Re: Serial TCP/IP - all the same?


Steve Pope (agate!pasteur!zabriskie!spp@ucbvax.Berkeley.EDU)
23 Aug 88 18:38:06 GMT


>The justifications you gave explain why there must be SOME escape
>convention (which should go without saying), but not why that
>particular one was chosen. Why is this particular escape convention
>better than the old "double the special characters" convention or
>preceding a special character by the escape character?
>
>Barry Margolin

Let me attempt an answer -- the SLIP frame-escape method has the
property that the only place a FRAME_END character appears in the
SLIP-encoded data is between packets, i.e. FRAME_END doesn't occur
within a packet even in escaped form. Thus, transmitting SLIP's use
one or more FRAME_ENDs to clear an idle channel, and a receiving slip
always knows to reset itself if it gets a FRAME_END. This approach
might have a slight robustness advantage. Other escape conventions
might not provide the transmitting SLIP with a definite way of
resetting the receiver if the receiver is in an unknown state.

steve pope (spp@berkeley.EDU)



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