[Asterisk-Users] UDP Fragmentation Problem

[Adam Hart]

Andrew Kohlsmith wrote:

> On October 31, 2004 05:36 pm, Bastian Schern wrote:
> 
>>I've got no success to get a friend in Bogota (Colombia) connected to my
>>Asterisk. He has got a ISDN Internet connection and the UDP packets will
>>be fragmented. It seems that the MTU of this connection is round about
>>400 to 500 Bytes. Therefore most UDP-SIP packages are fragmented.
>>Is Asterisk not able to handle fragmented UDP packages?
>>Is it possible to use SIP over TCP with X-Lite?
>>Or has somebody another hint for me?
> 
> 
> As far as I am aware there is no such thing as a fragmented UDP packet; each 
> packet is sent out on its own, there is no coherency between UDP packets like 
> there is with TCP packets.
> 
> I could be very wrong here, it's been a late night with the kids.  :-)
> 

Packet fragmentation is at the IP layer, so UDP will have fragmented 
packets too. But... the OS should handle that and Asterisk shouldn't 
find out - it's a all or none policy, so it should receive the whole 
packet at once or nothing.