ARPANET host availability data (RFC0308)
Original Publication Date: 1972-Mar-13
Included in the Prior Art Database: 2005-May-22
Internet Society Requests For Comment (RFCs)
Several months ago a SURVEY program was implemented on the MIT-DMCG ITS PDP-10 system to aid in gathering information on the availability of various HOSTS on the ARPANET. The purpose of this Request for Comments is threefold:
Network Working Group Marc Seriff
Request for Comments 308 MIT-DMCG
NIC 9259 13 MARCH 1972
References: RFC 254
ARPANET HOST AVAILABILITY DATA
ago a SURVEY program was implemented on the
MIT-DMCG ITS PDP-10 system to aid in gathering information on the
availability of various HOSTS on the ARPANET. The purpose of this
Request 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.
SURVEY program works as follows: At 15-minute
intervals whenever the MIT-DMCG ITS Time-Sharing system is in normal
operation, a SURVEY is started. The SURVEY program attempts to
establish a connection to the LOGGER (socket 1) of each HOST listed in
its table. The results of each connection attempt are recorded for
future reference. The Initial Connection Protocol is aborted prior to
reading the transmitted socket number so as to cause the minimum
amount of processing at SURVEYed HOSTS. If the LOGGER connection
succeeds, the average request-for connection response time (in
seconds) for the HOST is updated. This information can later be
viewed in several formats using the MIT-DMCG server TELNET "NETWRK" as
results in the assignment of one of the following
1. LOGGER available - connection completed.
2. LOGGER not responding - RFC sent (HOST-HOST
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.
Below you will find a summary of the information gathered to
date. It must be remembered that the SURVEY program can only run when
MIT-DMCG ITS Time-Sharing System is in normal operation and the MIT
IMP is operational. Thus the current figure of 94% for MIT-DMCG is
inaccurate. (It should actually be closer to 66%.)
There are, in
addition, two other shortcomings of which we are
aware. The first is that SURVEY is on a 24-hour basis and does _not_
consider advertised up time. For example, MIT-DMCG will never be
better than 67% on a Tuesday since the machine is always unavailable
from 4 p.m. to midnight. The second shortcoming is the fact that the
Lincoln Lab's TX-2 shows as "never available". This reflects an as
yet undiagnosed problem currently under inv...