Re: Network stack/ethernet driver issues
Re: Network stack/ethernet driver issues
- Subject: Re: Network stack/ethernet driver issues
- From: Michael Cashwell <email@hidden>
- Date: Thu, 10 Apr 2008 13:35:50 -0400
On Apr 10, 2008, at 11:44 AM, Justin C. Walker wrote:
On Apr 10, 2008, at 06:45 , Michael Cashwell wrote:
The point in rimas' case is that just because the data are UDP does
not give the Ethernet driver more permission to drop them than if
they were TCP [corrected] nor does it mean they are less important.
You are correct that an ethernet driver does not have permission to
drop one kind of packet over another, I don't think you are correct
in your implication that it cares about network-layer packet types
Did I imply it does? I didn't intend to.
: these are all one to the driver (it's possible for the driver to
obey QOS indicators of some type, but it can't know about the IP
frame type: in particular, it may not know that a particular packet
is in fact (part of) a UDP frame). After all, it's ethernet. Even
if the packet gets to the media layer, there's no guarantee that (a)
it will make it out the door; or (b) even if it gets out the door,
it may not survive the trip across the local link :-}).
Fragmentation is fun. :-)
I don't think TCP/UDP or QoS is involved in rimas' problem. That
really does look like a driver issue.
My point was only to underscore that there are different dimensions to
the question of what delivery characteristics are most important. If
you're transferring live video having data arrive late is no different
from it not arrive at all. In fact, if "late" requires retries and
resends (and this consumed even more bandwidth and resources) only to
just be dropped anyway then late is actually worse than not at all.
Assuming that someone's data is less important just because they used
UDP is flawed.
-Mike
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