network #2

Physical Topology

How devices are physically connected with cables, ports, and hardware.

Example of Star Topology (Physical)

All devices connect to one central device (router, switch, or hub).

Example of Bus Topology (Physical)

All devices share one main cable.

Example of Ring Topology (Physical)

Devices are connected in a loop.

Logical Topology

How data flows through the network, regardless of the physical layout.

Logical Bus Example

Data travels as if devices share one line, even if wired differently.

Logical Ring Example

Data flows device-to-device in a circle, even if not physically wired that way.

10 Mbps Meaning

10 million bits per second.

How Data Moves in 10 Mbps Ethernet

Data travels 1 bit at a time down the cable.

Collisions in 10 Mbps Networks

Only one device can talk at a time; two devices talking causes a collision.

UTP (Unshielded Twisted Pair)

A common Ethernet cable made of twisted copper wires without shielding.

Star Topology Definition

A physical layout where each device connects directly to a central hub or switch.

How Star Topology Works

Each PC has its own cable running to the central device.

CSMA/CD

A method old Ethernet uses to avoid and detect collisions on shared cables.

Carrier Sense

A device listens to the cable and waits if it is busy.

Multiple Access

All devices share the same cable and may try sending data.

Collision Detection

If two devices send at the same time, a collision happens and devices must stop and retry.

What Happens During Collision Detection

Devices stop sending, send a jamming signal, wait randomly, then retry.

Network with a Hub

All devices connect to a hub; data is broadcast to everyone, causing collisions.

Hub Network Behavior

Physical star, but logical bus because all traffic is shared.

Bridge

A Layer 2 device that connects two LAN segments and forwards traffic only where needed.

What Bridges Reduce

They reduce collisions and unnecessary traffic.

Bridge vs Switch (Bridge Side)

A bridge connects two LAN segments and filters traffic using MAC addresses.

Bridge vs Switch (Switch Side)

A switch is faster, has many ports, and sends frames only to the correct port.

Switched Network

Uses switches so each device gets its own port and avoids collisions.

How Switched Networks Work

The switch sends data only to the correct device using MAC addresses.

Routed Network

Uses routers to connect different networks using IP addresses.

What Routers Do

Routers choose the best path to send data to another network.

Firewall

A device that allows or blocks network traffic based on security rules.

What Firewalls Protect

Firewalls protect networks from unsafe or unwanted traffic.