Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uwm.edu!uwvax!ub.d.umn.edu!cs.umn.edu!cs.umn.edu!peiffer From: peiffer@umn-cs.cs.umn.edu (Tim Peiffer (the net guy)) Newsgroups: comp.protocols.tcp-ip Subject: Re: SLIP documents Message-ID: Date: 9 Feb 91 04:27:15 GMT References: <1991Feb6.172144.12605@nmt.edu> <4320@ns-mx.uiowa.edu> <5827@auspex.auspex.com> Sender: news@cs.umn.edu (News administrator) Reply-To: peiffer@cs.umn.edu Organization: computer science labs Lines: 35 In-Reply-To: guy@auspex.auspex.com's message of 8 Feb 91 18:41:18 GMT Nntp-Posting-Host: cs.umn.edu In article <5827@auspex.auspex.com> guy@auspex.auspex.com (Guy Harris) writes: Well, I might not go *that* far. Ethernet has a checksum, and SLIP doesn't, so if you're, say, using UDP without checksums, Ethernet may be more reliable than SLIP.... This sounds like you are willing to compare apples to oranges. IP differs not at all whether it originates on a coaxial Ethernet, or a slow speed serial line. UDP without checksums is only mentioning that you are willing to disallow checksums at the transport level. This option exists under both Ethernet and SLIP connections. The network level (IP) still has a checksum that resides at byte 12. I believe that V. Jacobsen (RFC 1144) states that the COMPRESSED_IP checksum will be accomplished at byte 5. RFC1055 refers one back to the IP document for the content of the IP header. Tim Peiffer ----------- Tim Peiffer peiffer@cs.umn.edu or Computer Science Dept ..!rutgers!umn-cs!peiffer University of Minnesota MPLS MN 55455 ** Internet Protocol A summary of the contents of the internet header follows: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Version| IHL |Type of Service| Total Length | | Identification |Flags| Fragment Offset | | Time to Live | Protocol | Header Checksum | | Source Address | | Destination Address | | Options | Padding | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+