7 Sep
2018
7 Sep
'18
11:30 p.m.
On Sep 7, 2018, at 5:03 PM, Jeffrey H. Johnson <jhj
at trnsz.com> wrote:
Do you mean the X.25 client packets, or the bits coming out the bottom of X.25? The
former is straightforward so long as the clients send multiples of 8 bits. The bottom of
X.25 is not quite so simple since HDLC is a bit stream datalink, not a byte stream like
Ethernet or DDCMP.
The analogs you could draw on: for the client side, that's like the "Simulated
DMC" that appeared for a short while in SIMH 3.9 and can still be found in my
PyDECnet. For the bottom of the datalink, the current DDCMP emulation in SIMH is a good
model. I suppose you probably would not do bit stuffing. Not a multiple of 8 bits could
still be handled if needed.
paul
On Sep 7, 2018, at 1:00 PM, Paul Koning
<paulkoning at comcast.net> wrote:
My idea was a little lower level, hoping to use emulated serial links (tunneled over TCP
links and thus error free) to create point-to-point connections in a way that would be
compatible with Dynamips, so I could leverage the Cisco IOS X.25 support for the DCE
(provider) side of the network. On Sep 6, 2018, at 7:47 PM, Jeffrey H. Johnson
<jhj at trnsz.com> wrote:
[snip] virtual hobbyist Telenet/Tymnet-like PSN network for X.25 systems. [snip]
X.25 is basically a datalink layer (HDLC with some tweaks). What would such a virtual
network look like? I figure something like tunneling X.25 semantics over TCP, or
something along those lines. Or sending approximate X.25 PDUs over UDP, the way the SIMH
DDCMP implementation does for that data link.