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Newbie
Newbie
5,701 Views
Registered: ‎11-29-2010

lwIP Web Server Uploading Issues (HTTP POST)

We have a web server, which is implemented with lwIP in socket mode (in Xilkernel), that we are trying to upload and download files from using HTTP POST and GET. The documentation for lwIP says that the max bandwidth, under good circumstances, for both upload and download is 7Mbps. We are currently pulling ~5Mbps for our HTTP GET (downloading a file from the server), which is quite acceptable for us. However, we are having issues with the HTTP POST (uploading a file to the server). We have been stuck on this issue for quite some time now. We are getting ~20Kbps (a complete maximum). Not only are our upload speeds quite shot, but the TCP/IP interaction is not very stable. We are getting a number of different packet issues, which we identified by Wiresharking the transaction:

 

  • TCP Retransmission (From the client to our web server)
  • TCP Window Update (From the web server to the client)
  • TCP Dup ACK (From the web server to the client. This doesn't happen as often as the other two.)

 

The Retransmissions and Window Updates are quite frequent and happen about every 2-5 packets received by the web server. 

 

Our server is running in thread priority mode (with the web server thread and netif thread at highest priorities). We have a low priority debug thread that toggles the LEDs every 10ms, so when the server is being taxed (e.g. When we have an HTTP GET and a client is downloading a file from the server) the LEDs lag, and don't blink because of the low priority. This does NOT happen when we are testing the HTTP POST. 

 

Any help would be greatly appreciated. Thank you.

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2 Replies
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Xilinx Employee
Xilinx Employee
5,621 Views
Registered: ‎08-01-2007

Re: lwIP Web Server Uploading Issues (HTTP POST)

Is it a direct connection from PC to board in a subnet?
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Newbie
Newbie
5,608 Views
Registered: ‎11-29-2010

Re: lwIP Web Server Uploading Issues (HTTP POST)

We are on the same subnet, but it is not a direct physical connection. Both the PC and the Spartan 3E are connected via a router.

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