FSC-0004

Date: Mon  9 Feb 87 21:46
From: Randy Bush on 105/6, PSG Portland of VanPort Area, Portland OR
To:   Wynn Wagner on 124/108, The POLE: Opu of Dallas Metrop, Dallas TX
Subj: Re: Zones

The FSC has been working with existing implementations based on a year or two
old paper by Kilgore Trout describing Zones and Points, zone gates, and nodes
supporting points.  [ The paper was published in FidoNews last year, but
unfortunately was mostly to do with exploiting FidoNet financially, but had
pretty good technical requirements buried underneath. ] 

The FSC's goal is to send to some place for which one does not have the 
nodelist.  The underlying problem we are addressing is nodelist growth.  We 
envision over 10^5 nodes in a few years.  Our approach may be a bit more 
disjoint than you were considering.  

We have private nodelists already, and many of us use them (including 
remapping to private nodelists using Points and/or addressees' names). This 
has been in use for long enough that we almost understand half the uses to 
which folk seem to put it.  But the important part of Zones is not the 
nomenclature, rather the mapping of addresses.  

What the FSC was seeking with Zones (and is implemented and being tested) is
a method of getting mail to Bialystok (sp) without having a Polish phone 
book.  In the following example, please imagine possible sugar such as using
POLAND for 42 etc.  

When I, 1:105/6 address a message to Krzystzof in Bialystok, 42:451/666, it 
addresses the message header to <irrelevant> and creates a ^a line something
like 

  ^aINTL 42:451/666 1:105/6

The ^aINTL line is noticed by a smart router at either my node, or my 
outbound host's node.  To date the only ways to create the ^aINTL line are 
SEAdog's Mail program and some private utilities.  

Either in a batch run on the smart node (currently implemented by the program
ZoneGate) or in a truely smart mailer program (not yet known) the smart
router changes the destination net/node of the message containing the ^aINTL
to the outbound gateway to (or toward) zone 42 by a simple algorithm shown
below.  Thus, the message will travel within zone 1 (this zone) as if its
final destination was the net/node of the outbound gate.  This allows Opera
and Fidos 11w to carry it on its meanderings within any particular zone.  

When it arrives at the destination outbound zone gate, the smart router there
notices it, and 
  o may strip the seenbys (we had thought of it but not yet implemented it)
    except for that of the zonegate 
  o hands the message to the corresponding inbound zone gate by an unspecified
    means (intl zone gates tend to be other than FidoNet) 

The recipient inbound zone gate looks at the message's ^aINTL line and, using
the same algorithm as all the other smart routers that have seen the message,

  (* I hope you were waiting for the algorithm *) 
  IF msg.aINTL.toZone = myzone THEN 
     msg.address := msg.aINTL.toNetNode 
  ELSE 
     msg.address := outboundZoneGate [ msg.aINTL.toZone ] 

And thus the message travels onward, with its header address net/node 
representing it's intra-zone routing within the current zone and the ^aINTL 
line showing smart routers the true final destination.  

Observe that smart routers and zone gates only need know the local addresses
of the outbound zone gates from their own zone's nodelist, and nothing about
the nodelists of other zones.  One imagines the truely international FidoNet
having more than 10^5 nodes, with Opera and Fidos and other pre-Zone clones
will carrying the international traffic on its way within a zone in complete
innocence.  

The return address for the message is also stored in the ^aINTL line, so a 
'smart' recipient node can reply.  

Rather than trading private nodelists, the only information that needs to be
given to smart routers is the addresses of zone gates out of the current 
zone.  And, of course anybody can set up Zones, zone gates, and all those 
nice egalitarian sentiments, all they need is a simple mapping utility and a
way of telling folk that they're a zone gate and to what.  

There are some who consider a Unix gate merely a zone gate.  Usenet certainly
is another zone.