Siemens 6GK5991-4AC00-8AA0 SCALANCE X MM991-4LD 4x 100 Mbit/s BFOC Single-Mode 26 km Media Module

The Siemens 6GK5991-4AC00-8AA0 (MM991-4LD) is a SCALANCE X media module that adds four 100 Mbit/s BFOC optical ports for single-mode fiber. Each port covers a link of up to 26 km at 1310 nm, letting one media module fan a switch out to four long single-mode runs. It operates from 0 to 60 degrees C, weighs 0.3 kg, and latches into the media module slot.

Certifications & Standards

• CE
• C-Tick
• KC
• BV
• EPD

Selection Notes

The LD single-mode optics on the MM991-4LD push each of its four ports to 26 km, more than five times the 5 km reach of the multimode MM991-4 in the same family, so it is the module to specify when the switch cabinet is far from its neighbors rather than on the same plant floor. Because all four ports sit on one card, use it when four separate single-mode runs need to originate from a single switch slot; for a single long-haul link plus spare port budget on other slots, an individual single-mode SFP is the more flexible option. The identical mechanical footprint to the multimode MM991-4 means either can occupy the same media module slot without changing the switch configuration otherwise.