RFC 1027 (rfc1027) - Page 1 of 8
Using ARP to implement transparent subnet gateways
Alternative Format: Original Text Document
Network Working Group Smoot Carl-Mitchell
Request for Comments: 1027 Texas Internet Consulting
John S. Quarterman
Texas Internet Consulting
October 1987
Using ARP to Implement Transparent Subnet Gateways
Status of this Memo
This RFC describes the use of the Ethernet Address Resolution
Protocol (ARP) by subnet gateways to permit hosts on the connected
subnets to communicate without being aware of the existence of
subnets, using the technique of "Proxy ARP" [6]. It is based on
RFC-950 [1], RFC-922 [2], and RFC-826 [3] and is a restricted subset
of the mechanism of RFC-925 [4]. Distribution of this memo is
unlimited.
Acknowledgment
The work described in this memo was performed while the authors were
employed by the Computer Sciences Department of the University of
Texas at Austin.
Introduction
The purpose of this memo is to describe in detail the implementation
of transparent subnet ARP gateways using the technique of Proxy ARP.
The intent is to document this widely used technique.
1. Motivation
The Ethernet at the University of Texas at Austin is a large
installation connecting over ten buildings. It currently has more
than one hundred hosts connected to it [5]. The size of the
Ethernet and the amount of traffic it handles prohibit tying it
together by use of repeaters. The use of subnets provided an
attractive alternative for separating the network into smaller
distinct units.
This is exactly the situation for which Internet subnets as
described in RFC-950 are intended. Unfortunately, many vendors had
not yet implemented subnets, and it was not practical to modify the
more than half a dozen different operating systems running on hosts
on the local networks.
Carl-Mitchell & Quarterman
