A Brief Introduction to Cisco Single-Mode SFP Modules


Small form-factor pluggable (SFP) module is a hot-pluggable interface transceiver which links switches and routers to network. These small, modular optical interface transceivers offer a convenient and cost effective solution for the adoption of Gigabit Ethernet and Fibre Channel in data center. Cisco’s industry-standard SFPs can be used and interchanged on a wide variety of Cisco products and can be intermixed in combinations of IEEE 802.3z compliant 1000BaseSX, 1000BaseLX/LH, or 1000BaseZX interfaces on a port-by-port basis. Cisco SFP modules are commonly available in several different types: 1000BASE-T, 1000BASE-SX, 1000BASE-LX/LH, 1000BASE-EX, 1000BASE-ZX, and 1000BASE-BX-D/U. This post will give an introduction to Cisco single-mode SFP modules.

Cisco 1G single-mode SFP

Cisco 1G Single-Mode SFP Modules

Cisco 1G single-mode SFP modules consist of 1000BASE-LX/LH, 1000BASE-EX, 1000BASE-ZX, 1000BASE-BX-U, 1000BASE-BX-D, GLC-BX40-D-I, GLC-BX40-DA-I, GLC-BX40-U-I, GLC-BX80-D-I, and GLC-BX80-U-I. The 1000BASE-LX/LH SFP is compatible with the IEEE 802.3z 1000BASE-LX standard, functions on single-mode fiber-optic link and its transmission range can cover 550 m to 10 km on any multimode fibers. 1000BASE-EX SFP functions on standard single-mode fiber-optic link with spanning up to 40 km in length. 1000BASE-ZX SFP functions on standard single-mode fiber-optic link and its transmission range reaches approximately 70 km in length.

The 1000BASE-BX-D and 1000BASE-BX-U SFPs which are compatible with the IEEE 802.3ah 1000BASE-BX10-D and 1000BASE-BX10-U standards function on a single strand of standard SMF (Single-Mode Fiber) and its operating transmission range covers up to 10 km. The Cisco GLC-BX40-D-I, GLC-BX40-DA-I, and GLC-BX40-U-I SFPs also operate on a single strand of standard SMF and its transmission range can reach 40 km. A GLC-BX80-D-I and GLC-BX80-U-I device function on a single strand of standard SMF with an operating transmission range up to 80 km.

Another difference between these SFP modules is the transmission direction: 1000BASE-LX/LH, 1000BASE-EX and 1000BASE-ZX’ transmission is duplex while 1000BASE-BX-U, 1000BASE-BX-D, GLC-BX40-D-I, GLC-BX40-DA-I, GLC-BX40-U-I, GLC-BX80-D-I, and GLC-BX80-U-I’s transmission is simplex. One thing they have in common is that all these Cisco single-mode SFP modules adopt LC interfaces and Cisco SFP 1G transceivers can transmit optical signals through simplex or duplex LC patch cable.

Transmission of a Single Strand of SMF

Features and Benefits

Cisco single-mode SFP modules feature a variety of different types of modules supporting different transmission ranges and direction, and they are also compatible with products of other categories. The hot-swappable input/output device directly plugs into an Ethernet SFP port of a Cisco switch, which maximizes uptime and simplifies serviceability when installing or replacing. The robust design enhances capability and the small factor features great density per chassis. Its flexibility of media and interface choice on a port-by-port basis bring you convenience. “Pay as you Populate” model lowers initial costs. It can support digital optical monitoring (DOM) capability for strong diagnostic capabilities. Cisco quality identification (ID) feature enables a Cisco platform to identify whether the module is certified and tested by Cisco and it can be interoperable with other IEEE-compliant 1000BASE interfaces where applicable.


This post briefly introduces Cisco single-mode SFP modules, covering its definition, types of these SFPs and introduction of each type, and features and benefits of Cisco single-mode SFP modules. Now there are a number of modules for you to choose, but be sure to find the right one based just on your needs and at the same time take a few factors into consideration.

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