[Asterisk-Users] UDP Fragmentation Problem

[Bastian Schern]

Rich Adamson schrieb:
>>Bastian Schern wrote:
>>
>>>Hi everybody,
>>>
>>>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?
>>>
>>
>>Fragmentation should not matter for the end-point (the source or 
>>destination of the UDP datagram), since the IP stack itself should take 
>>care of the reassembly..
>>But....it is quite weird they have such a small MTU. Many websites that 
>>have problems with Path MTU discovery would be broken by that (dumb 
>>websites, but still, way too many...).
> 
> 
> Fragmentation shouldn't make any difference as the sip/rtp/g711 packets 
> are roughly 250 bytes anyway.

In the case of SIP is imho not correct. E.g. a SIP REGISTER packet is 
round about 656 Bytes long.

RTP I don't know. And what is with RTP-GSM/G729 packets?

Regards
	Bastian