Now, with the rapid development of technology, 100G Ethernet is becoming closer and closer to us. Fiber connectivity in higher-speed active equipment is being condensed and simplified with plug-and-play and hot-swap transceivers. And these transceivers are necessary to achieve the reliable and effective 100G Ethernet. Interfaces for 100G active equipment include CFP and CXP. So, what are CFP and CXP? And what’s the relationship between CFP and CXP? You may find the answer in this post.
The C form-factor pluggable (CFP) is a multi-source agreement (MSA) to produce a common form-factor for the transmission of high-speed digital signals. CFP was designed after the small form-factor pluggable transceiver (SFP) interface, but is significantly larger to support 100 Gbit/s.
The CFP form factor, as detailed in the MSA, supports both single mode and multimode fiber and a variety of data rates, protocols, and link lengths, including all the physical media-dependent (PMD) interfaces encompassed in the IEEE 802.3ba Task Force. For 40GbE, the optical interface of CFP transceiver consists of 40Gbase-SR4 for 100m and 40Gbase-LR4 for 10 km. The CFP 100GbE module has three kinds of PMD interfaces: 100Gbase-SR10 for 100 m, 100Gbase-LR4 for 10 km and 100Gbase-ER4 for 40 km. Its size of CFP is optimized for longer-reach interfaces and single-mode fiber applications. It is 120 mm long and 86 mm wide, which is twice the length and six times the width of a 10GbE SFP+. The package includes two electrical connectors. The connector itself has two rows of metal connectors located at the top and bottom, which greatly increased the density of the overall surface area.
Meanwhile, CFP transceiver has good performance in heat dissipation, which can result in less power consumption. The available optical modules of 100G in FS.COM includes CFP-100G-SR10, CFP-100G-LR4, CFP-100G-ER4, and CFP2-100G-LR4 (The following figure takes the HUAWEI optical module as an example). These transceivers can achieve different transmission distance by connecting to different optical fibers.
High Density CXP
CXP optical modules are designed for use in data center, core-routing, and high-performance computing applications up to 120 Gigabit per second links over multimode fiber. They are compliant with the InfiniBand Trade Association (IBTA) CXP Specification, IEEE 802.3ba 100GBASE-SR10 and CPPI interfaces supporting 12 parallel, bi-directional data channels at rates from 1G/bs to 11.3Gb/s per channel.
The CXP transceiver is 45 mm in length and 27 mm in width, making it slightly larger than an CFP module. It includes 12 transmit and 12 receive channels in its compact package. This is achieved via a connector configuration similar to that of the CFP transceiver. It’s typically used with parallel multimode fibers, and the transmission distance is as high as 100 meters. Also take HUAWEI optical module (CXP-100G-SR10) as an example, and the parameters of this optical module is shown as follows.
Technically, the CFP optical modules will work with multimode fiber for short-reach applications, but it is not really optimized in size for the multimode fiber market, most notably because the multimode fiber market requires high faceplate density. The CXP optical module was created to satisfy the high-density requirements of the data center, targeting parallel interconnections for 12x QDR InfiniBand (120 Gbps), 100 GbE, and proprietary links between systems collocated in the same facility.
CFP transceiver and CXP transceiver not only share something in common but also share differences. In some cases, there exists competition between them, because CFP can also work with multimode fibers. And in some cases the CFP and CXP form factors are complementary, with the CFP likely gaining traction in applications like Ethernet switches, core routers, and optical transport equipment, and the CXP module covering the data center market. But in general, it depends on customers’ choice. If you are constructing a network that can accommodate a wide range of speeds，then CFP optical module is preferred; If it’s used for short distance, then CXP is needed.
According to the aforementioned introduction, I hope it will help you understand the 100GbE transceivers, whether CFP or CXP. Similarly, you could know the 40GbE transceiver through this post as the CFP and CXP also support the 40GbE.