Internet Research Task Force (IRTF) S. Lee Internet-Draft ETRI Intended status: Informational S. Pack Expires: April 26, 2015 KU M-K. Shin ETRI E. Paik KT October 23, 2014 Resource Management for Dynamic Service Chain Adaptation draft-lee-nfvrg-resource-management-service-chain-00 Abstract This document specifies problem definition and use cases of dynamic service chain adaptation for traffic optimization, failover, load balancing, etc. It further describes design considerations and relevant framework for the resource management capability that dynamically creates and updates network forwarding paths (NFPs) considering resource state of VNF instances. 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 April 26, 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 Lee, et al. Expires April 26, 2015 [Page 1] Internet-Draft Resource Management for Service Chain October 2014 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. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Dynamic service chain adaptation . . . . . . . . . . . . . . 4 3.1. Use cases . . . . . . . . . . . . . . . . . . . . . . . . 4 3.2. Design considerations . . . . . . . . . . . . . . . . . . 6 3.3. Framework . . . . . . . . . . . . . . . . . . . . . . . . 7 4. Related works in IETF SFC WG . . . . . . . . . . . . . . . . 7 5. Security Considerations . . . . . . . . . . . . . . . . . . . 7 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 7.1. Normative References . . . . . . . . . . . . . . . . . . 8 7.2. Informative References . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 1. Introduction Network Functions Virtualisation (NFV) [ETSI-NFV-WHITE] offers a new way to design, deploy and manage network services. The network service can be composed of one or more network functions and NFV relocates the network functions from dedicated hardware appliances to generic servers, so they can run in software. Using these virtualized network functions (VNFs), the network service can be described by a service chain (or VNF forwarding graph; VNF-FG) which defines an ordered sequence of VNFs for the composed service. The VNF-FG can be instantiated by creating or selecting VNF instances and virtual links (VLs) among them, which results in a network forwarding path (NFP). The performance or state of the NFP depends on the ones of VNF instances and underlying NFVI resources. For example, if one of the VNF instances in a NFP gets failed, the whole network service using the NFP also gets failed. Thus, the VNF instances per NFP need to be carefully selected at VNF-FG instantiation or dynamically replaced by other VNF instances at run-time for better performance and resilience. This document specifies problem definition and use cases for dynamic service chain adaptation for traffic optimization, failover, load balancing, etc. It further describes design considerations and Lee, et al. Expires April 26, 2015 [Page 2] Internet-Draft Resource Management for Service Chain October 2014 relevant framework for the resource management capability that dynamically creates and updates NFPs considering resource state of VNF instances. This document mainly focuses on the resource capability in the ETSI NFV framework [ETSI-NFV-ARCH] but also studies its applicability to the control plane of SFC architecture [I-D.ietf-sfc-architecture]. 2. Terminology This document uses the following terms and most of them were reproduced from [ETSI-NFV-TERM]. o Network Functions (NF): A functional building block within a network infrastructure, which has well-defined external interfaces and a well-defined functional behavior. o Network service: A composition of network functions and defined by its functional and behavioural specification. o NFV Framework: The totality of all entities, reference points, information models and other constructs defined by the specifications published by the ETSI ISG NFV. o Virtualised Network Function (VNF): An implementation of an NF that can be deployed on a Network Function Virtualisation Infrastructure (NFVI). o NFV Infrastructure (NFVI): The NFV-Infrastructure is the totality of all hardware and software components which build up the environment in which VNFs are deployed. o NF Forwarding Graph: A graph of logical links connecting NF nodes for the purpose of describing traffic flow between these network functions. o VNF Forwarding Graph (VNF-FG): A NF forwarding graph where at least one node is a VNF. o Virtual Link: A set of connection points along with the connectivity relationship between them and any associated target performance metrics (e.g. bandwidth, latency, QoS). The Virtual Link can interconnect two or more entities (VNF components, VNFs, or PNFs). o Scaling: Ability to dynamically extend/reduce resources granted to the Virtual Network Function (VNF) as needed. Lee, et al. Expires April 26, 2015 [Page 3] Internet-Draft Resource Management for Service Chain October 2014 3. Dynamic service chain adaptation The goal of dynamic service chain adaptation is to optimize the performance of network services. To meet this goal, NFPs of the network services need to consider the state of NFV resources (such as VNF instances or virtual links) at construction. The NFPs also need to dynamically adapt to the changes of the resource state at run- time, such as availability, load, and topological locations of VNF instances. The adaptation of NFPs can be executed by monitoring the resource state of VNF instances and VLs and replacing the original VNF instances of the NFP with new VNF instances that constitute a NFP with better performance. This functionality can be a part of Orchestrator functional building block in the NFV framework [ETSI-NFV-MANO] but it needs further study. 3.1. Use cases There are several use cases of dynamic service chain adaptation: fail-over, end-to-end service optimization, traffic optimization, load balancing, energy efficiency, and so on. Fail-over When one of VNF instances in a NFP gets failed to run due to failure of its VM or underlying network, the whole chain of network service also gets failed. For service continuity, the failure of VNF instance needs to be detected and the failed one needs to be replaced with the other one which is available to use. Figure 1 presents an example of the fail-over use case. A network service is defined as a chain of VNF-A and VNF-B; and the service chain is instantiated with VNF-A1 and VNF-B1 which are instances of VNF-A and VNF-B respectively. In the meantime, failure of VNF-B1 is detected so that VNF-B2 replaces the failed one for fail-over of the NFP. Lee, et al. Expires April 26, 2015 [Page 4] Internet-Draft Resource Management for Service Chain October 2014 +--------+ +--------+ | VNF-B2 | #| VNF-B2 |### +--------+ +--------+ +--------+ # +--------+ ###| VNF-A1 | _|_ ###| VNF-A1 |# _|_ +--------+ (___) +--------+ (___) ___/ # / \ \ ___/ / \ (___)+---#------+ + ===} (___)+----------+ + # \ ___ / / \ ___ / # (___) (___) # | | # +--------+ +--------+ ######| VNF-B1 |### (failure)--> | VNF-B1 | +--------+ +--------+ ### NFP Figure 1: A fail-over use case End-to-end service optimization Traffic for a network service traverses all of the VNF instances given by a NFP before reaching a target end point. Thus, stretch of the traffic route along a NFP may vary according to topological locations of VNF instances and such stretch needs to be kept low to make topological distance of two end points of the network service short. This stretch can be managed by constructing or adapting the NFP considering topological locations of the VNF instances. Traffic optimization A network operator may provide multiple network services with different VNF-FGs and different flows of traffic traverse between source and destination end-points along the VNF-FGs. For efficiency of network management resource usage, the NFPs need to be built as to localize the traffic flows or as to avoid bottleneck links shared by multiple traffic flows. In this case, multiple NFV instances of different NFPs need to be considered together at constructing a new NFP or adapting one. Load balancing A single VNF instances may be shared by multiple traffic flows of the same of different network services. In order to avoid bottleneck points due to overloaded NFV instances, NFPs need to be constructed or maintained to distribute workloads of the shared VNF instances. Energy efficiency Lee, et al. Expires April 26, 2015 [Page 5] Internet-Draft Resource Management for Service Chain October 2014 Energy efficiency in the network is getting important to reduce impact on the environment so that energy consumption of VNF instances using VNFI resources (e.g., compute, storage, I/O) needs to be considered at NFP construction or adaptation. For example, a NFP can be constructed as to make traffic flows aggregated into a limited number of VNF instances as much as its performance is preserved in a certain level. 3.2. Design considerations To support the aforementioned use cases, it is required to support resource management capability which provides service chain (or NFP) construction and adaptation by considering resource state or attributes of VNF instances and virtual links among them. The resource management operations for service chain construction and adaptation can be divided into several sub-actions: o Select a VNF instance o Evaluate a VNF instance and a virtual link o Replace a VNF instance to update a NFP o Monitor attributes of a VNF instance and a virtual link o Migrate a VNF instance to a different topological location Note: While scaling-in/out or -up/down of VNF instances is an essential action for NFV resource management, sub-actions with scaling for service chain adaptation are still under study. As listed above, VNF instances are selected or replaced according to monitoring or evaluation results of performance metrics of the VNF instances and virtual links. Studies about evaluation methodologies and performance metrics for VNF instances and NFVI resources can be found at [ETSI-NFV-PER001] [I-D.liu-bmwg-virtual-network-benchmark] [I-D.morton-bmwg-virtual-net]. The performance metrics of VNF instances and virtual links specific to service chain construction and adaptation can be defined as follows: o availability (or failure) of a VNF instance and a virtual link o a topological location of a VNF instance o a utilization rate of a VNF instance o a throughput of a VNF instance Lee, et al. Expires April 26, 2015 [Page 6] Internet-Draft Resource Management for Service Chain October 2014 o energy consumption of VNF instance o bandwidth of a virtual link o latency of a virtual link 3.3. Framework The resource management functionality for dynamic service chain adaptation takes role of NFV orchestration with support of VNF manager and Virtualised Infrastructure Manager (VIM) in the NFV framework [ETSI-NFV-ARCH]. Detailed functional building block and interfaces are still under study. 4. Related works in IETF SFC WG IETF SFC WG provides a new service deployment model that delivers the traffic along the predefined logical paths of service functions (SFs), called service function chains (SFCs) with no regard of network topologies or transport mechanisms. Basic concept of the service function chaining is similar to VNF-FG where a network service is composed of SFs and deployed by making traffic flows traversed instances of the SFs in a pre-defined order. There are several works in progress in IETF SFC WG for resource management of service chaining. [I-D.ietf-sfc-architecture] defines SFC control plane that selects specific SFs for a requested SFC, either statically or dynamically but details are currently outside the scope of the document. There are other works [I-D.ww-sfc-control-plane] [I-D.lee-sfc-dynamic-instantiation] [I-D.krishnan-sfc-oam-req-framework] [I-D.aldrin-sfc-oam-framework] which define the control plane functionality for service function chain construction and adaptation but details are still under study. While [I-D.dunbar-sfc-fun-instances-restoration] and [I-D.meng-sfc-chain-redundancy] provide detailed mechanisms of service chain adaptation, they focus only on resilience or fail-over of service function chains. 5. Security Considerations TBD. 6. IANA Considerations TBD. Lee, et al. Expires April 26, 2015 [Page 7] Internet-Draft Resource Management for Service Chain October 2014 7. References 7.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. 7.2. Informative References [ETSI-NFV-ARCH] ETSI, "ETSI NFV Architectural Framework v1.1.1", October 2013. [ETSI-NFV-MANO] ETSI, "Network Function Virtualization (NFV) Management and Orchestration V0.6.3", October 2014. [ETSI-NFV-PER001] ETSI, "Network Function Virtualization: Performance and Portability Best Practices v1.1.1", June 2014. [ETSI-NFV-TERM] ETSI, "NFV Terminology for Main Concepts in NFV", October 2013. [ETSI-NFV-WHITE] ETSI, "NFV Whitepaper 2", October 2013. [I-D.aldrin-sfc-oam-framework] Aldrin, S., Pignataro, C., and N. Akiya, "Service Function Chaining Operations, Administration and Maintenance Framework", draft-aldrin-sfc-oam-framework-00 (work in progress), July 2014. [I-D.dunbar-sfc-fun-instances-restoration] Dunbar, L. and A. Malis, "Framework for Service Function Instances Restoration", draft-dunbar-sfc-fun-instances- restoration-00 (work in progress), April 2014. [I-D.ietf-sfc-architecture] Halpern, J. and C. Pignataro, "Service Function Chaining (SFC) Architecture", draft-ietf-sfc-architecture-02 (work in progress), September 2014. Lee, et al. Expires April 26, 2015 [Page 8] Internet-Draft Resource Management for Service Chain October 2014 [I-D.krishnan-sfc-oam-req-framework] ramki, r., Ghanwani, A., Gutierrez, P., Lopez, D., Halpern, J., Kini, S., and A. Reid, "SFC OAM Requirements and Framework", draft-krishnan-sfc-oam-req-framework-00 (work in progress), July 2014. [I-D.lee-sfc-dynamic-instantiation] Lee, S. and M. Shin, "SFC dynamic instantiation", draft- lee-sfc-dynamic-instantiation-00 (work in progress), July 2014. [I-D.liu-bmwg-virtual-network-benchmark] Liu, V., Liu, D., Mandeville, B., Hickman, B., and G. Zhang, "Benchmarking Methodology for Virtualization Network Performance", draft-liu-bmwg-virtual-network- benchmark-00 (work in progress), July 2014. [I-D.meng-sfc-chain-redundancy] Meng, W. and C. Wang, "Redundancy Mechanism for Service Function Chains", draft-meng-sfc-chain-redundancy-00 (work in progress), July 2014. [I-D.morton-bmwg-virtual-net] Morton, A., "Considerations for Benchmarking Virtual Network Functions and Their Infrastructure", draft-morton- bmwg-virtual-net-01 (work in progress), July 2014. [I-D.ww-sfc-control-plane] Li, H., Wu, Q., Boucadair, M., Jacquenet, C., and W. Haeffner, "Service Function Chaining (SFC) Control Plane Achitecture", draft-ww-sfc-control-plane-03 (work in progress), September 2014. Authors' Addresses Seung-Ik Lee ETRI 218 Gajeong-ro Yuseung-Gu Daejeon 305-700 Korea Phone: +82 42 860 1483 Email: seungiklee@etri.re.kr Lee, et al. Expires April 26, 2015 [Page 9] Internet-Draft Resource Management for Service Chain October 2014 Sangheon Pack Korea University 145 Anam-ro, Seongbuk-gu Seoul 136-701 Korea Phone: +82 2 3290 4825 Email: shpack@etri.re.kr Myung-Ki Shin ETRI 218 Gajeong-ro Yuseung-Gu Daejeon 305-700 Korea Phone: +82 42 860 4847 Email: mkshin@etri.re.kr EunKyoung Paik KT 17 Woomyeon-dong, Seocho-gu Seoul 137-792 Korea Phone: +82 2 526 5233 Email: eun.paik@kt.com Lee, et al. Expires April 26, 2015 [Page 10]