Guide to Optical Transceiver Standards

Transceiver part codes are typically made up of a set of technical and logical factors related to the specific optical transceiver. Often they start with the form factor of the transceiver for example, SFP, QSFP, etc. One key defining set of letters in the part code is defined by the transceiver standard the module is set to. A number of standards have been defined which refer to the transmission range.

These are designated by letters at the end of the optical transceiver description. For example: 10G SFP+ CWDM LR, where in this case “LR” refers to “Long Range”, and in the case of this transceiver the maximum distance it can transmit over is 10 km at a data rate of 10G.

There are a range of different acronyms, and the ones we’ll be taking a look at are the most commonly seen.

1G Transceivers specific standards

Standards for transceivers with a data rate of up to 1G were set by IEEE, and include:

SX, FX, LX, EX, ZX

SX- Short Wavelength – these transceivers are optimized for transmission via multimode fiber (MMF) via the 850 nm wavelength over short distances of up to 550 meters and are used in LAN and data center applications.

FX – Fast Ethernet – refers to an Ethernet network standard, with transceivers designed to operate at 100Mbps over short distances in local area networks.

LX – Long Wavelength – operating in the long wavelength range of 1310 nm over singlemode fiber, LX transceivers can typically support a reach of up to 10 km and are used in a wide range of network environments, including data centers. Enterprise networks and telecommunications.

EX – Extended Wavelength – EX transceivers operate at different wavelengths over singlemode fiber and the standard varies among different vendors, typically they use the 1310 nm wavelength and are able to translmit up to 40 km.

ZX – Also known as “Extended Wavelength” – are optimized for transmission via singlemode fiber at 1550 nm over long-distances up to 80 km and are used in long-haul telecoms networks, metropolitan areas, etc.

Standards for High Speed Transceiver Ranges

The acronyms: SR, LR, ER, FR, DR, LRM and ZR/ZR+ refer to the distances reached by high-speed transceivers. The designations SR, LR and ER were defined by the IEEE, whereas DR and FR where defined by the MSA group of vendors to ensure compatibility.

In a similar way to the designations for SFP transceivers, SR refers to short range transceivers, LR is long reach, while ER and ZR refer to extended reach transceivers.

SR – Short Range – designed for short-distance transmissions of up to 550 meters (OM2) and 300 meters (OM3/OM4) over multimode fiber on the 850 nm wavelength, these transceivers are ideal intra-rack or intra-datacenter where low-latency and high bandwidth are called for.

SR4 – Short Range 4 channel – mostly used in 40G and 100G applications with a maximum range of 100 meters over multimode fiber(?) at 850 nm.

SR8 – Short Range 8 channel – these transceivers support 8 x 50G channels resulting in a data rate of 400G on OM4 multimode fiber. With a range of up to 100 meters they are used in data center applications, cloud computing and for big data.

LR – Long Range Transceivers – are optimized for longer distances from 10 km to 40 km over singlemode fiber using the 1310 nm wavelength and are used for inter-rack connections and connecting between buildings and across metropolitan areas.

LR4 – Long Range 4 Channels – transceivers designed for distances up to 10 km. The transceiver converts 4 x 25 G channels into optical signals to be sent over a single 100G fiber.

LR4-20 – long range transceivers transmit 4 x 25G channels over 100G singlemode fiber up to 20 kilometers.

LR8 – Long Range 8 Channels – these transceivers are dsigned to transmit 8 x 50G channels with a combined data rate of 400G over singlemode fiber up to 10 km.

ER – Extended Range – transceivers are designed for distances beyond those of LR transceivers. ER transceivers can cover distances of between 40 km and 8 km over single mode fiber on the 1550 nm wavelength. Used in applications such as metro networks and long-haul telecommunications, they support data rates from 40G to 100G.

ER4 – these transceiver modules transmit to distances of up to 40 km via single mode fiber using DWDM on 4 channels (1295 nm, 1300 nm, 1305 nm, 1310 nm).

ER8 – extended reach transceiver modules are designed for transmitting 400G to a distance of up to 40 km over dual single mode fiber using 8 x 50G channels.

ZR/ZR+ – ZR stands for “Zero Dispersion Shifted Range” designed for long-distance connections up to 80 km (ZR+) between cities and different regions at 100G. Some of the latest transceivers, such as the 400G QSFP-DD ZR+ have a range of up to 480 km.

Other designations you might come across are:

DR – Double Reach – which are transceivers capable of supporting both short and long-range distances in a single transceiver module. They provide flexible and cost-effective solutions for network expansion and optimization where a single type of transceiver can be deployed across the network. Available for data rates of between 10G and 400G (DR4).

FR – Far Reach – transceivers are optimized for longer distances than LR transceivers for ranges of 100 km to several hundred kilometers over single-mode. They are suited to long-haul telecommunications and other applications over vast distances.

Other transceiver standards are available, so if in doubt, check out the transceivers on our portal, or our quick reference chart download >