AFDDN.TCP-IP@GUNTER-ADAM.ARPA.UUCP (09/23/87)
To anyone who might know, especially Andy or Sharon, I've been trying to get someone(mostly DCA) to specify to me exactly what a "packet" is in terms of the billing algorithm. Since the billing algorithm is based on the traffic stats gathered by the PSN's, I'm really asking what are the packets reflected on the throughput reports. I make the differentiation between X.25 packets which can be anywhere from 128 to 1024 bytes, and the subnet "packets" passed between E-to-E in the PSNs. If memory serves me, the EE's break "messages" into 128 byte subnet "packets" for sending thru the backbone. X.25 packets, (basic that is) are viewed as messages, therefore a 1024 byte X.25 packet is 8 subnet "packets". With standard X.25, your message is a complete packet sequence and is actually now the length of you IP datagrams. But the the datagram is still broken into 128 byte "packets" by EE. If all this is true then a you could calculate the minimum number of "packets" to send x number of bytes thru the network. Not really that easy, but a place to start. Darrel Beach AF DDN PMO -------
CERF@A.ISI.EDU.UUCP (09/23/87)
Public data nets in the U.S. and in other countries, utilizing X.25 and X.75, have chosen an accounting fiction, the "segment" as a way to deal with variance in actual and in maximum packet sizes. Exchange tariffs and user tariffs are based on the number of segments sent or received by a particular pair of parties. Typically the bill is accumulated against the originator of the virtual circuit although reverse charging is permitted; usually only domestically as international reverse charge calls are sometimes hard to collect for. The public network administration announces the segment size (in octets) and the charges are for the number of octets sent on a given virtual circuit. If a packet contains less than one segment's worth or an integral number plus a fraction of segments, the accounting is rounded up to the nearest segment for that packet. Between administrations that normally charge for service using DIFFERENT segment sizes, there is an agreement at the X.75 interconnect on an interexchange segment size for purposes of calculating balances due between each administration. Charges to users are up to each domestic public data net - some stick with their standard domestic segment size and some use the smaller of the domestic and the size for going to the target administration. This assumes, of course, that the target administration's network is "one hop" from the originating network. There are cases of transit nets, and these require 3-way negotiations to determine how much of the user charges will be shared by each administration. In the case of datagram systems, similar segment size accounting methods can be used - binding the charges to a particular user rather than to a host might be the easier path since datagrams often don't have user level identifying information in them.l Vint Cerf
malis@CC5.BBN.COM (Andy Malis) (09/24/87)
Darrel, I'm afraid I'm not going to be able to be much of a help. You really are going to have to get the billing algorithm from DCA. The PSN is quite flexible in what it reports with regards to host traffic. For accounting purposes, it reports both octet and "segment" counts, where a segment is a configurable (power of 2) number of octets. When a host sends a message (X.25 "packet"), the number of octets and segments in that message are added to running totals (a partial segment counts as a segment), and these running totals are periodically reported to the MC. Thus, what gets reported and billed depends on the billing algorithm and the PSN configuration settings used by DCA. Regards, Andy
PADLIPSKY@A.ISI.EDU (Michael Padlipsky) (09/24/87)
Vint-- Shades of the October, 1971 Network Working Group meeting! Not positive you were there (seem to think so, but Early Middle Age does funny things to the memory, as we saw the other week in re the "But My NCP Costs $500 a Day..." RFC), so for the List's benefit at least and maybe yours as well, the relevant incident was that at one point Larry Roberts said that ARPA's intention was eventually to be charging 30 cents a kilo-packet and Frank Heart called out "Don't you mean 30 cents a mega-bit?"; Larry replied that he really maent 30 cents a kilo-packet and there was a small round of applause from those of us whose Hosts were line-at-a-time rather than character-at-a-time by nature. (For the benefit of non-oldtimers, Larry was head of ARPA's Information Processing Techniques [or Technology--but I always got confused over that even before EMA] Office at the time [a/k/a Our Sponsor] and Frank was either still a Division Head at BBN or maybe already a VP [I think the former, but ...].) It sure sounds to me as if the time has finally come when we really have to deal with the Remote Controlled Echoing issue, in light of the apparent return of the point of view which holds that it doesn't matter whether you've got one word or several pages in the metaphorical envelope, it still requires a metaphorical stamp. As you know (but as I'm not sure it's proper to go into detail about on the List), I'm not in a position to volunteer to head up an ad hoc working group on RCTE (T for Terminal, as I recall) at present, but I'd certainly urge somebody to step forward and I'd be glad to offer whatever help I'm in a position to offfer when it gets going, or even, if it makes the pot sweeter, to offer to stay out of it entirely, if that's what it takes to get a volunteer. If Dave Clark is watching, perhaps he'd like to do the convening, or mabye it's within the purview of one of the existing task forces, but in any event it does seem that if there's a clear and present danger of having to pay per character for all the character-at-a-time transmissions it's incumbent on us to decrease the number of those transmissions. cheers, map -------
piet@cwi.nl (Piet Beertema) (09/25/87)
...have chosen an accounting fiction, the "segment" as a way to deal with variance in actual and in maximum packet sizes. The public network administration announces the segment size (in octets) and the charges are for the number of octets sent on a given virtual circuit. Note that the accounting entity "segment" comprises pure user data only, no headers and other stuff. -- Piet Beertema, CWI, Amsterdam (piet@cwi.nl)
STJOHNS@SRI-NIC.ARPA (10/14/87)
Darrel, billing by packet is based on the X.25 packet, not the subnet tinygram. Mike