[Serusers] UDP fragmentation

[Thilo Salmon]

On Fri, 2004-01-02 at 18:42, Nils Ohlmeier wrote:
[INVITE messages to large to avoid fragmented UDP packets]
> You can remove header fields with the remove_hf() function from the textops 
> module. You should verify that you do not remove required header fields, but 
> basicly it should be possible to do it that way. Allthough i think this not a 
> very good solution because you will never know to which size the request will 
> grow and if you will be able to strip it down under 1500.

Thanks a lot for pointing this out. I was looking for this function. It
has not yet been documented, I believe.  Do you happen to know, if there
is a similar function to determine the size of the current message? That
would come in handy, since you could refrain from stripping information
unless the message was too large. Or even strip a little more, if you
knew for certain that a call could not be set up unless you avoid
fragmentation.

> I think the better choice is to switch to TCP to eliminate the MTU
problem. 
> Either directly at the starting UA, or you can also switch the transport at 
> SER with forcing the transport for forwarding to TCP.

I guess I have to read up on SIP over TCP. With regards to NAT it sounds
a little like trading lemons, since by the sounds of it you are
introducing a whole new set of problems. 

That comes hard, since I was just too happy I had solved all my SIP
through NAT issues...

Thilo