Load Balancer Function Discription
draft-li-opsawg-loadbalance-description-00

Internet Engineering Task Force (IETF)                             C. Li
Internet-Draft                                                     L. Li
Intended status: Standards Track                            China Mobile
Expires: September 6, 2012                                 March 5, 2012

                   Load Balancer Function Discription
               draft-li-opsawg-loadbalance-description-00

Abstract

   This document presents a functional description of the load balancer.
   The Load Balancer (LB) is a network device to distribute workload
   across multiple servers, network links, central processing units,
   disk drives, or other resources, to achieve optimal resource
   utilization, maximize throughput, minimize response time, and avoid
   overload.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
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   This Internet-Draft will expire on September 6, 2012.

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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   3.  Function description  . . . . . . . . . . . . . . . . . . . . . 4
   4.  Security Considerations . . . . . . . . . . . . . . . . . . . . 5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 5
   7.  Normative References  . . . . . . . . . . . . . . . . . . . . . 5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 5

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1.  Introduction

   The Load Balancer (LB) is a network device to distribute workload
   across multiple servers, network links, central processing units,
   disk drives, or other resources, to achieve optimal resource
   utilization, maximize throughput, minimize response time, and avoid
   overload.  Using multiple components with load balancing, instead of
   a single component, may increase reliability through redundancy.  The
   load balancer is usually provided by dedicated software and hardware,
   such as a multilayer switch which we name layer4/7 switch.

2.  Overview

   LB provides a cost-effective, efficient, and transparent method to
   expand the bandwidth of network devices and servers, increase the
   throughput, and enhance data process capability, increasing the
   flexibility and availability of networks.  There are always three
   scenarios using LB: Server Load Balancing, Gateway Load Balancing,
   Link Load Balancing.

   1.  Server Load Balancing

   The increase of services brings large traffic to networks especially
   to data centers, large enterprises and portal websites.  In addition,
   server websites provide more and more information by using
   applications such as HTTP, FTP and SMTP.  Most websites (especially
   electronic business websites) have to provide all-day services, and
   any service interruption or key data loss in communication will
   result in business loss.  All these require high performance and high
   reliability on application services.

   However, the increase of server processing speed and memory access
   speed is greatly lower than that of the network bandwidth and
   applications.  In addition, the increase of network bandwidth makes
   server resource consumption more serious.  Therefore, the servers
   become the network bottleneck, and the traditional single device mode
   becomes the network failure point.

   LB is the most appropriate way to solves the problem.Multiple servers
   form a server cluster, with each server providing the same or similar
   services.  A load balancing device (LB device) is deployed at the
   front end of the server cluster to distribute user requests in the
   server cluster according to pre-configured load balancing rules,
   provide services, and maintain the servers.

   2.  Gateway Load Balancing

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   Gateways such as SSL VPN gateways, IPsec gateways, and firewalls are
   easy to be the bottleneck of networks due to the complexity of
   service processing.  Take firewalls as an example: Firewalls are an
   indispensable part in network deployment.  However, firewalls need to
   filter packets, which will result in low forwarding performance of
   the firewalls, so they will become the bottleneck of the network.  If
   hardware upgrade is performed by discarding the available devices,
   resources will be wasted.  With the increase of services, devices
   will be upgraded frequently, which brings a high cost.  The concept
   of gateway cluster is addressed to solve this problem.  Multiple
   gateways are connected to the network to form a gateway cluster to
   enhance the network processing capabilities.

   3.  Link Load Balancing

   To avoid the network availability problem brought by carrier
   dedicated line fault and solve the network access problems brought by
   shortage of network bandwidth, an enterprise may rent two or more
   carrier dedicated lines.  To make better use of dedicated lines and
   provide better services for enterprises, policy routing can be
   applied.  However, policy routing is not easy to configure and cannot
   adapt to network structure changes.  In addition, it cannot
   distribute packets based on bandwidth, and the links with a high
   throughput cannot be used to a full extent.  Link load balancing can
   balance load among multiple links by a dynamic algorithm and adapt to
   network changes.

3.  Function description

   The following subsections describe the basic function contained in
   LB.

   1.  Virtual service

   Services provided by LB devices are virtual services.  Configured on
   an LB device, a virtual service is uniquely identified by VPN
   instance, virtual service IP address, service protocol, and service
   port number.  Access requests of users are sent to the LB device
   through a public or private network.  If matching the virtual
   service, the requests are distributed to real services by the LB
   device.

   2.  Real service

   Services provided by real servers are real services.  A real service
   can be a traditional FTP or HTTP service, and can also be a
   forwarding service in a generic sense.  For example, a real service

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   in firewall load balancing is the packet forwarding path.

   3.  Load balancing scheduling algorithm

   An LB device needs to distribute service traffic to different real
   services (a real service corresponds to a server in server load
   balancing, a gateway in gateway load balancing, and a link in link
   load balancing) according to a load balancing scheduling algorithm.

   4.  Health monitoring

   The health monitoring function allows an LB device to detect whether
   real servers can provide services.  Based on different detection
   methods (health monitoring methods), the LB device can detect whether
   servers exist and whether they can provide services.

4.  Security Considerations

   TBD

5.  IANA Considerations

   It is no necessary to request new IANA code in the draft.

6.  Acknowledgements

7.  Normative References

Authors' Addresses

   Chen Li
   China Mobile
   No.32 Xuanwumen West Street, Xicheng District
   Beijing  100053
   P.R. China

   Email: lichenyj@chinamobile.com

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   Lianyuan Li
   China Mobile
   No.32 Xuanwumen West Street, Xicheng District
   Beijing  100053
   P.R. China

   Email: lilianyuan@chinamobile.com

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