Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!cs.utexas.edu!sun-barr!apple!agate!ucbvax!TWG.COM!lefty From: lefty@TWG.COM Newsgroups: comp.protocols.tcp-ip Subject: Re: LAT Message-ID: <9101141048.aa22177@Mercury.TWG.COM> Date: 15 Jan 91 10:04:16 GMT Sender: daemon@ucbvax.BERKELEY.EDU Organization: The Internet Lines: 27 writes: >A good question to ask is whether LAT performs checksumming. Given that LAT >is a LAN protocol, it seems that it is quite possible that it (perhaps >optionally) does no checksumming and instead relies on the LAN to detect >and discard corrupted packets (as does ethernet). If this is the case then >it would have a natural, and arguably unfair, advantage over TCP due to the >rather CPU intensive nature of checksumming. LAT does _not_, in fact, perform any checksumming of the data streams. It should probably be pointed out that LAT, unlike IP, was originally designed specifically with an Ethernet environment in mind; checksumming in those circumstances was probably felt to be unnecessary. >I believe that checksumming is *not* a TCP option (although in practice it >is usually possible to turn it off in BSD derived implementations), but >even if it is the above comparison is less meaningful without knowing >whether both protocols were running with checksumming on or off. Of course, with telnet, checksumming is occurring at both the IP and TCP layers of the protocol. LAT, having been derived independently of any particular protocol stack, doesn't incur this kind of overhead... - David N. Schlesinger (lefty@twg.com) | Sr. Software Engineer | "And you may ask yourself, The Wollongong Group | 'How do I work this?'" 415/962-7100 |