At 11:33 AM 10/1/96 -0400, long-morrow @
CS .
YALE .
EDU wrote:
>
>Yes. We use a subnet with all zeros (128.36.0.0, where our subnet mask
>is 255.255.255.0) for legacy reasons.
>
>Whenever we bring up a new CISCO router on the 128.36.0 subnet we run the
>router through the EZ config with a terminal --- and then after it refuses
>to talk to the zero subnet we enter the advanced configuration command
>'service subnet-zero' or 'ip subnet-zero' (depending on the CISCO IOS
>release).
>
>- Morrow
>
It also depends on the routing protocol; classful routing protocols
cannot distinguish IP subnet 0 from a network address.
Subnetting with a subnet address of zero generally is not allowed
with classful routing protocols because of the confusion inherent
in having a network and a subnet with indistinguishable addresses.
For example, if network 128.36.0.0 is subnetted as 255.255.255.0,
subnet zero would be written as 128.36.0.0 -- which is identical
to the network address.
- paul
--
Paul Ferguson || ||
Consulting Engineering || ||
Reston, Virginia USA |||| ||||
tel: +1.703.716.9538 ..:||||||:..:||||||:..
e-mail: pferguso @
cisco .
com c i s c o S y s t e m s
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