From: Godswill Oletu (oletu@inbox.lv)
Date: Fri May 19 2006 - 11:29:29 ART
Radioactive,
Agreed, you are within your class C (/24) boundary, but by subnetting the
class C address furteher, you are creating another set of bit boundaries and
you must also be within that set boundaries.
A good example is this..for your 192.168.1.0/24 class C boundary, you will
agree that, your broadcast for that class is 192.168.1.255. Now in one of
your earlier post, you rightly said that for 192.168.1.0/30, the broadcast
will be 192.168.1.3. The ip address 192.168.1.3 is a valid host address on
the larger /24 subnet, but since you have further subnet that class to a
/30, that ip address is no longer a valid host address on the /30 subnet but
a broadcast address, so are addresses like 192.168.1.7/30; 192.168.1.11/30,
etc.
So you see that, you have created a new boundary and set of rules that you
must play by, the same apply for /29, /28, /27, etc each have it own bit
boundary, valid host addresses, broadcast addresses, etc and one must not
over lap with the other but they are all part of the larger /24 address
space.
These are your valid subnets from the class C (192.168.1.0/24) address
space.
192.168.1.0/30 <valid hosts 192.168.1.1 - 192.168.1.2>< 2 valid hosts>
192.168.1.4/30 <valid hosts 192.168.1.5 - 192.168.1.6>< 2 valid hosts>
192.168.1.8/29 <valid hosts 192.168.1.9 -192.168.1.14>< 6 valid host>
192.168.1.16/28 <valid hosts 192.168.1.17 - 192.168.1.30><14 valid hosts>
192.168.1.32/27 <valid hosts 192.168.1.33 - 192.168.1.62><30 valid hosts>
192.168.1.64/26 <valid hosts 192.168.1.65 - 192.168.1.126><62 valis hosts>
192.168.1.128/25 <valid hosts 192.168.1.129 - 192.168.1.254><126 valid
hosts>
I just wasted 12 ip addresses from my original /24 block just to get this
subnetting going.
HTH
Godswill Oletu
----- Original Message -----
From: "Radioactive Frog" <pbhatkoti@gmail.com>
To: <alexeim@orcsoftware.com>
Cc: "Jai Prakash" <jpjsr06@gmail.com>; <ccielab@groupstudy.com>
Sent: Friday, May 19, 2006 9:16 AM
Subject: Re: Subneting - Basic Question but doubt full
> HI Alexei,
>
> I am within the subnet boundary. I am only talking about subneting the
> 192.168.1.0. my first subnet would be /30, second subnet would be /29
third
> could be /28, remember its still under the /24 boundary. Why can't I
subnet
> this IP block like this ?
>
> Frog!
> Jumping on the wall
>
>
>
> On 5/19/06, Alexei Monastyrnyi <alexeim@orcsoftware.com> wrote:
> >
> > No, you cannot do like this.. since /30+/30=/29 you have to assign one
> > more /30 network after 192.168.1.0/30 to be able to change from /30 to
> > /29 , etc /29+/29=/28..
> > i.e. you cannot allocate smaller subnet from any place of /24 network,
> > you have to consider bit boundaries. in your example you cannot allocate
> > /27 subnet from 192.168.1.4...
> >
> > If I am not missing something here.... :-) pls do correct me otherwise
> >
> > A.
> >
> >
> >
> > on 19/05/2006 02:58 Radioactive Frog wrote:
> > > 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
> > >>>
> > >
> > >
This archive was generated by hypermail 2.1.4 : Thu Jun 01 2006 - 06:33:22 ART