PB530836
This bulletin describes the necessary steps to help ensure that Gigabit and 10 Gigabit Ethernet laser-based transmissions over multimode fiber (MMF) are successfully implemented and supported. It depicts the requirements for mode conditioning patch (MCP) cables.
Cisco Transceiver Modules and Mode Conditioning Patch cables
Table 1. Optical Transceivers
Table 2. Mode Conditioning Patch Cables
Figure 1. Mode Conditioning Patch Cable Installation
Types of Multimode Fiber
Table 3. Types of MMF
|
Naming Convention |
Core Size in Microns |
Modal Bandwidth at 850 nm (MHz*km) |
OFL Modal Bandwidth at 1310 nm (MHz*km) |
|
FDDI-grade |
62.5 |
160 |
500 |
|
OM1 |
62.5 |
200 |
500 |
|
OM2 |
50 |
500 |
500 |
|
OM3 |
50 |
1500 |
500 |
Requirements for Gigabit Ethernet Transmissions
Notes:
1. Some customers might be tempted to connect 1000BASE-LX/LH devices over short reaches of MMF jumper cables without MCP cables. There is a risk associated to this type of nonstandard deployment, especially when the jumper cable is an FDDI-grade or OM1 type. In such case the power coupled directly into a 62.5-micron fiber could be as high as a few dBm (typically 5 to 6 dBm), and if the jumper cable is short, the adjacent receiver will be saturated, causing high bit error rate, and eventually irreversibly damaged. We recommend the use of MCP, but if the customer remains reluctant to the deployment of MCP, a 5-dB attenuator for 1300nm should be used and plugged at the transmitter of the optical module on each side of the link.
2. Another alternative for short reaches within the same location is to use a single-mode patch cable. There will be no saturation over single-mode fiber.
Requirements for 10 Gigabit Ethernet Transmissions
Notes for LX4:
1. In some cases, customers might experience that a link would be operating properly over OM2 fiber type without MCP.
2. Some customers may be tempted to connect 10GBASE-LX4 devices over MMF jumper cables without MCP cables. This includes the case of links over OM3 cable for which the MCP should not be used. There is a risk to overload and saturate the adjacent receiver causing high bit error rate, link flaps and eventually irreversible damage. In such cases, a 5-dB attenuator for 1300nm should be used and plugged at the transmitter of the optical module on each side of the link.
3. Another alternative for short reaches within the same location is to use a single-mode patch cable. There will be no saturation over single-mode fiber. Please note the 10GBASE-LX4 devices can reach up to 10km over single-mode fiber as per compliance to IEEE.
Notes for LRM:
1. With 10GBASE-LRM interfaces, a conditioned launch is preferred for applications over FDDI-grade, OM1 and OM2. If no MCP is used, a MMF jumper cable of 2 to 5 meters long should be inserted between the transceiver and the cable plant.
2. For customers using MMF jumper cables of any type to connect 10GBASE-LRM devices without MCP or intermediate patch panels or connectors, it is preferable to measure the power level before plugging the fiber into the adjacent receiver. When the power is measured to be above 0.5dBm, a 5-dB attenuator for 1300nm should be used and plugged at the transmitter of the optical module on each side of link.
3. Another alternative for short reaches within the same location is to use a single-mode patch cable. There will be no saturation over single-mode fiber.
For More Information
• Cisco SFP data sheet: http://www.cisco.com/en/US/prod/collateral/modules/ps5455/ps6577/product_data_sheet0900aecd8033f885.html
• Cisco GBIC data sheet: http://www.cisco.com/en/US/prod/collateral/modules/ps5455/ps6577/product_data_sheet09186a008014cb5e.html
• Cisco X2 data sheet: http://www.cisco.com/en/US/prod/collateral/modules/ps5455/ps6574/product_data_sheet0900aecd801f92aa.html
• Cisco XENPAK data sheet: http://www.cisco.com/en/US/prod/collateral/modules/ps2797/ps5138/product_data_sheet09186a008007cd00_ps5455_Products_Data_Sheet.html