Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!seismo!ut-sally!husc6!mit-eddie!ll-xn!ames!sdcsvax!ucbvax!ALEXANDER.BBN.COM!scohn From: scohn@ALEXANDER.BBN.COM (Steve Cohn) Newsgroups: comp.protocols.tcp-ip Subject: Re: Something has changed dramatically Message-ID: <8707171340.AA21710@ucbvax.Berkeley.EDU> Date: Fri, 17-Jul-87 09:42:59 EDT Article-I.D.: ucbvax.8707171340.AA21710 Posted: Fri Jul 17 09:42:59 1987 Date-Received: Sat, 18-Jul-87 13:48:32 EDT References: <8707170455.aa00520@VGR.BRL.ARPA> Sender: daemon@ucbvax.BERKELEY.EDU Distribution: world Organization: The ARPA Internet Lines: 25 Here's something that changed. BBN modified the metric used for calculating SPF routes in the Arpanet on Sunday, 12 July. A detailed description and analysis of how it works and a report on measured changes in performance in the Arpanet will be forthcoming eventually. In brief, this change in the metric leads to more stable routing behavior when the network is overloaded, thereby reducing the tendency for congestion to spread from overloaded paths to the rest of the network. This modification also tends to make satellite trunking more attractive. Other potential sources for improvement include recent topology changes including the addition of transcontinental VSAT trunks between MIT-77 and SRI-51. These trunks became operational about 1 July. The routing effort is still in the experimental/tuning stage. We expect that performance on many PSN-to-PSN flows will be improved by this modification. It is also possible that some PSN-to-PSN flows will receive degraded performance. We at BBN would like to hear both the good news and the bad news. Please send your observations about recent changes in internet/Arpanet performance to Fred Serr (fserr@bbn.com), Bob Pyle (rpyle@bbn.com) and myself (scohn@bbn.com) and I suppose to the list if your observation is of general interest. Stephen Cohn Director of Network Analysis BBN Communications