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cat crashess Article 56 of comp.dcom.telecom: Path: csustan!lll-lcc!styx!ames!ucbcad!ucbvax!kitty.UUCP!larry From: larry@kitty.UUCP Newsgroups: comp.dcom.telecom Subject: Submission for mod.telecom ("Crashing" a Central Office) Message-ID: 8704261435.AA29050@seismo.CSS.GOV Date: 26 Apr 87 14:35:33 GMT Sender: daemon@ucbvax.BERKELEY.EDU Distribution: world Organization: The ARPA Internet Lines: 35 Approved:

Finally, If both my best friend and myself set call forwarding to
each other, what happens when someone calls?

[ … Also, if you forward to someone who forwards to
you the call goes "click", "click", busy. The two clicks are the
trunks going between your central offices. If you do this to someone
on the same ESS machine, it gives you a busy immediately. This is
useful especially if you have your calls forwarded from home to work
and vice versa. You can safely forward your calls bi-directionned until
you get home and clear the forwarding. Also, I crashed our central office
forwarding once to someone on the same machine (that was 12 years ago).
      Re: the comment about "crashing" the central office...
      If anyone finds this hard to believe, I know of a specific example

where there was a bug in a particular generic software release used on some early #2 ESS machines which had just been installed by New York Telephone to replace SxS CDO's during the mid 70's.

      By using three telephone lines, and setting them up to forward as

A –> B –> C –> A, a call from another telephone to A as a "seed" would force the #2 ESS to crash and switch to the standby processor, whereupon a second occurence would wipe out the standby processor until the call attempt was discontinued. This situation would also set off remote alarms at the SCC which handled these unattended #2 ESS machines.

      Needless to say, a software patch was quickly developed by WECO...
      The above scenario was probably unanticipated by the WECO team

that designed and wrote the software. The public, however, seems to have a knack for discovering these flaws rather quickly.

<> Larry Lippman @ Recognition Research Corp., Clarence, New York <> UUCP: {allegra|ames|boulder|decvax|rocksanne|watmath}!sunybcs!kitty!larry <> VOICE: 716/688-1231 {hplabs|ihnp4|mtune|seismo|utzoo}!/ <> FAX: 716/741-9635 {G1,G2,G3 modes} "Have you hugged your cat today?"


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