I tried the ipolex, Wiitek, HiFiber, and FLYPROFiber 10G SFP+ to RJ45 Transceivers (as reviewed in the buyer's guide) in a MikroTik CRS305-1G-4S+IN switch and they all exhibit this behavior (using iperf, speedtest.net, CrystalDiskMark, etc.).
Tested with PC A that has an Intel X540-T1 NIC and PC B with integrated Intel I211 ethernet.
PC A -> Transceiver -> Transceiver -> PC B
This gets ~300/940 Mbit/s send/receive
If I connect either PC to the 1G PoE/BOOT/MGMT port on the switch, it will perform at ~940/940.
PC A -> MGMT -> Transceiver -> PC B
PC A -> Transceiver -> MGMT -> PC B
In the first situation, the 10G client is forced to connect at 1G, so both clients are communicating at 1G.
In the second situation, the 10G client is connected at 10G, but the switch's own 1G port is used to connect to the 1G client.
For both situations, I can get ~940/940 throughput. But not with a 10G transceiver connected to the 1G client.
It seems that the switch's own 1G port can handle talking to a 1G client without a performance hit, but performance cuts to 1/3rd if I use any of the 10G transceivers to connect to the 1G client.
Has anyone else observed this, and is this to be expected?
Tested with PC A that has an Intel X540-T1 NIC and PC B with integrated Intel I211 ethernet.
PC A -> Transceiver -> Transceiver -> PC B
This gets ~300/940 Mbit/s send/receive
If I connect either PC to the 1G PoE/BOOT/MGMT port on the switch, it will perform at ~940/940.
PC A -> MGMT -> Transceiver -> PC B
PC A -> Transceiver -> MGMT -> PC B
In the first situation, the 10G client is forced to connect at 1G, so both clients are communicating at 1G.
In the second situation, the 10G client is connected at 10G, but the switch's own 1G port is used to connect to the 1G client.
For both situations, I can get ~940/940 throughput. But not with a 10G transceiver connected to the 1G client.
It seems that the switch's own 1G port can handle talking to a 1G client without a performance hit, but performance cuts to 1/3rd if I use any of the 10G transceivers to connect to the 1G client.
Has anyone else observed this, and is this to be expected?