Subject: Re: NFS problem.
To: None <email@example.com>
From: Michael van Elst <firstname.lastname@example.org>
Date: 12/10/2005 08:52:11
email@example.com (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.
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.