Hubs, Switches and Routers

What are Hubs, Switches and Routers?

We have talked about the Network Devices before. Now, let’s go deeply with some of the important ones: Hubs, Switches and Routers. Here, we will focus on Ethernet Hub vs Switch vs Router. We will learn the main similarities and the differences of these three basic Network Equipment. Let’s start.

 

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What is a Hub?

Ethernet Hubs are the network devices that works at Layer 1. They are not smart devices. They do not make any decisions on traffic. Hubs only provide extra ports and they expand the network with these ports.

 

There are two types of Hubs:

• Passive Hub
• Active Hub

 

Passive Hubs are only provide network expansion and extra ports. Basically it is only a medium. But Active Hubs provide network expansion also. Beside, they strenght the signals.

Hubs divides the network bandwith according to the hub ports. They are half duplex devices. Whole Hub is one collision domain. So at the same time only one port can communicate. If other one tries to communicate, then collision occurs.

The whole the Hub is one broadcast domain. So when a packet is sent to one node to another, all the nodes receive that traffic.

 

In large networks, hubs are not used. The area of Hubs are small networks. They are the basic network building equipment. So, they are cheap devices.

 

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What is a Switch?

Switches are the smart network devices that works at Layer 2 generally. But there are also Multi Layer Switches that work on multiple layers, Layer 2, Layer 3 and Layer 4. Basically, they have many ports on them to expand the network and they can be used for network expansion.

Switch is a Full Duplex device. Each of the ports of the switch is one collision domain. So, all port are communicate independantly.

 

And the whole Switch is one broadcast domain. Without any VLAN configuration, all switch ports are in the same network. So if you send traffic from a port to another port, all the pors can see this.If you use VLANs, then, each VLAN become a separate Broadcast Domain.

Switches are smart devices and. Switches collects information about the network and then do switching according to this information. These information is ports and MAC address of connected devices. They store this information in CAM tables.

 

So, how does Switching occurs? When a traffic come to a switch, the source port of this traffic and the source MAC address is writen in the CAM table of the switch.Then, switch sends the traffic to all of its ports, this is called “flooding”.

 

All of the ports and MACs are writen to the CAM table via such attempts. A packet comes and its information is recorded. And the next time, bacause of the fact that switch has this information in CAM Table, switch do the swicthing without flooding.

 

Switches uses hardware to forward the packets. Multi layer swicthes uses ASICs(Application Specific Integrated Circuits).

 

Layer 2 Switches works on LAN. But Multi Layer switches can work on WAN also.

 

According to the switch types, the switch prices are very different. Layer 2 switches are cheaper but there are many expensive Multi Layer Switches that operate in different Service Providers network.

 

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What is a Router?

Routers are the most important and smart devices in computer networks. They are smart devices that work on Layer 3. They uses IP addresses and do routing between different networks. Basically they are the devices that connects different networks.

Each of the port of the router is one network, so it is also one broadcast domain. And each of these ports are one collision domain.

 

Routers calculate routes to different networks with their mechanisms. They store this information in Routing Tables and they make the route decision according to these route tables.

 

So, how does Routing occurs? IP addresses are the addresses of Layer 3. Routers uses these IP addresses. They use Static Routing or Dynamic Routing with different Routing Protocols to determine Routing Paths. They calculate the paths according to these parameters and then stores in the Routing Tables and Forwarding Tables. So, whenever a packet is sent, they sent the packet according to this information.

 

Routers works on both LAN and WAN. Beside LAN support, they support different WAN technologies with different interface card and port types.

 

Routers are very expensive devices. According to their capability, this rance can change. There are many very expensive routers are used in different Service Provider networks. Here, are talking about very large and high capacity routers that the ones you use in your houses.

 

In this article, we have learned basic network devices. And we have compared their characteristics as Ethernet Hub vs Switch vs Router.