5-Jan-82 03:40:43-PST,10378;000000000001 Mail-from: ARPANET host BRL rcvd at 5-Jan-82 0340-PST Date: 5 Jan 82 3:07:55-EST (Tue) From: Mike Muuss To: list: Subject: TCP-IP Digest, Vol 1 #10 Bcc: TCP/IP Digest Tuesday, 5 Jan 1981 Volume 1 : Issue 10 Today's Topics: Administrivia ComputerWorld on the TCP/IP Cutover Amateur Packet Radio using InterNet Overloading the Poor Dot (.) ---------------------------------------------------------------------- From: Mike Muuss Subject: Administrivia Folks - It looks like somebody on this list is feeding copies of the TCP/IP Digest to ComputerWorld magazine, which seems delighted with this newfound source of "inside" information. While it is my intention that this list receive as broad a distribution as possible, several tightropes must be carefully traversed: Networking plays a vital part in the Mission of the Ballistic Research Laboratory (BRL), which fully supports the distribution of the TCP/IP Digest. However, the ArpaNet is intended for U.S. Government business, and is not supposed to compete with commercial packet networks. This has a rather limiting effect on the group of people who can freely use the ArpaNet. More importantly, though, is a question of content. If it becomes known that contributions to the TCP/IP Digest will appear in ComputerWorld, possibly verbatim, or perhaps cast in the wrong light, then I suspect that there will be a marked decrease in the quantity of information that is offered. Few of us expect our net mail to wind up published in the commercial press, and only the brave will knowingly open themselves up to this kind of direct, external exposure. And the cost? Those readers who desperately need the information on what is happening may find their information sources again reduced to RFC's and official notices, carefully worded for public scrutiny. This digest was intended as an open forum? Is a direct pipeline to the outside world too open? I solicit discussion on this matter. Maybe we can reach a consensus? Happy New Year! -Mike Muuss ------------------------------ From: chico!duke!unc!grumpy.smb at Berkeley Subject: Computerworld on the TCP/IP cutover Well, they're at it again. Here are some excerpts from the December 14 issue: Arpanet, the Pentagon-sponsored packet network that supports U.S. computing research, is slated for Jan. 1, 1983 cutover to two protocols that some experts predict will revolutionize commercial data communications. Considered the world's first packet network, Arpanet is expected to become an internet -- a network of networks -- ... said an informed source, who revealed the cutover date. It was secret? ... Arpanet was not built to support wartime communications among the military, but the planned cutover to TCP/IP -- roughly a year away -- suggests that computer scientists have a lot of confidence in the protocol pair. An Arpanet crash would seriously disrupt American research and development in many fields of science and technology, one expert maintained. ... A number of TCP/IP developers seem to believe that Arpanet will be ready Jan. 1, 1983 cutover [sic] -- but not all of them, Arpanet correspondence revealed. Available to all Arpanet subscribers, electronic mail files on TCP/IP include the following dispatch by a Stanford University researcher: "Some people [believe] that TCP work on [Digital Equipment Corp.'s] Tops-20 [operating system] is 'done.'... I believe the 1983 deadline for TCP conversion will not be met. I have worked on BBN's TCP at the user program level; specifically, I have implemented general user Telnet for TCP as part of a general multiple-network Telnet for Tops-20. "Briefly, the Tops-20 TCP implementation in its present form is unacceptable to Stanford and many othe Tops-20 sites. It is sad that so many bright people at BBN have had to maintain this dog instead of working on a complete rewrite." This critic wrote, in his Arpanet communique, that "the TCP process consumes between 40% and 60% of the CPU. We simply cannot sacrifice that much of an already-loaded CPU to implement a network ." [ I suppose that the TCP Digest quoting ComputerWorld quoting the TCP Digest is only fair! -Mike ] ------------------------------ From: John C. Gilmore Subject: Amateur Packet Radio using Internet To: CERF at USC-ISI cc: Tcp-ip at BRL From: CERF at USC-ISI Your TCP-IP digest entry caught my attention concerning addressing capability in the IP protocol. I'd like to know more about your "internet packet radio" since it isn't one of the projects ARPA is supporting. Is this something you are pursuing as a graduate or undergraduate effort or supported by another funding agency? Vint Cerf DARPA/IPTO Amateur Packet Radio is an experimental networking implementation among Amateur Radio Operators under the regulation of the FCC. It is a group of "hams" creating a network for digital communication among citizens. It is not supported by ARPA or any government agency (although AMRAD hosted an "Amateur Radio Computer Networking Conference" in conjunction with NBS in October). We currently favor the Internet Protocols, with minimal modifications, to encourage timely comprehension, software development, and extramural connection. Our network has two constraints that we hope are not unique, which is why I sent my query to TCP-IP, hoping for known solutions. They are: There is no underlying software protocol; IP Datagrams are transmitted without enclosure at the lowest level. (This is not, so far, a problem, but we're wondering if anyone else is doing similarly.) The medium is broadcast and there are contention problems. There is no central authority; no user sign-up; no fixed connectivity or user location. Each terminal node runs the same program with a small number of variables different (at least one unique). Nodes can appear, disappear, and move at any time; connectivity depends on electromagnetic weather. We had trouble with 24-bit addresses in this environment, since we have no way to create unique addresses that short. If the TCP-IP mailing list is for Official U. S. Government users only, rather than for the clarification, distribution, evolution, and improvement of the standard among all who are gaining experience with it, then please excuse my assumption and have me removed from it. [ Nope, you are in the right place. -Mike ] ------------------------------ Subject: Re: Amateur Packet Radio using Internet From: CERF at USC-ISI To: GNU at MIT-AI Cc: Tcp-ip at BRL In-Reply-To: Your message of 30 December 1981 05:51-EST 1. TCP-IP Digest is an open forum and your entry was perfectly valid - just caught my attention since I didn't know about the internet protocol choice by the Amatuer Packet Radio group. I did know a little about the private Packet Radio work. 2. Use of raw IP formats could cause you some trouble. The current architectural assumptions are that a gateway can "direct" an IP THROUGH another gateway, but to do this, it uses a lower layer of addressing (encapsulation philosophy). This seemed quite natural to us during design of IP since all the nets we were concerned with or knew about had a lower layer format with local addressing - even Ethernets. In a single network architecture, populated with a blizzard of private packet radios, you are faced with a number of challenges. First, the generation of unique identifiers. Second, the use of these identifiers to aid in routing decisions. I am not entirely convinced that a geographic basis is necessarily helpful - in the ARPA packet radio net, for example, the actual location of a radio is not always a good indicator of its radio connectivity into the system. Routing towards its geophysical location may in fact fail while routing "away" toward the high mountain peak which is in LOS may help. In your case, some geographic knowledge may help to structure the system hierarchically - this is sometimes used to effect "area routing." 3. As long as you stay within the confines of a single net, 24 bits allows some 16 million destination identifiers which seem to me to be quite a few for a respectable amateur packet radio network. One might artificially use up several network numbers if it appeared that 16 million wasn't enough. The harder problem is to make these numbers useful for routing purposes and to do this, one obviously needs to bind the identifiers to some location. Clearly you have attempted to do this with the lat/long strategy. 4. Quite frankly, we didn't envision this particular use when we designed IP - and your trick of using an option format to provide more detailed information is certainly the kind of extension we designed options for - even if it does strain your esthetic senses. 5. As to handling true internetting and providing for routing THROUGH gateways without losing track of the final net/destination, either the amateur packet radio network needs to define a lower level addressing structure, or you need to consider another option which identifies not only the source and destination but also the "next" gateway. This is really just a form of source routing. 6. The hardest problem, really, is going to be handling the area routing and dissemination of routing information throughout the system. If connectivity changes frequently for physical reasons (propagation effects) or because repeaters go up and down whimsically, then managing the routing problem is going to be quite a challenge. Vint Cerf ------------------------------ From: Schauble.Multics at MIT-Multics Subject: Overloading the . Tops-20 isn't the only system that has problems with that use of the period. Multics does also. Notice, for instance, the sender of this message. Paul END OF TCP-IP DIGEST ********************