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Home > Archive > alt.certification.network-plus > November 2003 > Question Regarding Sub-Netting
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Question Regarding Sub-Netting
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| tehseen shamim 2003-10-28, 11:27 am |
| I want to ask a question that through Sub-Netting , is it possible
that number of IP Adresses get increase or do they decrease ?? plsss
help me by answering this question.I'll be obliged if someone does
so...
REGARDS..
Tehseen Shamim.
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| C. Philip Cutler II 2003-10-28, 12:27 pm |
| <shakes his head> Huh?
I digress for a second but there is a limited number of IP addresses on the
net (Approx 255^4, or slightly more than 4 billion). And yes I included
addresses in the 10 range, 127 range, and the test/broadcast address greater
than 223.
But what is your question about Sub Netting? You just asked if they
increase or decrease, based on what changes?
And Sub Netting has little to do with an increase or decrease really, it
just has to deal with wether a machine looks locally or sends the packet to
the default gateway for routing.
Philip
"tehseen shamim" <tehsu83@yahoo.com> wrote in message
news:a1c2fb07.0310280757.7a993d4e@posting.google.com...
> I want to ask a question that through Sub-Netting , is it possible
> that number of IP Adresses get increase or do they decrease ?? plsss
> help me by answering this question.I'll be obliged if someone does
> so...
> REGARDS..
> Tehseen Shamim.
| |
| Charles M. Kozierok 2003-10-28, 12:27 pm |
| In article <a1c2fb07.0310280757.7a993d4e@posting.google.com>,
tehseen shamim <tehsu83@yahoo.com> wrote:
} I want to ask a question that through Sub-Netting , is it possible
} that number of IP Adresses get increase or do they decrease ?? plsss
} help me by answering this question.I'll be obliged if someone does
} so...
The number of IP addresses in a block that can be used for hosts
always decreases when subnetting. The larger the number of subnets, the
more addresses you lose.
peace,
-*-
charles
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| You can use the subnet mask to both increase or decrease the amount of hosts
per subnet. A subnet mask of 255.255.254.0 will have twice the hosts of
255.255.255.0. A subnet mask of 255.255.255.128 will have half as many per
subnet.
Dave
"tehseen shamim" <tehsu83@yahoo.com> wrote in message
news:a1c2fb07.0310280757.7a993d4e@posting.google.com...
> I want to ask a question that through Sub-Netting , is it possible
> that number of IP Adresses get increase or do they decrease ?? plsss
> help me by answering this question.I'll be obliged if someone does
> so...
> REGARDS..
> Tehseen Shamim.
| |
|
| Even if Charles and I sometimes have different opinions,  He is totally
right here and you are wrong!
Look at it like this.
SubNetting is a process of dividing a NetWork ID into multiple logical
SubNets.
What you are doing is comparing different SubNets!
AT
"DaveL" <dave1027@comcast.net> wrote in message
news:tPudnVGw-eCfjjmiRVn-tg@comcast.com...
> You can use the subnet mask to both increase or decrease the amount of
hosts
> per subnet. A subnet mask of 255.255.254.0 will have twice the hosts of
> 255.255.255.0. A subnet mask of 255.255.255.128 will have half as many
per
> subnet.
>
> Dave
>
>
> "tehseen shamim" <tehsu83@yahoo.com> wrote in message
> news:a1c2fb07.0310280757.7a993d4e@posting.google.com...
>
| |
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| I don't want to get embroiled in an argument but I think DaveL is
correct.
Moving the dividing line (separating Network ID and Host ID) to the
right is called Subnetting. Subnetting will increase the number of
subnets but decrease the number of hosts per subnet. It's worth noting
(in respect of the original question) that after subnetting the total
number useable IP addresses available to you will decrease (due to the
inefficiencies of subnetting).
BUT is it also possible to move the dividing line to the left. This is
called Supernetting. Supernetting will increase the number hosts (as
DaveL said).
Here's how it works:
You could use Supernetting to combine two adjacent class C network
blocks into one network. For example, you might already have the class
C network 195.1.0.0. If needed more than 254 IP addresses (but didn't
want to purchase a class B
network) you could purchase the adjacent class C network 195.1.1.0.
Then to combine these two class C networks into one network you would
change the subnet mask to 255.255.254.0. You can then have up to 510
hosts on your network.
This is called Supernetting.
Classless InterDomain Routing (CIDR) provides a form of Supernetting
to hand out IP address blocks more efficiently than the traditional
Class A, B or C blocks. In my example, the combining of two class C
networks would be equivalent to a CIDR slash 23 (/23) network.
In theory you could also Supernet a private IP address range (in this
case you don't have to worry about who owns adjacent blocks because
they are only used on your intranet).
Thanks,
Bruce.
"AT" <torgny@@direcway.com> wrote in message news:<k_Frb.7459$6c3.6738@newsread1.news.pas.earthlink.net>...[color=blue]
> Even if Charles and I sometimes have different opinions, He is totally
> right here and you are wrong!
> Look at it like this.
> SubNetting is a process of dividing a NetWork ID into multiple logical
> SubNets.
> What you are doing is comparing different SubNets!
>
> AT
>
> "DaveL" <dave1027@comcast.net> wrote in message
> news:tPudnVGw-eCfjjmiRVn-tg@comcast.com...
> hosts
> per
| |
|
| If you had read it all and been thinking of what you read you could have
saved yourself that post.
As you say in your post, it is possible and it is called
SuperNetting......not SubNetting.
To just move the dividing line to the left inside a class C Network and call
it SuperNetting is nothing I agree with. For me that is to make a change of
a SubNet. SuperNetting is a little bit more complicated then combining a few
SubNets together to get back to the original Classful Network ID.
The original post was "I want to ask a question that through Sub-Netting ,
is it possible that number of IP Adresses get increase or do they decrease."
The only possible answer to that is "They decrease". If they don't decrease
you have not beenSubNetting.
AT
"Bruce" <codwars@hotmail.com> wrote in message
news:6a8eb75a.0311100556.32dfd9b4@posting.google.com...
> I don't want to get embroiled in an argument but I think DaveL is
> correct.
>
> Moving the dividing line (separating Network ID and Host ID) to the
> right is called Subnetting. Subnetting will increase the number of
> subnets but decrease the number of hosts per subnet. It's worth noting
> (in respect of the original question) that after subnetting the total
> number useable IP addresses available to you will decrease (due to the
> inefficiencies of subnetting).
>
> BUT is it also possible to move the dividing line to the left. This is
> called Supernetting. Supernetting will increase the number hosts (as
> DaveL said).
>
> Here's how it works:
>
> You could use Supernetting to combine two adjacent class C network
> blocks into one network. For example, you might already have the class
> C network 195.1.0.0. If needed more than 254 IP addresses (but didn't
> want to purchase a class B
> network) you could purchase the adjacent class C network 195.1.1.0.
> Then to combine these two class C networks into one network you would
> change the subnet mask to 255.255.254.0. You can then have up to 510
> hosts on your network.
>
> This is called Supernetting.
>
> Classless InterDomain Routing (CIDR) provides a form of Supernetting
> to hand out IP address blocks more efficiently than the traditional
> Class A, B or C blocks. In my example, the combining of two class C
> networks would be equivalent to a CIDR slash 23 (/23) network.
>
> In theory you could also Supernet a private IP address range (in this
> case you don't have to worry about who owns adjacent blocks because
> they are only used on your intranet).
>
> Thanks,
>
> Bruce.
>
>
> "AT" <torgny@@direcway.com> wrote in message
news:<k_Frb.7459$6c3.6738@newsread1.news.pas.earthlink.net>...[color=blue]
totally[color=blue]
of[color=blue]
many[color=blue]
| |
| FireSword 2003-11-11, 7:24 pm |
| Hey guys, what's all the fighting about??
by definition if use subnetting the amount of valid hosts will always
decrease.
superneting is related to CIDR Classless Interdomain Routing, and it is used
to agregate adjacent routes so the routing tables are smaller.
CIDR should not be used to get for example more than 254 hosts from a cass C
address, in fact you can't do it with a global address.
And there is no point on doing it with a private address.
"AT" <torgny@@direcway.com> wrote in message
news:TeXrb.8832$6c3.6618@newsread1.news.pas.earthlink.net...
> If you had read it all and been thinking of what you read you could have
> saved yourself that post.
> As you say in your post, it is possible and it is called
> SuperNetting......not SubNetting.
> To just move the dividing line to the left inside a class C Network and
call
> it SuperNetting is nothing I agree with. For me that is to make a change
of
> a SubNet. SuperNetting is a little bit more complicated then combining a
few
> SubNets together to get back to the original Classful Network ID.
> The original post was "I want to ask a question that through Sub-Netting ,
> is it possible that number of IP Adresses get increase or do they
decrease."
> The only possible answer to that is "They decrease". If they don't
decrease
> you have not beenSubNetting.
>
> AT
>
> "Bruce" <codwars@hotmail.com> wrote in message
> news:6a8eb75a.0311100556.32dfd9b4@posting.google.com...
> news:<k_Frb.7459$6c3.6738@newsread1.news.pas.earthlink.net>...
> totally
of[color=blue]
hosts[color=blue]
> of
> many
plsss[color=blue]
>
>
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