On May 28, 2014, at 12:17 AM, Peter Lothberg <roll at Stupi.SE> wrote: On May 27, 2014, at 3:17 PM, Bob Armstrong <bob at jfcl.com> wrote: in Phase IV the hello timer value is sent in the hello message and that value times 3 (or 2) is used for the listen timer =20 That would explain why having LEGATO send hello messages more often doesn't make any difference=85 If you send hellos more often, you time out sooner; either way, you time ou= t if you lose 3 hellos in a row (or, probably just barely, if you lose two = in a row). The assumption is that no LAN is that badly broken. The way to run DECnet over a flaky long distance network is to use point to= point mode with a data link layer that deals with packet loss. DDCMP is a= n example of such a data link layer; X.25 is also (after a fashion). That= =92s what the DECnet design intended. paul Putting a PTP DECnet link in TCP would do the same as DDCMP/X.25/Lapb -P The earlier DMC emulation in SIMH 3.9 (payload only, not DDCMP) was essentially point to point over TCP. Yes, that gives you what DDCMP does. It s better than X.25/LAPB because those suffer from having a two way rather than three way handshake. paul