Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!seismo!husc6!cmcl2!rutgers!sri-spam!ames!ucbcad!ucbvax!CC5.BBN.COM!malis From: malis@CC5.BBN.COM (Andy Malis) Newsgroups: comp.protocols.tcp-ip Subject: Re: Internet Uselessness Message-ID: <8707212125.AA14211@ucbvax.Berkeley.EDU> Date: Tue, 21-Jul-87 17:28:53 EDT Article-I.D.: ucbvax.8707212125.AA14211 Posted: Tue Jul 21 17:28:53 1987 Date-Received: Thu, 23-Jul-87 04:47:53 EDT References: <8707211807.AA09192@mitre.arpa> Sender: daemon@ucbvax.BERKELEY.EDU Distribution: world Organization: The ARPA Internet Lines: 50 Craig, I would like to respond to a couple of points in your message. On the need for "clever engineering", and defending the ARPANET: for all of its sophistication, the PSN's dynamic routing algorithm was originally designed for, and worked very well in, an environment where the offered load did not come close to congesting the network's resources. This is no longer the case, with network subnet congestion as the predictable result. The recent changes in routing are actually slight modifications to one part of the algorithm, to try to prevent routing oscillations as a result of congested paths and to make the cross-country satellite link more attractive when the land lines start congesting. As Steve Cohn said in a previous message, a more detailed description of the change, and its effects, will be forthcoming. Congestion control will further help the network in these days of plentiful load and scarce resources. I really don't see what we are doing as defending ourselves from network-hostile hosts; rather, we are trying to allocate scarce resources as fairly and evenly as possible, and trying to keep the network from going past the point where additional load would cause the network's total throughput to start degrading. Of course, that doesn't mean that there aren't "hostile" hosts out there. On 40 octets of header per packets: I was referring to the internals of the ARPANET and MILNET subnets when I was discussing packet headers and such. However, they are only two networks on an internet of over 100 networks now. I am not a TCP/IP implementer so I won't get into whether any of the 40 octets can be squeezed out; you just have to realize that the environment TCP/IP runs in is nothing like that of commercial and PTT networks. X.25 does internetting (X.75) using fixed routes though transit networks and X.75 gateways without an end-to-end transport layer like TCP, and is nowhere as reliable and survivable as the TCP/IP internet. But you have to pay for this by using large datagram headers and end-to-end retransmissions. I do agree that some of the assumptions that were made during the TCP/IP design days (such as a richly configured backbone network) may no longer be valid. It may be time to revisit TCP/IP's design, especially in light of the OSI protocol suite, just as long as we keep in mind the overall requirements of the internet. Andy