According to the report of IHS Infonetics, 100G will make up over 50% of data center optical transceiver transmission capacity by 2019. CFP/CFP2/CFP4 and QSFP28 are main components of 100G optical module market. 100G CFP transceiver module emerges earlier than 100G QSFP28 transceiver, but it is now gradually replaced by QSFP28. As the basic principles of optical modules remain the same, we can still learn from CFP transceiver module to understand 100G optical module. This article would touch the basics of CFP modules, CFP vs QSFP28 and CFP vs CXP.
The C form-factor pluggable (CFP) is a multi-source agreement to define the form-factor of the optical transceiver for the transmission of high-speed digital signals. CFP modules are defined by CFP MSA to enable 40Gb/s, 100Gb/s and 400Gb/s applications. It includes pluggable CFP, CFP2, CFP4 and CFP8 transceivers to support the high bandwidth requirements of data communication networks. The CFP transceivers feature a new concept known as the riding heat sink, which makes it very easy for the operator to insert the module into the host board. The CFP module offer Ethernet users another option for 100G connectivity.
Figure from CFP Multi-Source Agreement(MSA)
CFP (C=100 in Roman numerals; Centum) refers to 100G form-factor pluggable, which features as a new ultra high speed pluggable I/O interface. The optical connection can support both 4 x 10Gbps, 10 x 10Gbps and 4 x 25Gbps variants. For 40G CFP modules, you can read it in this article 40G Transceiver Module: QSFP+ Module And CFP Module. 100G CFP modules include 100GBASE-SR10 CFP for 100m on MMF, 100GBASE-LR10 CFP and 100GBASE-LR4 CFP for 10km via SMF, and 100GBASE-ER10 CFP and 100GBASE-ER4 CFP for 40km on SMF. They are an ideal choice for data center applications.
CFP2 was specified by CFP MSA in a form factor of 1/2 in size of the CFP module. The module electrical interface has been generically specified to allow for supplier-specific customization around various 4 x 25Gbit/s interfaces, but it can also support 10x10Gbit/s, 4x25Gbit/s, 8x25Gbit/s, or 8x50Gbit/s lanes. 200G CFP2 and 400G CFP2, however, are not being put into use so far. CFP2 has been chosen to accommodate a wide range of power dissipations and applications.
CFP4 form factor is the half size of CFP2 module, which is designed to support Singlemode (SMF) and Multimode(MMF) Ethernet optics. CFP4 has 4x25G TX and RX I/O electrical pairs, so its nominal signaling lane rate is 25Gbit/s. Its electrical interface is specified to support both 4 x 25Gbit/s and 4 x 10Gbit/s interfaces. CFP MSA defined the CFP4 to apply for 40G/100G Ethernet, telecommunication and other applications.
The CFP8 name follows the CFP2 and CFP4 naming, and its form factor is similar to CFP2 module. Featuring a small 40mm x 102mm x 9.5mm form factor, the new CFP8 module delivers four times more bandwidth than existing 100G solutions. Its electrical interface has been generally specified to allow for 16 x 25 Gb/s and 8 x 50 Gb/s mode. CFP MSA demonstrated CFP8 (16X 25 Gb/s) form factor for 400 Gigabit Ethernet at OFC 2017. 400G CFP8 transceiver provides Ethernet users with a dense-port and high-throughput solution with its compact size and low power consumption.
CFP2 and CFP4 are specified as form-factor of 1/2 and 1/4 respectively in size of the CFP modules. QSFP28 transceiver’s form factor is smaller than CFP4, which means QSFP28 transceiver has a higher port density on the switch.
Figure from etulinktechnology
CFP modules, like CFP, CFP2 and CFP4, are supporting a 10-channel setup divided into 10G signals (10x10G) as well as a 4-channel setup divided into 25G signals(4x25G). But QSFP28 only supports a 4-channel setup of which each lane is capable of carrying up to 28G Ethernet(4x28G). Hence, CFP modules are more versatile than QSFP28 transceivers in terms of channel setups.
CFP module’s power consumption is normally ranging from 6W to 24W, while QSFP28 is generally less than 3.5W. Therefore, QSFP28 transceiver has lower power consumption than CFP modules.
CFP, CFP2 and CFP4 transceiver modules can be used for both 40G and 100G Ethernet, while QSFP28 can be used only for 100G Ethernet. But CFP modules have not been broadly adopted compared to QSFP28 transceivers in data centers, enterprise, and service provider networks.
As a rule of thumb, the CFP price is a little bit higher than QSFP28 modules based on the same transmission length.
If you want to learn more about QSFP28 transceiver, you can read Decoding 100G QSFP28 Fiber Optic Transceiver.
Both CFP and CXP modules are supposed to support 100G Ethernet, and their relationship is complementary, not competitive. CXP module has smaller form factor than CFP, which was created to satisfy the high-density requirements of the data center. So it targeted at the clustering and high-speed computing markets. CFP modules are designed for 40G and 100G applications, such as Ethernet switches, core routers, and optical transport equipment. The CXP works with multimode fiber for short-reach applications, while CFP works with both singlemode and multimode fiber to accommodate a host of data rates, protocols, and link lengths.
Figure from Optcore
For 40G CFP modules, FS offers generic 40GBASE-LR4 CFP, Cisco CFP-40G-LR4 and customized 40GBASE-LR4 CFP to meet your requirement for long-haul transmission. For 100G CFP/CFP2/CFP4 transceiver modules, FS covers a wide range of 100G CFP modules which are compatible to major brands, such as Cisco, Juniper, Brocade, etc. All of our CFP modules are fully tested in our test center to guarantee the compatibility. What is also worth noticing is that our CFP modules can be customized, you can customize the module model of compatible major brands you want here.Related Article: Why CPAK Transceiver Is Different in 100G Solutions?
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