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Load Sharing using IP Network Address Translation (LSNAT) (RFC2391)

IP.com Disclosure Number: IPCOM000002964D
Original Publication Date: 1998-Aug-01
Included in the Prior Art Database: 2000-Sep-13
Document File: 15 page(s) / 42K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

P. Srisuresh: AUTHOR [+2]

Abstract

Network Address Translators (NATs) translate IP addresses in a datagram, transparent to end nodes, while routing the datagram. NATs have traditionally been been used to allow private network domains to connect to Global networks using as few as one globally unique IP address. In this document, we extend the use of NATs to offer Load share feature, where session load can be distributed across a pool of servers, instead of directing to a single server. Load sharing is beneficial to service providers and system administrators alike in grappling with scalability of servers with increasing session load.

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Network Working Group P. Srisuresh

Request for Comments: 2391 Lucent Technologies

Category: Informational D. Gan

Juniper Networks, Inc.

August 1998

Load Sharing using IP Network Address Translation (LSNAT)

Status of this Memo

This memo provides information for the Internet community. It does

not specify an Internet standard of any kind. Distribution of this

memo is unlimited.

Copyright Notice

Copyright (C) The Internet Society (1998). All Rights Reserved.

Preface

This document combines the idea of address translation described in

RFC 1631 with real-time load share algorithms to introduce Load Share

Network Address Translators(or, simply LSNATs). LSNATs would

transparently offload network load on a single server and distribute

the load across a pool of servers.

Abstract

Network Address Translators (NATs) translate IP addresses in a

datagram, transparent to end nodes, while routing the datagram. NATs

have traditionally been been used to allow private network domains to

connect to Global networks using as few as one globally unique IP

address. In this document, we extend the use of NATs to offer Load

share feature, where session load can be distributed across a pool of

servers, instead of directing to a single server. Load sharing is

beneficial to service providers and system administrators alike in

grappling with scalability of servers with increasing session load.

1. Introduction

Traditionally, Network Address Translators, or simply NATs were used

to connect private network domains to globally unique public domain

IP networks. Applications originate in private domains and NATs would

transparently translate datagrams belonging to these applications in

either direction. This document combines the characteristic of

transparent address translation with real-time load share algorithms

to introduce Load Share Network Address Translators.

The problem of Load sharing or Load balancing is not new and goes

back many years. A variety of techniques were applied to address the

problem. Some very ad-hoc and platform specific and some employing

clever schemes to reorder DNS resource records. REF [11] uses DNS

zone transfer program in name servers to periodically shuffle the

order of resource records for server nodes based on a pre-determined

load balancing algorithm. The problem with this approach is that

reordering time periods can be very large on the order of minutes and

does not reflect real-time load variations on the servers. Secondly,

all hosts in the server pool are assumed to have equal capability to

offer all services. This may not often be the case. In addition,

there may be requirement to support load balancing for a few specific

services only. The load share...