RFC849 - Suggestions for improved host table distribution

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Network Working Group Mark Crispin

Request for Comments: 849 Stanford

May 1983

SUGGESTIONS FOR IMPROVED HOST TABLE DISTRIBUTION

This RFCmay be something unique among modern-day RFC's, an RFC

that actually is a request for comments. The issue dealt with is that

of a naming registry update procedure, both as exists currently and what

could exist in the future. None of the proposed solutions are intended

as standards at this time; rather it is hoped that a general consensus

will emerge as the appropriate solution, leaving eventually to the

adoption of standards.

THE PROBLEM

I am somewhat dissatisfied with the current level of Internet name

service and name registry updating. Each site is eXPected to

individually maintain a copy of the [SRI-NIC]<NETINFO>HOSTS.TXT file,

and in fact has to, since SRI-NIC is simply not reliable enough to

depend upon as a name server. Neither the Tenex operating system nor

the Foonly computer are known for exceptional reliability or

performance. Probably they serve the NIC's internal operations well;

that is not at issue. What is needed is a name service that is

available at all times. Only then could a site sacrifice maintaining

its own local copy of "the host table".

The NIC indirectly acknowledges this, by providing a service by

which the entire Internet name registry can be dumped, as well as

ANONYMOUS FTP Access to the <NETINFO>HOSTS.TXT file. The problem is,

some individual has to know to retrieve the latest version of the file

from the NIC. The NIC has not always been careful to announce updates

to the name registry. My experience with maintaining an independent

name registry from the NIC's in the past leads me to appreciate the

NIC's problems.

There also seems to be no good automated way to cross-check the

version at the local site with the NIC's. It is clearly inefficient to

go to the effort of retrieving the same version of the host table that

already has been installed on site.

SOME SOLUTIONS

One could argue that a solution is to replace or augment the

present SRI-NIC system with VAX Unix system(s) dedicated to name service

and network information. A reliable and highly-responsive name service

would ultimately lead to the elimination of the necessity to maintain

copies of the registry locally. This solution requires money, time, and

effort, which may or may not be immediately available; it must therefore

be considered a longer-term solution.

Crispin [Page 1]

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 RFCthat 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.

 
 
 
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