greid@adobe.com (Glenn Reid) (06/01/89)
In article <6982@cbnews.ATT.COM> mark@cbnews.ATT.COM (Mark Horton) writes: >In networking, there are three key concepts: names, addresses, and routes. > >A "name" is a high level, user guessable way to identify a person, >machine, or other entity. For example, "Mark Horton". Names may >be ambiguous, especially when abbreviated "M Horton". Names can be >made unambiguous by adding more information. "Mark Randolph Horton >who works for AT&T in Columbus Ohio and whose SSN is 1234567890" > >An "address" is a medium level, unambiguous way to identify *where >something is*. For example, "Room 234, 1234 Main St, Columbus Ohio, USA". >Addresses depend on the underlying technology, and one entity can have >several addresses, e.g. postal, latitude/longitude. > >A "route" amounts to giving directions to get to an address. >"Get on I-70 eastbound, drive to Columbus and take the 4th street >offramp, turn north on 4th, turn east on Main, drive until you see >a building with 1234 on it, park the car, go in the side door, up >the stairs to the 2nd floor, down the B hallway to room 234." >Routes tend to be different, depending on where the entity following >the directions is starting from. Routes are usually tied to the >underlying technology. ...and a large amount of other helpful, true stuff. I read this message and essentially agreed with everything Mark said. But then a thought started brewing in my mind. A thought that is rooted in the fact that a lot more of my mail has been bouncing recently than ever before. A thought that embraces heterogeneity, anarchy, shifts in the political winds, backbones, byte limits, and real worlds in general. A thought that makes me question whether you can really "solve" this problem. Let's say you start with a fully qualified name and address, like Joe_User@Host.Domain.NETWORK. This can then be resolved into an actual route by a mail router that finds the appropriate stuff in its tables, and the mail can be delivered to Joe_User. However, it seems that 30% of the time, Joe_User cannot reply to the mail, because the routing is sometimes non-deterministic and may in fact not be reversible. The "From:" and other lines in the mail are almost certainly rewritten by partially damaged software along the way. Also, my name and address may not be in his host table, or my router doesn't know about JANET or the domain for New Zealand or whatever. So the mail bounces. The bangity!bangity!user stuff is pretty crude, but it was very reliable in terms of reversing the path and getting mail returned to the sender. That's valuable, in my opinion. And sorely missed in today's world. Glenn Reid Adobe Systems