Optical Transceiver Transition From 40G to 100G for Data Center

Optical transceivers always play an important role in the modern data center. And their importance will continue to grow in the following years. The modern data centers usually have 10G access ports that interface to 40G switching fabrics. However, the 25G access ports and 100G switching fabrics will be propelled soon. Actually, one key factor to decide the applications of optical transceivers in data center is form factor.

Nowadays, the data center have consolidated around optical transceivers in the SFP form factor for server access and around QSFP transceivers for switch-to-switch interconnects. Moreover, when the distance to the access port is less than 5 meters, direct attach copper cables are usually utilized while active optical cables are used for longer distances.

SFP+ transceivers play an important role in 10G transmission. SFP+ transceivers have the advantages of compactness, high performance and cost savings and are widely used in 10G access ports. But this situation will be changed when the access speed increases to 25G and the 10G access ports turn to SFP28. Besides, the ecosystem around 25G lanes will be expected to leverage in application such as next-generation enterprise networks that will drive demand for SFP28 modules operating over single-mode fiber for reaches of 10 km to 40 km.

QSFP transceiver is a parallel transceiver, because it is able to accept 4 electrical input lanes, and operate at 4 x 10 Gbps. At present, 40G QSFP+ transceivers are widely deployed in data center switching fabrics and ramping up hard as data centers deploy 40GbE, especially as a high-density 10G interface via breakout cables. However, a research said that QSFP28 transceiver modules will be deployed in large quantities as data centers transition from 40G to 100G switching fabrics starting in 2016. What is QSFP28? It is well known that the first-generation QSFP optical transceivers are equipped with four Tx and Rx and each channel has a rate of 10 Gbps. With the development of technology, now each channel of QSFP transceiver is able to transmit and receive data up to 28 Gbps. Such kind of transceiver is called QSFP28 . It is a new trend for 100G applications.

The first optical transceivers shipped with 100G transceivers were CFP which supports 100 Gbps and 10 x 10G lane electrical interface defined in 802.3ba. But CFP2 soon came along and achieved 5 x 25G or 10 x 10G lane electrical interface with reducing the form factor by half of CFP. But it is too expensive and the footprint is too large to trigger mass deployment. CFP4, half the size of CFP2 has been launched after CFP2. At the same time, QSFP28 is competing with it. Currently, CFP4 and QSFP28 seem to be neck and neck. CFP4 has higher maximum power consumption giving it the advantage on longer reach optical distances while QSFP28 has higher density. In addition, in data center, there is another trend that nearly all link lengths are less than 2km. Thus for intra-connection and the aggregation switch design, QSFP28 transceivers which have almost the same size of QSFP+ seem to be a superior choice for data center applications although there are still some technical issues of QSFP28 waiting to be solved.

If you are going to have your data center converted to 40G or 100G, Fiberstore is a good place to select optical transceivers. Fiberstore offers comprehensive solutions for optical transceivers that meet the needs of 1G to 100G applications.

Reference: How Will Fiber Optic Transceivers Evolve for Future Data Centers