RFC 849 (rfc849) - Page 2 of 2

Suggestions for improved host table distribution

     A more short-term solution is to make possible faster and more
thorough updating of the various local copies of the name tables.  I
have several suggestions in this area, and would like to hear comments
(I said this was an RFC that requested comments!):

     (1) a new protocol by which the NIC could ship updated name
registries to the hosts itself.  This would take the form of a server
process on each site listening on a registered port for updates from
certain "trusted" sites (specifically SRI-NIC but possibly other sites
as well).  This would allow for nearly immediate updates for cooperating
sites, provided that the hosts in question are up.  There should be some
sort of checksum applied to the updated name registry, to make sure it
arrived complete and intact.

     (2) a new protocol by which the NIC will report the current
"version" of the host table.  Tenex and TOPS-20 sites would find the use
of the file generation number natural.  I presently maintain a
SYSTEM:HOSTS.TXT with the same generation as it existed on the NIC, and
just check at the NIC from time to time to see if the generation number
changed there.  I would like to automate this.

     (3) A variation on (1), whereby the NIC would mail the updated host
table to a mailing list of "host table update" recepients and each site
would establish its own update procedures.  This is the simplest to
implement for the NIC, but is fraught with all sorts of problems.  Mail
is not a good means for bulk-shipping files to many recepients,
especially when the files are likely to become hugh.

     I like (1) best of these three, because that would guarantee
immediate updating without a local necessity to periodically poll the
NIC.  That does place the burden on the NIC to make sure all sites
receive the update, and also requires that the NIC remember which sites
are dead to retry the update later.  This leads me to what I think is
the best solution, which is:

     (4) A combination of (1) and (2).  The NIC will ship updates to all
hosts which are registered with it to receive the updates, and will try
only once.  Each site, as part of its system startup procedure, will run
a program to poll the NIC for a possible update and if one is available
retrieve it.  As a backup, there could also be a periodic poll on, say,
a daily basis.













Crispin