Internet DRAFT - draft-li-opsawg-loadbalance-description
draft-li-opsawg-loadbalance-description
Internet Engineering Task Force (IETF) C. Li
Internet-Draft L. Li
Intended status: Standards Track China Mobile
Expires: January 17, 2013 July 16, 2012
Load Balancer Function Discription
draft-li-opsawg-loadbalance-description-01
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
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on September 6, 2012.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.
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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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