I just returned from the 2012 BICSI Winter Conference & Exhibition. It was great to get together with other colleagues and individuals that all have one thing in common: we respect layer one! One of the great benefits of this conference is the educational opportunities, and BICSI certainly delivered this year.
The most common theme that I heard throughout the conference was that 40/100G Ethernet isn’t just on the horizon, it’s already here. This will have profound effects on data center structured cabling – which wasn’t a surprise to me, we’ve been preparing for this for years!
One of the choices data centers must consider when migrating to 40/100G Ethernet is whether to use fiber or copper cabling. Based on what I’ve seen, fiber will be the primary cabling type. The IEEE 802.3ba standard for 40/100G Ethernet states a maximum distance of 7M to run 40/100G, and that will be using “active” cables. (An active cable is a cable with a transceiver hard-wired to it.) This limitation rules out copper as a primary medium of transport.
Fiber optic cabling does offer the choice between multi-mode and single-mode cabling. There are a few key factors to weigh here: distance, transmission type and total link cost. Single-mode fiber will run longer distances and will still utilize a serial transmission. Multi-mode fiber will require parallel transmission, which is a dramatic change for many, and can only run limited channel lengths.
Cost is, of course, key factor here – which makes multi-mode fiber an attractive option. Single-mode fiber is cheaper, but the transceivers are very expensive. Overall, a multi-mode link is projected to be about half the cost of a single-mode. This cost delta is based largely on the expensive lasers required for single-mode transmission. The link distances for multi-mode fiber running 40/100G Ethernet is 100M using OM3 fiber, and 150M using OM4. Since roughly 90% of data center link distances are within the multi-mode distance limitation, it appears to be a no-brainer.
Because of this, it is evident that multi-mode fiber will be the predominant cabling of choice for these higher network speeds. Single-mode will be used only when necessary, and copper could potentially be utilized in specialized areas where short link distances occur. Another consideration for copper: copper transceivers will utilize more power.
Choosing your cabling infrastructure is a critical decision for any data center team, but there is a wealth of information out there (and this site!), and I would suggest doing a little research until you feel comfortable with your decision. We also have a dedicated team to help answer any further questions you may have – give us a call and 800.913.9465 to find out more.