Networking #4 - Layer 2 - ethernet and intro to TCP-IP

Layer 2

-----------------------------------

- What is ethernet?
- List the types of cables. Types of connectors normally associated with ethernet. (normally layer 1)

- Can any other protocols / technologies run using the same cables / connectors?

- What is a MAC address?
- What information can we get from the MAC address itself? (with a little help from google)

- What is a hub? what is a switch?
- What are the fundamental differences between both?
- what is a switching table and what does it contain?

- What is a bridge? how is it similar to hubs and switches?

- Layer 2 Broadcast traffic: (different but very related to L3 broadcast traffic)

Read this:
https://www.juniper.net/documentation/en_US/junos/topics/concept/broadcast-qfx-series-understanding.html

- What is broadcast traffic?
- What is a broadcast storm?
- What is a loop?

- What is STP?
- What is a BPDU?
- What is a root bridge?

- List the types of STP and their characteristics.

Networking #3 - Layer 1 technology

What is considered as Layer 1?
Layer 1 in the OSI model.
-----------------------------------
Connectors:

• RJ11 connector
• RJ45 connector
• SFP ports
• SFP+ ports
• Infiniband
• HDMI (yes! for networks!)

• legacy: BNC connector
• New stuff in network connectors:

          - TERA connectors: https://en.wikipedia.org/wiki/TERA
          - ARJ45 - for high speed applications up to 1000MHZ

Copper cables:

• Coaxial
• Cat 1,2,3,4
• Cat 5
• Cat5e
• Cat6
• cat 6e,7 and beyond
• UTP 

Optic-Fibre  connectors, cables and similar:

• Single-mode
• Multi-mode
• Twinax cable

Make a list of the most popular types of optical connectors.

WIFI

• 2.4 ghz and 5 ghz
• B standard
• G standard
• N standard
• A, C standard

We will do a module on wireless tech later on, so there is no need to go very deep this time.

Questions that need answering:
What is an RJ11 traditionally used for?
What is ISDN?
What is RJ45 traditionally used for? how many cables does it contain?

What does "twisted pair" mean? what is the objective of the "twisted pair" ?

Check out: http://www.pearsonitcertification.com/articles/article.aspx?p=1816014

How many cables does 10/100 use? 

What are the cabling standards?
What is autonegotiation?
How many cables does gigabit use?

Can you manually negotiate to 1Gbit?

Can I run gigabit ethernet over a Cat5e cable?
when and why do we use a crossover ethernet cable?
what is the difference between shielded and un-shielded cable?

What is the difference between Multimode and Single mode fiber
What is the maximum speed of an SFP ? and an SFP+ ? Why?
What is the maximum distance supported by mono-mode and multimode fiber?

[trick question]
In a netgear switch stack configuration we can use a regular sfp+ to achieve speeds of 12-14 gigabit per second for the switch interconnection. Why?

-----------------------------------
[More questions will be added]

Layer 1 devices and applications:

Bridge
Hub
Optical splitter
Dark Fibre

HISTORY

- Who was Dennis Ritchie? What did he create? what is it?

Networking#2 - Numbering systems, Standards and the OSI model.

We need to build a solid base for all the stuff we're going to learn afterwards, so this will be a bit like building the foundations for a skyscraper.

1.- Numbering systems:

- Define the following numbering systems:

 - binary
 - octal
 - decimal
 - hexadecimal

Why does a computer use binary?
Internally, does a computer use anything but binary?
Why do we use decimal and hexadecimal numbers then? how are they useful?
Incidentally, why do Ram modules follow an increment in space like this: 2Gb-4GB-8Gb-16Gb-32Gbmb, processors also go  8bit, 16bit- 32bit-64bit... why is this?

We will see a bit later why this is important and relevant.

2.- Standards, RFCs and the IETF:

- What is a Standard? (hint: read RFC 2026 and )
- Who are the IETF ? What do they do?
- What is an RFC? how are RFCs relevant¿?
- What is the IRTF?

How have the IETF and IRTF had an impact on how the internet works?

3.- OSI model:

(This part is hard theory, so you're just going to have to suck it up and learn it)

- What is the OSI model?

- What are "layers"?

- How do layers interact with eachother?

- What is a protocol?
- What is a "protocol stack"? (I call it the protocol Lasagna)
- What are the different layers? what does each layer do?

(there are definitely more questions to be asked, but in this case you must simply "know" the OSI model, because we will use it later to correlate it to the Ethernet + TCP/IP stack of protocols.

4.- Networking history

Legacy

- Token ring /  Arbitrated Loop

- BNC network connectors

- IPX protocol
- Novell networks
- Nortel

Read:
https://visual.ly/community/infographic/technology/brief-history-computer-network-technology

Networking #1 - The internet and the web / WWW

Welcome to the networking Module!!

Here we're going to learn a bit of how networks in general work (and the internet in particulad)  it's history it's inner workings, and how to fix that router at home that keeps on failing (and how to fix it)

This ties in with the previous module, as we need a computer to do any sort of networking, and how the computer works affects how it behaves on the network.

The idea here is to have a bit of an introduction. There is not necessarily any sense or direction to this first post on the subject, just a throw around of several concepts so that you can start to get an idea of how everything is tied together, a "high level view" to start with, with some more specific bits of knowledge. It will all make better sense when we go into a more granular and systematic approach.

1.- History

      Arpanet / DARPA net --> start here!
      Norad and the movie "War Games" , check it out!
      What was the first non-military "internet" connection?
      Who sent the first email?
      What was a BBS ?
         

2.- concepts / questions:

     Serial connection - the first network - what are the speeds? how does it work?
     How does a modem work? Read a bit about it.
     What is the typical speed of a modem based network connection?


      What is a web browser? (look for an actual definition)
      Make a list of the 5 most popular web browsers.
      What is HTTP?
      What is HTML?
      Differences Between HTTP 1.1 and HTTP/2
      What is HTTPS?
      What is the difference between HTTP and HTTPS ? (we will see this in more detail later)
   
      What is an IP address? (rough idea)
      What is a private IP address?
      And a Public IP address?
      And what is the difference between them?

      How can I buy a domain name?
      How much does it cost roughly
      What is a subdomain?
      What is a URL?
      What is the difference between a URL and a subdomain?

3.- More history:

     The browser wars, rise and fall of netscape, internet explorer and others.
     Check out the story of: Worldcom, Pets.com and the dot.com crash.
     Check Cisco systems stock price between 1990 and 2018 - Why does it look the way it looks?

4.- Lab:

    Find 4 websites that would sell you a domain name.
    Find out what else you need to get a website up and running.

IT Lesson #5 - Building a computer (part 4) - Box, Motherboard formats, hybrid hard drives and more.

We've seen the different types of CPU, but let's expand a bit on that. 1-2 h max)

- What happened to Cyrix and why? (Cyrix was a CPU manufacturer back in the 90's)
- What is the difference between a normal Intel processor and a Celeron processor?
- Why is the Celeron different in price? (is it more expensive or cheaper?)
- Why can I not use an ARM processor on a PC ?
- Can I run windows on ARM ?
- What are the major PC processor manufacturers?

- IMPORTANT: what is thermal compound / paste and why do we need it?

Storage / Hard drives: (30-45 min max)

- What is an M.2 Hard drive?
- M.2 --> AHCI vs NVMe What is the difference?
    (https://mygaming.co.za/news/hardware/118533-different-types-of-ssds-explained-sata-vs-m-2-vs-pcie.html)
What is a SSHD? (Hybrid SDD-HDD) check the Seagate firecuda for example-
PCIe hard drives: what types are there?
Why would I want a hard drive with M.2 interface and not a SATA interface?
What is SAS?

Graphics cards
What was AGP ? (read 5-10 minutes max)
NVIDIA or ATI ?
What is the effect of cryptocurrency mining on graphic card prices?
Remember that the Graphics card needs a lot of power. Have you picked a PSU that will supply all the power needed?
Check the differences between VGA, DVI, DisplayPort, HDMI, Thunderbolt (mini display port)
Can HDMI transmit audio? If so in what formats? What else can HDMI be used for?

Power supply:

- Make sure the power rating of the PSU is higher than the total power consumed by the computer.
(Keep in mind that the PSU consumes a lot of power)

- Make a list of all the different connectors you will find on a PSU

BOX:

We have to pick a computer case for our project!
Make sure that the form factor of the box matches the size and form factor of the motherboard (IE that it fits)
Investigate why airflow is important
Pick a fan speed regulator, unless you picked liquid cooling.
Note why you picked

Monitor:

What is the difference between screen resolution and pixel density?
What is the difference between CRT, TFT, LED, and OLED?


FINAL:

Make two computer configurations:

- One for a high end gaming PC
- One for an affordable office computer

History:

Internet explorer vs Netscape. The first browser war.

IT Lesson #4 - Building a computer (part 3) - Graphics, power.

1.- Graphics card

What is a graphics card and what do you use it for?
What are the fundamental differences between a GPU and a CPU ?
What is a CPU / GPU core?
How many cores do CPUs usually have?
How many cores do GPUs usually have?
For a given graphics card how much power is consumed? (what are WATTS )
Why does that make a difference?

PCIe speed --> how does the speed on the motherboard PCIe port influence the performance of the graphics card?
What is SLI ?

What are polygons?
What are textures?
What is screen resolution?
What do 720p and 1080p stand for?
Color bit depth, how does that make a difference?
How is the performance of a CPU measured? And a GPU? how is this measure different?

Concepts:

Core(s)
Flop / teraflop
PCIe (+speed)
Polygons
Textures
Resolution
Color bit depth

------

Connectors:

Take a look at the different video connectors and standards and make a list.
Which are analog and which are digital? Why does that make a difference?

Build the computer (Task):

Pick a graphics card (or several) for your setup, make note of power consumption, extra electric connections to the PSU and anything else that you might need.

2.- Power

Check power supplies on a computer hardware website.

Make a list of different power supply standards (Types)
Make a list of important characteristics for a power supply
Make a list of the different connector types on power supplies

What voltages does a PC PSU work with?
What is the voltage on a USB port?

Pick a power supply that will work with the hardware you have selected so far and has enough power to work. Justify your choice in one paragraph.

3.- History

Read about:

DARPA //
DARPANET/ARPANET //
NORAD

4.- Extra!!

- What is pixel density? (PPI)
- What is the "Native resolution" of a screen?

IT Lesson #3 - Building a computer (part 2) - Data Storage

1.- First watch this youtube video:

A History of Hard Disk Drives (and How They Work)

https://www.youtube.com/watch?v=HLgzqanGHIg


2.- Concepts

• RPMs
• SATA version
• IDE, SCSI, SAS

Key questions:

• What are RPMs ? (on a disk drive)
• 5400 vs 7200 RPM, what's the difference?
• IDE, SCSI, SATA1,2,3 (etc),  SAS what are they?

3.- More concepts

• Bus speed vs disk speed
• Sequential Read / Write
• Random Read / Write

We will go back to hard drives in more detail later.

4.- A bit of history

• The GNU project
• Richard Stallman

Bonus:

Download Data Lifeguard Diagnostics from WDC, we will use it in a later module to check hard drive health.
https://support.wdc.com/downloads.aspx?lang=en