[Asterisk-Users] Received packet with bad UDP checksum

[Peter Svensson]

On Mon, 20 Dec 2004, Matthew Boehm wrote:

> Searched google for this and didn't get much help.
> 
>     -- Executing SetVar("Zap/1-1", "SIP_CODEC=alaw") in new stack
>     -- Executing Dial("Zap/1-1", "SIP/15126800411 at Voex|60") in new stack
>     -- Called 15126800411 at Voex
>     -- Accepting call from '2819870065' to '5126800411' on channel 0/1, span
> 1
>     -- SIP/Voex-9b0a is making progress passing it to Zap/1-1
> Dec 20 15:08:36 NOTICE[11117]: rtp.c:355 ast_rtcp_read: RTP: Received packet
> with bad UDP checksum
> 
> The call went thru and sounded fine. But I was worried about this notice. Am
> I correct in understanding that since it says "Recieved", that means I got a
> packet into asterisk from @Voex that was bad? ie: they sent me a bad packet?

The error message is not entierly correct. It is generated when a read on 
from the upd port socket returns EAGAIN. While it is true that Linux does 
this when a corrupted upd packet would have been read, this is not the 
only possible cause of the EAGAIN. EAGAIN is not an error, it simply 
states that there was nothing to be read at the moment.

Peter