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Network Working Group                   Marc SeriffRequest for Comments 308                MIT-DMCGNIC 9259                                13 MARCH 1972References:RFC 254                     ARPANET HOST AVAILABILITY DATA     Several months ago a SURVEY program was implemented on theMIT-DMCG ITS PDP-10 system to aid in gathering information on theavailability of various HOSTS on the ARPANET.  The purpose of thisRequest for Comments is threefold:     1. to inform the Network Working Group of the        existence of this information gathering service        and about getting access to it,     2. to present the results of SURVEY for its first        few months, and     3. to correct errors in our data or collection methods.     Briefly, the SURVEY program works as follows: At 15-minuteintervals whenever the MIT-DMCG ITS Time-Sharing system is in normaloperation, a SURVEY is started.  The SURVEY program attempts toestablish a connection to the LOGGER (socket 1) of each HOST listed inits table.  The results of each connection attempt are recorded forfuture reference.  The Initial Connection Protocol is aborted prior toreading the transmitted socket number so as to cause the minimumamount of processing at SURVEYed HOSTS.  If the LOGGER connectionsucceeds, the average request-for connection response time (inseconds) for the HOST is updated.  This information can later beviewed in several formats using the MIT-DMCG server TELNET "NETWRK" asdescribed below.     Each test results in the assignment of one of the followingfive statuses:     1.  LOGGER available - connection completed.     2.  LOGGER not responding - RFC sent (HOST-HOST OK), but         no response (20 seconds allowed).     3.  LOGGER rejecting - CLOSE returned by NCP.     4.  NCP not responding - RESET timed out (15 seconds allowed).     5.  HOST dead - host-dead status returned by IMP.                                                                [Page 1]

Below you will find a summary of the information gathered todate.  It must be remembered that the SURVEY program can only run whenMIT-DMCG ITS Time-Sharing System is in normal operation and the MITIMP is operational.  Thus the current figure of 94% for MIT-DMCG isinaccurate. (It should actually be closer to 66%.)     There are, in addition, two other shortcomings of which we areaware.  The first is that SURVEY is on a 24-hour basis and does _not_consider advertised up time.  For example, MIT-DMCG will never bebetter than 67% on a Tuesday since the machine is always unavailablefrom 4 p.m. to midnight.  The second shortcoming is the fact that theLincoln Lab's TX-2 shows as "never available".  This reflects an asyet undiagnosed problem currently under investigation.     To get availability information from DMCG, you must first followthe scenario inRFC 254.  Once in NETWRK, the DMCG user-TELNET, thereare seven available commands which pertain to SURVEY data:     SUMMARY.OF.SURVEYS - summarizes most recent information.     HISTORY.OF. <host name> - gives a detailed recent history                    of the given host.  This generates a lot                    of output, so use it sparingly.     ACTIVE.HOSTS - lists those hosts who accepted a connection                    at least once during the last 24 hours.     BEST.SURVEY - lists the best of the recent surveys.     LONGTERM SUMMARY.OF.SURVEYS - summarizes all past                    information.  This was used to generate                    the table on the next page.     LONGTERM HISTORY.OF <host name> - gives a summary of                    past history of the given host.  It                    does not generate as much output as the                    HISTORY command.     LONGTERM ACTIVE.HOSTS - lists those hosts who accepted a                    connection at least once since December 13,                    1971.                                                                [Page 2]

For the above seven commands, "recent" is define as "within thelast 24 hours or less".     For help in accessing SURVEY data and comments on improving theadmittedly limited SURVEY service, please contact:          Marc Seriff          M.I.T. - Project MAC          545 Main Street          Cambridge, Mass. 02139          (617) 864-6900 ext. 1458                                                                [Page 3]

6528 Surveys from 09:55:18 on 12/13/71 to 08:50:41 on 03/20/72--HOST-- -#- -%-UP- -RESP- *ucla-nmc 001  064%   00.93sri-arc  002  064%   02.96ucsb-75  003  048%   00.53utah-10  004  057%   03.23bbn-ncc  005  000%   00.00multics  006  047%   05.60rand-rcc 007  000%   00.13sdcadept 010  000%   02.60harv-10  011  022%   00.23ll-67    012  021%   03.70su-sail  013  000%   00.00ill-11   014  000%   00.06case-10  015  000%   00.00cmu-10   016  034%   00.23burr     017  000%   00.00ames-67  020  000%   00.00radc-645 022  000%   00.00 **nbs-11   023  000%   00.00 **tink-418 025  000%   00.00 **usc-44   027  000%   01.13 **ncar7600 031  000%   00.00 **ucla-ccn 101  070%   00.30sri-ai   102  000%   02.26tenex    105  060%   02.40mit-dmcg 106  093%   01.10 ***rand-csg 107  013%   02.96 **harv-1   111  000%   00.23ll-tx2   112  000%   01.76ill-6500 114  000%   00.00burrtest 117  000%   00.00 **tenexb   205  018%   02.93mit-ai   206  000%   00.00harv-11  211  000%   00.00* Remember that "UP is defined as "Logger Accepting connections."** Surveyed only since February 18, 1972.*** MIT-DMCG is actually up about 66% of the time.       [ This RFC was put into machine readable form for entry ]       [ into the online RFC archives by BBN Corp. under the   ]       [ direction of Alex McKenzie.                   12/96   ]                                                                [Page 4]