Linux shaping packet loss

Joe Abley jabley at
Tue Dec 8 09:13:48 CST 2009

On 2009-12-08, at 15:01, sthaug at wrote:

>> Won't say I'm an expert with TC, but anytime I see packet loss on an 
>> interface I always check the interface itself...10% packet loss is 
>> pretty much what you would get if there was a duplex problem. I always 
>> try to hard set my interfaces on both the Linux machines and Switches.
> Used to set everything hard five years ago. Nowadays auto works just
> fine most of the time.

I find there is a lot of hard-coded wisdom that hard-coded speed duplex are the way to avoid pain.

The last time I saw anybody do a modern survey of switches, routers and hosts, however, it seemed like the early interop problems with autoneg on FE really don't exist today, and on balance there are probably more duplex problems caused by hard-configured ports that are poorly maintained in the heat of battle than there are because autoneg is flaky.

I've also heard people say that whatever you think about autoneg in Fast Ethernet, on Gigabit and 10GE interfaces it's pretty much never the right idea to turn autoneg off.

I am profoundly ignorant of the details of layer-2. It'd be nice to have more than vague rhetoric to guide me when configuring interfaces. What reliable guidance exists for this stuff?


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