[nycbug-talk] Good article about gigabit performance issues

[pete wright]

On 4/17/05, Tillman Hodgson <tillman at seekingfire.com> wrote:
> On Sat, Apr 16, 2005 at 10:35:58AM -0700, pete wright wrote:
> > On 4/16/05, Mikel King <mikel.king at ocsny.com> wrote:
> > > http://www.enterpriseitplanet.com/networking/features/article.php/3497796
> >
> > Nice one, although I'm suprised that they downplay the benefits of
> > "Jumbo Packets".  The benefits are pretty real, and there are plenty
> > of switches available now that support large MTU's.
> 
> For smaller networks, jumbo packets often don't work.
> 
> Lots of small networks want one or two critical servers to be on gigabit
> (filesharing, mostly) and the rest of the network on fast ethernet. Lots
> of the low-end of "real" switches are built to accommodate this: 24
> 100Mbit ports and 2 gigabit ports.
> 
> Unfortunately, ethernet frames must be the same size within a network.
> The 100Mbit ports will determine the maximum frame size. That's
> unfortunate, because it means that even between the two gigabit ports
> on a switch like that you can't use jumbo frames.
> 
> -T

yea no doubt, I can't see many small networks implementing this.  You
make a good point about the shared gig-e/100Mbit switches.  I guess I
have always kept my gig-e interfaces on gig-e only networks.  This is
where a real benefit fat packets comes into play.

For example, in the FX world it is not uncommon to connect multiple
IRIX compositing workstations together via Gig-E to share data
(film/video clips) between hosts.  This used to be done via HIPPI
networks (and still is to some extent), altho as gig-e has become more
mainstream the use of HIPPI has become less common.  This network is
seperate from the regular office LAN (could you imagine an office wide
HIPPI land ;).  Obviously, this example is an exception to the
"typical" network...

Another, maybe more typical, architecture I have found is using
"fat-packets" on a seperate gig-e only network for backend servers. 
The idea is that you would have backups, DB and NAS servers talking to
each other via this quicker network which will hopefully speed up some
client/server operations.

-p

-- 
~~o0OO0o~~
Pete Wright
www.nycbug.org
NYC's *BSD User Group