mac@esl.UUCP (Mike McNamara) (12/15/86)
One thing I would highly recommend to anyone trying to upgrade their system performance is a terminal server. I am speaking about a box which sits on the ethernet, allows you to plug in ~16 terminals, and allows those terminals to communicate to any box that speaks TCP/IP. This removes the high cost of interrupt per character to and from your terminal, times the number of users, which is a significant drain on your cpu bandwidth. It also allows users to select which machine they would like to log in to, without (a) using their "main" host as just an rlogin frontend, or (b) requesting that system support change their configuration. Terminal servers also work much better than the switchers, like Develcons. We are using Annexes from Encore, but I think any such products would serve well. I am not connected with anyone who makes anything. -- Michael Mc Namara ESL Incorporated ARPA: mac%esl@lll-lcc.ARPA
chris@mimsy.UUCP (Chris Torek) (12/16/86)
In article <366@esl.UUCP> mac@esl.UUCP (Mike McNamara) writes: >One thing I would highly recommend to anyone trying to upgrade >their system performance is a terminal server. I am speaking about >a box which sits on the ethernet, allows you to plug in ~16 terminals, >and allows those terminals to communicate to any box that speaks >TCP/IP. This removes the high cost of interrupt per character to >and from your terminal.... But be careful! On standard 4.2 and 4.3BSD systems, a telnet or rlogin session presents considerably more load than a directly connected terminal, because the telnet and rlogin servers run in user code and require many context switches to transfer characters in and out of ptys. With kernel hacks such as those from Rutgers or NYIT, this overhead is considerably reduced, though a TCP connexion is still more of a load than a good hardware terminal multiplexor---unless perhaps your network interface implements TCP internally, in which case you should look *very* closely to make sure it is bug-free. Incidentally, if your multiplexors interrupt on every character, you may be well advised to replace them. >It also allows users to select which machine they would like to >log in to.... This too is an important consideration. -- In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7690) UUCP: seismo!mimsy!chris ARPA/CSNet: chris@mimsy.umd.edu