Network Working Group Rong Gu Vic Liu Internet Draft China Mobile Intended status: Informational Expires: January 2015 July 4, 2014 Problem statements of Virtual Load Balancers draft-gu-sfc-ps-vlb-00.txt Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. This document may not be modified, and derivative works of it may not be created, and it may not be published except as an Internet-Draft. This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. This document may not be modified, and derivative works of it may not be created, except to publish it as an RFC and to translate it into languages other than English. This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. 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It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html This Internet-Draft will expire on January 4,2015. Copyright Notice Copyright (c) 2014 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 described in the Simplified BSD License. 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. Abstract This document describes the development of virtual load balancer with a recent test in function and performance of virtual load balancer shared. Several problems of deploying virtual load balancer practically are presented. And requirements of further work in virtual load balancer are suggested with internet community. Table of Contents R.Gu & V.Liu Expires January 4, 2015 [Page 2] Internet-Draft PS for Virtual Loadblancer July 2014 1. Introduction ................................................ 3 2. Test overview ............................................... 4 3. Problem statement ........................................... 4 4. Summary and requirement...................................... 6 5. Security Considerations...................................... 6 6. IANA Considerations ......................................... 6 7. References .................................................. 6 7.1. Normative References.................................... 6 7.2. Informative References.................................. 7 8. Acknowledgments ............................................. 7 1. Introduction According to the network operators, Network Functions Virtualization (NFV) brings many benefits such as equipment cost reduction, power consumption reduction, optimization of network configuration and automated network installation. Virtual load balancer (VLB) is a piece of software acting as a reverse proxy to distribute network or application traffic over different servers. Instead of the form of hardware, VLB is a virtual machine (VM) which is a part of NFV performing application-level optimization by distributing the workload across multiple servers. VLB can be realized by some OSS (open-source software) such as LVS, Nginx and HA Proxy. Besides, many vendors launch virtual load balancers as commercial products as well as their hardware load balancers (LBs). Either the open-source software or the commercial software can perform the basic function of the Layer 4-7 server load balancing. The open-source software limits the features with additional function needing to be further developed. The commercial software load balancer acts almost the same as hardware load balancer with the function of IPv4/IPv6 server load balancing, powerful application scripting, SSL offload, high availability, prevention from attacks and so on. Because of the form of software, the VLB has superiority in the application scenarios of elasticity, flexibility and agility such as cloud computing and IDC (Internet Data Center). a. The software load balancer performs great flexibility and saves your space. b. Virtual load balancer is a program which can be deployed anywhere, such as very close to the servers that need to have the information flow metered. R.Gu & V.Liu Expires January 4, 2015 [Page 3] Internet-Draft PS for Virtual Loadblancer July 2014 c. Software load balancer has the advantage of agility which can be moved and reconfigured quickly. d. Software load balancer can be installed in several hypervisors such as VMware ESX/ESXi and Linux KVM. e. Software load balancer supports extensible management and orchestration. 2. Test overview Recently, we have tested several demos of VLB from different vendors. The test mainly includes both the function and performance of VLB. Results show that basic function of load balancing, health monitoring and persistence are well supported by commercial VLB products and partly supported by VLB of OSS. The performance of new session, concurrent, and throughput of VLB is poorer than that of hardware load balancer. Test topology -------- ------------ ----------- | Client |-----| VLB |-----| Server | -------- ------------ ----------- 3. Problem statement The virtual load balancer shows vast potentialfor future development of NFV. However, there are a number of challenges in deploying VLB due to its immaturity. a. The performance of VLB is an obvious disadvantage comparing with the hardware load balancer, since software rather than chips achieves the load balancing function. Reading from our exploratory test, there is a huge gap of performance including new session, concurrent session and throughput between VLB and the hardware LB. According to our testing data, the number of new session of VLB can be increased to ten thousand, the number of concurrent session can reach up to several million, and the throughput can reach up to tens Gbps. Performance of VLB after optimization still can't catch up R.Gu & V.Liu Expires January 4, 2015 [Page 4] Internet-Draft PS for Virtual Loadblancer July 2014 with the hardware LB of low performance, as performance of the software is subject to the physical server. And the performance of VLB realized by OSS is much poorer than the commercial products of VLB, several thousand of new session, tens thousand of concurrent session and one Gbps in details, which shows that commercial products do the performance optimization by their private technology. b. The VLB shows instability when operating in the network. VLB acts as a VM coexisting with other VMs in the physical server. Other VMs sometimes have an influence on VLB. Virtual bridge or virtual switch takes the role of forwarding datagram in the physical server.In our test, performance of server NIC and virtual bridge has an impact on the operation of VLB which leads to unsuccessful request sometimes. c. The VLB occupies the CPU and memory of the physical server working as a VM. And VLBs of different vendors give variability in large scale of the utilization rate of CPU and memory when operating. And performances are influenced largely by the hardware resources. Thus the utilization rate of CPU and memory of a physical server should be taken into consideration in choosing the suitable VLB, while the problem of bench mark exists in measuring VLB from this aspect. d. VLB shows problems of compatibility with various platforms of VMware ESX/ESXi, Citrix Xenserver, Microwave Hypervisor, RedHat/CentOS/Ubuntu Linux KVM and community Xen. From the result of our study, VLB of different vendors support most of the platforms. However, several platforms are not supported by VLB of some vendors or some specific license of VLB of one vendor. e. Some additional functions such as access control list (ACL) and SSL acceleration are not fully supported by VLB of all the vendors due to the progress of software development. Because of the performance of software, functions like SSL acceleration prefer to be achieved by hardware and ACL can be performed by other devices. What's more, VLB realized by OSS only has basic functions by default, with more functions added by specific modules which needs to be developed and debugged. f. Open APIs such as Openflow, OpenStack, OpenNaaS or OGF's are partly supported by VLBs from different vendors, which may have an impact on the management and data plane control. R.Gu & V.Liu Expires January 4, 2015 [Page 5] Internet-Draft PS for Virtual Loadblancer July 2014 4. Summary and requirement Network Functions Virtualization is already on the road. In order to accelerate the progress of large-scale deployment of VLB, further work should focus on responding to these challenges nowadays. a. Compatibility with various platforms should be optimized. And open APIs should be fully developed contributing to centralized management. b. Standard methods of measuring hardware resources such as the CPU and memory of physical servers occupied should be set in making it easier for horizontal comparison of different VLBs. c. High availability of VLB as a VM should be ensured by either virtual machine migration or master-standby with two VLBs. The restoration time should be controlled when one VLB breaks down. d. Performance of VLB should be further improved by advanced techniques such as traffic migration. 5. Security Considerations 6. IANA Considerations 7. References 7.1. Normative References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [2] Crocker, D. and Overell, P.(Editors), "Augmented BNF for Syntax Specifications: ABNF", RFC 2234, Internet Mail Consortium and Demon Internet Ltd., November 1997. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. R.Gu & V.Liu Expires January 4, 2015 [Page 6] Internet-Draft PS for Virtual Loadblancer July 2014 [RFC2234] Crocker, D. and Overell, P.(Editors), "Augmented BNF for Syntax Specifications: ABNF", RFC 2234, Internet Mail Consortium and Demon Internet Ltd., November 1997. 7.2. Informative References [3] Faber, T., Touch, J. and W. Yue, "The TIME-WAIT state in TCP and Its Effect on Busy Servers", Proc. Infocom 1999 pp. 1573- 1583. [Fab1999] Faber, T., Touch, J. and W. Yue, "The TIME-WAIT state in TCP and Its Effect on Busy Servers", Proc. Infocom 1999 pp. 1573-1583. 8. Acknowledgments Authors' Addresses Rong Gu China Mobile 32 Xuanwumen West Ave, Beijing, China Email: gurong@chinamobile.com Vic Liu China Mobile 32 Xuanwumen West Ave, Beijing, China Email: liuzhiheng@chinamobile.com R.Gu & V.Liu Expires January 4, 2015 [Page 7]