Basic Subnetting Question

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We are going to open up a remote office soon and here at the home office we
are close to running out of ip addresses on our private network. It is
obvious that we need to address this so i am just wondering, if we changed
our current 10.1.1.0/24 scheme to a 10.1.1.0/23 (which should give us
10.1.0.1 - 10.1.0.254 and 10.1.1.1 - 10.1.1.254) would we have any problems
routing data to and from the two ranges both internal to our home office and
out to the remote office? or would the remote office have to be on an
entirely different subnet?


Thanks!
 
rstutte said:
We are going to open up a remote office soon and here at the home office we
are close to running out of ip addresses on our private network. It is
obvious that we need to address this so i am just wondering, if we changed
our current 10.1.1.0/24 scheme to a 10.1.1.0/23 (which should give us
10.1.0.1 - 10.1.0.254 and 10.1.1.1 - 10.1.1.254) would we have any problems
routing data to and from the two ranges both internal to our home office and
out to the remote office? or would the remote office have to be on an
entirely different subnet?
Click to expand...

It really doesn't matter. It would work either way. I would suggest
limiting the number of hosts per segment to around 250-300. So you might
just want to add a new segment at you current site instead of rolling the
mask back by one Bit. You'd have to buy a LAN Router but you'd be better off
in the long run and the standard 24bit mask would keep a simpler and
"cleaner" LAN Design.

You could build a "poor man's" Router out of an old 486 with NT4 Workstation
or Linux. There are even "Linux routers" running off a bootable CD so it
wouldn't even need a HardDrive. I think you could find those CD ISO images
on the Net somewhere.
 
By changing the subnet mask your IP subnet would be as follows

Network ID: 10.1.0.0 (255.255.254.0)
Host Range : 10.1.0.1 to 10.1.1.254
Broadcast: 10.1.1.255

There is only one subnet here, not two. Depending on your traffic, you might
what to keep the original /24 and add another one with a router in between.
Your remote office could be another /24.

10.1.0.0 /24 --ROUTER--10.1.1.0 /24
|
|
10.1.2.0 /24 (remote office)

A simple routing protocol (RIPv2 or EIGRP) or a couple of static routes will
allow proper communications between all subnets.
 
How will the offices be interconnected? If via a VPN and it's one big
subnet, how would the VPN system know to route the traffic to a same-subnet
IP address over the VPN instead of locally?

You don't want more than 250-300 computers on a single subnet, as the one
person pointed out, because it will cause collision problems in the
broadcast domain. You're much better off going with separate subnets. If
nothing else it makes it easier to track the origin of an "event."

Ray
 
Ray said:
How will the offices be interconnected? If via a VPN and it's one big
subnet, how would the VPN system know to route the traffic to a same-subnet
IP address over the VPN instead of locally?
Click to expand...

I think it can work as "bridging" (Layer2) instead of "routing". But you
make a good point, I'm not sure myself how to have it "bridge" and I would
much rather they be different subnets on each end and keep things more
"normal".
You don't want more than 250-300 computers on a single subnet, as the one
person pointed out, because it will cause collision problems in the
broadcast domain. You're much better off going with separate subnets. If
nothing else it makes it easier to track the origin of an "event."
Click to expand...

Collisons can be avoided by using Switches instead of Hubs, but that is
extra money spent if it currently uses only Hubs and it still leaves
Broadcasts as a problem. Broadcasts would of course be eliminated if they
are different subnets on each end.
 
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