method that maps to the IEEE 802.3 standard for Ethernet networks
           - multiple access means that all machines have equal access to the wire
           - collision domain is a group of nodes that have the capability of sending frames at the same time as each other
         

10BaseT:
            - created in 1990
            - 10 Mbps
            - signaling type: baseband
            - the cable only carries one type of signal
            - uses twisted pair cable
            - RJ-45 connector
            - enables devices to put voltage on the individual wires within the cable
            - designates some of these numbered wires for specific

Ubuntu Install on Student Laptop

Today I began installing Ubuntu on a students laptop.

The language was set to English(US).

The user-name was set by default by the system. The password was set as directed. The home directory was NOT encrypted.

Ubuntu is currently installing and will hopefully finish by the end of the class period.

The second laptop has no contact information on it and it is unknown exactly what should be done with it so nothing will be done to it until further information is discovered.

In addition today, the battery was changed out on the Dell tower for the elderly woman is now fully functional. It is ready for pickup.

Student Laptop Repair

The first set of projects began with replacing the LCD screen on a Dell laptop. The video that I watched made the project seem a lot easier than it actually is however, disconnecting the inverter is a lot less self explanatory than it may sound. The screen came out eventually and has been replaced.

I will now begin installing Ubuntu on the last two student laptops and create user accounts for them.

In addition, the woman's computer that was asked of us to repair has been repaired and it ready to return to her for use.