Networking

In optical communication, duplex and parallel optical links are two of the most commonly deployed cabling structures. This post will discuss some specific connectivity solutions using 2-fiber duplex and 8-fiber/20-fiber parallel fiber optic modules. Duplex and Parallel Optical Links A duplex link is accomplished by using two fibers. The most commonly used connector is the duplex LC. The TIA standard defines two types of duplex fiber patch cables terminated with duplex LC connector to complete an end-to-end fiber duplex connection: A-to-A patch cable (a cross version) and A-to-B patch cable (a straight version). In this article the LC to LC duplex cables we use are all A-to-B patch cables. It means the optical signal will be transmitted on B connector and received on A connector. Figure 1: two types of fiber patch cables A parallel link is accomplished by combining two or more channels. Parallel optical links can be achieved by using eight fibers (4 fibers for Tx and 4 fiber...

Since the introduction of Base-12 connectivity in the mid 1990s, the  12-fiber MTP/MPO connector  and Base-12 connectivity have served the data center for about twenty years. It has helped a lot in achieving high-density and manageable cabling. Recently, many documents and posts are discussing about a new technology—Base-8. Its appearance is regarded as the evident need of future networks. Even though most of the words are promoting the overwhelming advantages of Base-8 system, we should still consider the defects and merits of these two systems based on some facts before taking the next step by ourselves. This post is a discussion on this topic. Facts of Base-12 and Base-8 In this part, the design features of Base-12 and Base-8 systems will be introduced. And their dominant advantages are going to be discussed too. Design Features Base-12 connectivity makes use of links based on groups of 12, with 12-fiber connectors such as the MTP. In Base-12 connectivity, for exam...

For 40GbE direct cabling between two devices using QSFP+ port, there are several options including QSFP+ transceiver option, QSFP+ DAC (Direct Attach Copper) cable, and QSFP+ AOC (Active Optical Cable). Among these options, each of them has its own merits. Today, I’d like to make a comparison between them from the perspective of the costs. Case 1: Distances Below 5 m If the transmission distances is under 5 m, like the case that two switch ports are connected within the same rack or between racks located within the same room. The QSFP+ passive DAC cable is recommended. Take the Cisco compatible QSFP+ optics (Fiberstore Brand) for example: DAC 5m Cisco QSFP-H40G-CU5M Compatible 40G QSFP+ Passive Direct Attach Copper Cable US$ 65.00 AOC 5m Cisco QSFP-H40G-AOC5M Compatible 40G QSFP+ Active Optical Cable US$ 140.00 Transceiver & Cable Cisco QSFP-40G-SR4 Compatible 40GBASE-SR4 QSFP+ 850nm 150m DOM Transceiver US$ 85.00 5M OM4 12-fiber MTP Fiber Optic Trunk Cable for 40GBASE-SR...

In telecommunication, fiber loopback is a hardware designed to provide a media of return patch for a fiber optic signal, which is typically used for fiber optic testing or network restorations. When we need to know whether our fiber optic transceiver is working perfectly, we can use a fiber loopback cable as an economic way to check and ensure it. Basically, the loopback aids in debugging the physical connection problem of the transceiver by directly routing the laser signal from the transmitter port back to the receiver port. Since fiber optic transceivers have different interface types and connect different types of cables, it is not that simple to choose a right loopback for our transceiver. This post will be a guide on how to choose a right loopback cable for specific transceiver module. Fiber Loopback Types and Configurations Before deciding which loopback cable to use, we should firstly know the structure and classification of fiber loopback cable. Generally, a fiber loopbac...