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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.

a b


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

c d

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


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

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


On the transmitter end:

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

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closed as unclear what you're asking by Dave M, Simon Sheehan, Moses, Dave, Joe Taylor Nov 1 '13 at 16:40

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question.If this question can be reworded to fit the rules in the help center, please edit the question.

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. – Ƭᴇcʜιᴇ007 Oct 31 '13 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 '13 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". – sammyg Oct 31 '13 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? – sammyg Oct 31 '13 at 17:12
up vote 3 down vote accepted

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 and, mask Only one of them can/should have a gateway, and if you need to put one in, just pick one of those IPs ( 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 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"? – sammyg Oct 31 '13 at 17:42
@Sammy No, just use the ip addresses. – cmorse Oct 31 '13 at 17:43
Ok. Which one do you use? The TTCP (original), PCATTCP, WSTTCP, or NTttcp? Which one is the easiest to use? – sammyg Oct 31 '13 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. – Ƭᴇcʜιᴇ007 Oct 31 '13 at 17:50
When I do ping or ping 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 – sammyg Oct 31 '13 at 17:55

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