Nowadays, the development momentum of optical modules is unstoppable, among which the 100G optical modules take up most of the market share, such as 100G CFP and QSFP28. Then 100G CFP vs QSFP28, what are the differences and how to choose? This article will give a detailed introduction to CFP and QSFP28 with their specific applications involved.
For the differences between 100G CFP and QSFP28, this article will have an introduction to them in these aspects of definition, power consumption, port density, cost, and application.
CFP is a multi-source agreement (MSA) to define the form-factor of the optical transceivers for high-speed digital signal transmission. The electrical connection of a CFP uses 10x 10 Gbit/s lanes in each direction (RX, TX). While, the optical connection can support both 10x 10 Gbit/s and 4x 25 Gbit/s variants of 100 Gbit/s. 100G CFP modules offer connectivity options for a wide range of service provider transport, data center networking, and enterprise core aggregation applications.
Figure 1: 100G CFP
QSFP28 transceiver module integrates 4 transmit and 4 receive channels. “28” means each lane carries up to 28G data rate. QSFP28 can do 4x 25G breakout connection, or 1x 100G connection depending on the transceiver used. For example, you can use 100G QSFP28 to 4 SFP28 DAC cables to realize 4x 25G breakout connection and LC-interface based QSFP28 with a single mode fiber (or MTP/MPO-interface based QSFP28 transceiver with a 12-fiber MTP/MPO patch cable) to get 1x 100G connection directly.
Figure 2: CFP vs QSFP28
Considering budget, network configuration, and overall bandwidth capabilities, power consumption plays an important role in transceiver hardware decision. The power consumption of QSFP28 optical module is usually lower than 3.5W, while the power consumption of other 100G optical modules is 6W to 24W.
The size of QSFP28 is the smallest 100G transceiver on the market. CFP4 is only a quarter of the width of the first generation of CFP. But it is still about 66% larger than QSFP28 in packaging form. This difference in size indicates that QSFP28 is much more efficient in port utilization than CFP.
Considering the power consumption and the port density, it will cost less to use QSFP28 in the system. Also, QSFP28 is less expensive than CFP.
CFP, one of the recommended 100G optical modules, is mainly applied in metro network and long-distance transmission (normally over 10km).
As shown in the following picture, to achieve high cabling density and long-distance transmission with CFP transceiver, the architecture mixed a 16-channel dual fiber DWDM Mux Demux by adding MTP harness cable and WDM SFP+ OEO converter to transfer the regular SR wavelength to DWDM wavelengths. Thus, a long-distance DWDM network with 100G CFP module is achieved.
Figure 3: 100G CFP Application
There are many QSFP28 products on the market, which are mainly divided into the following four applications according to the transmission distance:
Copper DAC Used Inside Racks Within 5m
QSFP28 DAC cables are ideal to use in short-range connections within 5m. They can offer a complete cable assembly in a cost-effective manner.
QSFP28 AOC/SR4 Transceiver for 5-100m
QSFP28 AOC is the best fit for 3-20m, and QSFP28 SR4 transceiver with 12-fiber MTP OM3/OM4 cable can support a transmission distance of up to 100m.
QSFP28 PSM4/CWDM4/CLR4 Transceiver for 100m-2km
For 100m to 2km, QSFP28 PSM4/CWDM4/CLR4 transceivers can offer cost-effective solutions. They can support up to 500m over 12-fiber MTP single mode fiber and 2km over duplex LC single mode fiber respectively.
QSFP28 LR4/ER4/ZR4 Transceiver for Long Span
For long-span 100GbE deployment, such as connectivity between two buildings (mostly up to 10km), QSFP28-100G-LR4 with duplex LC single mode fiber is the preferred option defined by IEEE. For longer distances (up to 40km and 80km), 100G QSFP28 ER4/ZR4 transceivers are better.
As for 100G CFP vs QSFP28, which to use for your network construction? Actually, it depends on two main aspects: the port type of your hardware device and application scenarios. CFP modules have a much larger size than QSFP28 modules. 100G QSFP28 appears to be the mainstream and is mostly used in shorter distances (0-10km) between switches or sometimes in long distances (up to 40/80km) with QSFP28 ER4/ZR4 and single mode fibers. While, although 100G CFP can be used in short distances as well, it is more common in metropolitan area networks (MANs) and long-haul WDM transmissions.