Identify Collision Domains
In previous chapters, you gained a better understanding of switches and how they work. Let’s take this a little further.
Switches work with each other but also with other devices to prevent collisions and reduce network congestion:
A collision occurs when two packets are released at the same time on a network segment.
Network congestion (or increase in traffic) occurs when the network is slowed down drastically.
In traditional Ethernet segments based on a concentrator (more commonly known as a hub), network devices would compete for common resources. These network segments that share the same bandwidth between devices are known as collision domains. When two or more devices in the same collision domain attempt to communicate at the same time, a collision occurs. This is what used to happen when concentrators were used.
If a switch port is operating in half-duplex mode, each segment exists in its own collision domain.
If we take the agency’s network diagram, you can define the collision domains as follows:
Identify Broadcast Domains
A set of interconnected switches forms a single broadcast domain. Only a network layer device such as a router can split a layer 2 broadcast domain. Routers are used to segment broadcast domains but they can also segment collision domains.
If we take our network diagram, you can define the broadcast domains as follows:
When a switch receives a broadcast frame, it transfers it to all of its ports except for the port where it was received. Each device connected to the switch receives a copy of the broadcast frame and processes it.
The broadcast reduces the network’s efficiency. Also, the network bandwidth is used to transmit the broadcast traffic. A number of broadcasts and an overloaded network can result in congestion that slows down network performance. You need to realize that our broadcast domain is far too big. We need to resolve this!
Let's Recap!
In this chapter, you’ve seen:
that collision domains are packets conflicting with each other on a network segment.
that broadcast domains are network segments where any computer connected to the network can communicate directly with all other computers on the same LAN without needing to pass through a router.
Now that you know how to identify collision and broadcast domains, let’s see how we can use VLANs to reduce broadcast domains.
