[CentOS] [OT] Network switches

Tue Mar 24 15:24:07 UTC 2009
Rainer Duffner <rainer at ultra-secure.de>

Rob Townley schrieb:
> Every time i read these posts they are filled with contradictions in
> that one person loves HP and hates CiscoLinksys while another hates
> HP.  Let's get a more scientific approach.  Switch performance still
> depends on the NICS in the client machines. 

Uhm. No. Not any longer, AFAIK.
At least, once you leave the SOHO region (AFAIK, the OP wanted >= 48
ports. I don't want to work in such a home-office, really...).
Backplane-performance is an issue.
Especially with iSCSI.

Also, as demonstrated, different switch-vendors offer different
feature-sets at different price-levels.
There's also the compatibility-question: if you already have a number of
devices, the new ones must fit in well into the existing landscape
(VLANs etc.pp.)

> Performance data would need to have details such as the NIC on the
> client machine and other hw characteristics.  How many machines ran
> the benchmark simultaneously.  Cat5e vs Cat6 or Fiber connected.

That's already more variables in the equation than is healthy for a
typical benchmark...

> http://www.netperf.org           ( OpenSource started by HP, )
> ftp://ftp.netperf.org/netperf/    (Looks like 2.4.4 is the latest
> version.  Not sure what 4.0.0 is)
> http://sourceforge.net/projects/jnetperf  (java version of netperf)
> There may be another project from some Italian Professor, but didn't
> find it in my bookmarks.
> Yes, there is the unix way of time dd ... but that wouldn't work for
> windows clients and does not give enough details in terms of metrics.

Switch performance is extremely difficult to measure IMO. You need
enough clients to make sure you're not accidentally measuring

In the end, the only thing that counts is real-world data. Netperf
et.al. don't really provide a real-world scenario, where you have a
mixture of packet-sizes and protocols.
Same for artifical load/packet generators (ixia et.al).

Because (almost) nobody has the time to do extensive tests, past
real-world experience/performance data and word-of-mouth becomes an
integral part in choosing such products.
That, or you have enough money to buy everything from Cisco ;-)