Duplex and Parallel Transmission over Multimode Fiber
Andrew Jimenez, vice president of technology at Anixter, explains the uses of multimode and single-mode optical fiber and the difference in data rates that can be supported via duplex versus parallel transmission over multimode fiber.
Read our TECHbrief on innovations in optical fiber to learn more about this topic.
Transcript: Duplex and Parallel Transmission over Multimode Fiber
Hi, I’m Andy Jimenez, and I’d like to talk about duplex and parallel transmission over multimode optical fiber technology.
Optical fiber’s ability to deliver increased bandwidth over longer distances compared to twisted-pair and wireless media options make it an ideal choice for data center and building planners looking for a path to 10, 40 or 100 Gigabit Ethernet.
There are two optical fiber types used in inter-networking applications—multimode and single-mode fiber. The key difference is in the physical core sizes of the fiber. Laser optimized multimode fiber utilizes a 50 micron core, whereas single-mode fiber is characterized by a smaller core size in the range of 8 to 10 micron.
Multimode fiber typically serves as the cabling backbone in commercial buildings and data centers, as it connects the aggregation network layer to the core and access layers. Single-mode fiber is ideal for covering long distances, in the order of kilometers, between buildings or within the backbone of hyperscale data center environments.
Multimode fiber is the more economical choice for most commercial buildings and smaller data centers. Multimode infrastructure has the advantage of utilizing lower-cost short wavelength optics operating at 850 nm, which drives a lower overall system cost compared to the more expensive single-mode optics, which use longer wavelength optics in the 1310 to 1550 nm range.
Multimode fiber can support data rates in the range of 1 to 100 Gigabits per second. Depending on the type of optical transceiver that is used, these data rates can be delivered via duplex or parallel transmission over multimode fiber.
Duplex transmission has a single-lane or serial architecture that can support data rates of 10 to 40 Gigabits per second. A duplex architecture is desirable, as it minimizes the number of fibers required to support the desired data rate. One fiber is used to transmit and the other to receive data.
Parallel transmission utilizes multiple lanes that can support 40 to 100 Gigabit per second data rates; however, parallel architectures require multiple fibers to transmit and receive data. In the case of 40 Gigabit Ethernet, many short wavelength parallel optical transceivers require 4 lanes using 8 fibers. The early generation 100 Gigabit short wavelength transceivers required 10 lanes or 20 fibers to operate.
While parallel transmission provides an economical choice for high-speed data center backbones, careful planning is required due to the increased complexity associated with parallel versus duplex infrastructures.
To learn more on this topic, read our TECHbrief on innovations in optical fiber technology, and talk to your local Anixter representative.