CCNA Learning Journey

Day 2 : Interfaces and Cables

RJ-45

• RJ : Registered Jack

• 45 : Designed number

• Ethernet is a collection of network protocols/standards.

Ethernet Standards:

• Defined in IEEE 802.3 stanadard in 1983
• IEEE = Institute of Electrical and Electronics Engineers

• BASE : refers to baseband signalling
• T : twisted pair

UTP Cables

2 Pairs (4 wires): - 10Base-T - 100Base-T

4 Pairs (8 wires): - 1000Base-T - 10GBase-T

• Straight Through Cable: connects Pin 1 on one end to Pin 1 on other end and so on.

Auto MDI-X

• allows devices to automatically detect which pins their neighbouring devices is transmitting data in and adjust itself to transmit or receive data.

SFP Transceiver (Small Form-Factor Pluggable)

Fiber-Optic Connections

• Uses separate cable to transmits and receive data.

Multimode Fiber

• Core diameter is wider than single mode fiber.
• Allows multiple andles (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)

Single Mode Fiber

• Core diameter is narrower than multimode fiber.
• 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)

UTP Vs Fiber-Optic Cabling

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