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Conceptual question: Reasoning behind private subnetting scheme?

 
 
John H.
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      03-09-2010
We have a geographically dispersed WAN. All of the offices have
192.168.n.0/24 local IP address. The point-to-point links between all
of our routers are taken from the 192.168.65.0/24 network which has
been subnetted into 64 two host subnets 192.168.65.0/30.

Is there a reason the engineer that set up our network chose the
192.168.65.0/24 network to subnet into the site-to-site links? Is
this a standard or customary practice, or just his preference? Why
not subnet 192.168.254.0 into the site-to-site networks?

Iím just curious. I have looked all over and have not been able to
find any documentation on customary use of private subnets in a
situation like this. Is there a best practice defined somewhere?

Thanks,
John
 
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Doug McIntyre
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      03-09-2010
"John H." <(E-Mail Removed)> writes:
>We have a geographically dispersed WAN. All of the offices have
>192.168.n.0/24 local IP address. The point-to-point links between all
>of our routers are taken from the 192.168.65.0/24 network which has
>been subnetted into 64 two host subnets 192.168.65.0/30.


>Is there a reason the engineer that set up our network chose the
>192.168.65.0/24 network to subnet into the site-to-site links? Is
>this a standard or customary practice, or just his preference? Why
>not subnet 192.168.254.0 into the site-to-site networks?


>I=92m just curious. I have looked all over and have not been able to
>find any documentation on customary use of private subnets in a
>situation like this. Is there a best practice defined somewhere?


They just picked it out of thin air.
There is no best practice to choosing IP addressing like this, it just happens.
 
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bod43
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      03-09-2010
On 9 Mar, 14:58, Doug McIntyre <(E-Mail Removed)> wrote:
> "John H." <(E-Mail Removed)> writes:
> >We have a geographically dispersed WAN. *All of the offices have
> >192.168.n.0/24 local IP address. *The point-to-point links between all
> >of our routers are taken from the 192.168.65.0/24 network which has
> >been subnetted into 64 two host subnets 192.168.65.0/30.
> >Is there a reason the engineer that set up our network chose the
> >192.168.65.0/24 network to subnet into the site-to-site links? *Is
> >this a standard or customary practice, or just his preference? *Why
> >not subnet 192.168.254.0 into the site-to-site networks?
> >I=92m just curious. *I have looked all over and have not been able to
> >find any documentation on customary use of private subnets in a
> >situation like this. *Is there a best practice defined somewhere?

>
> They just picked it out of thin air.
> There is no best practice to choosing IP addressing like this, it just happens.


Well err, there is a reason for choosing particular
addresses.

If route summarisation is anticipated then it is
a decent idea to chose addresses appropriately.

For example:-

192.168.0-63.x can be summarised into a single prefix.

Similarly 128-255.

So if 254 had been chosen then the opportunity to
summarise 128-255 would have been lost.

So perhaps the original designer was thinking ahead

 
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John H.
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      03-10-2010
Thanks Bob43. Route summarization makes since. That was the concept
I was not seeing.
 
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