Two methods for the transmission of IP datagrams over IEEE 802.3 networks (RFC0948)
Original Publication Date: 1985-Jun-01
Included in the Prior Art Database: 2019-Feb-14
Internet Society Requests For Comment (RFCs)
This RFC describes two methods of encapsulating Internet Protocol (IP) datagrams on an IEEE 802.3 network. This RFC suggests a proposed protocol for the ARPA-Internet community, and requests discussion and suggestions for improvements.
< INC-PROJECT, WINSTON-RFC.NLS.6, >, 11-Jun-85 21:31-PDT JBP ;;;;
Winston [Page 0]
Network Working Group Ira Winston Request for Comments: 948 University of Pennsylvania June 1985
TWO METHODS FOR THE TRANSMISSION OF IP DATAGRAMS OVER IEEE 802.3 NETWORKS
Status of this Memo
This memo describes two methods of encapsulating Internet Protocol (IP)  datagrams on an IEEE 802.3 network . This RFC suggests a proposed protocol for the ARPA-Internet community, and requests discussion and suggestions for improvements. Distribution of this memo is unlimited.
The IEEE 802 project has defined a family of standards for Local Area Networks (LANs) that deals with the Physical and Data Link Layers as defined by the ISO Open System Interconnection Reference Model (ISO/OSI). Several Physical Layer standards (802.3, 802.4, and 802.5) [2, 3, 4] and one Data Link Layer Standard (802.2)  have been defined. The IEEE Physical Layer standards specify the ISO/OSI Physical Layer and the Media Access Control Sublayer of the ISO/OSI Data Link Layer. The 802.2 Data Link Layer standard specifies the Logical Link Control Sublayer of the ISO/OSI Data Link Layer.
The 802.3 standard is based on the Ethernet Version 2.0 standard . The Ethernet Physical Layer and the 802.3 Physical Layer are compatible for all practical purposes however, the Ethernet Data Link Layer and the 802.3/802.2 Data Link Layer are incompatible.
There are many existing Ethernet network installations that transmit IP datagrams using the Ethernet compatible standard described in . IEEE 802.3 Physical Layer compatible connections can be added to these networks using an an Ethernet Data Link Layer compatible method for transmitting IP datagrams without violating the 802.3 standard. Alternatively, an 802.2/802.3 Data Link Layer compatible method for transmitting IP datagrams can be used.
Ethernet Compatible Method
IEEE 802.3 networks must use 48-bit physical addresses and 10 megabit/second bandwidth in order to be Ethernet compatible.
The IEEE 802.3 packet header is identical to Ethernet packet header except for the meaning assigned to one of the fields in the header. In an Ethernet packet header this field is used as a protocol type field and in an 802.3 packet header the field is used as a length field. The maximum allowed length field value on a 10 megabit/second
Winston [Page 1]
RFC 948 June 1985 Transmission of IP Datagrams Over IEEE 802.3 Networks
802.3 network is 1500. The 802.3 standard states that packets with a length field greater than the maximum allowed length field may be ignored, discarded, or used in a private manner. Therefore, the length field can be used in a private manner as a protocol type field as long as the protocol types being used are greater than 1500. The protocol type for IP, ARP and trailer encapsulation are all greater than 1500. Using this technique, the method for transmitting IP datagrams on Ethernet networks described in  can be used to...