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From: michaud@devax.dec.com (Jeff Michaud)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: rwhod protocol and >42 users
Message-ID: <5345@shlump.nac.dec.com>
Date: 12 Oct 89 01:24:41 GMT
References: <7370@xenna.Xylogics.COM> <1178@celit.fps.com>
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> Finally, you can just chuck rwhod and use Sun's "rusers/rup" instead.
> It works, albeit not very well.

	Is rusers like remote finger (ie. like "f @some-host-name")?

	A more efficient method all around would be to have a dedicated system
	act as a "remote who" server.  On a timer the server system (lets call
	this one the master server) will send out a udp broadcast advertising
	itself as a "remote who" server.  Hosts that want to advertise who's
	logged on the system (call these slave servers) send the info directly
	to the "remote who" server.   Clients which want info on whos logged
	in on the network asks the local slave server (who knows who the master
	server is) who in turns asks the master server (or the slave server
	can store the master servers address/port away where clients can use
	it to request the info directly from the master server).

	To extend this just a bit further so improve on the availability
	problem if the master server is down, we can allow for multiple
	master servers to exist.  Slave servers will remember all the master
	servers and also send their "whos logged on me" messages to each
	of the masters.  3-4 servers on a lan should be sufficient if
	a high assurance of availability is needed.

	This reduces udp broadcast traffic for an equiv service to rwho
	down to 4/minute if there is 4 master servers which each advertise
	themselves once a minute.  It also removes the beating on the
	disk to keep writing out to the /usr/spool/rwho/whod.* files
	(my workstation has been up 7 days and rwhod already has 47 minutes
	of cpu time, and this is on a fast DECstation 3100!).

	This would probably be a good job for a location brokerage service?

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|Jeff Michaud    michaud@decwrl.dec.com  michaud@decvax.dec.com|
|DECnet-ULTRIX   #include <standard/disclaimer.h>              |
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