Resend Packet Requests

[ajp000]

I'm configuring a Prosilica GX camera (GigE) to run on two cables, link aggregated.  I had some problems with dropped packets initially, but I think I've sorted that by limiting the packet size, frame rate, etc.  Now Lost Packet Count = 0, but I still get Resend Packets Requested/Received in the hundreds or thousands.

Are resend packet requests a sign that something is still wrong in my system, or a sign that the communication protocol is working?  Good or bad?

My gut feeling is that as long as packets aren't dropped, it's okay - but I'd like to learn more.

Thanks,

Anne

[ScottSmith]

Hi Anne,

It depends.  On the one hand, ethernet is designed to handle packet collisions and resends... as long as things are configured withing overall throughput capacity of system.   So hundreds of resends per 5 minutes, or thousands per hour... could be fine... if all info gets through ultimately.   It's dropped (lost) packets that would be the potential worry.  But you say that's zero, so if "good enough is good enough" you can stop tuning.

If you want further help, please state what NIC, whether set for jumbo packets, what the NIC settings are and StreamBytesPerSecond are, verify you are using Cat5e or better cables known to be good, etc. ... so we can all take a look.

Regards,

Scott  (...at AVT Applications Engineering)

[ajp000]

Hi Scott,

My dropped packets problem has continued to occur intermittently (but not constantly).  Sometimes it works fine.  Here are some details:

I'm using a Prosilica GX 1050C with two Cat6 cables.  I teamed both ports of an Intel Pro/1000 PT Dual Port Server Adapter, and jumbo packets are enabled (up to 9014)

IMAQdx version 4.2.0

MAX version 5.5.0f0

Windows 7 Professional computer

NI Gige Vision Adaptor driver installed, version 1.5.2.49153

Intel Pro/1000 PT Dual Port Server Adapter, driver version 9.16.10.0

Running my link-aggregated camera on the NI driver causes a near-immediate crash, so I usually use the Intel driver, which has much more stable performance.  Sometimes it works well if I set it to the GigE driver, restart the computer, return it to Intel driver and restart again...?  Could be looking too hard for patterns here.

On a good day, I can send packets as large as 4000bytes, but no bigger, despite jumbo packets being on.  I've attached my .icd with the camera settings.