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The motherboard of my desktop PC features two Ethernet ports. Each port has its own network controller from Realtek and they are both capable of Gigabit Ethernet. Now, I have this crazy idea to take a short Ethernet category 5e cable and connect it between the two ports, to create a loop. The idea is to test the throughput of both of these ports using the shortest possible cable length.

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I have already connected the two ports. One of the connections is identified as Network 6, and I have chosen Home as network type to make it discoverable. The other one got stuck at "identifying". But it's seen as unidentified network now and I have manually changed the type from Public to Home. I was then prompted by Windows Media Player to share media files between these two. Under Network, one is seen as a network computer and the other one shows up as a portable media player. There are three devices with the same name.

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Update


I have set one connection to IP 10.1.1.1 and mask 255.255.255.0 and the other one to IP 10.1.1.2 and mask 255.255.255.0. I also added 10.1.1.1 as gateway on the second connection.

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After doing this, "Network 7" has now been identified.

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Using pcattcp...

On the receiver end:

C:\PCATTCP-0114>pcattcp -r
PCAUSA Test TCP Utility V2.01.01.14 (IPv4/IPv6)
  IP Version  : IPv4
Started TCP Receive Test 0...
TCP Receive Test
  Local Host  : GIGA
**************
  Listening...: On TCPv4 0.0.0.0:5001

  Accept      : TCPv4 0.0.0.0:5001 <- 10.1.1.1:8127
  Buffer Size : 8192; Alignment: 16384/0
  Receive Mode: Sinking (discarding) Data
  Statistics  : TCPv4 0.0.0.0:5001 <- 10.1.1.1:8127
16777216 bytes in 0.089 real seconds = 184089.89 KB/sec +++
numCalls: 2061; msec/call: 0.044; calls/sec: 23157.303

C:\PCATTCP-0114>

On the transmitter end:

C:\PCATTCP-0114>pcattcp -t 10.1.1.1
PCAUSA Test TCP Utility V2.01.01.14 (IPv4/IPv6)
  IP Version  : IPv4
Started TCP Transmit Test 0...
TCP Transmit Test
  Transmit    : TCPv4 0.0.0.0 -> 10.1.1.1:5001
  Buffer Size : 8192; Alignment: 16384/0
  TCP_NODELAY : DISABLED (0)
  Connect     : Connected to 10.1.1.1:5001
  Send Mode   : Send Pattern; Number of Buffers: 2048
  Statistics  : TCPv4 0.0.0.0 -> 10.1.1.1:5001
16777216 bytes in 0.091 real seconds = 180043.96 KB/sec +++
numCalls: 2048; msec/call: 0.045; calls/sec: 22505.495

C:\PCATTCP-0114>
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  • What makes you think it's NOT possible? What exactly have you tried already? What were the results? Where are you getting stuck? "Does this make sense?" and "Is this possible?" are not good questions for SU. Oct 31, 2013 at 16:50
  • What would the purpose of this be? What problem are you trying to solve other than simple curiosity?
    – Dave M
    Oct 31, 2013 at 17:06
  • @techie007 I have already connected the two ports. One of them is identified as Network 6, and I have chosen Home as network type to make it discoverable. The other one is stuck at "identifying".
    – Samir
    Oct 31, 2013 at 17:10
  • @DaveM The idea is to test the throughput, i.e. to see what kind of transfer speeds I can get. But there's no way to do that on the same computer? I would need a second computer?
    – Samir
    Oct 31, 2013 at 17:12

1 Answer 1

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I'll preface this by saying I've never actually tried this, but I can't see why it wouldn't work as such:

  • Hook up the wire (since they're Gb ports, you shouldn't need a crossover cable to get Link).

  • Configure the adapters to be on the same subnet (say 10.1.1.1 and 10.1.1.2, mask 255.255.255.0). Only one of them can/should have a gateway, and if you need to put one in, just pick one of those IPs (10.1.1.1 or .2).

Even if it's stuck on "identifying" you can should still be able to use the connection ('identifying' often requires DNS, which may act weird if not available, but won't prevent IP address-based connections).

You also don't need to make them 'discoverable' per-se. Just turn off the firewall and use IP addresses for targeting.

  • Test with ping: ping 10.1.1.1 to ensure connection.

  • Run a host-to-host TCP bandwidth tester. I like this one for Windows use.

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  • Wouldn't I need two "hosts"?
    – Samir
    Oct 31, 2013 at 17:42
  • @Sammy No, just use the ip addresses.
    – cmorse
    Oct 31, 2013 at 17:43
  • Ok. Which one do you use? The TTCP (original), PCATTCP, WSTTCP, or NTttcp? Which one is the easiest to use?
    – Samir
    Oct 31, 2013 at 17:46
  • The Windows one -- the one that page is for: PCATTCP. :) "The PCATTCP program is simply PCAUSA's port of TTCP to Windows Sockets". They're just offering links to the original Unix program it was based on. Oct 31, 2013 at 17:50
  • When I do ping 10.1.1.1 or ping 10.1.1.2 in cmd I get a response in less than 1 ms. Are these being sent out from the "localhost"? When I do ping localhost I see "Pinging GIGA [::1] from ::1 with 32 bytes of data". What does this mean? Why is it not saying 127.0.0.1?
    – Samir
    Oct 31, 2013 at 17:55

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