Subject: Re: prioritizing ACK's without ALTQ
To: Geert Hendrickx <>
From: None <>
List: tech-net
Date: 03/08/2006 16:03:47
On Wed, Mar 08, 2006 at 03:43:14PM +0100, Geert Hendrickx wrote:
> the most popular/basic traffic shaping application seems to be prioritizing
> ACKS's (for asymetric network connections).  I haven't used ALTQ before, so
> I don't know how hard/simple it is to implement this with ALTQ (or any
> other traffic shaping tools), but could this feature be implemented
> directly in the network stack, tunable with some sysctl?  That would be
> very handy (i.e. only having to enable e.g. net.inet.tcp.prioritize_ack
> instead of editing a config file and starting altq).  

You can implements hacks like ppp by using an alternative queue for
management stuff etc., but it is certainly not trivial. For anything
else you need to classify the packet first, which means about half of
the problems with ALTQ.

Keep in mind that the feature you ask for is a major layer violation,
since between ACKs and network queues are at least IP/IPv6 headers.