Re: [lwip-users] Ping Causing "not enough space for new header size" Over PPP

[address@hidden]

Greg Smith wrote:

Hello.

Using lwIP 2.0.0 Beta1, I have been able to connect my target via PPP to an embedded Linux control.  After successful connection, I am trying to ping the lwIP target.  It has about 25-33% packet loss over time.  From the debug output, I see that I'm occasionally getting a "(not enough space for new header size)" message from pbuf_header_impl() in pbuf.c.

 

I don't really understand what that's trying to tell me since I'm only receiving about 90 bytes from the ping packet, but I think I have my pbuf size set well above that.  (I've tried setting PBUF_POOL_BUFSIZE to 500, 600, 1500, and 1520).

PBUF_POOL_BUFSIZE has nothing to do with this. This is not a RAM issue but a config issue. Can you tell us the call stack when pbuf_header() fails? Without this info, I can't tell you where the problem is right now...

To give you an insight: when rx packets are fed into the various layers, headers are stripped. pbuf_header() is later used to restore the space for more headers at the front of the buffer. Somehow, this fails for your configuration. This is a only problem when having PPP *AND* ethernet, since the two interfaces require different header sizes...

Simon