X.25 TYPE NUMBERS CCITT defines the high order two bits of the first octet of call user data as follows: 00 - Used for other CCITT recomendations (such as X.29) 01 - Reserved for use by "national" administrative authorities 10 - Reserved for use by international administrative authoorities 11 - Reserved for arbitrary use between consenting DTEs Call User Data (hex) Protocol Reference ------------------- -------- --------- 01 PAD [GS2] C5 Blacker front-end descr dev [AGM] CC IP [RFC877,AGM]* CD ISO-IP [AGM] CF PPP [RFC1598] DD Network Monitoring [AGM] *NOTE: ISO SC6/WG2 approved assignment in ISO 9577 (January 1990). REFERENCES [RFC877] Korb, J., "A Standard for the Transmission of IP Datagrams Over Public Data Networks", RFC 877, Purdue University, September 1983. [RFC1598] Simpson, W., "PPPin X.25", RFC 1598, Daydreamer, March 1994. PEOPLE [AGM] Andy Malis <malis_a@timeplex.com> [GS2] Greg Satz <satz@CISCO.COM> []