Re: Does my network have a bear pit?
- From: "Phillip Windell" <philwindell@xxxxxxxxxxx>
- Date: Fri, 20 Apr 2007 11:36:04 -0500
"Phydeux" <Phydeux@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:A4AE658D-43D7-4037-9971-6CAF4BFD9A9A@xxxxxxxxxxxxxxxx
About 5 months ago we had a network engineering consultant totally redo our
entire company network from the ground up, and since then I've noticed that
one specific address, 192.168.6.255 seems like a bear pit for anyone who gets
it. They can get the IP, everything looks right, and you can ping them. But
they can't reach any network services or the internet. Our DHCP range is
192.168.6.200 - 7.255 with a subnet mask of 255.255.254.0. I'm not nearly as
educated in TCP/IP as an engineer would be, but it seems to me there
shouldn't be a dead spot at 6.255.
Can anyone shed some light on why this might be happening?
Make sure an incorrect mask isn't being used somewhere. A /24bit mask will
treat the address as a broadcast address. You shouldn't be using that subnet
scheme anyway.
You shouldn't have IP Segment with more than 250-300 hosts. In other words you
should not be running a /23 bit mask. You should be running a /24 bit mask and
if there are more than 254 total hosts then you should run two IP Segments
(/24bit mask, 254 hosts each) with a router between them. The consultant should
have been smart enough to do this since he had to best rare opportunity that
could ever be given someone,...rebuilding a network from the ground up. A lot
of people would kill for an opportunity like that,..and hopefully they wouldn't
blow it.
The [correct] purpose of a 23 bit mask is to supernet two IP segments together
for routing purposes with the intent of splitting them back apart further down
the line with another router.
Here's an example:
<subnet 1> /24bit
|
[Router1]
|
<subnet2> /24bit
|
[Router2]
/ \
/ \
<subnet3> <subnet4> both /24bit
The supernetted route on Rotuer1 would look like:
192.168.6.0 mask 255.255.254.0 <Router2 IP# on Subnet2>
In this example Router1 would have a single route that "supernets" subnet3 and
subnet4 into a single "route". Once it gets to Router2, the Router2 separates
them into two separate /24 bit-254host IP subnets.
--
Phillip Windell
www.wandtv.com
The views expressed, are my own and not those of my employer, or Microsoft, or
anyone else associated with me, including my cats.
-----------------------------------------------------
.
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