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HIER.DOC
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1991-08-17
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W0RLI, VE3GYQ, and N6VV have devised a scheme called hierarchical
addressing. Here's their description of their idea:
----------------------------------------------------
It has become obvious by now that the work-horse of our so-called packet
network is the venerable BBS program. In fact, some will argue that it
has been too successful. Every time that a band-aid is needed to "fix"
the network, it is applied through the various BBS programs. It is
probably fair to say that the maintenance of the forwarding tables is a
drudgery that most sysops could do without. This point also
under-scores a serious problem faced by all networks: ROUTING.
With the introduction of W0RLI V7.00 and support for Hierarchical
routing designators, we have an opportunity to improve traffic routing
particularly for international traffic. Since N6VV is at the present
time responsible for traffic to Asia and the Pacific, and occasionally
Europe and Africa, he has implemented some Hierarchical routing
designators which will assist him in international routing.
Using this structure mail can now be addressed :
JA1ABC @ JA1KSO.JPN.AS
or
VK4AHD @ AX4BBS.AUS.AU
[I have excerpted the codes into COUNTRY.DOC]
State and province codes shall be the recognized two-character code
established by the American and Canadian Post Offices. These may also
be found in the Callbook listings.
It is after we get down to the state/province/county level where the
trouble may begin. To understand why, we must examine how the BBS code
goes about matching things in the route. The first principle is that it
attempts to find a match between the items in its forward file and the
left-most item in the address field. As an example, say that we send
something to W0RLI @ W0RLI.CA.USA.NA, and that the only entries that we
have in the forward file are for CA. That match would be sufficient to
allow the message to be forwarded. If W0RLI were found, that entry
would take precedence (because it is more left in the field than CA) and
would of course also ensure delivery. The best way to look at it is
"W0RLI AT W0RLI which is in CA which is in USA which is in NA". So far
so good.
But the Japanese network wants to use area routing numbers. For
example, JA1ABC @ JA1KSO.42.JPN.AS ... and everyone says, "So what, let
them!" Of course, that is very mature of all of us, but the trouble is
that the 42 in that string may also match wild-card ZIP codes that some
folks keep in their forward file, such as 42*. The solution we propose
is to use an agreed upon key character for designators below the state
and province level, and we recommend the octothorpe, "#".
So now the above address would be JA1ABC @ JA1KSO.#42.JPN.AS . Other
examples could be:
1) W0RLI @ W0RLI.#SFO.#NOCAL.CA.USA.NA - W0RLI within SFO (San
Francisco) within North California, etc.
2) VE3BTZ @ VE3GYQ.#LONDN.#SONT.ON.CAN.NA - VE3BTZ at VE3GYQ in
London, in Southern Ontario, in Ontario, etc.
There is another added benefit to this scheme. It involves Gatewaying
between the BBS world and other networks, such as TCP/IP via SMTP. Much
of the pioneer work in setting up the gatewaying protocols has been done
by NN2Z, N3EUA, and PA0GRI, amongst others. The W0RLI BBS package
allows for the forwarding of mail between the BBS world and the SMTP
world. Of note is the fact that the WA7MBL package has allowed such
message exporting and importing for some time now. This means that we
can take advantage of the the TCP/IP host-names and their domain or
hierarchal format for forwarding. Thus it is possible to send mail from
the BBS to VE3BTZ as ve3btz@pc.ve3btz.ampr.org or from SMTP to
w0rli@w0rli.ca.usa.na and not have any ambiguity.
We expect that WA7MBL will also be implementing hierarchal routing in
the near future. This system is still compatable with older style
systems, as a system that handles hierarchal forwarding identifies with
the H feature letter: [RLI-8.00-CH$]. If it does not get an appropriate
response, it uses the left-most item in the "@ BBS" string as the "@
BBS" for the message.
The authors hope that this paper will serve as a starting place for
improved message routing by means of implicit routing. Low-level (VHF)
BBSs need only maintain state or province or country codes for distant
BBSs, and route such traffic to their nearest HF Gateway. In turn, the
HF station routes it to the desired state, where the receiving Gateway
station would have a detailed list of the BBSs it serves.
Correspondence may be addressed to the address given at the start of
this paper, or to VE3GYQ @ VE3GYQ.ON.CAN.NA or N6VV @ N6VV.CA.USA.NA .
----------------------------------------------------------------------
BB version 2.0 and higher support hierarchical addressing.
BB searches for the word in the BBS and H fields for a match in
route file. Thus, given a message addressed to:
N6TFX @ AA4RE.#NOCAL.CA.USA.NA
we will search for AA4RE, #NOCAL.CA.USA.NA, CA.USA.NA, USA.NA, and NA
The first match determines the path the message would take. I could
have a ROUTE.BB file like this:
CA\.USA\.NA W0RLI
NA N6VV
**** BB V2.11 change ****
*** Note the use of the \ ***
This prevents ambigious routings. The \ says that The string to the
right of the \ is optional. It can be present and if so must match. If
it is missing, it is a match. Example: a\a will match with a or aa but
not ab
The CA.USA.NA would be the first match and the message sent to W0RLI.
If a message was sent to W3IWI @ W3IWI.MD.USA.NA, the NA would be the
first match and the message would be sent to N6VV.
If everyone used hierarchical addressing, your ROUTE.BB file would be
much smaller. You would only need ROUTE.BB entries for local mailboxes
and a few entries pointing to various forwarding points.
One minor note. I showed #NOCAL in the example. You must be very
careful when putting this in your ROUTE.BB file. #NOCAL would mean a
NUMBER followed by NOCAL (See WILDCARD.DOC). Instead, use "#NOCAL. The
" is the escape that says that # is not a wildcard character.
----------------------------------------------------------------------
Don't generate #xxxxx willy nilly. You should have the agreement of
everyone in your state or providence to agree on a designator.
----------------------------------------------------------------------
BB Version 2.6 contains an server to automatically address outgoing
messages. The server is invoked by the GH command. The file it works
from is pointed to by H_LOOKUP_FILE in PARMS.BB. The format of the file
is simple:
AA4RE .#SOCAL.CA.USA.NA
The first column is the call of BBS. The second column is the
hierarchical address to use. The first column can support wildcards so
GB* .GBR.EU
will address all BBS starting with GB to .GBR.EU. The program only
works on mail that has not been read nor marked for forwarding (the flag
must be "N"). Onlt the @BBS field is checked. In addition, no
hierarchical address can be assigned to the message that already has
one.
There are several servers around that support generating the HLOOKUP
file automatically from incoming headers.