On Tue, 28 Nov 2000, David Ross wrote:

> If you look at how ethernet works, most of time anything you do will
> mask errors. EtherNet has error recovery built in. So an undemanding
> transfer, such as a Finder copy, will tend to get through, errors or
> not. It's those programs that really hammer the network, like a backup
> program trying to keep a tape at speed, that tend to fail.

Here's something to consider as a *possible* cause for 519 (and other
Ethernet) errors:  We have several new G3 and G4 servers that connect
directly to high-end switches via six-foot certified Cat 5e patch cables.
When these computers boot, and the switch ports are set to auto-negotiate,
both ends *always* come up full duplex.  However, if a patch cable is
briefly disconnected (or power is removed from the switch), the switch
port comes back up at *half* duplex.

A duplex mismatch can be invisible at low to moderate traffic loads on a
given connection, but at high loads the connection breaks down with
massive numbers of errors.  Accordingly, on switch ports connected to
servers we force the duplex setting to full (which probably has little or
no throughput improvement over half duplex, because of limitations in the
Mac OS).


Mark E. Ingram


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