[TriLUG] OT - gigabit switches

[OlsonE at aosa.army.mil]

<snip>
One other point that I wanted to verify is that one of the jobs of the
switch is to keep traffic away from parts of the network that are not
involved with the sender or receiver.  For example - the switch in our
test lab is hooked to the switch for the rest of the office, to which
the rest of our desktops are connected.  So when we are running tests in
the lab, none of that traffic bleeds into the rest of the network
affecting performance there.  My understanding (and anecdotal evidence)
is that this is true...is it?
</snip>

...that's more or so the purpose of a VLAN. In a flat network, you have
what I call "packet grenades" being thrown around....

-----Original Message-----
From: trilug-bounces at trilug.org [mailto:trilug-bounces at trilug.org] On
Behalf Of Christopher L Merrill
Sent: Thursday, September 21, 2006 10:20 AM
To: Triangle Linux Users Group discussion list
Subject: Re: [TriLUG] OT - gigabit switches

Wow!  What a great bunch of responses, especially those from Greg, Ryan
and Aaron.  Most of it was over my head...but I'm hoping to absorb just
enough to make an intelligent decision for our test lab.

I've tried to identify which specs of a switch are actually important
for our use-case.  To recap, we're are moving towards having (at most)
20 computers in our test lab with GigE NICs (some with multiples).
When we care about the performance, the scenario will be that most of
those computers will be hammering one or more web servers, also on the
same switch, with as much traffic as it/they can handle.  In some cases,
each "load engine" will be aliasing multiple IP addresses on each NIC.
All of the machines will be on the same subnet.  When we run tests, we
would like the network to be invisible...meaning that it is never the
bottleneck.

So I've seen a few specs mentioned in switch literature and mentioned in
the discussions -- I am trying to assess how those relate to our
situation.
1. MTU - larger is better to improve bandwidth efficiency 2. # of MAC
addresses - since we have a small number of computers on a small
network, I would guess this is unimportant to us.
3. Switching Capacity - pretty important to us, I would think, but also
seems to be the same for all models within a given line from a given
manufacturer - is the published number meaningful?
4. Forwarding Rate - I have no idea what this is...important?


One other point that I wanted to verify is that one of the jobs of the
switch is to keep traffic away from parts of the network that are not
involved with the sender or receiver.  For example - the switch in our
test lab is hooked to the switch for the rest of the office, to which
the rest of our desktops are connected.  So when we are running tests in
the lab, none of that traffic bleeds into the rest of the network
affecting performance there.  My understanding (and anecdotal evidence)
is that this is true...is it?

TIA,
C


I wrote:
> We would like to upgrade our testlab to a gigabit switch.
<snip>



--
------------------------------------------------------------------------
-
Chris Merrill                           |  Web Performance, Inc.
chris at webperformance.com                |  http://webperformance.com
919-433-1762                            |  919-845-7601

Website Load Testing and Stress Testing Software & Services
------------------------------------------------------------------------
-
-- 
TriLUG mailing list        :
http://www.trilug.org/mailman/listinfo/trilug
TriLUG Organizational FAQ  : http://trilug.org/faq/ TriLUG Member
Services FAQ : http://members.trilug.org/services_faq/