RFC 948 (rfc948) - Page 2 of 6
Two methods for the transmission of IP datagrams over IEEE 802
Alternative Format: Original Text Document
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) [1] datagrams on an IEEE 802.3 network [2]. This RFC
suggests a proposed protocol for the ARPA-Internet community, and
requests discussion and suggestions for improvements. Distribution
of this memo is unlimited.
Introduction
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) [5] 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 [6].
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 [7].
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