Hey I'm Clint Garrett (Ace Networker)! What is a multi-layer switch? We've heard about and used
plenty of Layer 2 switches in computer networks all over the world but now we're
starting to hear the term "multi-layer" switch and this may be somewhat confusing
when you first hear the term. So let's first look once more at what a Layer 2 switch does
and its functions. We'll revamp the big points about all the other switch videos in this series,
then we'll look at a Layer 3 and Layer 4 switch and how they each differ. Coming up!
So what is a multi-layer switch? We know that a Layer 2 switch performs fast switch functions
of forwarding and separating traffic based on its configuration settings (again, those given to it
by you as the admin, technician or engineer) and it forwards that traffic using ASICs (Application
Specific Integrated Circuits) which are hardware integrated chip circuits that are really efficient
at forwarding and doing the job a switch needs to do on a network. When we hear the term "Layer"
in front of a number on a switch 99 percent of the time (in fact most of the time) it's referring
to the layer in the OSI Model that it handles and deals with. If you haven't watched it yet,
I recommend this video showing what the OSI Model is and why it needs to be studied and known.
So a Layer 2 switch deals with the Data Link Layer of the OSI Model Layer 2 and it forwards traffic
again using the ASIC hardware. It forwards traffic based on Destination and Source MAC addresses
in each frame received from the rest of the network. Now different technology building
companies that build network hardware and software components have begun developing
multi-layer switches for use. This leads us to the Layer 3 switch. Now a Layer 3 switch still uses
fast switching with ASICs but it can also perform similar routing functions similar to an actual
router. This is important because on many Layer 3 switches in networks and environments where they
can be used they can perform a Layer 3 routing function or functions much faster than an actual
router because a router uses software to route traffic. The biggest differences
between a Layer 3 switch and a router is that a Layer 3 switch uses hardware to forward and
route traffic with those ASIC chips and a router uses software. A Layer 3 switch can often contain
more physical ports for connectivity of cables and or devices than a router can and a layer 3 switch
in most cases is unable to route between different types of cables whereas an actual router can more
often route between different types of cables or connections. On a Layer 2 or Layer 3 switch,
you typically have to have all or most connections to it running using ethernet. But a router can
actually route and connect between ethernet and other types of technologies and protocols.
So those are the primary differences between Layer 2 Layer 3 switches and routers. But Layer
3 switches aren't the only multi-layer switches on the market. Now there are Layer 4 switches which
can actually load balance by sending traffic to one or many servers that perform the same function
for replication, and there's now actually a Layer 7 switch that can read and route traffic based on
Layer 7 or the application layer traffic (things like FTP, HTTP, etc.) Also you'll see more of
these on the market but there's a Layer 4-7 switch that can or sometimes they just call it a 4 7
switch that can load balance between multiple servers and look at application layer data.
Also so some are all of these may be required for you to know on the Network+ exam. But it's
really a good idea to know them anyway because as technology advances you'll see more and more
of these multi-layer switches being used in more and more networks around the planet.