Transceivers are used to provide a modular networking environment. In this video, you’ll learn about Ethernet transceivers and the differences between SFP, SFP+, QSFP, and QSFP+.
Transceiver is a combination of two words– “transmitter” and “receiver.” And these are usually combined within the same piece of equipment or the same component. A transceiver allows for modularity. You may have a switch like this one. You can see there are a number of open interfaces in this switch. You slide in the transceiver that’s appropriate for the media or the network type that you would like to use. And now that particular interface will operate with that particular configuration.
So if you need a copper configuration for Gigabit Ethernet, you slide in a copper Gigabit Ethernet transceiver. Or if you need a fiber-based 10-gig connection, you slide in a 10-gig fiber transceiver. This means that you can have every interface on this switch have a different type of media, depending on what transceiver you are planning to use.
There are different types of transceivers, different form factors, and different transceivers depending on the media. For example, if you are using an Ethernet switch, you need an Ethernet transceiver. If you’re using a Fibre Channel switch, then you will need a Fibre Channel transceiver. You can’t use Fibre Channel transceivers in an Ethernet switch or vice versa.
This means you get to decide what media type works best for your configuration. If you need copper connections, you can use a copper transceiver. And if you need fiber connections, you can use a fiber transceiver. And if you need to change those connections midway through your installation, you can remove the copper transceiver and replace it with a fiber transceiver. This type of modularity often comes at an additional cost. But it does provide you with a way to plug into whatever network type you might need.
One common transceiver type is the SFP type. This stands for Small Form-factor Pluggable. For example, you can plug in a fiber SFP and connect your fiber connections to that particular transceiver. But if you needed copper, you could easily slide in a copper SFP and plug in your RJ45 connector.
SFP’s are commonly associated with Gigabit Ethernet. So that’s 1 gigabit per second. There is an enhanced version of SFP called Enhanced Small Form-factor Pluggable, or SFP+. They look identical in size to an SFP, but they support much higher speeds, up to 16 gigabits per second. So if you have a 10-gig connection, then you’re probably using SFP+.
When you’re installing equipment into a rack that’s in a data center, you have a limited amount of space available. First, the equipment is only 19 inches wide. And the total amount of space available in the rack is limited by the amount of space you have in the data center. So we want to be sure that we can put as much connectivity into a single space as possible.
To that end, we’ve created the QSFP, or the Quad Small Form-factor Pluggable. This effectively allows you to have four times the amount of throughput into a space that’s very similar to that of an SFP. For example, an SFP in this form would be a Quad Small Form-factor Pluggable, or QSFP, which consists of four channels of SFP. So if one SFP is a 1 gigabit per second connection, a Quad SFP would be compatible with a 4-gigabit throughput.
The same thing applies for the SFP+. There is a Quad SFP+ that is a four-channel SFP+. Since it’s common to see a 10-gigabit connection on a single SFP+, a Quad SFP+ can support four of those, for a total throughput of 40 gigabits per second. This is where we start to see a benefit not only in the amount of space that we’re using inside of these devices, but we can take a single fiber connection and effectively extend four separate links over that single fiber. There’s cost benefit there for equipment and for the media itself.
Although the names are very similar, the form factors are slightly different between an SFP and SFP+ and a Quad SFP or Quad SFP+. On the left is an SFP or SFP+. Both the SFP and SFP+ use the same form factor, although the transceivers are obviously very different. The Quad SFP or Quad SFP+ also share the same form factor. But you can see it’s slightly larger than the traditional SFP or SFP+. Although it is slightly larger than an SFP, it’s not four times the size of an SFP. So we are getting an efficiency in space by using a Quad SFP or Quad SFP+.