Re: Multiple TCP/IP servers on one host


Roger Fajman (RAF%NIHCU.BITNET@CUNYVM.CUNY.EDU)
Fri, 02 Sep 88 13:55:01 EDT


> I'd just like to say that multiple terminal servers on one host will be
> a problem for us too. Right now we have a host that has about 700
> async dial ports. We expect that network access will begin to supplant
> modem access in the near future, as we get our network connections in
> gear. Even a cisco ASM with 96 ports (the biggest terminal server that
> I know of) wouldn't be enough. Even if it were compatible with our
> host, which it isn't.
>
> The solution using the domain name system sounds best because it
> doesn't require changing all the Telnet implementations on the
> Internet. If the choosing is done in the name server (which seems
> necessary to avoid changing all the Telnets), then it is necessary to
> set the time to live to a small value, so that the random response
> won't be cached and reused many times. This increases the number of
> name server requests, but nothing is perfect.

After further reflection, I think that I did not phrase this very well.
What I should have said is that it would be useful if the domain name
server could be told to somehow vary (i.e., randomly or cyclically) the
order of the addresses in its responses to queries. Combined with a
short TTL, this should tend to spread the load over all the servers for
the large host, instead of filling the first server to capacity before
going on to the next. There's an implicit assumption here that given a
list of addresses for a host that are all on the same network number,
that most Telnet implementations would tend to try them in the order in
which they appear in the list. Please correct me if that is wrong.

I also wonder if the ability to try multiple addresses is common in
Telnet implementations, especially those for MS-DOS.



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