[LARTC] Suggestion - table of QoS mechanisms

[Jason Boxman]

On Tuesday 04 January 2005 23:24, Jonathan Day wrote:
> Hi,
>
> A thought for the list. As I mentioned in another
> posting, there are a lot of QoS mechanisms out there.
> Linux supports some, but not all. Some patchsets add
> others, but don't work for all kernels. There are also
> userland implementations, usually sitting in software
> routers, but there are other packages.
>
> Would it be helpful if I worked on a table of what's
> out there for Linux and in what form?

Possibly.

I only know of CBQ, HTB, HFSC, SFQ, TBF, PFIFO, PRIO, G/RED for Linux offhand.

> The main drawback of such a list is that while I can
> tell you if such-and-such an implementation exists,
> that doesn't mean the implementation is any good, or
> that the QoS concept is valid. There are plenty of
> arguments amongst QoS researchers as to whether RED is
> useful or not, and those are the people most qualified
> to know the answer. Nor would I be able to verify what
> kernel patches work well together, so the individual
> existance of specific mechanisms doesn't mean you can
> combine them usefully.

Yeah, QoS isn't exactly a plug and play experience.

> On the other hand, there doesn't seem to be any easy
> way for people to find out what does exist, what
> doesn't exist YET for Linux but could easily be
> written, or what used to exist but has been dropped
> for reasons known or unknown.

I wrote a guide, Practical Guide to Linux Traffic Control[1], which I keep up 
to date as developments change.  I only cover stuff in the mainline kernel 
for the most part, though.

[1] http://trekweb.com/~jasonb/articles/traffic_shaping/

> For example, SGI's "Scheduled Transfer Protocol",
> MPLS, WRR and ESFQ are all examples of networking
> algorithms that are apparently deceased. The Layer 7
> packet classifier isn't dead, but doesn't apply
> cleanly to kernels 2.6.9 or later.

Layer 7 does patch against 2.6.9 with an experimental patch available since 
the beginning of December on the project's SF page.  It Works For Me (tm) but 
I guess it hasn't been tested sufficiently such that it's now available as a 
stable 2.6.9+ patch.

> Finding these can be fun, too. I've got a copy of the
> Scheduled Transfer Protocol patches, but that's
> because I downloaded them while they were still on
> SGI's FTP site. If they exist anywhere on the Internet
> today, I haven't the foggiest where. The site for ESFQ
> is dead, and the only known patches forward-ported to
> recent kernels is merged into the qnet patch series,
> making it hard to extract.

That's too bad.  I had wanted to include something about ESFQ but never got 
around to it, since SFQ generally suits my needs.

-- 

Jason Boxman
Perl Programmer / *NIX Systems Administrator
Shimberg Center for Affordable Housing | University of Florida
http://edseek.com/ - Linux and FOSS stuff