Fibre Channel Connection Scheme Based on OM3/OM4

In enterprise data centers, OM3/OM4 multimode fibers are currently mainly used as Fibre Channel FC transmission media to connect servers and storage devices. High-performance server and storage technologies continue to drive the growth of FC channel rates, which also require FC channels to have higher reliability and lower costs. This article will focus on high-speed OM3/OM4 multimode fiber connections between servers and storage devices.

OM3/OM4 fiber

FC Fibre Channel—supports high rates

Because of its high speed, low jitter, and high reliability, Fibre Channel FC has become the first choice for server and storage device connections. With the continuous development of server and storage technology, the speed of Fibre Channel FC is also increasing.

Today, multi-core processor servers deployed in enterprise data centers range from 4 to 12-core processors, each with typically 2 GHz of processing power, or 24 GHz for 12-core computing. In addition, servers now generally use PCIe3 (8G/line) and PCIe4 (16G/line) bus interfaces, which have gradually solved the bus interface bottleneck caused by the increase in the number of processors. Increased server computing power requires higher Ethernet data rates, as well as higher Fibre Channel rates. Future server bandwidth trends will be Ethernet 50/100Gbps (NIC) and 64 Gbps Fibre Channel (HBA) interconnects.

Compared to traditional hard disk drives (HDDs), all-flash arrays (AFAs) significantly improve storage performance with high data density, high endurance, lower energy consumption, and rack space savings. According to Brocade's demonstration, it uses 32G Fibre Channel to access 8G flash memory, which reduces the response time by 71% compared to using 8G Fibre Channel.

Data center multimode fiber connection distance

Based on Ethernet and Fibre Channel transmission standards, technological developments, and commercial viability, Corning has modeled the length of multimode and single-mode fiber optic connections in the data center. The data shows that as the Ethernet rate increases from 10G to 40G and 100G, and the Fibre Channel rate increases from 8G to 16G and 32G, data center users deploy OM3/OM4 multimode fiber, and more than 90% of the distances are within 100 meters. In other words, for the vast majority of data center users, a 100-meter channel distance is sufficient for their needs.

FC Fibre Channel—mainly using OM3/OM4 multimode media

Fibre Channel FC is a point-to-point connection, and OM3/OM4 multimode fiber is the main medium for short-distance transmission, with a transmission distance of up to 150 meters. Now 16GFC and 32GFC channels are mainly deployed with OM3/OM4 multimode fiber. In addition, OM3/OM4 multimode fiber uses VCSELs lasers, so it is also more economical.

To date, Fibre Channel FC has used small form factor pluggable (SFP+) transceivers to interface with duplex LCs in storage area network (SAN) connections. The pre-terminated MTP cable is usually deployed as the backbone on the bridge or under the raised floor between the server cabinet and the storage equipment cabinet. MTP/LC modules or fan-out jumpers are used in the equipment cabinet to convert to LC connectors to connect equipment. Of course, the use of MTP/LC fan-out jumpers can more effectively reduce the number of cables and reduce the difficulty of installation and maintenance. At the same time, the MTP/LC fan-out jumper provides a stepped LC leg length, which can better meet the space of the line card port.

The Fibre Channel FC-PI6 standard includes the 128GFC protocol, using QSFP transceivers and 8 or 12-core MTP interfaces. 128GFC adopts parallel transmission technology. Parallel transmission is different from the traditional two-core serial mode. Each core fiber transmits 32GFC, namely: 4 cores carry transmit signals (4x32GFC) and 4 cores carry receive signals (4x32GFC). 128GFC is also the first Fibre Channel transmission technology defined as parallel transmission. In the future, FC-PI7 will also promote the 256 GFC parallel transmission method.

Initially, 128GFC was expected to be deployed in the switch internal link (ISL) and connect the entire link with MTP. Compared to traditional Fibre Channel with duplex serial connections, parallel transmission will use 8-pin MTP connectors and adapter panels instead of MTP-to-LC interconnects.

Fiber transmission channel FC requires higher speed to improve the response speed of servers and storage devices. At present, the distance of FC channel is mostly within 100 meters, so OM3/OM4 multimode fiber connection is a wise choice with high cost performance.