Understanding Ethernet and Fiber Op
Tags: network, ethernet, security, beginners
Published: 2024-02-08 20:24:55

Greetings all,

Back at it and not wasting time at all. I mean eh, it is 2024 right?! Goals were drafted and now the skill must be crafted. In the prior post, I spoke a bit about the world of networking and the basics. Things such as switches and routers were discussed as well as type of networks. Now I go a bit more into the interfaces and cable side of things. Yes, many would say to skip this part, but in my case I want to be a master of the field cybersecurity. I also have a background in electronics so a bit of this is a review well needed. Well, let's not wait and get into more of the notes surrounding networking. Specifically Ethernet and Fiber-optic cable will be reviewed with much in addition. Ok... I'll hush. LOL.


**What are bits and bytes?**

**Bit:**
- A value represented by 0 and 1. When communicating over copper cable, the data is sent is interpreted by the receive device using 0 or 1.



**Byte:**
- A series of 8 bits. 8 bits = 1 Byte.




Remember, speed is measured by bits per second. Kbps, Mbps, Gbps, etc. Never bytes per second.

- 1 Kb = 1,000 bits
- 1 Mb = 1,000,000 bits
- 1 Gb = 1,000,000,000 bits
- 1 Tb = 1,000,000,000,000 bits





**What is Ethernet?**
- A collection of network protocols and standards.


**What is RJ-45?**

- RJ-45:( Registered Jack- 45 )ie: Ethernet Connection


**What are Ethernet Standards?**

- IEEE 802.3 standard in 1983. (Institute of Electrical and Electronics Engineers)

- ie: 10-BASE-T, 100BASE-T, 1000BASE-T, 10GBASE-T)

* Be sure to look up the standards listed above.




**Listed in the standards are the following:**

- Speed
- Common Name
- IEEE Standard
- Informal Name
- Max Length



**What are UTP Cables?**
(ie: Cat 6 cable )


- UnShielded Twisted Pair (No metallic shield which it vulnerable to electrical interference)
- The Twist protects against EMI (Electromagnetic Interference)
- Lower cost than fiber-optic 
- Shorter max than fiber-optic (up to 100 meters)
- RJ45 ports usd with UTP are cheaper than SFP ports.
- Emit (leak) a faint signal outside of the cable which can give security risks.


**What are Fiber Optic Cable?**
- Sends light over glass fibers having one connection to send and one connection to receive.


**Two Types of Fiber-Optic Cable are below:**


**Single-mode Fiber Optic Cables:**

- core diameter is narrower
- light enters at a single angle mode from a laser based transmitter.
- allows longer cables than both UTP and multimode fiber.
- more expensive than multimode fiber (due to more expensive laser-based SFP transmitters)

- They use separate cable to send and receive connections
	1. fiberglass core 
	2. cladding that reflects light
	3. a protective buffer
	4. the outer jacket of the cable.




**Multi-mode Fiber Optic Cables (Cheaper than Single Mode):**

- core diameter is wider than single-mode fiber
- allows multiple angles (modes) of light waves to enter the fiberglass core.
- allows longer cables than UTP, but shorter cables than single-mode fiber.
- cheaper than single-mode fiber due to cheaper LED-based SFP transmitters.
- Does NOT emit any signal outside of the cable (=no sec risk)



**What is a SFP Transceiver?**

- (Small form-factor pluggable): Connect a fiber optic cable to them.






**Resources:**

[What is Ethernet?](https://www.wired.com/story/what-is-ethernet/)



[What are Ethernet Standards and Protocols?](https://www.computernetworkingnotes.com/networking-tutorials/ethernet-standards-and-protocols-explained.html)



[Straight-Through vs Crossover Cable](https://www.cables-solutions.com/difference-between-straight-through-and-crossover-cable.html)


[What are Fiber-Optic Cable?](https://www.cablematters.com/Blog/Networking/fiber-optic-cable-types-a-complete-guide)