[CentOS] [OT] Network switches

[Rainer Duffner]

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
client-performance.

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 ;-)


Rainer