From: William Swedberg (bs.ccie@xxxxxxxx)
Date: Sun Aug 06 2000 - 17:32:25 GMT-3
Subnet 0 is the all zero subnet while subnet 7 is the all 1s subnet.
When calculating subnets you use 2 to the nth minus 2. N being the number
of subnet bits. And -2 being the all 0 and 1s subnets. In your example you
get 2 to the 3rd - 2 giving you 8 - 2 = 6. By using the IP SUBNET-ZERO
command you are now able to us the all 0 and all 1s subnets.
William Swedberg CCNP CCDP
----- Original Message -----
From: Harbir Kohli <harbirk@sympatico.ca>
To: 'Ccielab <ccielab@groupstudy.com>
Sent: Sunday, August 06, 2000 12:50 PM
Subject: subnetting question
> Hello all,
>
> What is the problem with using subnet 7 in the following:
>
> IP Subnet Calculation & Design
>
> --------------------------------------------------------------------------
--- > > IP Class: C IP Address: 192.168.5.0 > Mask Bits: 3 Subnet Mask: 255.255.255.224 > Subnets: 6+1 IP Major Net: 192.168.5.0 > Hosts/Subnet: 30 Major Net Bcast: 192.168.5.255 > > Subnets for Fixed Length Subnet Masking > . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . > . . . > No. Subnet Hosts Hosts Broadcast > Address From To Address > > 0 192.168.5.0 192.168.5.1 192.168.5.30 > 192.168.5.31 > 1 192.168.5.32 192.168.5.33 192.168.5.62 > 192.168.5.63 > 2 192.168.5.64 192.168.5.65 192.168.5.94 > 192.168.5.95 > 3 192.168.5.96 192.168.5.97 192.168.5.126 > 192.168.5.127 > 4 192.168.5.128 192.168.5.129 192.168.5.158 > 192.168.5.159 > 5 192.168.5.160 192.168.5.161 192.168.5.190 > 192.168.5.191 > 6 192.168.5.192 192.168.5.193 192.168.5.222 > 192.168.5.223 > 7 192.168.5.224 192.168.5.225 192.168.5.254 > 192.168.5.255 > > Don't use subnet 0 (unless using ip subnet-zero command) and subnet 7. > Address space wasted by subnetting = 29.13% ( 17.32% with ip > subnet-zero) > -------------------------------------------------------------------------- --- > > > > >
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