UUCP over X25 on Sun 3

[Carl S. Gutekunst]

In article <18341 at watmath.waterloo.edu> egisin at watmath.waterloo.edu (Eric Gisin) writes:
>I think there is also an 'x' protocol, which uses X.25 directly
>and can use all 8 bits.  'f' was designed for use over X.2[89],
>which has the 7 bit restriction.

'x' provides no error correction at all, and does not permit in-band flow
control (XON/XOFF). It is suitable only for simple point-to-point links using
dedicated internal X.25 hardware. 

The 7-bit-printable-ASCII restriction comes from international X.25 gateways,
many of which insist on swiping the eigth bit for parity or somesuch. A few
also do funny mappings of control characters, like munging tabs. If I set up a
raw X.25 virtual circuit between here and West Germany, it will be 7 bits and
there is nothing I can do about it.

The X.29 and X.28-1980 standards require 8-bit transparency. Not until 1984 is
there any mention of DTE-to-PAD parity generation (X.3 parameter 21), and it
is disabled by default. Note that everyone who connects to uunet for UUCP via
dialup Tymnet is using the 8-bit 'g' protocol over X.29; similarly, we run 'g'
over X.28 PADs all the time. (Of course, we have to disable flow control on
parameters 5 and 12. But calling into a Pyramid, it does that automatically.)

Finally, many sites (e.g., munnari) run 'f' right on top of X.25, and don't
bother with the hassle of X.29 at all.

<csg>