Network Working Group S. Jeong Internet-Draft M-K. Shin Intended status: Informational ETRI Expires: September 5, 2010 T. Egawa NEC H. Otsuki NiCT March 4, 2010 Network Virtualization Problem Statement draft-shin-virtualization-meta-arch-01.txt Abstract This document analyzes and discusses the problem space of supporting network virtualization in the networks. Furthermore, some key requirements for enabling network virtualization in the networks are investigated and described. Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." 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 September 5, 2010. Copyright Notice Copyright (c) 2010 IETF Trust and the persons identified as the document authors. All rights reserved. Jeong, et al. Expires September 5, 2010 [Page 1] Internet-Draft Network Virtualization PS March 2010 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 BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Definition of Network Virtualization . . . . . . . . . . . 4 2. Problem Statement for Network Virtualization . . . . . . . . . 4 3. Requirements for Network Virtualization . . . . . . . . . . . . 5 4. Applicability and Use Cases . . . . . . . . . . . . . . . . . . 6 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 7 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 7 7. Informative References . . . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8 Jeong, et al. Expires September 5, 2010 [Page 2] Internet-Draft Network Virtualization PS March 2010 1. Introduction Conventionally, virtualization generally refers to a technique to hide the physical characteristics of resources so that other systems, applications, or end users can interact with those resources without the knowledge of the physical characteristics. The main objectives of virtualization are to simplify the use of the underlying resource, to create multiple logical instances of the resource, and to separate the uses of the underlying resources. The followings list the benefits of virtualization. o Partitioning: Multiple applications or operating systems can be simultaneously supported within a single physical machine. Multiple physical machines can be consolidated into virtual machines on either a scale-up or scale-down architecture. Computing resources are treated as a uniform pool to be allocated to virtual machines in a controlled manner. o Isolation: Virtual machines are completely isolated from the host machine and other virtual machines. Even though a virtual machine crashes, the others are not affected. Data in one virtual machine do not leak across virtual machines and applications can only communicate over configured network connections. Unauthorized accesses to other virtual machines are prohibited. o Encapsulation: Complete virtual machine environment can be saved as a single file that enables easy backup, move, and copy. Standardized virtualized hardware is presented to the application guaranteeing compatibility. The virtualization technology has been extensively studied for decades and the network virtualization is expected to be realized on the basis of traditional virtualization technology, especially server virtualization. The server virtualization is the ability to run an entire virtual machine with its own guest OS on another OS or on a bare-machine. So, it allows multiple virtual machines with heterogeneous guest OSes to run in isolation on the same physical machine. Each virtual machine has its own set of virtual hardware in order to load a guest OS and applications. The guest OS can utilize a consistent, normalized set of H/W regardless of the characteristics of physical H/W specification. The advantages of server virtualization are as follows. o Since several virtual servers share a single set of hardware, it is possible to achieve better resource utilization and to lower hardware cost. Jeong, et al. Expires September 5, 2010 [Page 3] Internet-Draft Network Virtualization PS March 2010 o Server virtualization makes it easier to provision and to reallocate servers by setting up a server using a pre-existing template and shifting server images from one physical server to another to balance workloads or improve efficiency. o Secure environment can be provided among virtual servers because each server is isolated from the others. This document analyzes and discusses the problem space of supporting network virtualization in the networks. Furthermore, some key requirements for enabling network virtualization in the networks are investigated and described. 1.1. Definition of Network Virtualization Network virtualization is the technology that enables the creation of logically isolated network partitions over shared physical network infrastructures so that multiple heterogeneous virtual networks can simultaneously coexist over the shared infrastructures. Also, network virtualization allows the aggregation of multiple resources and makes the aggregated resources appear as a single resource [1]. The virtual networks over physical infrastructure are completely isolated each other, so different virtual networks may use different network technologies, for example, different protocols and packet formats can be supported on each virtual network without interference. When combined with programmability feature in network elements, users of virtual networks can program the network elements on any layers from physical layer to application layer according to users' requirements. Furthermore, it is even possible to define a new layering architecture without interfering the operation of other virtual networks. In other words, each virtual network can provide the corresponding user group with full network services similar to those provided by a traditional non-virtualized network. From the users' perspective, each user accesses a dedicated network independently. Also, network virtualization can reduce the total cost by increasing the utilization of resources [1]. 2. Problem Statement for Network Virtualization The motivation of network virtualization is to de-ossify the current network architectures. Network virtualization allows multiple virtual networks to coexist on top of a shared physical infrastructure. It can realize virtual networks with programmable network elements, so that users can perform experimentation on any layers. It also supports the architecture of multiple architectures. For example, by utilizing network virtualization technology, Jeong, et al. Expires September 5, 2010 [Page 4] Internet-Draft Network Virtualization PS March 2010 different virtual networks can provide different end-to-end packet delivery systems and may use different protocols and packet formats [2]. The followings summarize the problem statement for network virtualization [3]. In the current networks, such as Internet, users can utilize multiple network services over a shared physical infrastructure, so unexpected behavior of a service may affect other coexisting services and may cause security problems, performance degradation of other services, and so on. Network virtualization guarantees isolation of network services by creating isolated logical network environments between users belonging to separate groups. In the current networks, the network service providers hardly offer resources encompassing the physical capability of the resources. However, by leveraging network virtualization, it is possible to provide high performance resources for users by logically aggregating multiple resources into single resource. Therefore, a logical network consisting of requested resources can guarantee users' performance requirements. It is actually restricted to scale physical resources according to users' demands in the current networks. Users of network virtualization, however, can add as many virtual resources to their virtual network as they need. That is, requested size of a virtual network can be provided. In addition to the size, coexistence of multiple logical networks is one of the fundamental motivations behind network virtualization. Legacy networks hardly provide multiple networks, but multiple virtual networks can be created in a shared physical network with the same resources. 3. Requirements for Network Virtualization The following list summarizes some key functions, which need to be supported by the network to provide network virtualization feature [2]. o Since today's network application traffic tends to indicate more and more unpredictable variations, each virtual network would like to adjust available bandwidth according to traffic demand changes. Furthermore, a network application may dynamically request new capability that is not supported by the current network configuration. Thus, the network virtualization should offer a method that the virtual networks are capable of easily and rapidly creating their own network topologies and dynamically Jeong, et al. Expires September 5, 2010 [Page 5] Internet-Draft Network Virtualization PS March 2010 reconfiguring them. o Virtual networks can be multiplexed over a shared network infrastructure. However, this can be liable to restrict network performance and cause instability due to interference by other virtual networks. The network virtualization should be capable of providing the complete performance isolation among virtual networks. o It is known that some of emerging network services will require extremely high bandwidth, for example more than hundreds Gbps with low latency and jitter. However, it may not be possible to satisfy such high end requirements with the current network and transport layer technologies. Thus, each virtual network should be capable of directly utilizing lower-layer transmission technologies such as wavelength and TDM (time-division multiplexing) provided by a transport network. o To support diverse network services, the virtual network should retain the capability of customizing network control and operations independent from those in the physical network or other virtual networks. At the same time, the virtual network may want to avoid complex physical network operations that are fully dependent on the types of network layers and equipment vendors. To disengage the virtual network from the complexity of the physical network, the network virtualization should be capable of abstracting the physical network information and provides the simple interface for resource control to the virtual networks. o Considering the utility of customers, each virtual network should be capable of using physical network resources and constructing a network topology. However, one possible problem is that some abnormal virtual networks may occupy most of the resources, which deteriorates other virtual network performance due to network resource exhaustion. So, the network virtualization should provide the capability to regulate the upper limit of resource consumption by each virtual network in order to maintain the overall utility and performance. 4. Applicability and Use Cases This section describes the applicability of network virtualization. The applicability of network virtualization may be classified into two broad categories according to the characteristics of virtualization; namely isolation and aggregation [2]. From the view point of isolation, network virtualization enables the Jeong, et al. Expires September 5, 2010 [Page 6] Internet-Draft Network Virtualization PS March 2010 complete isolation between each logical network partition. Typical use case of this category is that it is possible to create new business model by separating the conventional Internet service provider's role into network provider and service provider. The network provider creates customized logical network partitions according to the service providers' requirements, such as network bandwidth, the number and functional capability of network elements in the logical network partitions, total cost, and so on. The service provider can provide various services and applications for users without the burden of building its own network infrastructure. Moreover, the service provider can safely test an innovative pilot service or application that requires special features of network without affecting other existing services. From the perspective of network providers, they can increase the hardware utilization ratio and can reduce the operational cost of network infrastructure. From the viewpoint of service providers, it is possible to reduce the cost for building network infrastructure. Also, they can utilize the flexibility for the creation of network and application services. The second applicability is aggregation. In the computing field, it is common to logically aggregate multiple computing resources into a single resource in order to support applications or services that require very high performance exceeding single resource's capability. Building a high performance computing node by clustering many smaller nodes would be the typical use case of resource aggregation. Similar to this use case, network virtualization can allow building a logical network element whose capability is hard to be supported by a single one. The logical network element can support various functions and can easily expand its capability by aggregating multiple network elements. 5. Security Considerations TBD 6. Acknowledgments This version of the problem statement reflects the discussion results of the following people. Many thanks to Takashi Kurimoto, Takashi Miyamura, Alex Galis for their comments. 7. Informative References [1] Anderson, T., "Overcoming the Internet Impasse through Virtualization", IEEE Computer , 2005. Jeong, et al. Expires September 5, 2010 [Page 7] Internet-Draft Network Virtualization PS March 2010 [2] Jeong, S. and H. Otsuki, "Framework of Network Virtualization", ITU-T Focus Group on Future Networks , January 2010. [3] Mosharaf, N. and R. Boutaba, "A Survey of Network Virtualization", Technical Report: CS-2008-25 , October 2008. Authors' Addresses Sangjin Jeong ETRI 138 Gajeongno, Yuseong Daejeon, 305-700 Korea Phone: +82 42 860 1877 Email: sjjeong@etri.re.kr Myung-Ki Shin ETRI 138 Gajeongno, Yuseong Daejeon, 305-700 Korea Phone: +82 42 860 4847 Email: mkshin@etri.re.kr Takashi Egawa NEC Corporation 1753 Shimonumabe Nakahara-Ku, Kawasaki Kanagawa, 211-8666 Japan Phone: +81 44 431 7770 Email: t-egawa@ct.jp.nec.com Jeong, et al. Expires September 5, 2010 [Page 8] Internet-Draft Network Virtualization PS March 2010 Hideki Otsuki NiCT 4-2-1 Nukui-Kitamachi Koganei Tokyo, 184-8795 Japan Phone: +81 42 327 6931 Email: hideki.otsuki@nict.go.jp Jeong, et al. Expires September 5, 2010 [Page 9]