vixie@decwrl.dec.com (Paul A Vixie) (02/18/89)
It's true, you can't spoof the ACKs since IP doesn't have any and TCP can have an arbitrarily large number of VCs sharing the circuit. What you can do, though, is preempt based on IP TOS (type of service). That way if the modem is buffering a lot of data (which the Telebit does), a newly submitted telnet or rlogin keyboard-data or keyboard-echo packet can go out before the larger and less interesting rcp and ftp data packets. Van Jacobson's SLIP driver does this in the host, but this doesn't help much if the modem is just going to buffer it all up again, accepting more data from the host than it's actually able to send out on the wire "right now". In order to do TOS queuing, the Telebit needs to know where the packet starts and ends and how to find the TOS inside of the packet. They're waiting on some folks in the PPP IETF to define a standard framing before they release a product, but according to Mike Ballard of Telebit (who spoke at a BOF at the San Diego Usenix), they very much plan to offer this in their product some day. -- Paul Vixie Work: vixie@decwrl.dec.com decwrl!vixie +1 415 853 6600 Play: paul@vixie.sf.ca.us vixie!paul +1 415 864 7013
gandrews@netcom.COM (Greg Andrews) (04/08/91)
In article <25759@hydra.gatech.EDU> ar12@prism.gatech.EDU (REGISTER,ANDREW H) writes: >In article <1991Apr7.091025.15876@netcom.COM>, gandrews@netcom.COM (Greg Andrews) writes: >> >> The T2500 doesn't have SLIP spoofing. Just the V.32 modulation (and >> MNP/V.42 error correction protocols). >> > >This is the first time I have heard of SLIP spoofing. What is it and how >does it help? > No such thing, at least as far as Telebit modems are concerned. It doesn't exist, so it won't help you much... ;-) -- .------------------------------------------------------------------------. | Greg Andrews | UUCP: {apple,amdahl,claris}!netcom!gandrews | | | Internet: gandrews@netcom.COM | `------------------------------------------------------------------------'