Re: Subnetting and masking

Tech-Archive recommends: Fix windows errors by optimizing your registry

From: Roland Hall (nobody_at_nowhere)
Date: 02/16/04 

Date: Mon, 16 Feb 2004 17:44:28 -0600

"Stephan Barr" wrote:
: Goal is to set up a lab environment to simulate a w2k domain over a WAN
: connection hence the routers each with their own public IPs.

That might have been important to include in your original post. I
apologize if I missed it.

Still, you cannot route individuals addresses where routers are over-lapping
their subnets.
If you want to use mask: 255.255.255.248 or CIDR: /29, then you need to set
your subnets on your routers on boundaries of 8.
Ex.
192.168.51.0/29 - network (all 0s)
192.168.51.1-6/29 - user
192.168.51.7/29 - broadcast

Next subnet:
192.168.51.8/29 - network (all 0s)
192.168.51.9-14/29 - user
192.168.51.15/29 - broadcast

...and so on...

If these routers are in different locations then the ISP will route them
separately. If the ISP is routing all of them to one location, and you had
4 subnets, then they would route a 32 address subnet and you would subnet it
out on your end. You lose two usable addresses for each subnet, so 2 * 4 =
8. 32 - 8 = 24. So, you can assign 24 addresses. If you need more then
the ISP has to provide addressing not in the same subnet or increase the
subnet size which would mean 64 or greater depending.

HTH... 

-- 
Roland Hall
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