[e2e] Types Of Service

Bob Braden braden at ISI.EDU
Thu Jul 31 15:24:06 PDT 2003

  *> >   *> However, only TCP, UDP, and RTP (which is built over UDP) come to my 
  *> > mind,
  *> >   *> they don't guarantee any specific type of service (for example, "low
  *> >   *> delay", "high throughput", etc.) by themselves.
  *> >   *>
  *> >But in principle, they could.  The original IP specification DID
  *> >include a TOS byte with delay and throughput bits.
  *> Yes, but it didn't *guarantee* the service.

By and large, guarantees are for lawyers.  It is not clear that users
really care about guarantees that much.  They just want it to
work well enough.

  *> >   *> Besides that, for example, TCP provides a "realiable" byte stream. 
  *> > However,
  *> >   *> there are some errors that TCP won't catch, so if reliability is a real
  *> >   *> issue, then another layer of error control must be built up on top 
  *> > of TCP.
  *> >   *>
  *> >Presumably you are referring to local system errors between TCP and the
  *> >applications.  This would ultimately have to be dealt with at the
  *> >application layer, of course (see the classic E2E argument paper.)
  *> What's the author/title of that paper? Is it available online?

Saltzer, J., Reed, D., and D. Clark, End-To-End Arguments in System Design. ACM Transactions on
     Computer Systems 2, 4 (November 1984) pp. 277-288. An earlier version appeared in the Second International
     Conference on Distributed Computing Systems (Paris, April 1981) pp. 509-512

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