So…this post is not meant to dwell on the technical side of switches but there will be concepts you need to understand to realise the differences between the various switches available. So lets go!!!
Firstly lets discuss the layers involved….no not your favourite cake but something much more exciting! The OSI model (Open Systems Interconnection), there are 7 layers in this model but we will be concerned with the first 3 layers. Please stay awake for this, it is essential knowledge for this post to make a difference in your life!
Layer 1: The physical layer is concerned with the electrical and physical properties of the switch and how it sends it packets.
Layer 2: The data layer is concerned with sending packets according to the Media Access Control (MAC) address involved.
Layer 3: The network layer is concerned with sending data using the Internet protocol (IP) address involved
Now lets try briefly go through the switches available
Layer 1 switches or hubs:
These switches rely on their physical properties to switch packets between ports. For example if we had a 5 port switch and a packet was sent from port 1 to port 3 about its horrid social life….port 2, 4 and 5 would recieve this packet as well. Packets are broadcasted to all ports regardless of there only being one recipient. The switch is not intelligent enough to know who actually needs the packet. The disadvantage is there are many packet collisions because all the ports are sending packets to every other port and not everyone wants to know about your social life!!!! This is why you would use this switch for small networks that have low bandwidth requirements.
Layer 2 Websmart switches:
Here the first step towards moon walking begins…these switches build up a table of mac addresses and record which port is connected to each address. It will then send a packet only to the port that is affiliated with that MAC address since it can identify packets according to the MAC address unlike its dumb little brother, the hub. Websmart switches allow you to login via an IP address and offer a web user interface. Due to the reduced collisions, packet switching becomes much faster and is a perfect solution for single small to medium networks with high bandwidth requirements.
Layer 2 Managed switches:
These switches operate on the same switching protocol but they offer a few more features in terms of error reporting and remote configuration. They would typically use Simple Networking Management Protocol (SNMP) which is a network monitoring and reporting protocol and allow telnet or command line based interface. Some switches would also offer a console port allowing a technician to still access the switch even if it becomes corrupt. The console port allows access to the root to enabling you to attempt to restore the switch.
Layer 3 Managed Switches:
Have you gotten this far? Well done, we have just landed on the moon…Layer 3 is a step up on the rest because it now enables you to route packets based on their IP addresses. You can now create multiple VLAN’s or subnets and link them using one switch. The layer 3 switch will enable communication between these logical network clusters. This is perfect for medium to large networks with high bandwidth requirements using many subnets and VLANs. The error reporting tools and the console port still apply here, they will obviously be more advanced.
What is a Subnet?
Within a network you can have groups of nodes and one way of grouping is subnetting which is based on the IP address
What is a VLAN?
Another way of segmenting a network is using a VLAN, this is according to the MAC address instead
Back to layer 3 switches!!! Imagine a layer 3 switch as a router with lots and lots of ports….mikrotik 1100AH2 ring any bells? Exactly the same idea but a switch dedicated to layer 3 switching will be much easier to configure since its functionality is focused on switching and routing only.
Lastly due to large networks needing switching systems that are centrally managed and are able to expand readily, 2 technologies have stormed in to save the day!!!!!
Imagine you had a 24 port layer 3 switch and….you wanted another 24 ports but you do not want to add another IP address to manage? Well a stackable solution may solve you problem! These switches allow one to stack switches with a backbone linking them. Once assembled together they behave as one switch.
Advantage: Brilliant if you want 72 ports in one room!
Disadvantage: Not so brilliant if you want the same solution but with switches spread out in a building.
This is where you will seek a Clustered Switch:
“One small hub for man or one giant centrally managed layer 3 switch for mankind” Clustered switches offer the same functionality as a stacked switch but now you can give one switch to marketing, one to accounting and another to logistics. Thereafter once they are all in synch, you can access them all via one IP address!!!
Gents! Imagine having many wives all over South Africa with one number to contact all of them! Alright this may not be practical here but in relation to switches they can offer flexibility and central management.
Now….based on this, are you using the right switch?