Path: utzoo!attcan!uunet!cs.utexas.edu!mailrus!wuarchive!texbell!vector!telecom-gateway From: bmk@mvuxi.att.com (Bernard Mckeever) Newsgroups: comp.dcom.telecom Subject: Re: Need Information on "Bit Slippage" Message-ID: Date: 20 Nov 89 12:37:55 GMT Sender: news@vector.Dallas.TX.US Reply-To: bmk@cbnews.ATT.COM (bernard.mckeever,54236,mv,3b045,508 960 6289) Organization: AT&T Bell Laboratories Lines: 64 Approved: telecom-request@vector.dallas.tx.us X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@vector.dallas.tx.us X-TELECOM-Digest: volume 9, issue 524, message 7 of 9 [Moderator's Note: I am rather confused by this message which arrived here from Mr. McKeever with a different title, and was signed by John Kennedy of Annapolis, MD. I assume McKeever wrote to Kennedy, who then replied to him? But no introduction or cover note came with what follows below. PT] I hope this provides several answers. >Several questions: >1) Does the problem I described seem like a fair diagnosis? Very close. Most likely you are experiencing frame slips on the/a digital facility. A slip happens when both ends of a synchronous [as opposed to asynchronous] facility are not operating at the same average clock rate. If one terminal runs slow the buffer will overflow and a full frame of information will get tossed. If the same terminal is running fast not enough information is available so the last frame is repeated. >2) Where is this "slippage" problem occur - between the subscriber > and the switch, or between the two switches? Several possibilities here. If the trouble is between digital switchs both should have alarms. Slips do not have a noticeable affect on VF so the alarms are shut off. The slips can be caused by one switch free running [stratum 3] and the other timed from a standard. [stratum 1] If the trouble is between the station and the CO it could be a SLC system with a direct digital interface not being looped timed. [My first choice] Other equipment may also cause this problem if the Telco is sloppy with timing distribution. >3) Can this problem be addressed by doing something with the subscriber's > interface to the local switch? No. All you can do is install a modem with excellent error correction. >4) What can the subscriber do about it? Does he have the > right to have the problem corrected? Would ordering a so-called > "conditioned line" either correct the problem or give the subscriber > a right to have the problem corrected? In order, pray, no, yes. >5) Are the local telco's sympathetic to residential customers' data > problems? Not only no, but @$$# NO. Your best bet is to look around for somebody that knows what is going on, is in a position to do something about it THEN BEG. >6) Is there someone to ask for in a local office, if the usual > customer assistance people are unable to help? Try to get the repair supervisor if you have SLC systems to the CO, or the CO analyzer if you don't. The trouble can be any place in the network. Thanks, John Kennedy johnk@opel.uu.uunet Second Source, Inc. Annapolis, MD