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Because someday you’ll need that fantastic collection of stamps

April 20, 2015

15-04-20 stuff
I have a minor problem with the w5500-based servers. Sometimes you get a session established but when you check how many bytes of data have been sent the answer is zero. I used to just drop those sessions with the w5200 but now it seems to hang some browsers sometimes. Specifically, safari coming from outside the lan almost always does this and it doesn’t like it if you just ignore or close the session. I get around this by re-reading the data length up to 10X with a 20ms delay between reads. I am not a fan of this because sometimes, with other browsers(I’m looking at you chrome) they cause a session and there never IS any data so the server is tied up for 200ms waiting in vain. Also, it’s icky.

I posted a query on the wiznet forums and they asked for a wireshark capture. So here we have, on the left, a windows PC running wireshark, my laptop serving as power supply and serial console for the olduino, and, behind the olduino, an ancient powered ethernet hub that puts the desktop pc on the same ethernet segment as the olduino so it can see the packets. The cable modem is plugged into the hub as are the desktop and olduino. The phone, which sent the transaction, is taking the picture. I needed the hub because most routers act as switches as well. Packets for one port are only visible on that port.

I have no idea at all what the packet trace data shows but there are plenty of retries and such, I’m hoping for wisdom from afar.
15-04-20 packets

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From → web server

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