Three Common High Density Host Ports – SFP+, QSFP+ and CXP

The push behind users’ requests for high-quality video content, whether for live Internet video or video downloads from servers, is the principal driver of extremely high growth of Internet traffic. Besides, more and more complex technical computing applications are demanding even greater bandwidth. In such cases, these SFP+, QSFP+ and CXP high density host ports are used to increase the bandwidth, enabling the high speed networking connections. This article gives an overview of these three ports, including their cabling solutions and bandwidth density.

High Speed Solutions: SFP+, QSFP+ and CXP Ports

Leading companies and industry organizations related to telecommunications have made their great efforts to develop specifications to assure commonality, compatibility and networking functionality of hardware connections, signaling and software communications. These specifications for high speed networking solutions include SFP+, QSFP+ and CXP links.

SFP+ Ports

In today’s data center, SFP+ links are supplanting SFP links for both Ethernet and Fibre Channel. Using the same board space as SFP, SFP+ provides a 10x bandwidth improvement over SFP for Ethernet (10Gb/s vs. 1Gb/s) and 2x improvement for Fibre Channel (8.5Gb/s vs. 4.25Gb/s). The SFP+ system also offers capability to freely designate or configure any available system port with either copper- or fiber-based cabling as dictated by the specific installation environment.

QSFP+ and CXP Ports

The other two high speed parallel link specifications which allow for even higher bandwidth are QSFP+ and CXP systems. The QSFP+ system uses a 4 x 10 Gb/s link configuration for a 40Gb/s port. Similarly, the CXP system provides 12 lanes that can be deployed to support 100 to 120Gb/s aggregated port bandwidth. QSFP+ and CXP are specified for 4x and 12x Infiniband Quad Data Rate (QDR) interconnect links. CXP ports can also be used for 40G links.

Comparison Among SFP+, QSFP+ and CXP Ports

The comparison among these three ports starts form their cabling solutions, then bandwidth density.

Three Common Cabling Solutions for SFP+, QSFP+ and CXP

The SFP+, QSFP+ or CXP host ports can accept either a passive copper-based cable solution for generally cable lengths of 5 to 7 meters, an active copper-based cable solution for typical cable lengths up to 15meters (or longer depending on the acceptance criteria), or a plug-in optical transceiver module with an optical connector on the rear of the module to accept passive fiber optic cable assemblies to enable even longer cable lengths. These cabling approaches enable flexibility to configure the cables needed to cater to different working environments. Take QSFP+ copper cabling solutions for example, Intel XLDACBL5 is the QSFP+ to QSFP+ passive copper cable assembly designed for 40-gigabit links with the distance up to 5m. Fiberstore compatible Intel XLDACBL5 is shown below.

A Fourth Cabling Solution for QSFP+

With the widespread use of QSFP+ for Ethernet transmission in high performance computing systems, there emerged a fourth cabling solution: active optical cable (AOC) assembly. In an AOC, the optical fiber is terminated directly to an optical transceiver that is sealed within the metal backshell on each end of the cable assembly. The integrated electro-optical assembly lowers cost in component reduction and presents an electrical interface to the outside world. Like 721070-B21 module, Fiberstore compatible HP 721070-B21 is the QSFP+ to 4SFP+ breakout AOC assembly used for 40G links.

Bandwidth Density

The SFP+, QSFP+ or CXP host ports can increase I/O port bandwidth density along the edge of a switch line card. A single SFP+ port operating at 10Gb/s provides about 16 Gb/s bandwidth per inch, QSFP+ offers 3x improvement to 48Gb/s per inch, and CXP offers a further 2.3x improvement to 113 Gb/s per inch. The port configurations give system designers options to achieve even higher linear bandwidth density with
some port types.


These high density SFP+, QSFP+ and CXP ports can provide increased communications bandwidth for data center networking. Fiberstore offers various SFP+, QSFP+ and CXP ports, and their cabling solutions. These cabling modules are fully compatible with major brands, like Intel (XLDACBL5), HP (721070-B21), Dell and Force 10 (CBL-QSFP-40GE-PASS-1M). You can visit Fiberstore to know more about SFP+, QSFP+ and CXP ports.