From: Vishal Patel (vpatel@accessproviders.com.au)
Date: Thu May 18 2006 - 22:22:25 ART
Hi,
Cisco has a IP subnet calculator on it's website.
http://www.cisco.com/cgi-bin/Support/IpSubnet/home.pl
It requires a CCO login to use it though.
Or else u can find lots of subnet calculator softwares on the internet ,
google is our friend.
Cheers
Vishal
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Radioactive Frog
Sent: Friday, 19 May 2006 10:59 AM
To: Jai Prakash
Cc: ccielab@groupstudy.com
Subject: Re: Subneting - Basic Question but doubt full
Hi Jaiprakash,
thanks for answering to my query:
Can't we subnet 192.168.1.0 to as below :
a) first subnet 192.168.1.0/30 --> valid host 192.168.1.1 to
192.168.1.2broadcast IP
192.168.1.3
b) Second subnet 192.168.1.4/27 --> valid host 192.168.1.5 to 192.168.1.34 ?
and next subnet /28 and next subnet /30 ??????????
OR
It has to be either 192.168.1.0/26 or /27 or 38, I mean the whole subnet
?????
REgards,
Frog
Ans of 2nd Qusetion ) Subnet mask for /25 will be 255.255.255.128 ( Here U
can use 2
valid Network subnets with 126 valid host
IPs in each subnet)
Subnet mask for /26 will be
255.255.255.192( Here U can use 4
valid Network subnets with 62 valid host
IPs in each subnet)
Subnet mask for /27 will be
255.255.255.224 (Here
U can use 8
valid Network subnets with 30 valid host
IPs in each subnet)
On 5/19/06, Jai Prakash <jpjsr06@gmail.com> wrote:
>
> Hi Frog
>
> As per my understanding, when u take calss C as a major network and
> divides into subnets, it takes all available subnets with valid hosts.
>
> In your case, if you divide 192.168.1.0/24 into subnets of 30 block
> host IP.........you will get 8 valid subnet blocks with each having 30
> valid hosts IP. You can use any subnet from these 8 subnets block.
>
> The theory says.....don't use 1st IP and the Last IP of the subnets
> because, they represent Network IP and Broadcast IP accordangliy for
> that particular subnet.I never seen that books says don't use 1st
> subnet and last subnet, when you divide Major Network into subnets.
>
> The whole discussion outcome is :
>
> Ans of 1st Qusetion ) U can use 1st and Last subnet of Major Network
>
> Ans of 2nd Qusetion ) Subnet mask for /25 will be 255.255.255.128 (
> Here U can use 2
> valid Network subnets with 126 valid
> host IPs in each subnet)
> Subnet mask for /26 will be
> 255.255.255.192 ( Here U can use 4
> valid Network subnets with 62 valid
> host IPs in each subnet)
> Subnet mask for /27 will be
> 255.255.255.224 (Here U can use 8
> valid Network subnets with 30 valid
> host IPs in each subnet)
>
> Correct me , if I m wrong................
>
> Best Regards,
> Jai
>
>
>
> On 5/18/06, Radioactive Frog <pbhatkoti@gmail.com> wrote:
> >
> > Hi Guys,
> >
> > Very basic question but lots of doubt.
> >
> > 1) First question:
> >
> > If class C subnet 192.168.1.0 is routed to ISP-B (small) by ISP-A
> > (BIG ISP).
> > When ISP B starts subneting the 192.168.1.0 IP block for different
> > customer why do he starts distributing from the first subnet from
> > 192.168.1.0/24 (which sholdn't be used)???????????
> > The books and theory says first and last subnet shouldn't be used
> > (as network and broadcast subnets), hence we shouldn't use the
> > 192.168.1.0/24(first <http://192.168.1.0/24%28first> subnet)
> >
> > Means the ISP should start distributing from second subnets e.g.
> > 192.168.1.32 (see below).
> >
> > ---------------------------------------------------------
> > Subnet , Valid Hosts , Broadcast
> > 192.168.1.0 , 192.168.1.1 to 192.168.1.30 , 192.168.1.31
> > 192.168.1.32 , 192.168.1.33 to 192.168.1.62 , 192.168.1.63
> > 192.168.1.64 , 192.168.1.65 to 192.168.1.94 , 192.168.1.95
> > 192.168.1.96 , 192.168.1.97 to 192.168.1.126 , 192.168.1.127
> > 192.168.1.128 , 192.168.1.129 to 192.168.1.158 , 192.168.1.159
> > 192.168.1.160 , 192.168.1.161 to 192.168.1.190 , 192.168.1.191
> > 192.168.1.192 , 192.168.1.193 to 192.168.1.222 , 192.168.1.223
> > 192.168.1.224 , 192.168.1.225 to 192.168.1.254 , 192.168.1.255
> >
> >
> >
> > 1) Second question:
> >
> > What if ISP starts distributing /25 /26 /27 IP blocks from
> > 192.168.1.0/24 IP
> > block to the customers ? In this case what subnet mask shouldn't be
> > used (still first and the last in 192.168.1.0/24 blocks) ?
> >
> > Appreciate your answers to this basic topic!
> >
> > Frog!
> >
> > ____________________________________________________________________
> > ___ Subscription information may be found at:
> > http://www.groupstudy.com/list/CCIELab.html
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