This document provides technical descriptions, applications, and compatibility information for the Small Form-Factor Pluggable (SFP) and 10-Gigabit Small Form-Factor Pluggable (XFP and SFP+) optics modules used in the Cisco® Carrier Packet Transport product family.
Cisco offers a comprehensive range of pluggable optical modules for the Cisco ONS Family of multiservice platforms. The wide variety of modules gives you flexible and cost-effective options for all types of client interfaces. Cisco offers a range of gigabit interface converters (GBICs) for Gigabit Ethernet use, a wide variety of SFP modules, and has recently introduced XFP modules. These small, modular optical interface transceivers offer a convenient and cost-effective solution for a variety of applications in the data center, campus, metropolitan-area access and ring network, storage area network, and long-haul network.
A SFP transceiver module (Figure 1) is a bidirectional device with a transmitter and receiver in the same physical package. The module interfaces to the network through a connector interface on the electrical ports and through an LC termination connector on the optical ports. Electrical interfaces and dimensions are defined in the SFF-8472 industry-standard multisource agreement (MSA).
Figure 1. SFP Transceiver Modules for the Cisco ONS Family
A schematic of the SFP transceiver module functional block diagram is illustrated in Figure 2. It contains three parts: the transmitter, receiver, and Electrically Erasable Programmable Read-Only Memory (EEPROM) storage chip. This block diagram is intended for information purposes only and does not illustrate design requirements.
Figure 2. SFP Module Block Diagram
• Transmitter: In the transmit direction, the SFP transceiver module receives the electrical signal and transmits this data in an optical signal by using a laser driver that controls the laser diode. The optical output power is held constant by an automatic power control circuit.
• Receiver: In the receive direction, the SFP transceiver module receives a nonreturn to zero (NRZ) optical signal and converts it to an electrical equivalent. The receive portion of the module will use some kind of amplifier to control the converted electrical signal.
• EEPROM: This type of SFP transceiver is identified by the standard two-wire serial interface used in EEPROM with an I2C interface (with serial ID functions) that is part of the GBIC specifications and the SFF-8472 MSA. In addition, EEPROM offers an enhanced monitoring interface for optical transceivers as described in SFF-8472, which allows real-time access to the device to support monitoring of received optical power, laser bias current, laser optical output power, etc.
The XFP transceiver module (Figure 3) is a bidirectional device with a transmitter and receiver in the same physical package. The XFP module contains a 30-pin surface mount connector on the electrical interface and a duplex LC connector on the optical interface.
Figure 3. XFP Transceiver Module for the Cisco ONS Family
Figure 4 shows an XFP transceiver module functional block diagram. It contains two parts: the transmitter and the receiver.
Figure 4. XFP Module Block Diagram
• Transmitter :In the transmit direction, the transceiver module receives a 10-Gbps electrical data signal and transmits the data as an optical signal through an electrical to optical converter. The optical output power is held constant by an automatic power control circuit. The transmitter also contains a Clock Data Recovery (CDR) circuit. The function of this circuit is to attenuate and reshape any jitter received on the electrical interface.
• Receiver: In the receive direction, the transceiver module receives a 10-Gbps optical signal and converts it to an electrical equivalent. The receiver contains a CDR circuit.
The SFP+ transceiver (Figure 5) is an evolution of the SFP optic developed for 1-Gbps Ethernet and 1-Gbps, 2-Gbps and 4-Gbps Fibre Channel. It extends the data rate up to 11.10 Gbps while meeting low power and low electromagnetic interference (EMI) requirements for datacom and storage applications.
Similar to SFP, the SFP+ module is a bidirectional device with a transmitter and receiver in the same physical package. It has a 20-pin connector on the electrical interface and a duplex LC connector on the optical interface.
Figure 5. SFP+ Transceiver Module for the Cisco ONS Family
Figure 6 shows an SFP+ transceiver module functional block diagram. It contains two parts: the transmitter and the receiver.
A possible SFP+ module functional block diagram is shown in. It contains three parts: a (A) Transmitter, (B) Receiver, and (C) I2C Management interface. This architecture does not exclude other possible implementations that can be compliant to the SFP+ specs (such as CDR-based designs).
Figure 6. SFP+ Module Block Diagram
In the transmit direction, the SFP+ transceiver module receives a 8.5- to 10.3125-Gbps electrical signal (signaling rate) from the host board Asic/SerDes and converts the data to an optical signal through the laser driver that controls the laser diode in the Transmitter Optical Sub-Assembly (TOSA).
To receive a clean electrical 1-Gbps signal for optical transmission, the preemphasis from host ASIC provides the precompensation and wave-shaping of the transmit waveform. This effectively eliminates the need for equalizers or retimers in the SFP+ module, thus saving power and cost to the SFP+ module.
In the receive direction, the transceiver module receives a 8.5/10.3125 Gbps optical signal through a photodiode mounted together with a trans-impedance preamplifier(TIA), and converts it to an electrical equivalent. Depending on the SFP+ architecture, either a limiting or a linear electrical interface will be implemented on the module.
For a limiting interface, the host ASIC Receive Equalizer compensates the printed circuit board (PCB) trace impairment between the module and the ASIC.
For a linear interface, the host Electronic Dispersion Compensation (EDC) provides the adaptive signal processing that is capable of compensating for impairments due to optical fiber, connector, electro-optics and PCB trace effects.
It is worth noting that cost tradeoffs favor the limiting interface, but the linear interface provides better performance.
(C) I2C Management Interface
The third functional capability of the SFP+ module is the 2-wire serial, I2C, interface. I2C is used for serial ID, digital diagnostics and module control functions. The enhanced digital diagnostics monitoring interface allows real-time access to the device, allowing monitoring of received optical power, laser bias current, laser optical output power, etc.
Pluggable Modules: List and Description
Cisco ONS Family modules have well-defined product IDs, making it easy for you to order the appropriate module.
The product ID is structured as follows: ONS-"AB"-"CCC"-"DD":.
• A = S for SFP, G for GBIC, and X for XFP
• B = C for commercial temperature (0 to 70°C), E for extended temperature (-10 to 85°C), and I for industrial temperature (-40 to 85°C)
• CCC = Supported bit-rate or signal type: 155 Mbps for OC-12/STM-1 signal or 2 GF for a tri-rate Gigabit Ethernet, Fibre Channel, and 2G Fibre Channel signal support
• DD = Supported reach: S1 for short-reach/intra-office 1310 nm interface or SX for Ethernet
There are still some older product IDs for the Cisco ONS 15454 platform, but those IDs will migrate toward the newer ID scheme for the Cisco ONS Family.
Data SFP Modules
Cisco offers a wide range of different data SFP modules capable of transmitting Gigabit Ethernet, Fibre Channel, IBM Fiber Connection (FICON), and Enterprise Systems Connection (ESCON) signal format. Table 1 provides details.
Table 1. Data SFP Modules
Temperature Range (°C)
SFP - 100 Mbps Long Reach - 1310 nm - SM - LC, ITEMP
-40 to +85
SFP - 100 Mbps Short Reach - 1310 nm - MM - LC, ITEMP
-40 to +85
SFP - 1000BASE-BX U - GE Bidirectional Upstream - Ext Temp
-10 to +85
SFP - 1000BASE BX D - GE Bidirectional Downstream Ext Temp
-10 to +85
SFP - 1000BASE-SX Gigabit Ethernet, 850 nm, MM, I-TEMP
Please select ONS Pluggable Optics Series as the Product Family.
The use of third-party equipment in place of Cisco ONS SFP products is not recommended, for the following reasons.
• Cisco can guarantee service-level agreements (SLAs) only on parts that have undergone the Cisco test plan and validation process. Without comprehensive testing and validation, SFP products may display anomalous behavior that can impact host-board performance.
• Cisco SFP modules reserve specific EEPROM fields to store inventory data such as Product ID, Part Number, Serial Number, and CLEI CODE that are specific to Cisco SFP modules and are required for SLAs.
• The Cisco Technical Assistance Center (TAC) and Cisco Customer Advocacy can only support Cisco modules and boards for the Cisco ONS Family products.
A different approach is used for DWDM SFP/XFP modules. Based upon customer usage, Cisco has identified and selected particular high-usage wavelengths, and will maintain shorter lead times on these items.
Short lead-time DWDM SFP or XFP modules are those from 1546.1 to 1560.6, with a 4 skip 1 approach.
Unforecasted pluggable optics on different lambdas could require 16 weeks of delivery time.