Study Notes

Regardless of what impact the deal has triggered in the marketplace over the past year, ultimately it’s about meeting market requirements. Instead, they want to be able to better and more easily manage their IT assets no matter what hardware or OS platforms.

If you make it through the CCNA and are still interested in Cisco and internetworking, you’re headed down a path to certain success. To learn every bit of the material covered in this book, you’ll have to apply yourself regularly, and discipline. Try to set aside the same time every day to study, and select a comfortable and quiet place to do so. If you work hard, you will be surprised at how quickly you learn this material. Arrive early at the exam center so you can relax and review your study materials.

Since there are a bunch of different types of devices specified at the different layers of the OSI model, it’s also very important to understand the many types of cables and connectors used for connecting all those devices to a networks.

Hub, also called multi-port repeater, does not segment a network; they just connect network segments together. MAC address, known as a hardware address, is burned right into the network card.

Switches aren’t used to create internetworks, they do not break up broadcast domain by default. They’re employed to add functionality to a network LAN. The main purpose of a switch is to make a LAN work better, to optimize its performance, providing more bandwidth for the LAN’s users. And switches don’t forward packets to other networks as routers. Instead, they only “switch” frames from one port to another within the switched network.

Switches create separate collision domains but a single broadcast domain.

Collision Domain: an Ethernet term used to describe a network scenario wherein one particular device sends a packet on a network segments, forcing every other device on that same segment to pay attention to it. At the same time, a different device tries to transmit, leading to a collision, after which both devices must retransmit, one at time. Not very efficient! This situation is typically found in a hub environment where each host segment connects to a Hub that represents only one collision domain and only one broadcast domain. By contrast, each and every port on a switch represents its own collision domain.

It’s also likely that at same point you’ll have to break up one large network into a bunch of smaller ones because user response will have dwindled to a show crawl as the network grew and grew. And with all that growth, your LAN’s traffic congestion has reached epic proportions. The answer to this is breaking up a really big network into a number of smaller ones. Something called “networking segmentation”, you do this by using device like routers, switches and bridges.

Two advantage of using routes: They don’t forward broadcast by default; They can filter the network based on Layer 3. Router function: Packet Switching/Filtering/Internetwork communication/Path selection.

Remember their routers are really switches, they’re actually what we call layer 3 switches. Switch is layer 2, switch frames.

Router, not only break up broadcast domains for every LAN interface, it will break up collision domains as well. Each port on that switch breaks up collision domains, but it’s not all good – all devices are still in the same broadcast domain. Do you remember why this can be really bad thing? Because all devices must listen to all broadcast transmitted, that’s why. And if your broadcast domains are too large, the users have less bandwidth and are required to process more broadcasts, and the network response time will slow to a level that could cause office riots.