SFP-10G-SR, LR and LRM modules - what are they really and what do they mean for your network? If you haven't spent time delving into the technical details of fiber optic technology and optical modules, these abbreviations may sound like a random set of letters without much meaning. However, there is a specific term behind each of these names: SR stands for “Short Range”, LR - “Long Range”, and LRM - “Long Range Multimode”. 

But does “short range” always mean limitations? Is “long range” a one-size-fits-all solution? What about networks that need to combine different technologies? The key to the answer lies in the technical details, which in this article we will translate into clear and practical guidelines to help you make the best decision.  

 

What is the SFP+ module and what is it used for?  

Before we go any further, we'll remind you what an SFP+ (Small Form-Factor Pluggable Plus) module actually is. In a nutshell, it's a compact fiber optic module designed to transmit data at speeds of up to 10 Gbps over Ethernet. In other words, an “adapter” between a fiber optic cable and a switch, enabling flexible connections between network devices. It is available on the market in various variants that differ in range, cabling type and purpose - the most popular types of these modules are SFP+ SR, LR, LRM and SFP+ BIDi (single fiber).

 

What is the difference between SR, LR and LRM SFP? 

  1. SFP-10G-SR (Short Range) 
  • Range: Up to 300 m on multimode fibers (OM3) or 400 m (OM4). 
  • Application: Short-distance connections, mainly in data centers and campus networks. 
  • Number of fibers needed to transmit the signal: 2 fibers (duplex)

 

  1. SFP-10G-LR (Long Range) 
  • Range: Up to 10 km or 20 km on singlemode fibers. 
  • Application: Links over longer distances, such as between buildings or in urban networks. 
  • Number of fibers needed to transmit the signal: 2 fibers (duplex)

 

  1. SFP-10G-LRM (Long Range Multimode) 
  • Range: The SFP-10G-LRM module can be used with both multi-mode fiber (MMF) and single-mode fiber (SMF). On multimode fibers, depending on cabling, the range can be from 100m (OM1) to 220m (OM3), while on SMF it can be up to 300m.  
  • Application: Upgrade multi-mode networks without replacing cabling. 
  • Number of fibers needed to transmit the signal: 2 fibers (duplex)

 

  1. SFP-10G-BiDi (WDM)  
  • Range: Up to 10 km or 20 km on singlemode fibers. 
  • Application: Links over longer distances, such as between buildings or in urban networks. These modules are chosen in situations where fiber needs to be spared, the number of fibers is insufficient, or the cost of leasing them is involved. 
  • Number of fibers needed to transmit the signal: 1 fiber (simplex)

 

This can be summarized in a table: 

 

SFP-10G-SR 

SFP-10G-LR 

SFP-10G-LRM 

Type of fiber 

Multimode (MMF) 

Singlemode (SMF) 

Multimode (MMF)/singlemode (SMF) 

Waveleght

850 nm 

1310 nm 

1310 nm 

Range

Up to 300-400 m (OM3/OM4) 

Up to 33m (OM1/OM2) 

Up to 10 km (SMF) 

Up to 220 m (OM3), up to 300 m (SMF) 

Up to 220m (OM1/OM2) 

Application 

Short connections

Building-to-building connections 

Upgrading older networks

 

How to choose the right module? 

Your choice depends on the specific needs of your network: 

  1. Short distances: SFP-10G-SR modules are the best choice in data centers, offering low cost and high performance on multimode fiber 
  2. Long distances: SFP-10G-LR provides reliability on single-mode fiber, chosen most often for longer distance connections such as between buildings or on campuses.
  3. Network Modernization: the SFP-10G-LRM allows for 10G deployment using existing MMF cables. 
  4. Fiber Saving: SFP-10G-BiDi - single-mode 1-wire, selected in situations where fiber saving is necessary. 

 

Looking for something for longer distances? A few words about SFP+ ER, ZR and ZR+ 

In situations where standard modules are not enough, advanced solutions come into play: 

  • SFP-10G-ER: Range up to 40 km on single-mode fiber. Ideal for sprawling campuses or data centers. 
  • SFP-10G-ZR: It offers transmission up to 80 kilometers, making it ideal for metropolitan area networks (MANs). 
  • SFP-10G-ZR+: An even more advanced module, providing a range of up to 120 km with improved dispersion management. 

These modules are rarely used in standard corporate networks, but are indispensable in telecommunications and for Internet service providers. 

 

Clearing up doubts, or FAQ

Can I use the SFP-10G-SR module with single-mode fiber? 

No, the SFP-10G-SR module is designed to work with multimode fiber (MMF) and is not optimal for use with single-mode fiber (SMF). Purely theoretically it can be combined, but in practice the signal will be so weak as to be undetectable. Definitely not a recommended solution. 

 

Will the SFP-10G-LR work with multimode fiber optics? 

No, the SFP-10G-LR is not compatible with multimode fibers. It operates only on single-mode fiber (SMF), offering a range of up to 10 km. 

 

What does LRM stand for and how does it differ from LR and SR? 

LRM is Long Range Multimode, a module that runs on multimode fiber, offering longer range than SR, but less than LR, which uses single-mode fiber.