Matthew Seaman wrote: > Vincent Hoffman wrote: >> Gary Hartl wrote: > >>> I thought I could do it by using the /class ie /32 for class c but i >>> can't >>> remember what the class delegation is for that size of pool, I think >>> it is a >>> class B. > >> 192.168.0.0/16 for your example. >> and yes this is a class B (not all /16s are though.) >> >> the /x notation is called CIDR (classless interdomain routing.) >> http://en.wikipedia.org/wiki/Classless_Inter-Domain_Routing > > Class C surely? 192.168.0.0/16 is the RFC1918 Class C reserved > range of 256 /24 networks. >
Doh yes indeed. no idea why i said B. not the stupidest thing i've said today either ;) Vince > Yes, Class B networks were /16s, but the A, B, C... classification > is derived from the number of leading 1's in the binary representation > of the first octet of the address, not the netmask. Thus > > Binary: Decimal: Class: Used for: > ----------------------------------------------------------------- > 0000 0000 -- 0111 1111 (0 - 127) Class A /8 Networks > 1000 0000 -- 1011 1111 (128 - 191) Class B /16 Networks > 1100 0000 -- 1101 1111 (192 - 223) Class C /24 Networks > 1110 0000 -- 1110 1111 (224 - 239) Class D Multicast > 1111 0111 -- 1111 1111 (240 - 255) Class E Reserved, experimental > > Hence the first /half/ of the address space was reserved for class A > network allocations (16777214 hosts per net) and half of the rest was > reserved for class B allocations (65534 hosts per net). Some large > Universities probably could justify a Class B allocation, but I don't > think any single institution or body has ever put enough machines onto > the Internet to justify having a whole Class A network to themselves > according to modern criterea. > > Needless to say, this was incredibly wasteful scheme in terms of > address space coverage. As the whole 'network class' thing was an > early attempt to just shave a few bytes of RAM in internet routers by > not having to store explicit netmasks -- an economy that was rapidly > made obsolete by the falling cost and increasing capacity of hardware > -- class based allocation is now completely obsolete and we live in a > fully CIDR world. > > Except that is, for the 'Class D' and 'Class E' (Multicast and > Experimental) ranges which still exist. It's also why the loopback > interface is given a /8 netmask -- 127.0.0.1 is a Class A address > by this scheme. > > Cheers, > > Matthew > _______________________________________________ firstname.lastname@example.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"