Chris Wedgwood
On Fri, Jun 08, 2001 at 09:45:31AM +1200, Don Stokes wrote:
Well, no, but then ethernet (in common with every other sensible link level protocol) doesn't send acknowledgments. TCP does and uucp (g protocol at least) does, so you have a bunch of TCP packets flying back to the other end carrying uucp acknowledgments.
Eh? What the hell are you on about?
The point I was making is that multiple layers of checksumming is hardly new, nor something I would consider bad (perhaps superfluous, the IPv6 designers choose to drop this and require lower-layers provide checksumming).
Checksums don't make a protocol reliable. Acknowledgement of received packets and retransmission of lost packets does, and layering one reliable protocol over another makes the windowing/retransmission algorithms conflict in a worst-of-both-worlds kind of way. This is yucky. Hey, I've done enough low-level comms hacking to be entitled to my opinions... (I've done uucp over X.25/X.29 too, and that was *much* yuckier.)
Yes, there is additional overhead, but who really cares? How many MUAs and MTAs support BDAT (rfc3030 ???) to avoid the >33% expansion that base64 encoding gives to attachments?
MIME is *very* yucky. The problem here is RFC 822 and its 7-bit ASCII requirement, not in the transport, so trying to fix it down at the SMTP layer (e.g. via BDAT) is very messy. RFC 822's 7 bit ASCII requirement was a mistake, albeit an understandable one back in the days when nobody could really agree on how many bits constituted a character. Anyway, just because something is yucky doesn't make adding more yuckiness OK. -- don --------- To unsubscribe from nznog, send email to majordomo(a)list.waikato.ac.nz where the body of your message reads: unsubscribe nznog