GENWiki

Network Working Group B. Kantor Request for Comments: 1226 Univ. of Calif San Diego

                                                              May 1991

          Internet Protocol Encapsulation of AX.25 Frames

Status of this Memo

 This memo describes a method for the encapsulation of AX.25 (the
 Amateur Packet-Radio Link-Layer Protocol) frames within IP packets.
 This technique is an Experimental Protocol for the Internet
 community.  Discussion and suggestions for improvement are requested.
 Please refer to the current edition of the "IAB Official Protocol
 Standards" for the standardization state and status of this protocol.
 Distribution of this memo is unlimited.

The AX.25 Amateur Packet-Radio Link-Layer Protocol

 The AX.25 Amateur Packet-Radio Link-Layer Protocol is described in
 the publication by that name [1], incorporated here by reference.

 Each AX.25 packet ("frame") is encapsulated in one IP datagram.
 Normally no AX.25 frame will exceed 330 octets, so fragmentation at
 the IP layer should not be necessary.  However, experiments with
 larger AX.25 frame sizes may require the use of standard IP
 fragmentation and reassembly procedures.

 When an AX.25 frame is encapsulated within an IP packet, HDLC framing
 elements (flags and zero-stuffing) are omitted, as the IP datagram
 adequately delimits the beginning and end of each AX.25 frame.  The
 16-bit CRC-CCITT frame check sequence (normally generated by the HDLC
 transmission hardware) is included.  In all other respects, AX.25
 frames are encapsulated unaltered.

 Each such IP datagram shall have a protocol number of 93.

Reference

 [1] AX.25 Amateur Packet-Radio Link-Layer Protocol Version 2.0
     October 1984.  Available from the American Radio Relay League,
     Newington CT USA 06111, and other sources.

Security Considerations

 Security issues are not discussed in this memo.

Kantor [Page 1] RFC 1226 IP Encapsulation of AX.25 Frames May 1991

Author's Address

 Brian Kantor
 University of California at San Diego
 Network Operations C-024
 La Jolla, CA 92093-0214

 Phone: (619) 534-6865

 EMail: brian@UCSD.EDU

Kantor [Page 2]