Transmitting IP traffic over ARCNET networks
RFC 1201
Document | Type |
RFC - Internet Standard
(February 1991; No errata)
Obsoletes RFC 1051
Also known as STD 46
Was draft-provan-iparcnet (individual)
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Author | Don Provan | ||
Last updated | 2013-03-02 | ||
Stream | Legacy | ||
Formats | plain text html pdf htmlized bibtex | ||
Stream | Legacy state | (None) | |
Consensus Boilerplate | Unknown | ||
RFC Editor Note | (None) | ||
IESG | IESG state | RFC 1201 (Internet Standard) | |
Telechat date | |||
Responsible AD | (None) | ||
Send notices to | (None) |
Network Working Group D. Provan Request for Comments: 1201 Novell, Inc. Obsoletes: RFC 1051 February 1991 Transmitting IP Traffic over ARCNET Networks Status of this Memo This memo defines a protocol for the transmission of IP and ARP packets over the ARCnet Local Area Network. This RFC specifies an IAB standards track protocol for the Internet community, and requests discussion and suggestions for improvements. 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. 1. Introduction This memo specifies a method of encapsulating Internet Protocol (IP) [1] and Address Resolution Protocol (ARP) [2] datagrams for transmission across ARCNET [3] using the "ARCNET Packet Header Definition Standard" [4]. This memo offers a replacement for RFC 1051. RFC 1051 uses an ARCNET framing protocol which limits unfragmented IP packets to 508 octets [5]. 2. ARCNET Packet Format In 1989, Apple Computers, Novell, ACTINET Systems, Standard Microsystems, and Pure Data Research agreed to use the ARCNET datalink protocol defined in "ARCNET Packet Header Definition Standard" [4]. We'll begin with a brief description of that protocol. 2.1. ARCNET Framing ARCNET hardware supports two types of frames: short frames, which are always 256 octets long, and long frames, which are always 512 octets long. All frames begin with a hardware header and end with the client's data preceded by a software header. Software places padding in the middle of the packet between the hardware header and the software header to make the frame the appropriate fixed length. Unbeknown to the software, the hardware removes this padding during transmission. Short frames can hold from 0 to 249 octets of client data. Long frames can hold from 253 to 504 octets of client data. To handle frames with 250, 251, or 252 octets of data, the datalink protocol Provan [Page 1] RFC 1201 IP on ARCNET February 1991 introduces a third frame type: the exception frame. These three frame formats are shown here. Except as noted, each block represents one octet. Short Frame Long Frame Exception Frame +---------------+ +---------------+ +---------------+ | source | | source | | source | +---------------+ +---------------+ +---------------+ | destination | | destination | | destination | +---------------+ +---------------+ +---------------+ | offset | | 0 | | 0 | +---------------+ +---------------+ +---------------+ . unused . | offset | | offset | . (offset - 3 . +---------------+ +---------------+ . octets) . . unused . . unused . +---------------+ . (offset - 4 . . (offset - 4 . | protocol ID | . octets) . . octets) . +---------------+ +---------------+ +---------------+ | split flag | | protocol ID | | protocol ID | +---------------+ +---------------+ +---------------+ | sequence | | split flag | | flag: FF hex | + number + +---------------+ +---------------+ | (2 octets) | | sequence | | padding: 0xFF | +---------------+ + number + +---------------+ . . | (2 octets) | | padding: 0xFF | . client data . +---------------+ +---------------+ . (256 - offset . . . | (protocol ID) | . - 4 octets) . . . +---------------+ . . . . | split flag | +---------------+ . . +---------------+ . . | sequence | . client data . + number + . (512 - offset . | (2 octets) | . - 4 octets) . +---------------+ . . . . . . . client data . . . . (512 - offset . . . . - 8 octets) . . . . . +---------------+ +---------------+ These packet formats are presented as software would see themShow full document text