chan@dciem.dciem.dnd.ca (Kam Tim CHAN) (10/20/89)
I am in the process of setting up a new subnetting environment, and I noted the following comment : In RFC950 (Internet Standard Subnetting Procedure) : : Special Addresses: : : From the Assigned Numbers memo [9]: : : "In certain contexts, it is useful to have fixed addresses : with functional significance rather than as identifiers of : specific hosts. When such usage is called for, the address : zero is to be interpreted as meaning "this", as in "this : network". The address of all ones are to be interpreted as : meaning "all", as in "all hosts". For example, the address : 128.9.255.255 could be interpreted as meaning all hosts on : the network 128.9. Or, the address 0.0.0.37 could be : interpreted as meaning host 37 on this network." : : It is useful to preserve and extend the interpretation of these : special addresses in subnetted networks. This means the values : of all zeros and all ones in the subnet field should not be : assigned to actual (physical) subnets. However, I was thinking of using just 1 bit to be the subnet field, therefore my subnet field is either all zero or all one. Would any one of you comment on this special case issue, please ? Thanks in advance. Tim Chan -- Tim Chan, Systems Specialist (416)-635-2073 Defence and Civil Institute of Environmental Medicine UUCP: uunet!mnetor!dciem!chan or {decvax|ihnp4|watmath}!utzoo!dciem!chan Internet: chan@dretor.dciem.dnd.ca or chan%dretor@zorac.dciem.dnd.ca
carlson@uxh.cso.uiuc.edu (10/22/89)
(This is a perfect example of quoting ASCII documents; I couldn't do this with a PostScript file!) RFC1122 INTERNET LAYER October 1989 IP addresses are not permitted to have the value 0 or -1 for any of the <Host-number>, <Network-number>, or <Subnet- number> fields (except in the special cases listed above). This implies that each of these fields will be at least two bits long. ^^ ^^^^^ ^^^ ^^^^ ^^^^ Internet Engineering Task Force [Page 31] -------------------- Brad Carlson <carlson@mrcnext.cso.uiuc.edu> or <brad-carlson@uiuc.edu> University of Illinois -- Consultant -- NeXT guru -- Windows Programmer