Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site glacier.ARPA Path: utzoo!watmath!clyde!burl!ulysses!allegra!mit-eddie!genrad!decvax!decwrl!glacier!reid From: reid@glacier.ARPA (Brian Reid) Newsgroups: net.news Subject: Re: The cost of a message Message-ID: <2963@glacier.ARPA> Date: Thu, 9-Jan-86 01:33:20 EST Article-I.D.: glacier.2963 Posted: Thu Jan 9 01:33:20 1986 Date-Received: Fri, 10-Jan-86 23:34:11 EST References: <2501@amdahl.UUCP> <871@vortex.UUCP> Reply-To: reid@glacier.UUCP (Brian Reid) Organization: Stanford University, Computer Systems Lab Lines: 51 Here are two independent computations of the cost of a a news message. They yield $27 per message and $32 per message, respectively (for a 1000-character message). The first computation is a forward computation based on the price of telephone calls and the connectivity of the network; the second computation is a backward computation based on Glacier's monthly phone bills and the amount of monthly traffic that we see. Forward computation: assume that... N=4000 Number of nodes on USENET C=1.5 Average redundant connectivity of a USENET node K=0.10 $US per minute for long-distance telephone time L=0.02 $US per minute for local telephone time S=80 Characters per second average throughput P=1000 characters in a news message Optimistic computation (all telephone calls local, no redundant connectivity). In this case there will be about N phone calls for N hosts; the cost of sending a message to those N hosts is N*L*P/(60*S), which is 4000*0.02*1000/(60*80) = $16.66 per 1000-character message. Pessimistic computation (all telephone calls long-distance; 50% redundant connectivity). This is N*C*K*P/(60*S), which is 4000*0.10*1000*1.5/(60*80), or $125 per 1000-character message. I think that a reasonable model--perhaps right to within a factor of 3--is that 10% of the phone calls are long distance, that there is very little local redundancy but about a factor of 1.5 long-distance redundancy (most of the backbone hosts have more than one long-distance feed path). This gives us the hybrid formula COST = 0.9*(4000*0.02*1000/(60*80)) + 0.1*4000*0.10*1000*1.5/(60*80) or COST = 14.94 + 12.50 = $27 for a 1000-character message. Backward computation: Glacier's phone bills for USENET are about $500/month and the monthly traffic is about 20 megabytes. That means that we are paying $500/20000 per 1000 characters, which is about 2 cents a message. If every node on the net pays a comparable amount, then the cost of that message is 4000*0.02 or $80/message. Maybe only 10% of the sites on the net have phone bills as large as $500/month--say the average monthly phone bill for a USENET site is only $200. That would result in a figure of $32 per 1000/character message. P.S: this message is 2500 characters as it leaves my terminal. That means it is costing about $100. I'd better shut up. -- Brian Reid decwrl!glacier!reid Stanford reid@SU-Glacier.ARPA