On Wed, 2002-07-17 at 02:40, Chao Jang Wei wrote: > But why are the .0 address unusable by hosts? It is not something like the > .255 broadcast address. There shouldn't be any confusion if a host is > assigned xxx.xxx.xxx.0. That host will be the 0th host (as opposed to the > 1st host). It doesn't make sense to reserved an IP address just because it > is designated as the network address. Unless it causes confusion to the > routers. (but how?) Can anyone try to explain?
This is sort of answered by the discussions of single bit subnets since by definition there is only two address, the network and the broadcast. from http://www.private.org.il/tcpip-faq/faq-1.htm#private-ip ********************************************************** * Can I use a single bit subnet? The answer used to be a straightforward "no", because a 1-bit subnet can only have a subnet part of all-ones or all-zeroes, both of which were assigned special meanings when the subnetting concept was originally defined. (All-ones meant "broadcast, all subnets of this net" and all-zeroes meant "this subnet, regardless of its actual subnet number".) However, the old definition of subnetting has been superseded by the concept of Classless Inter-Domain Routing (CIDR, pronounced 'cider'). Under CIDR the subnet doesn't really have an existence of its own and the subnet mask simply provides the mechanism for isolating an arbitrarily-sized network portion of an IP address from the remaining host part. As CIDR-aware equipment is deployed it becomes increasingly like that you will be able to use a 1-bit subnet with at least some particular combinations of networking equipment. However, it's still not safe to assume that a 1-bit subnet will work properly with all kinds of equipment. ******************************* I get from this that is is probably not a good idea. I guess if you had control over every machine and program that might see the packet and the were all CIDR aware (I usually see this as nework definitions like 192.168.0.0/24) then you might be ok. Still not considered a good procatice though. HTH Bret _______________________________________________ Redhat-list mailing list [EMAIL PROTECTED] https://listman.redhat.com/mailman/listinfo/redhat-list
