As technology develops, 100G transceiver modules have been officially published to meet the growing bandwidth requirement of data center networks, such as 100G QSFP28, 100G CFP modules and 100G CXP optical transceivers. In this article, we will introduce the CXP transceiver, including definition, working principles, applications, and FAQs.
CXP module is 45mm length and 27mm in width, a bit larger than an XFP (10 Gigabit small form-factor pluggable). A CXP module consists of 12 transmitting and 12 receiving channels in its compact form-factor and each channel supports up to 10 Gbit/s data rate. Its transmission distance can reach up to 100m over OM3 fibers, and 150m over OM4 fibers. So 100G CXP transceiver is designed for short-distance applications over multimode fibers, such as data center networking, high-performance computing networks, enterprise core aggregation, and service provider transport applications, etc.
Figure 1: FS CXP-100G-SR10 Transceiver
The 100G CXP transceiver incorporates the 850nm VCSEL (vertical-cavity surface emitting laser) technology, PIN array technology, and integrated laser driver and receiver IC technology, which combine to provide robust electrical and optical performance at high data rates. The CXP module is designed to operate over multimode fiber system using a nominal wavelength of 850nm. Its electrical interface uses an 84-contact edge type connector, and the optical interface uses a 24-fiber MPO connector. Usually, a CXP optical transceiver converts the 12 channels 10Gbps electrical signals into 12 channels 850nm optical signals and then using 2x 12-fiber or 24-fiber MPO/MTP MMF to connect devices (such as network switches, servers).
Figure 2: 100G CXP Module Working Principle
The CXP optics provide customers various high-density 120Gbps connectivity solutions. It can be used for 120Gbps direct connections between two network switches or servers or can be split into 3x 40Gbps and 12x 10Gbps connections.
The 100G CXP 120G-120G direct connection can be achieved by one 24-fiber MTP trunk cable. Figure 3 shows the application between the network switches by 24-fiber MTP female to female OM4 trunk cable, Type A.
Figure 3: 100G CXP 120G to 120G Direct Connection
In this CXP module 120Gbps to 3x 40Gbps interconnect cabling solution, one 120G CXP can be divided into 3x QSFP+ by 24-fiber MTP to 3x 8-fiber MTP multimode conversion harness cable as figure 4 shows. The 120Gbps transmission is broken into 3x 40Gbps transmissions, then each QSFP+ can be distributed to 10G switches through 12-fiber MTP harness cables.
Figure 4: CXP Module 120Gbps to 3x 40Gbps Interconnection
For the CXP transceiver 120Gbps to 12x 10Gbps transmission, one 120G CXP will be split into 12x 10G SFP+ transceivers, and a 24-fiber MTP to 12x LC harness cables can do the job. Figure 5 uses the customized high-density female 24-fiber MTP to 12x LC duplex OM4 breakout cable to complete the transmission.
Figure 5: CXP Transceiver 120Gbps to 12x 10Gbps Interconnection
100G CXP transceiver can not be connected with the QSFP-SR4-100G module even though they have the same wavelength 850nm. Because 100G QSFP only supports 4x 10G or 4x 25G interface, which means the supported data rate is 4x 10 Gbit/s or 4x 25 Gbit/s. However, 120G CXP delivers at 12x 10 Gbit/s.
When the CXP transceiver is connected with MTP harness cable, it only works with SFP+ module with 850nm wavelength, but not with other wavelengths.
From the above, we now have a clear understanding of the 100G CXP transceiver module. Its unique design and technology make it quite suitable for short-reach transmission. And CXP optics can be used in various connections for different requirements like 120Gbps, 3x 40Gbps and 12x 10Gbps connections.