Thanks to Bret and all those who had replied. It seems that the reservation of the .0 address is not out of necessity but "tradition". :) Anyway, I shan't pursue this issue any further.
Best, David Chao ----- Original Message ----- From: "Bret Hughes" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Wednesday, July 17, 2002 10:25 PM Subject: Re: OT: Network address of LAN. > 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 However, the old definition of subnetting has been superseded by the 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
