The IP over ATM Mailing List Archive by date

["mlg" <mlg@hill.com>]

     I have an IP addressing question - though it is not specific to ATM. I 
     was under the impression that, in IP, all-zero and all-one fields in 
     the NETID or HOSTID fields were not allowed. Therefore, there are only 
     126 Class A addresses because 0.X.X.X (00000000.X.X.X) and 127.X.X.X 
     (01111111.X.X.X) are "special" addresses. Likewise, the Class B 
     addresses 128.0.X.X (10000000.00000000.X.X) and 191.255.X.X 
     (10111111.11111111.X.X) are not allowed, and (finally) the Class C 
     addresses 192.0.0.X (11000000.00000000.00000000.X) and 233.255.255.X 
     (11011111.11111111.11111111.X) are not allowed.
     
     The material I have read says that all zero's means "this" and all 
     ones means "all."
     
     Is this true? Are there limitations on the subnet field if a Class B 
     address is subnetted using a "Class C" subnet mask (i.e., no all-zero 
     or all-one subnet fields)? 
     
     I need an answer as soon as possible...
     
     /Michel
     
     ================================================================== 
     Michel L. Gilbert                    +1 802-655-8621 (office, v-mail) 
     Hill Associates, Inc.                +1 802-655-0940 (main number)
     17 Roosevelt Highway                 +1 802-655-7974 (fax) Colchester, 
     VT  05446 (USA)          mlg@hill.com