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Li 4 Intended status: Standards Track China Mobile 5 Expires: January 17, 2013 July 16, 2012 7 Load Balancer Function Discription 8 draft-li-opsawg-loadbalance-description-01 10 Abstract 12 This document presents a functional description of the load balancer. 13 The Load Balancer (LB) is a network device to distribute workload 14 across multiple servers, network links, central processing units, 15 disk drives, or other resources, to achieve optimal resource 16 utilization, maximize throughput, minimize response time, and avoid 17 overload. 19 Status of this Memo 21 This Internet-Draft is submitted in full conformance with the 22 provisions of BCP 78 and BCP 79. 24 Internet-Drafts are working documents of the Internet Engineering 25 Task Force (IETF). Note that other groups may also distribute 26 working documents as Internet-Drafts. The list of current Internet- 27 Drafts is at http://datatracker.ietf.org/drafts/current/. 29 Internet-Drafts are draft documents valid for a maximum of six months 30 and may be updated, replaced, or obsoleted by other documents at any 31 time. It is inappropriate to use Internet-Drafts as reference 32 material or to cite them other than as "work in progress." 34 This Internet-Draft will expire on September 6, 2012. 36 Copyright Notice 38 Copyright (c) 2012 IETF Trust and the persons identified as the 39 document authors. All rights reserved. 41 This document is subject to BCP 78 and the IETF Trust's Legal 42 Provisions Relating to IETF Documents 43 (http://trustee.ietf.org/license-info) in effect on the date of 44 publication of this document. Please review these documents 45 carefully, as they describe your rights and restrictions with respect 46 to this document. Code Components extracted from this document must 47 include Simplified BSD License text as described in Section 4.e of 48 the Trust Legal Provisions and are provided without warranty as 49 described in the Simplified BSD License. 51 Table of Contents 53 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 54 2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 55 3. Function description . . . . . . . . . . . . . . . . . . . . . 4 56 4. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 57 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 58 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5 59 7. Normative References . . . . . . . . . . . . . . . . . . . . . 5 60 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 5 62 1. Introduction 64 The Load Balancer (LB) is a network device to distribute workload 65 across multiple servers, network links, central processing units, 66 disk drives, or other resources, to achieve optimal resource 67 utilization, maximize throughput, minimize response time, and avoid 68 overload. Using multiple components with load balancing, instead of 69 a single component, may increase reliability through redundancy. The 70 load balancer is usually provided by dedicated software and hardware, 71 such as a multilayer switch which we name layer4/7 switch. 73 2. Overview 75 LB provides a cost-effective, efficient, and transparent method to 76 expand the bandwidth of network devices and servers, increase the 77 throughput, and enhance data process capability, increasing the 78 flexibility and availability of networks. There are always three 79 scenarios using LB: Server Load Balancing, Gateway Load Balancing, 80 Link Load Balancing. 82 1. Server Load Balancing 84 The increase of services brings large traffic to networks especially 85 to data centers, large enterprises and portal websites. In addition, 86 server websites provide more and more information by using 87 applications such as HTTP, FTP and SMTP. Most websites (especially 88 electronic business websites) have to provide all-day services, and 89 any service interruption or key data loss in communication will 90 result in business loss. All these require high performance and high 91 reliability on application services. 93 However, the increase of server processing speed and memory access 94 speed is greatly lower than that of the network bandwidth and 95 applications. In addition, the increase of network bandwidth makes 96 server resource consumption more serious. Therefore, the servers 97 become the network bottleneck, and the traditional single device mode 98 becomes the network failure point. 100 LB is the most appropriate way to solves the problem.Multiple servers 101 form a server cluster, with each server providing the same or similar 102 services. A load balancing device (LB device) is deployed at the 103 front end of the server cluster to distribute user requests in the 104 server cluster according to pre-configured load balancing rules, 105 provide services, and maintain the servers. 107 2. Gateway Load Balancing 108 Gateways such as SSL VPN gateways, IPsec gateways, and firewalls are 109 easy to be the bottleneck of networks due to the complexity of 110 service processing. Take firewalls as an example: Firewalls are an 111 indispensable part in network deployment. However, firewalls need to 112 filter packets, which will result in low forwarding performance of 113 the firewalls, so they will become the bottleneck of the network. If 114 hardware upgrade is performed by discarding the available devices, 115 resources will be wasted. With the increase of services, devices 116 will be upgraded frequently, which brings a high cost. The concept 117 of gateway cluster is addressed to solve this problem. Multiple 118 gateways are connected to the network to form a gateway cluster to 119 enhance the network processing capabilities. 121 3. Link Load Balancing 123 To avoid the network availability problem brought by carrier 124 dedicated line fault and solve the network access problems brought by 125 shortage of network bandwidth, an enterprise may rent two or more 126 carrier dedicated lines. To make better use of dedicated lines and 127 provide better services for enterprises, policy routing can be 128 applied. However, policy routing is not easy to configure and cannot 129 adapt to network structure changes. In addition, it cannot 130 distribute packets based on bandwidth, and the links with a high 131 throughput cannot be used to a full extent. Link load balancing can 132 balance load among multiple links by a dynamic algorithm and adapt to 133 network changes. 135 3. Function description 137 The following subsections describe the basic function contained in 138 LB. 140 1. Virtual service 142 Services provided by LB devices are virtual services. Configured on 143 an LB device, a virtual service is uniquely identified by VPN 144 instance, virtual service IP address, service protocol, and service 145 port number. Access requests of users are sent to the LB device 146 through a public or private network. If matching the virtual 147 service, the requests are distributed to real services by the LB 148 device. 150 2. Real service 152 Services provided by real servers are real services. A real service 153 can be a traditional FTP or HTTP service, and can also be a 154 forwarding service in a generic sense. For example, a real service 155 in firewall load balancing is the packet forwarding path. 157 3. Load balancing scheduling algorithm 159 An LB device needs to distribute service traffic to different real 160 services (a real service corresponds to a server in server load 161 balancing, a gateway in gateway load balancing, and a link in link 162 load balancing) according to a load balancing scheduling algorithm. 164 4. Health monitoring 166 The health monitoring function allows an LB device to detect whether 167 real servers can provide services. Based on different detection 168 methods (health monitoring methods), the LB device can detect whether 169 servers exist and whether they can provide services. 171 4. Security Considerations 173 TBD 175 5. IANA Considerations 177 It is no necessary to request new IANA code in the draft. 179 6. Acknowledgements 181 7. Normative References 183 Authors' Addresses 185 Chen Li 186 China Mobile 187 No.32 Xuanwumen West Street, Xicheng District 188 Beijing 100053 189 P.R. China 191 Email: lichenyj@chinamobile.com 192 Lianyuan Li 193 China Mobile 194 No.32 Xuanwumen West Street, Xicheng District 195 Beijing 100053 196 P.R. China 198 Email: lilianyuan@chinamobile.com