RFC 1794 (rfc1794) - Page 1 of 7

DNS Support for Load Balancing

Alternative Format: Original Text Document
Next >
Network Working Group                                          T. Brisco
Request for Comments: 1794                            Rutgers University
Category: Informational                                       April 1995


                     DNS Support for Load Balancing

Status of this Memo

   This memo provides information for the Internet community.  This memo
   does not specify an Internet standard of any kind.  Distribution of
   this memo is unlimited.

1. Introduction

   This RFC is meant to first chronicle a foray into the IETF DNS
   Working Group, discuss other possible alternatives to
   provide/simulate load balancing support for DNS, and to provide an
   ultimate, flexible solution for providing DNS support for balancing
   loads of many types.

2. History

   The history of this probably dates back well before my own time - so
   undoubtedly some holes are here.  Hopefully they can be filled in by
   other authors.

   Initially; "load balancing" was intended to permit the Domain Name
   System (DNS) [1] agents to support the concept of "clusters" (derived
   from the VMS usage) of machines - where all machines were
   functionally similar or the same, and it didn't particularly matter
   which machine was picked - as long as the load of the processing was
   reasonably well distributed across a series of actual different
   hosts.  Around 1986 a number of different schemes started surfacing
   as hacks to the Berkeley Internet Name Domain server (BIND)
   distribution.  Probably the most widely distributed of these were the
   "Shuffle Address" (SA) modifications by Bryan Beecher, or possibly
   Marshall Rose's "Round Robin" code.

   The SA records, however, did a round-robin ordering of the Address
   resource records, and didn't do much with regard to the particular
   loads on the target machines.  Matt Madison (of TGV) implemented some
   changes that used VMS facilities to review the system loads, and
   return A RRs in the order of least-loaded to most loaded.

   The problem was with SAs was that load was not actually a factor, and
   TGV's relied on VMS specific facilities to order the records.  The SA
   RRs required changes to the DNS specification (in file syntax and in



Brisco
Next >