---
id: 1771825730-VZFA
aliases:
  - 02. Interfaces and Cables - CCNA
tags:
  - CCNA
---

# Interfaces and Cables

Front of a switch example phrase above the interfaces
10/100/1000 Base-T Ports ( 1 -24) - Ports are Auto MDIX

## [[RJ-45]]

Registerred Jack

## Etrhernet

Etrhernet is a collection of network protocols/standards.

## Network Protocols
Why do we need network protocols
For Industry standard that everybody follows

## [[Bits]] and [[Bytes]]

it a value represented by 0 and 1
a bytes is a series of 8 bits

Speed is measured in bits per second (kbps, Mbps, Gbps, etc) not bytes per seconds.

However for [[Hard drives]] we count the bytes

1 kilobit (kb) - 1,000 bits
1 megabit (Mb) - 1,000,000 bits
1 gigabit (Gb) - 1,000,000,000 bits
1 terabit (Tb) - 1,000,000 bits

## Etrhernet  standards

- Defined in the IEEE 802.3 standard in 1983
- IEEE = Institute of Electrical and Electronics Engineers

### Copper Ethernet standard

| Speed   | Common name         | IEEE      | Informal Name | Maximum Length |
| ------- | ------------------- | --------- | ------------- | -------------- |
| 10 Mbps | Ethernet            | 802.3i    | 10BASE-T      | 100m           |
| 100 Mbps| Fast Ethernet       | 802.3u    | 100BASE-T     | 100m           |
| 1 Gbps  | Gigabit Ethernet    | 802.3ab   | 1000BASE-T    | 100m           |
| 10 Gbps | 10 Gig Ethernet     | 802.3an   | 10GBASE-T     | 100m           |


#### BASE T

Base = refers to baseband signaling
T = twitsted pair

### UTP Cables

Unshielded Twisted Pair
Twisted mean that there sensitive against [[EMI]] Electronic Magnetic Interference
they got 8 pins

10Base-T and 100Base-T = 2 pairs (4 wires)

1000Base-T and 10GBase-T = 4pairs (8 wires)

#### UTP Cables (10Base-T, 100 Base-T)

Full-Duplex transmission
Both devices can send and received data at the same. no colission while occur

##### Straight-through cable


Transmit 1 - 1 Receive
(TX)     2 - 2  (RX)
Recieve  3 - 3 Transmit 
         4   4
         5   5 
(RX)     6 - 6 (TX)
         7   7 
         8   8 

##### Crossover cable

Transmit 1 - 3 Transmit
(TX)     2 - 6  (TX)
Recieve  3 - 1 Receive 
         4   4
         5   5 
(RX)     6 - 2 (RX)
         7   7 
         8   8 

##### Chart

| Device Type | Transmit (TX) Pins | Recieve (RX) Pins |
| ----------- | ------------------ | ----------------- |
| [[Router]]  | 1 and 2            | 3 and 6           |
|[[Firewall]] | 1 and 2            | 3 and 6           |
| [[PC]]      | 1 and 2            | 3 and 6           |
| [[Switch]]  | 3 and 6            | 1 and 2           |


##### Auto MDI-X

allows devices to automatically detect and adjust the the pins for transmiting data prevent colissions


#### UTP Cables (10Base-T, 100 Base-T)


##### Straight-through cable

Each pair is bidirectional

the pair are 

1 and 2
3 and 6
4 and 5
7 and 8

## Fiber-Optic Connection

[[SFP]] Transceiver Small-Factor Pluggable for Fiber Optics cable

Send light over glass fiber

TX - RX
RX - TX

there are 4 layers for this cable

1 : the fiberglass core itself
2 : cladding that reflects light
3 : a protective buffer
4 : the outer jacket of the cable

single-mode and multimode fiber

### Multimode fiber

- Core diameter is wider than single mode fiber.
- Allow mutiple angles (modes) of light waves to enter the fiberglass core
- Allows longer cables tha [[UTP]] but shorter cables than single-mode fiber. 
- cheaper than single-mode fiber (due to cheaper LED-based SFP transmitters)

### Single-Mode Fiber

- Core diameter is narrower than multimode fiber
- Light enters at a single angle (mode) from alaser-based transmitter
- Allows longer cables than both UTP and multimode fiber
- More expensive than multimode fiber (due to more expnesive laser based transmitters)

### Fiber-Optic cables standards


| Speed   | Cable Type          | IEEE      | Informal Name | Maximum Length   |
| ------- | ------------------- | --------- | ------------- | ---------------- |
| 1 Gbps  | multi or single-mode| 802.3z    | 1000BASE-LX   | 550m(MM) 5km (SM)|
| 10 Gbps | Multi-mode          | 802.3ae   | 10GBASE-SR    | 400m             |
| 10 Gbps | Single-Mode         | 802.3ae   | 10GBASE-LR    | 10km             |
| 10 Gbps | Single-Mode         | 802.3ae   | 10GBASE-ER    | 30km             |

## UTP vs Fiber-Optic Cabling

- UTP 
  - Lower cost than fiber optic. 
  - Shorter Maximum distance than fiber0-optic (100m).
  - Can be vulnerable to EMI
  - RJ45 ports used with UTP are cheaper than SFP ports.
  - Emit (leak) a faint signal outside of the cable, which can be copied (= security risk)
  
- Fiber-Optic
  - Higher cost than UTP.
  - Longer maximum distance than UTP.
  - No vulnerability to EMI.
  - SFP ports are more expnsive than RJ45 ports (singl-mode is more expensive than multimode).
  - Does not emit any signal outside of the cable (=no security risk)