SFP transceivers have many different kinds of sending and receiving, users can choose appropriate transceivers for each link, to provide based on the available optical fiber type (such as multimode fiber or single-mode fiber) can achieve "optical performance". Available optical SFP modules in general can be divided into the following categories: 850 nm wavelength / 550 m distance of MMF (SX), 1310 nm wavelength / 10 km distance SMF (LX), 1550 nm wavelength XD / 40 km distance 80 km, 80 km from ZX, distance of the EX or EZX, and DWDM. The SFP transceiver also provides the copper cable interface, so that the host equipment that is mainly designed for optical fiber communication can also communicate through UTP network cable. There is also the SFP of wavelength division multiplexing (CWDM) and single-fiber "bidirectional" (1310/1490 nm).
The commercial SFP transceiver can provide a speed of 4.25 G BPS. The packages of 10 Gbps transceivers are XFP, and the new variant "SFP+" that is basically consistent with SFP packaging.
Most of the optical SFP transceivers support SFF - 8472 (industrial standard multilateral agreements), according to SFF - 8472 agreement, must support Digital Diagnostic monitoring (DDM, Digital Diagnostic Monitor) function, this feature enables the end user to real-time detection of SFP parameters, such as the five monitoring: basic Temperature (Temperature), Power supply voltage (Vcc) transceiver, laser Bias Current (Tx Bias Current), light output Power (Tx Power), the input Power (Rx Power).
Many people don't know the difference between SFP and SFP +, so it sometimes brings unnecessary trouble. The 10G module experienced the development of 300Pin, XENPAK, X2, and XFP, and finally realized the signal with the same size as SFP, which is SFP +. By virtue of its low cost and low cost, SFP has satisfied the high density demand of the equipment for the optical module. Since the implementation of the standard in 2002, it has replaced XFP as the mainstream of 10G market by 2010.
Advantages of SFP+ light module:
1. SFP+ has a more compact appearance size than X2 and XFP (the same size as SFP);
2. Can connect directly with the same type of XFP,X2 and XENPAK;
3. Cost is lower than XFP,X2,XENPAK products.
Differences between SFP+ and SFP:
1. SFP and SFP+ appearance size are the same;
2. SFP protocol specification: IEEE802.3, SFF- 8472;
Differences between SFP+ and XFP:
1, SFP+ and XFP are all 10G fiber modules, and can be interrelated with other types of 10G modules;
2. SFP+ has a smaller appearance size than XFP;
3. Because the volume is smaller SFP+ will signal modulation function, serial/unsolver, MAC, clock and data recovery (CDR), and the electronic dispersion compensation (EDC) function will be transferred from the module to the main board card;
4. XFP compliance protocol: XFP MSA protocol;
5. Agreement of SFP+ compliance: IEEE 802.3 ae, SFF- 8431, SFF- 8432;
6. SFP+ is more mainstream design.