How to decide to subnet.

I have a growing network that uses one subnet. It uses a switch and gigabit
NICS.

How do you decide when it is time to subnet - to reduce broadcasts on the
network?

Any general help would be nice.

Thanks,

Mike

As a general rule,...250-300 hosts per subnet. Using a typical 24bit Mask
(255.255.255.0 ) handles that just fine (254 hosts).


--
Phillip Windell [MCP, MVP, CCNA]
www.wandtv.com
-----------------------------------------------------
Understanding the ISA 2004 Access Rule Processing
http://www.isaserver.org/articles/IS...cessRules.html

Microsoft Internet Security & Acceleration Server: Guidance
http://www.microsoft.com/isaserver/t...dance/2004.asp
http://www.microsoft.com/isaserver/t...dance/2000.asp

Microsoft Internet Security & Acceleration Server: Partners
http://www.microsoft.com/isaserver/partners/default.asp
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"Mike Klick" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> I have a growing network that uses one subnet. It uses a switch and
gigabit
> NICS.
>
> How do you decide when it is time to subnet - to reduce broadcasts on the
> network?
>
> Any general help would be nice.
>
> Thanks,
>
> Mike
>
>

Mike,

I would ping various nodes on the same subnet during peak time(s) but make
sure the ping packet is as large as the MTU will allow (i.e. ping -t -l
1472 -f 192.168.x.x). If the reply time exceeds your opinion of a threshold
(i.e. 50+ milliseconds) then subnet. Since you have 1Gb NICs in your nodes,
my ping example may have an MTU that is too small (i.e. 1472). In which case
you may want to try a much larger MTU (i.e. under 8192). In other words,
start from 8192 with the -l parameter and work you way down until you don't
get a reponse like

Packet needs to be fragmented but DF set.

Optimally, if you have or can rent a Fluke Networks OneTouch, OptiView, some
kind of traffic analyzer or a managable switch, look at the non-broadcast
traffic on the desired subnet. If the non-broadcast traffic exceeds 50% it
would be a good idea to subnet. This is the better of the two ways of
determining whether or not you should subnet.

Stacey Olsen

"Mike Klick" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
>I have a growing network that uses one subnet. It uses a switch and gigabit
>NICS.
>
> How do you decide when it is time to subnet - to reduce broadcasts on the
> network?
>
> Any general help would be nice.
>
> Thanks,
>
> Mike