mo@prisma.UUCP (Mike O'Dell) (12/08/88)
Has anyone considered the performance hit by doing this? My guess is that it will be non-trivial. One could argue that 96 bits is easily enough (fixed size) since that number is big enough to enumerate some very sustantial fraction of all the subatomic particles in the known universe. "If it's variable, it probably ain't fast." -Mike O'Dell
CERF@A.ISI.EDU (12/08/88)
Mike, the performance question is what caused us to select a fixed length, 32 bit address in the version 4 IP. Your question is a good one and I wonder whether anyone has hard data for the OSI IP version which does use a variable length address format. It seems clear that we must give serious thought, though, to a substantial increase in the number of networks addressable within the IP scope if we are to scale to the size of the global ISDN, for instance. Vint
Makey@LOGICON.ARPA (Jeff Makey) (12/09/88)
In article <8812071620.AA06614@uunet.UU.NET> mo@prisma.UUCP (Mike O'Dell) writes: >One could argue >that 96 bits is easily enough (fixed size) since that number >is big enough to enumerate some very sustantial fraction of all >the subatomic particles in the known universe. I whipped out the ol' calculator, and determined that 53 bits is more than enough to enumerate each square foot of the Earth's surface. How many Earth-sized planets to we expect to populate in the future? 128 million? Add another 27 bits for a total of 80. Another 16 bits will make room for 64K hosts per square foot (455 per square inch), and you get a 96-bit internet address. Not what I'd call a "very sustantial fraction of all the subatomic particles in the known universe", but it sounds big enough for an internet. Just for safety, though, throw in an extra 32 bits for a total of 128. Nice, simple, fixed-length processing. A mere 16 octets per address. This should keep us out of trouble until at least the year 2001. :-) :: Jeff Makey Department of Tautological Pleonasms and Superfluous Redundancies Department Disclaimer: Logicon doesn't even know we're running news. Internet: Makey@LOGICON.ARPA UUCP: {nosc,ucsd}!logicon.arpa!Makey