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 provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." 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. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as Li & Li Expires September 6, 2012 [Page 1] Internet-Draft LB Function Description March 2012 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 Li & Li Expires September 6, 2012 [Page 2] Internet-Draft LB Function Description March 2012 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 Li & Li Expires September 6, 2012 [Page 3] Internet-Draft LB Function Description March 2012 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 Li & Li Expires September 6, 2012 [Page 4] Internet-Draft LB Function Description March 2012 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 Li & Li Expires September 6, 2012 [Page 5] Internet-Draft LB Function Description March 2012 Lianyuan Li China Mobile No.32 Xuanwumen West Street, Xicheng District Beijing 100053 P.R. China Email: lilianyuan@chinamobile.com Li & Li Expires September 6, 2012 [Page 6]