Cisco - CCNA Certification 200-301 - Unicast, Multicast and Broadcast .09

Ninth Video in a Series covering all elements of Cisco Certified Network Associate (200-301 CCNA)
We start by ensuring we understand the different between unicast, multicast and Broadcast

Unicast - One to One
Multicast - One to Many
Broadcast - One to all

Then start by talking about a Broadcast domain. We use an example of a broadcast message to understand how far that message will travel within the network (broadcast domain). We now know broadcast messages are stopped by routers or can be split up further using VLANs

After broadcast domains we move into Collision domains. We said, every switch port is its own collision domain whereas with hubs, all their ports are within a single collision domain

After understand Collision domains and the problems caused by multiple devices sharing the same medium we jumped into CSMA/CD how understand how Ethernet combats multiple devices trying to send on a shared medium

CSMA/CD = Carrier sense multiple access collision detect

CS = Carrier sense, PC/host has to perform 'Carrier sense' to determine if anyone is talking and if the wire is free to send traffic

MA = Multiple access, Ethernet is called a multiple access medium simply because the original design was for a Bus topology to which everyone connected to the same think coax cable

CD = Collision detection, While transmitting data it's possible another host may start transmitting at the same time, as when they both waited at the carrier sense, they both thought the wire was clear. If a collision occurs during the transmission. The host will send a 'Jam' signal to everyone on the collision domain asking everyone to be quiet. The transmission station will then goes through a Random back off (timer) and perform carrier sense before transmitting again. This is why you should not have too many devices on a single Ethernet segment. Also to note every time a collisions occur the back off timer will get bigger. Ethernet will try and put data on the wire around 16 times and eventually give up.

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Don't forget to check out the free CCNA course itself, it covers everything required to pass your CCNA 200-301 exam


Full course: https://tinyurl.com/yah4k49x


 📚Books! 🎓🎓

CCNA 200-301 Official Cert Guide - https://amzn.to/2V1qeGk

My fav books:
Routing TCP/IP Volume I (CCIE Professional Development): Authorized CCIE Preparation: v. 1 - https://amzn.to/2LEGLgx

Routing TCP/IP (CCIE Professional Development): Volume 2 - https://amzn.to/2VgobuB

Learn all about TCP: - https://amzn.to/2JyHY6s
Another great TCP book - https://amzn.to/2EfO0ph

📚Books 🎓🎓

How to Study for an exam
Study for the CCNA
Tips and tricks for the CCNA
CCNA 200-301 Training
CCNA 200-301 Study
CCNA 200-301 Tutorials
CCNA 200-301 Full Course

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