DAC cables, or “Direct Attach Cables”, are a form of shielded high speed cable with SFP connectors on either end. They can be used to connect switches to routers and/or servers. They are becoming increasingly popular in the network industry, mainly because the price difference is so large when compared with regular optics. Another reason for their increased popularity is that RJ-45 10G is not widely adopted, and most high density 10G switches are delivered with 48x SFP+ ports in 1 Rack Unit.
There are different versions of cables on the market. Because high speed cables are sensitive to electromagnetic fields, the shielding is an important quality factor for the cables. This is written on the cables in the form of AWG ratings like 28AWG and 30AWG: The longer the distance, the higher the AWG rating should be.
The most basic version of this cable is the ‘Passive Assembly’ where the data cables are directly connected to the Transmitting and Receiving signal. Because this signal is not very strong you can reach up to 5 meters with this setup depending on the switch or router.
The active cable version contains more sophisticated electronics where the transmitting power is amplified to give a better data-pulse. You can see this in the product naming like ACU and not CU (e.g. SFP-H10GB-ACU5M vs SFP-H10GB-CU5M).
The third version is the ‘Active Optical Cable’. Instead of using a high speed copper wire, this cable uses a hardened glass fiber for transmission. These glass fiber cables are becoming more widely used because of the issues associated with lower-end cables. The main issues are with the coding: If each end has to be connected to a different brand of router or switch, this can cause issues with compatibility (as companies such as Cisco and HP are known for vendor blocking). Another common issue is where the Switch or Router does not give enough power for a (long) passive cable. In this case there are a lot of CRC errors or packet loss and unstable links – This can be solved by switching to Active or Active Optical cables.
Solid Optics specializes in recoding and rebranding these DAC patch cables
Our SFP10G-SR pricing with a glass fiber patch cable is around the same pricing as an Original Brand cable. Using these optics offers greater flexibility in the distance you want to deploy and avoid any compatibility and communication issues.
For more information not referenced here, please contact us and we can answer all of your questions.