What's true Powerline Adapter throughput when 1Gbps is advertised with 100Base-T Ports?

Question

Usually, marketing terms are technically true under certain narrow circumstances.

However, I don't understand why there are Gigabit Powerline Adapters that only have 100M Ports. It is physically impossible to reach 1 Gigabit. Some of them have 2 ports, so might be able to setup LAG to get to 200Mbps - but that's not even close to 1G.

What's the reasoning behind marketing these products like that?

Answer 1

That is because the real performance of PLC is very low, there are many factors to affect the real performance, such as distance between nodes/power line topology/load type online. In fact it is really crazy to run high speed communication on power line which is designed to deliver power which only require low DC resistance and isolation instead of data communication which requires uniform impedance/low cross talk/appropriate termination/point to point topology. But technologies is to make the impossible possible so here is Gigabit PLC. To get 100Mbps+ you need very good power line condition which is in most circumstances not satisfied. Even sometimes you can get 100Mbps+, other time when more appliance is online, the speed will drop substantially. For a 100Mbps PLC, you may get 10Mbps, then for a Gigabit PLC, you may get 100Mbps. A Gigabit LAN port need Gigabit PHY chips and Gigabit transformers which add cost and for most home use case, this extra cost doesn't bring you a guaranteed performance/experience boost. BTW some BroadCom chipsets seems to have built in Giga PHY, but you still need the transformer.

BTW you cannot get 200Mbps with the two 100Mbps ports since the built in LAN switch generally doesn't supports this feature.

PLC is never about performance, but Giga LAN and cutting edge Wifi is.

Answer 2

The question of true Powerline throughput has been thoroughly discussed by many sources.

You may find a website dedicated to the question in Powerline Charts, where one can query for empirical test results by various parameters such as model, benchmark and more.

You will find that most numbers advertised by companies are achieved under ideal conditions, where two adapters are branched on the same outlet. Just moving one adapter to the next room may make a big difference.

You will also find about "Total Simultaneous Throughput", meaning when the adapter is sending and receiving at the same time. Since Fast Ethernet is full-duplex, a port can transmit and receive simultaneously. Consequently, if a Fast-Ethernet port of 100Mbps is performing at its maximum throughput (e.g. sending and receiving), it can operate near its theoretical maximum - 200Mbps. This means that two ports can reach 400Mbps, which is that much nearer to 1Gbps.

I suggest reading the thread Powerline Adapter only providing 100mbps when I have a Gigabit Plan, 2 Cat 5E cables, and a Nighthawk N7000, where the question is discussed very thoroughly.

One of the comments there says that the documentation for Powerline adapters made by small Chinese companies may contain serious errors and is not to be trusted on technical details. A Powerline adapter may be advertised as 1Gbps and truly be so in spite of the documentation, because the advertised 100mbps port may truly be 1Gbps. (My own experience is that even a well-known Chinese company may have errors in its technical documentation.)