SFP-10G-SR and SFP-10G-LR: What's the Difference? SFP FAQs Answered

18 Oct.,2022


sfp manufacturers

The SFP and SFP+ formats are a wonderful invention, allowing a single piece of hardware - like a switch or firewall - to accommodate a wide variety of cable and connection types, simply by swapping out the connector being used.  Unfortunately, this also means that finding the right SFP/SFP+ transceiver for your application can sometimes be confusing and difficult, because of just how many connection types exist.

We tend to get a lot of questions about various types of Cisco-compatible 10g SFP+ transceivers, the differences between them, and which to use.  While not totally comprehensive, we wanted to address some of the most common inquiries we get about these popular and widely-used transceivers.

Answering Your Common Questions About Cisco SFP Transceivers

1 -How are single-mode and multi-mode fiber different?

The primary difference is how light is transmitted through the two fiber types.  Single-mode uses a single relatively straight beam of light, transmitted directly through a core of glass (or occasionally plastic) that's usually 50 microns across.  Single-mode accommodates large power levels, and is almost exclusively used for Long Range (LR) applications.

Multi-mode cable is more complex.  It utilizes multiple beams, which bounce diagonally throughout a somewhat larger (62.5 micron) core.  The beams are then collected at the receiving end and recombined.  This allows multi-mode to achieve high speeds at a lower power use -and usually slightly lower cost- but the nature of the format means that interference and signal degrading become an issue in longer cables.   So multi-mode is generally used for Short Reach (SR) applications.

2 - What's the difference between SFP-10G-SR and SFP-10G-LR?

This one is actually pretty easy.  SR stands for Short Reach, and LR stands for Long Reach.  SR transceivers are almost always multi-mode, and optimized for high speeds over relatively short distances.  However, the much higher-powered OM3 and OM4 formats can push that into the hundreds of meters for a single cable.

LR transceivers are designed for long-range communications, such as wiring buildings together on a large campus or even setting up a Metro Area Network (MAN).  They can be either multi-mode or single-mode, and are almost always intended for 100m+ applications.  Higher end cables and transceivers can support transmissions of several kilometers.

3 - What are SFP-10G-ER and SFP-10G-ZR?

Basically, these are just extremely long-range fiber variations.  ER stands for Extended Reach, and can achieve transmission distances of up to 40km over single-mode fiber.

ZR is actually an unofficial format, which is not technically part of the IEEE 802.3ae standards for networking hardware.  It pushes the range of single-mode ER fiber out to 80km, or about 50 miles.  Several hardware manufacturers -including Cisco- have their own implementations of ZR, but they aren't necessarily cross-compatible.  

4 - What does -X signify, as in 
SFP-10G-LR-X or SFP-10G-SR-X?

Whenever you see -X, that means it has extended ability to operate under wider temperature variation, from -40°C to 85°C (-40°F to 365°F).  There is no other significant difference from the standard versions, and no reason to use -X equipment unless you're operating in extreme temperatures.

By comparison, standard transceivers are generally restricted to operating temperatures from about 0°C to 70°C (32°F to 158°F).

3 - What are Cisco "S-Class" transceivers and how are they different?

"S-Class" is a somewhat confusing standard Cisco introduced a couple years ago.  It could be seen as the "budget" standard - it costs significantly less than other multigigabit SFP+ standards, but also has a reduced feature set.  The idea was to create transceivers that only incorporated the features most commonly seen in enterprise and data center applications.

Basically, S-Class:

  • Only supports Ethernet,
  • Does not support Optical Transfer Network (OTN) or Wide Area Network Physics (WAN-PHY) standards,
  • Has reduced temperature tolerances, and
  • Is not necessarily TAA (Trade Agreements Act) compliant.

Aside from these differences, an S-Class transceiver is identical to the equivalent non S-Class variation.  So, for most standard applications, S-Class is fine and will save some money compared to other Cisco transceivers.

Of course, Cisco-brand transceivers will cost you a lot in any case, and unnecessarily so...

Turn To Hummingbird Networks For Your Transceiver Needs

Choose Hummingbird Networks and save money!  Our own Hummingbird-brand transceivers are 100% compatible and truly no different aside from the name on the casing.  How do we do it?  Because other name-brand transceivers are incredibly overpriced, relative to production costs.  It truly is that simple.

To learn more about Hummingbird Networks brand transceivers, or for a deeper consultation on your specific transceiver needs, just contact us!