As the need for speed in the data center continues to grow, you’ve probably been bombarded with high speed assembly terms like SFP+, QSFP+, interoperability, DAC, AOC, EEPROM … and the list goes on! High speed assemblies are ideal for a number of different data center deployments, such as top of rack (ToR) and middle of row (MoR).

With new products and technologies being introduced at what feels like a daily rate, we thought a quick guide to various high speed assembly terms and acronyms would be useful. Here are some of the most commonly used phrases used when discussing high speed assemblies.

HSAs (High Speed Assemblies)

High speed assemblies are a low-cost option for applications with passive and active cable assemblies to support fiber channel, InfiniBand and Ethernet protocols.


The small form-factor pluggable is a compact, hot-pluggable transceiver used for both telecommunication and data communications applications; it is typically associated with 10G.


The quad small form-factor pluggable is the smallest form factor; it interfaces networking hardware to fiber optic cables; it is typically associated with 40G.

Advances in Multifiber ConnectivityTransceiver

This module connects or interfaces with the network device or appliance. The transceiver is the standalone module that contains a fiber optic port (LC for 10G or MTP for 40G). If you remove a transceiver’s black dust cap, you will be able to see the LC ports.


Serving as the brains of the unit, EEPROMs can be coded for compatibility with various industry equipment. EEPROM stands for Electrically Erasable Programmable Read-Only Memory.


Direct attach copper is the copper HSA product with a module that looks like a transceiver on each end, using twinaxial cable.


An active optical cable contains a transceiver on both ends and a fiber optic cable that connects them.


Some equipment vendors use a code or other mechanism to lock out non-approved cables. This is done by taking information from the EEPROM. A generic EEPROM can suit most of the recent switch models, while some legacy switch models, such as the Cisco Catalyst series, can refuse to activate the port with a generic unit inserted, or report a warning/error message. In such cases, Cisco-compatible modules (DAC, AOC, and transceiver) are available to solve the compatibility issue.


Active assemblies consume power and are sold in both DAC and AOC forms. Benefits include a much larger range for longer deployments.


Passive assemblies do not consume power and are only available as DAC. Typically, the maximum distance for a passive assembly is seven meters.