In Classless routing (CIDR), a network (or range of IP addresses) is specified by a network-id and a netmask.
Usually, where the bits are '0' in the netmask, the bits in the network-id are also '0'. The canonical network-id would be any IP address in the range ANDed with the netmask. In Ethernet networks, an address with all '0's or all '1's in the '0's part of the netmask are reserved. PPP is a Point-to-Point network. Hence all netmasks are 32-bit. So any value is game, except for 255.255.255.255, 0.0.0.0 and multicast addresses of course. KH > From: "Chng Tiak-Jung" <[EMAIL PROTECTED]> > CC: [email protected] > To: "Chiang Fong Lee" <[EMAIL PROTECTED]> > Date: Fri, 3 Aug 2007 11:24:21 +0800 > Subject: Re: [Slugnet] 255 octet in an IP address OK? > > I think what he meant was: isn't 255 reserved for some special purpose, just > like 0 ? > > But, I thought is this case, it is still alright because the special meaning > is only for the last octet - where 0 => network address, 255 => broadcast > address. > > Maybe someone who is familiar with the IP network standard should clarify. > > Regards, > T J > > On 8/2/07, Chiang Fong Lee <[EMAIL PROTECTED]> wrote: > > > > That's alright - there should be 256 components (somebody correct me) > > in an octet, as there's 8 bits per octet to make up 32 bits in an IPv4 > > address, which is counted as 0-255. Seeing 256 in an octet would be > > invalid. > > > > > > -cflee > > > > > > On 8/2/07, Anand Vaidya <[EMAIL PROTECTED]> wrote: > > > I used to think that IP addresses cannot contain "255" however I noticed > > that > > > Singtel ADSL has such IP addresses: > > > > > > anand pts/0 bb220-255-57-228 Thu Jul 5 08:52 - 09:25 (00:32) > > > > > > > > > Note that this is for the PPP connection with /32 netmask. > > > > > > Is this OK? Or is this another Singapore-only anamoly? > > > > > > Regards > > > Anand > > > > _______________________________________________ > > Slugnet mailing list > > [email protected] > > http://www.lugs.org.sg/mailman/listinfo/slugnet > > > > > > -- > Chng Tiak-Jung > email: [EMAIL PROTECTED] > > _______________________________________________ > Slugnet mailing list > [email protected] > http://www.lugs.org.sg/mailman/listinfo/slugnet > __________________________________________________________________ Yahoo! Singapore Answers Real people. Real questions. Real answers. Share what you know at http://answers.yahoo.com.sg _______________________________________________ Slugnet mailing list [email protected] http://www.lugs.org.sg/mailman/listinfo/slugnet
