taylor@hplabsc.UUCP (02/27/87)
in news.sysadmin, David Lesher at ncoast.UUCP comments: > I regularly see posting [like] "I would have mailed but my mailer choked.." > Now the same thing often happens to me...it is very wasteful of net.money > would it not be worthwhile to devote some fraction of net.genuis/net.GOD > (s) resources to inventing better, more dependable, mailers? I will state something that might be viewed (inevitably) as controversial: the mail systems we have are fine. There is nothing wrong with them (hang on before you slam down that "F" key!) but rather what we're seeing is the problems of: 1. having a system that expects dynamic routing in a static routing universe (e.g. pathalias) 2. having this system phased out (e.g. the use of 'domains') 3. not having the new system implemented yet much of anywhere 4. some serious delusions about how reliable the software is going to be. What this means, I surmise, is that the main reason we're seeing people unable to reply to postings and/or get email addresses is that we've reached a point where people don't really want to mess with the pathalias style of addressing (the static routing system) and where we can't rely on 'core mail backbone' sites (like the ex-ihnp4) to reroute stuff based on real paths (the fake-dynamic routing that smail allows). At the same time, since there is a perceived need for domains as a way to break up our massive ".UUCP" domain into smaller, more manageable chunks, we're seeing hostnames that are from out of the twilight zone as far as any pathalias system is concerned ANYway. "hplabs.HP.COM" is a fine example of this... For reasons I shan't enter here, ignoring domain information on an electronic address (e.g. "hplabs.HP.COM" --> "hplabs") is a very bad idea... What we're supposed to end up with is a system that says "oohhh... you're sending mail to <hostname>.HP.COM (or <hostname>.<localdomain>.HP.COM) so I'll just send it to machine X". As we further and further subdivide the UUCP domain into pieces (.EDU, .STANFORD.EDU, CS.STANFORD.EDU, etc) we should theoretically see simpler and simpler delivery systems. In reality, however, I suspect that it'll be quite a bit further along before we 'shake out' the system and get some real reliability. There are some inherent problems with static routing information masquerading as dynamic routing information that are poised to attack... BUT as far as what we're talking about here, the best solution I can make is for people to have mail systems that grab not only the From: address in the posting, but the Path: address too, and read the Path: backwards until it finds a 'backbone' that it knows (you can have a file containing the 10 or 15 main ones, if you want) and then figures out the optimal (static, alas) route to that backbone. For example, your posting has the headers: Path: hplabsc!hplabs!hp-sdd!ncr-sd!ncrcae!ece-csc!mcnc!seismo!lll-lcc!ptsfa!ihnp 4!cbatt!cwruecmp!hal!ncoast!wb8foz From: wb8foz@ncoast.UUCP (David Lesher) First we should check the From: address and (as would really happen) figure out that we have no idea how to get email to ncoast.UUCP. So as an alternative plan, instead of dropping it there, we'd read the Path: line and start from the right, building up a longer and longer route until we find a host that we know we can get to: hal!ncoast!wb8foz cwruecmp!hal!ncoast!wb8foz cbatt!cwruecmp!hal!ncoast!wb8foz We know how to get to 'cbatt' (from hplabs it's simply via 'cbosgd') so we now have the address: cbosgd!cbatt!cwruecmp!hal!ncoast!wb8foz which is pretty reasonable. The advantage to this scheme is that it is indeed dynamic - it only finds routes that are actually those that have been taken in the past few days (assume current articles). The list of backbone sites could be as small as 20 or 30 and we'd be ok...(check the list in the Path: line above - there are 5 'backbones' in the route: hplabs, mcnc, seismo, ihnp4, and cbatt). Gee... neat idea. Maybe I should implement it or something. Anyone have any comments? -- Dave Taylor --
paul@devon.UUCP (03/01/87)
In article <1354@hplabsc.UUCP>, taylor@hplabsc.UUCP (Dave Taylor) writes: > BUT as far as what we're talking about here, the best solution I can > make is for people to have mail systems that grab not only the > From: address in the posting, but the Path: address too, and read the > Path: backwards until it finds a 'backbone' that it knows (you can > have a file containing the 10 or 15 main ones, if you want) and then > figures out the optimal (static, alas) route to that backbone. > > [ example deleted ] > > Anyone have any comments? > Yeah. Two of them. First, the Path: line, although "newer" than the static information from pathalias, is not necessarily correct. Take the Path: line in the article I'm following up to: Path: vu-vlsi!cbmvax!rutgers!seismo!lll-lcc!pyramid!hplabs!hplabsc!taylor While this is the path that the article took to get here, it ignores the fact that devon (my system) talks directly with cbmvax for mail purposes (my news feed comes from vu-vlsi). It also ignores the fact that cbmvax exchanges mail with seismo directly, too. This is not necessarily a Bad Thing--routing through extra hosts. It would have the benefit of using more recent data to make a routing decisison. But (here comes the 2nd comment:) what if cbmvax exchanged ONLY NEWS with rutgers (yeah, I know, it doesn't. But what if it did!). Your mail-path-parsing scheme, not knowing this, would attempt to send mail via: ...!seismo!rutgers!cbmvax!vu-vlsi!... and rutgers would not be able to forward it to cbmvax. Although my example is not good, the point I'm making is that it would be A Bad Idea to assume that just because news follows a given path, that mail will be able to follow the same path. Does all this sound familiar? B-news 2.11, if compiled without the INTERNET definition, uses the Path: line to generate a return route for a reply (for reply-by-mail, not followups). I had more mail bounced back before I defined INTERNET here than I care to remember (Yes, I've installed smail and defined INTERNET to news now). Smail may be using "older" data, but I've had *far less* troubles with pathalias/smail generated paths than I had before using them. - paul -- Paul Sutcliffe, Jr. paul@devon.UUCP (or, if you prefer:) Devon Computer Services {seismo,ihnp4,allegra,rutgers}!cbmvax!devon!paul Allentown, PA "I love work. I could sit and watch people do it all day!"
jerry@oliveb.UUCP (03/04/87)
In article <228@devon.UUCP> paul@devon.UUCP (Paul Sutcliffe Jr.) writes: >Path: vu-vlsi!cbmvax!rutgers!seismo!lll-lcc!pyramid!hplabs!hplabsc!taylor > >While this is the path that the article took to get here, it ignores ... >Your mail-path-parsing scheme, not knowing this, would attempt to send >mail via: > > ...!seismo!rutgers!cbmvax!vu-vlsi!... NO, you have it backwards. Unlike reversing a UUCP address the "Path:" line is ALREADY in the correct format for a UUCP address. So for the example given it would be: ...!hplabs!hplabsc!taylor which doesn't seem especially long to me. I don't think the proposed algorithm should be the default way to route mail but if the automatic routing was unable to find the target site then it could privide an alternative. As for the other objection, I believe for every "news but not mail" link that exists there are 10 published connections that don't really work. With connections constantly changing routing is not exactly an exact science. Suppose you were trying to drive cross country and road maps were only published every year or so. Meanwhile the road crews were closing highways for repair and finishing new roads all the time. Wait, what am I saying? Jerry Aguirre Systems Administration Olivetti ATC
jordan@ucbarpa.Berkeley.EDU.UUCP (03/05/87)
it's really a shame that people like dave believe that the Path: line has any useful information in it. it should *never* be used for routing mail, not even for a hint. not even with any amount of AI you might code into your idea ... it's simply not going to work. i get a large amount of mail dumped into the postmaster mailbox all the time (this is on the machine ames, a backbone site) that is people trying to use the Path: line and who also have a broken From: line so that the bounce bounces ... when i had more time, i used to send a note back telling them what to do ... after 100 or so of these, i gave up. it made me wonder about why people think mail is so unreliable sometimes. it's probably due to the fact that the From: line is unrealiable and a bounce was unable to get sent back ... /jordan
mangoe@mimsy.UUCP (Charley Wingate) (03/06/87)
Jordan Hayes writes: >it's really a shame that people like dave believe that the Path: line >has any useful information in it. it should *never* be used for >routing mail, not even for a hint.[...] [I]t made me wonder about why >people think mail is so unreliable sometimes. it's probably due to the fact >that the From: line is unrealiable and a bounce was unable to get sent back. Well, I don't know about you, but often the Path: is the only information I have available to find a site. Our maps simply don't get udated that often. Furthermore, when I do construct a path that, according to the mailer, is going to work, often as not I end up just sending back over the path anyway, because the map information is somehow defective. (There's one site I have to construct a path to anyway, because there are two sites with the same name.) People have the opinion that mail is unreliable because, often enough, it is unreliable given the routing info they have available to them. Following the path back at least has the advantage of being current information, and one can just as well argue that a lot of the defects encountered in tracing it back arise because the path itself isn't being contructed correctly by the news software. And remember, the Ides of March are coming.... C. Wingate
jordan@ucbarpa.Berkeley.EDU (Jordan Hayes) (03/07/87)
Charley Wingate <mangoe@mimsy.UUCP> writes:
Well, I don't know about you, but often the Path: is the only
information I have available to find a site.
remember that the Path: line shows where the article has been, and it
has been transmitted via news ... let's all say this out loud once
again:
"NEWS LINKS DO NOT IMPLY MAIL LINKS"
i have to laugh every time someone sends mail over a news link that has
no corresponding mail link and the bounce winds up in my mailbox
because someone mangled the return address. i used to be concerned,
but now it's just silliness.
/jordanjohn@xanth.UUCP (John Owens) (03/09/87)
> "NEWS LINKS DO NOT IMPLY MAIL LINKS" > > i have to laugh every time someone sends mail over a news link that has > no corresponding mail link and the bounce winds up in my mailbox > because someone mangled the return address. i used to be concerned, > but now it's just silliness. > > /jordan I agree completely from a theoretical point of view, but from a practical point of view, when I see mail from a uucp site that's not in the uucp maps, I can almost always find how to get to them by looking on the Path: line - usually the next-to-last site will be in the maps. At worst, I have to go known-site!next-site!final-site!user. Also, whenever I set up a non-uucp news link, I try to make sure that mail returned via the Path: line will work somehow. This isn't always possible, but when it is, it allows not-so-smart sites to still get replies through. Remember, if you don't have INTERNET defined when you build news, it'll reply through the Path! -- John Owens Old Dominion University - Norfolk, Virginia, USA john@ODU.EDU old arpa: john%odu.edu@RELAY.CS.NET +1 804 440 3915 old uucp: {seismo,harvard,sun,hoptoad}!xanth!john