1. ETHERNET DEVICES
-BY MUJTABA FARAZ

2. OBJECTIVES CSMA/CD Algorithm Hubs Bridges Ether Switches
Working of Ethernet switches

3. CSMA/CD Algorithm Working of CSMA/CD:
CSMA/CD logic helps to prevent collisions and also defines how to act when a collision does occur.
Working of CSMA/CD:
Step 1: A device with a frame to send listens until the Ethernet is not busy
Step 2: When the Ethernet is not busy the sender(s) begin sending the frame
Step 3: The sender(s) listen to make sure that no collision occurred
Step 4: If a collision occurs, the devices that had been sending a frame each send a jamming signal to ensure that all stations recognize the collision
Step 5: After the jamming is complete, each sender randomizes a timer and waits that long before trying to resend the collided frame
Step6: When each random timer expires, the process starts over with step 1

4. Draw Backs of CSMA/CD:
It does not prevent collision rather it ensures that the Ethernet works well even though collision occurs
Only one device can send frame at any one instant of time
The logic of waiting to send a frame until a LAN is silent makes the Ethernet half duplex
Random timing after the jamming signal effects the speed of the Ethernet

5. HUBS
Hubs are also known as repeaters with multiple physical ports
Hubs regenerates the electrical signal that comes in one port and sends the same signal out every other ports
Hubs has one Collision and broadcast domain
Draw Backs of Hub:
High collision rate
Overall Network Performance is low
Not efficient for big network

6. Network Bridges Bridges are intelligent devices
They have the ability to learn MAC addresses
Bridges divides the network into multiple collision domains
Draw backs:
Bridges are slow devices
Separate software is used learning the MAC address

8. SWITCHES Ethernet switches eliminates the collisions in the network
Each port of a switch is one collision domain
Communication in a switch is full duplex
High Speed Communication

9. How Does Switch..Switches