leong@ANDREW.CMU.EDU (John Leong) (08/28/86)
Jan Officially, it is possible to negotiate for non-standard default size in the Call Request Packet (see section on Procedure and Formats for optional user facilities). In practice, most administration will limit you to either 128 or 256 bytes in order to achieve better resource ultilisation of the packet switching node. This effectively makes size negotiation pretty mieaningless. Of course if you are running TP-4 on top of X25, you can do TPDU size negotiation. If your TPDU size is greater than the NPDU size, then you have to do network level fragmentation and set M-bit in your X25 packet accordingly. John Leong