Networking Components

This page provides introduction to Networking Components.

Overview

A Computer Network is digital telecommunications network which allows nodes to communicate. Here is how computer network looks like:

Switches

For e.g. Catalyst $9200$, Catalyst $3650$.

• Switches are used to forward traffic within a Local Area Network (LAN).
• Switches have many network interfaces/ports for the end hosts to connect to (usually $24$+).
• Provides connectivity to hosts within the same Local Area Network (LAN).
• Do not provides connectivity between the LANs/over the internet.
• It uses source MAC address field to populate it's MAC address table. It associates the MAC address with the interface on which the frame was received. This allows switch to learn how to reach other devices on the network.

Routers

For e.g. ISR $1000$, ISR $900$ or ISR $4000$.

• Routers are used to provide connectivity between Local Area Network (LAN) and therefore used to send data over the internet.
• Routers have fewer network interfaces than switches.
• Routers provides basic security features.

Firewall

For e.g. ASA$5500$-X, Firepower $2100$.

• Firewalls are specialty network security devices that control network traffic entering and existing your network.
• Firewalls can be placed outside of your router or inside of your network.
• Firewalls must be configured with security rules to determine which traffic should be allowed and which should be denied.

There are two types of firewalls

• Network Firewalls: It is hardware device that filter traffic between networks.
• Host based Firewalls: It is software applications that filter traffic entering and existing a host machine.

Ethernet

Ethernet is a widely used technology for networking, providing reliable, fast, and efficient data communication between devices in a local area network (LAN). It defines the hardware (cables, connectors) and protocols for communication in wired networks.

Ethernet uses RJ-$45$ as an interface. It is $8$-pin modular connector with $8$ positions and $8$ contacts ($8$P$8$C). Below table shows pins on which each device receives and transmits the data:

Device	Transmit Pins	Recieve 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 $2$

Copper cables using ethernet standard are called Unshielded Twisted Pair (UTP) cables. It has $4$ pairs of cables twisted together, which makes $8$ wires in total. Ethernet and Fast Ethernet uses $2$ pairs or $4$ wires. Gigabit Ethernet and $10$ Gig Ethernet uses all $4$ pairs of UTP cables.

Below are ethernet standards for copper cables:

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

info

$1$ byte = $8$ bits

The speed of a connection is measured in bits per second, not bytes, using units like Kbps, Mbps, Gbps, etc. In contrast, data on a hard drive is measured in bytes per second.

Copper UTP wiring can transmit data over distances of up to 100 meters. For larger networks, fiber optic connections are preferred. Unlike copper wiring, which uses electrical signals, fiber optic cables transmit data as light through glass

Copper UTP cables use separate wire pairs within the cable for transmitting and receiving data. In contrast, fiber optic cables rely on separate cables for these functions.

Below are ethernet standards for fibre optics cables:

Speed	IEEE Standard	Informal Name	Maximum Length	Cable Type
$1$ Gbps	$802.3$z	$1000$BASE-LX	$550$ m - $5$km	Multimode Or Single Mode
$10$ Gbps	$802.3$ae	$10$GBASE-SR	$400$ m	Multimode
$10$ Gbps	$802.3$ae	$10$GBASE-LR	$10$ km	Single Mode
$10$ Gbps	$802.3$ae	$10$GBASE-ER	$30$ km	Single Mode