10GBASE-SR SFP+ Transceivers

Reach by fiber grade

The grade of multimode fiber in the wall sets how far an SR link runs. Cisco's 10GBASE SFP+ data sheet gives these lengths for its SR module at 850 nm:

Cisco also sets a 2 m minimum cable length for SR modules. Single-mode runs need LR optics, which are on the optical transceivers page with every other standard.

10GBASE-SR, LR, ER and ZR

SR is the short-reach, multimode member of the 10G SFP+ family; LR, ER and ZR use single-mode fiber for longer runs. Cisco's 10GBASE SFP+ data sheet lists the four:

Versions of the same standard

One SR standard comes in several builds. Cisco rates its modules for commercial (0 to 70 C), extended (-5 to 85 C) or industrial (-40 to 85 C) temperatures, sells an extended-temperature multirate SR module, and offers S-class modules without FCoE support. All of them use duplex LC/PC connectors, and Cisco does not support APC-polished patch cords; plan OM3 or OM4 duplex LC patch cords for the run. Cisco lists digital optical monitoring among the module features, so a switch can read the optic's light levels and temperature.

Match the coding to the port

Switches and NICs read an optic's coding: Cisco documents a Quality ID check that tells a Cisco switch whether an installed module has been certified and tested by Cisco. Order the coding of the device the optic plugs into, because each platform reads its own part numbers, and note that Cisco's S-class 10GBASE-SR module does not support FCoE.

Inside a rack, direct-attach cables replace a pair of optics. These modules fit 10GbE network adapters with SFP+ cages, 10GbE switches, and Cisco and Juniper switches. Neighbouring speeds: 1G SFP transceivers and 40G QSFP+. Each optic is sold with an Enterasource warranty; its listing gives the term.

10GBASE-SR questions

How far does 10GBASE-SR reach on OM3 and OM4?

300 m on OM3 and 400 m on OM4, per Cisco's 10GBASE SFP+ data sheet, with a 2 m minimum cable length. Older fiber shortens the link sharply: 82 m on OM2 and 33 m on OM1. For runs beyond 400 m, move to 10GBASE-LR on single-mode fiber, which reaches 10 km.

What is the difference between 10GBASE-SR and 10GBASE-LR?

The fiber and the distance. 10GBASE-SR transmits at 850 nm over multimode fiber, up to 400 m on OM4; 10GBASE-LR transmits at 1310 nm over single-mode fiber, up to 10 km. Both use duplex LC connectors and fit the same SFP+ ports, but the two ends of a link must match, so an SR optic cannot talk to an LR optic.

Will a 10GBASE-SR optic work in any SFP+ port?

It fits any SFP+ cage, but the device must accept its coding. Cisco switches run a Quality ID check on installed modules, and other platforms read their own part numbers, so order the coding of the switch or NIC it plugs into. Some uses are restricted by version too: Cisco's S-class SR module does not support FCoE.