IBM SC30-3865-04 - Manual (Page 270)

To communicate across X.25 WANs, VINES servers directly connected to the WAN
need these two options:
Server-to-server WAN
X.25 support on the server (hardware and software).
Running Banyan VINES over WAN Links
When you set up a PPP, Frame Relay, or X.25 link for use with VINES, you must
set the HDLC speed of the link, even if you set the clocking to external.
If you set the HDLC speed to zero, VINES assumes that the speed is 56 Kbps. Do
not set the speed to a value that is faster than the line.
Using VINES
240 MRS V3.2 Protocol Config Ref Vol 2