My network card appears to have two Ethernet ports. I'm trying to work out the theoretical maximum speed of those Ethernet ports - specifically if they are Gigabit (1000Mbit/s) ports or plain old 100Mbit/s.

I've tried a couple of different things:

  1. Device Manager shows me having Realtek PCI GBE Family Controller drivers. Does the GBE stand for Gigabit?

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  1. The controller properties shows both ports are 1.0 Gbps capable.

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  1. I've used WMIC to get the speed in bits. Which is 100000000 bits, so 100 Mb.

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  1. Finally I've checked the Ethernet status. Which is where my confusion lies as this says 100Mbps. Is this because I only have a Cat5 Ethernet cable plugged in, or is this the real speed.

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How can I determine the speed of my Ethernet ports?


You have gigabit ports connected to a 100 megabit switch (or equivalent device). GBE = Gigabit Ethernet. The 100 megabit will be coming from the speed negotiated with the switch or equipment on the other end of the link.

The cat5 cabling is probably not relevant - most cat5 cables will negotiate a gigabit connection (but you might not get the full gigabit throughput). That said, if your cabling is only using 2 of the 4 pairs, then it would negotiate 100 megabit.

  • As a test to prove this, you may be able to link the 2 ethernet ports on the system to each other - they won't get an IP/Internet connection, but they should negotiate a gigabit connection. – davidgo Jan 5 '16 at 1:26
  • Setting static IPs might be necessary there – Journeyman Geek Jan 5 '16 at 1:27
  • @JourneymanGeek surely they would negotiate a connection even in the absence of IP addresses ? (ie because the ethernet layer sits beneath the IP layer) – davidgo Jan 5 '16 at 1:28
  • maaaybe. For some reason I don't remember that happening the last time I went point to point. – Journeyman Geek Jan 5 '16 at 1:30
  • You'd need a cross-over cable, unless they're auto-sensing, to connect a host NIC to another host NIC. I'm not sure how modern OSes would treat a loop; it would be unlikely that even with IP addresses, any traffic would actually use the loop, as both addresses would be local addresses: sending a packet to either one would never even make it to the NIC. – Nevin Williams Jan 5 '16 at 2:07

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