Dual Rate/Multi-Rate Transceivers – An overview

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Dual rate transceivers

Continuous bandwidth demands are leading networks to upgrade their infrastructure more frequently than ever before. In this scenario, a multi-rate transceiver is a good pluggable option because you can upgrade one end and keep the other end at a low data rate.

What is a multi-rate transceiver?

Multi-rate transceivers can support multiple or dual data rates. Current examples in the market are SFP+ => 1G/10G, SFP28 => 10G/25G, QSFP+ => 10G/40G, QSFP28 => 40G/ 100G, etc. The main advantage of installing multi-rate transceivers is that it allows the use of existing infrastructure so that networks can operate at different rates and can be upgraded in increments. Multi-rate transceivers ease the transition from low to high data rate migrations, keeping forward/ backward compatibility. Another benefit of using multi-rate transceivers in networks is simplifying part inventory, resulting in cost savings.

 Types of multi-rate transceivers

There are four different types of multi-rate transceivers in the market today.

1.The first type is RS (Rate Select) with operating parameters change. In this type of transceiver, when you change the data rate, certain operating parameters within the transceiver have to be changed as well. These parameters are receiver bandwidth (Rx BW), transmitter (Tx) extinction ratio, and laser bias current. The transceiver specification or data sheet will include extended data rate parameters. An example of this type of dual rate transceiver is the SFP+1G/10G. This type of Multi-Rate transceivers is compliant with MSA standards.

Take a look at the table below:

Multirate transceivers

You can see why the parameters have to change to meet both 1G and 10G standards. These changes can be made on a 1G/10G platform.

 

2.The next type of multi-rate transceivers is also Rate Select but without any changes to operating parameters.

Here the CDR is simply bypassed.  So, the specification or data sheet may not include the extended data rate parameters. They may not be compliant to MSA standards. Examples include 10G MR (multi rate), 2G/4G/8G Fiber Channel, 10G/40G, 10G/25G.

Multi-rate transceiver

 

In the above example SFP28 10G/25G, you can see that for 10G and 25G data rates, the values are very close in extinction ratio, sensitivity, and very similar in transmitter power.

3.The third type of multi-rate transceivers use auto data rate detection to bypass CDR. Once you plug in the transceiver, the CDR will detect the different data rates and automatically switch to bypass mode on the CDR. Examples include 40G/ 100G.

4.The fourth type of multi-rate transceivers operates by inherent design.

This type of transceiver maximizes the data rates and optimizes performances to the extended data rate. They are compliant to MSA standards, and datasheets must include extended data rate parameters. Examples include Ethernet/ OTN OTU, GEth/ CPRI/ FC.

Conclusion

The key benefit of dual rate transceiver is that it offers operators flexibility allowing for incremental network upgrades.

Vitex offers 1G/10G, 10G/25G and 40G/100G multi-rate transceivers. Our 10G/25G multi-rate modules come in SR (Short Reach) and LR (Long Reach) versions.

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