Michael van Elst wrote:

>tron@zhadum.org.uk (Matthias Scheler) writes:
>
>  
>
>>Yes, but it hasn't changed and never will. Large UDP packets are sent
>>as IP fragments. If you lose one of the IP fragments the whole UDP
>>packet is lost because there is no selective retransmit. When a machine
>>e.g. loses 5% of incoming packets at least one of the IP fragments
>>of a 32KB UDP packet will always get lost. Retries will not help because
>>another single lost packet will prevent the reception of the UDP packet.
>>    
>>
>
>On the other hand, TCP isn't exactly fast with 5% packet loss either.
>  
>
No, but it still functions.  UDP functions fine in this environment --
if the UDP packets are small.  If the UDP packets are large, you're toast.

>The problem with some older machines however was not some arbitrary
>packet loss but a very specific packet loss caused by back-to-back
>sending of IP fragments. By using TCP or by reducing rsize/wsize to 1k
>the problem goes away.
>  
>


-- 
Garrett D'Amore                          http://www.tadpolecomputer.com/
Sr. Staff Engineer          Extending the Power of 64-bit UNIX Computing
Tadpole Computer, Inc.                             Phone: (951) 325-2134