Network Transceivers – CompTIA Network+ N10-007 – 2.1

Transceivers can provide options when connecting infrastructure equipment to the network. In this video, you’ll learn about transceiver technology, duplex and bi-directional transceivers, GBICs, SFP/SFP+, and QSFP transceivers.

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A transceiver is a device that is both a transmitter and a receiver, and usually it’s in a single device. This is commonly used in networking as a modular network interface. For example, you can see on this switch, I have interfaces that are here in copper for these two RJ-45s, but you also have the option to plug-in a transceiver that can be used for additional interfaces on the switch.

This would allow you to connect this switch with fiber connections, and they could be single mode fiber or multi-mode fiber, but you can choose exactly the type of interface you need using these transceivers. A traditional transceiver provides us with duplex communication, because there are two interfaces for two fibers on this particular transceiver. One of these connectors might be for transmit, and the other fiber coming in would be for receive.

But of course, fiber is relatively expensive to run, and of course, we have a limited number of interfaces on our networking equipment. That’s why some of your networking equipment may be able to support bi-directional transceivers or BiDi transceivers. These bidirectional transceivers allow you to transmit and receive over a single strand of fiber. So this effectively doubles the amount of use that you have for the fibers in your infrastructure. It’s using two different wavelengths to complete this, so you don’t have to run twice as much fiber. Instead you can use a bidirectional transceiver.

One of the earlier transceiver standards was created for gigabit networks, and this was the GBIC or the Gigabit Interface Converter. You can see the GBIC is right here next to this USB key, and it usually is connected with something like an SC connector on to the GBIC itself. These are commonly used on gigabit networks and fiber channel networks, but they are relatively large compared to some of the newer styles of transceivers.

Here’s a GBIC that’s being used with SC connectors in this gigabit Ethernet switch. You can simply slide the GBIC into an open slot, connect your fiber, and now you’ve got a fiber connection using this modular transceiver manufacturers soon found that they could perform similar functions using a much smaller transceiver, and this was the SFP or the small form factor pluggable.

The SFP you can see is a lot smaller than the older style GBIC. These are commonly used for one gig fiber connections. They’re also one gig copper connections that you can get instead of having a fiber connector at the end of this. We commonly associate transceivers with fiber connections, but you can also get transceivers that have RJ-45 copper connectors on there as well.

As our technology’s move towards 10 gig networking, we improve the technology by creating the enhanced small form factor pluggable or SFP plus. It looks and has exactly the same form factor as the older style SFP, but you’re able to support much higher data rates through these newer style transceivers. For very high speed networking, you may want to look into using a QSFP or quad small form factor pluggable. These effectively are four SFPs put into a single transceiver.

That means a four-channel SFP can support four 1 gig connections, and for higher speeds we could use a SFP for four-channel SFP plus. This would be four 10 gig connections or 40 gigabit per second through a single transceiver. By combining what would effectively be four individual transceivers into a single transceiver, we’re not only saving money on fiber, but we’re also saving money on the amount of equipment that we would need to support.

And when you combine the bidirectional features available in these transceivers, you can support very high speeds over a single strand of fiber optic. Here’s the form factor for all of these transceivers if we’re looking at it from the side that would plug into our networking equipment. So here’s the GBIC connector that would plug into the inside of our switch and the fiber that would plug into the outside. The SFP, you can see much smaller, and the quad SFP, which is really only a little bit larger than the SFP, but effectively can provide four times the functionality of the traditional SFP.