Truong-Xuan Do Internet Draft Younghan Kim Intended status: Informational Soongsil University, Korea Expires: April 2016 Oct 20, 2015 High Availability mechanism for Service Function Chains draft-xuan-sfc-chain-high-availability-00 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), 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/1id-abstracts.html The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html This Internet-Draft will expire on April 2016. 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. Expires April 20,2016 [Page 1] Internet-Draft Oct 20, 2015 Abstract This document describes mechanisms to achieve the high availability of the service function chains. This document considers the high availability in the perspective of entire chain. This means the SFC control plane needs to take into account some metrics related service chain in addition to individual service functions. This document covers both stateless and stateful service functions as well. Table of Contents 1. Introduction...................................................3 2. Conventions used in this document..............................3 3. High availability architecture of SFC..........................4 3.1. Metrics for back-up SFPs..................................5 3.2 SFP with all stateless service functions...................6 3.3 SFP with stateful service funtions.........................7 4. Security Considerations........................................8 5. IANA Considerations............................................8 6. References.....................................................8 6.1. Normative References......................................8 6.2. Informative References....................................8 Expires April 20,2016 [Page 2] Internet-Draft Oct 20, 2015 1. Introduction Service function chaining currently is redesigned with the support of the software-defined network (SDN) and network function virtualization (NFV) which provide more flexible and dynamical end-to-end services. In order to ensure the high availability of service function chains, some traditional mechanisms for individual service function are reused (e.g. Active/Standby or Active/Active). These mechanisms are based on the deployment of the backup or redundant service functions. The recovery of whole service chain relies on the recovery of individual service function. This document describe a mechanism which ensure the high availability of service chain based on some metrics of whole chain. The mechanism also considers both stateless and stateful service functions in the chain. 2. Conventions used in this document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC-2119 [RFC2119]. The terms about SFC are defined in [RFC7498] and [I-D.ietf-sfc-architecture] Expires April 20,2016 [Page 3] Internet-Draft Oct 20, 2015 3. High availability architecture of SFC Figure 1. shows the architecture for achieving the high availability of the SFC. We make assumptions that each service function has several instances which are connected to different service function forwarders (SFF). Each service function path (SFP) is created by the combination of different service instances of different service functions. We propose a new entity called SFC HA manager which is responsible for monitoring metrics which belong not only to the individual service functions, such as fail-over, load condition, but also the whole service chain, such as, latency, total load, and traffic engineering. The SFC HA Manager takes responsibilities of making the backup SFPs. SFC HA manager should be located in the control plane part [I-D.ietf-sfc-control-plane] of SFC architecture [SFC HA Manager] +****************+********+***>> back-up SFP +|.......+........|........|.........+.....>> current SFP || | | | | SFI1 SFI2 SFI2 SFI3 SFI3 | | | | | +---+----+ +----+---+ | | | | SFFI1 SFFI2 SFFI3 Figure 1. High availability architecture of SFC Expires April 20,2016 [Page 4] Internet-Draft Oct 20, 2015 3.1. Metrics for back-up SFPs Some metrics for whole service function chain are listed below: Fail-over: a back-up SFP with the replacement of failed service functions Total latency: a back-up SFP with better latency Total bandwidth: a back-up SFP with highest bandwidth Total path: a back-up SFP with shortest path Total load: a back-up SFP with the lowest load Traffic engineering: a back-up SFP with the pre-defined traffic engineering goals Expires April 20,2016 [Page 5] Internet-Draft Oct 20, 2015 3.2 SFP with all stateless service functions Procedures for making a back-up service function path + Gather and monitor the states of current service function paths + Evaluate the current SFPs based on collected data and above metrics + HA manager makes back-up SFPs for current SFP + When a critical event occurs, the back-up SFP can be invoked and replace the current SFP. + The information about new SFP (back-up) is updated to all corresponding SFFs. Expires April 20,2016 [Page 6] Internet-Draft Oct 20, 2015 3.3 SFP with stateful service funtions Procedures for making a back-up service function path + Gather and monitor the states of current service function paths + Evaluate the current SFPs based on collected data and above metrics + HA manager makes back-up SFPs for current SFP - For stateful service functions in the SFP, internal state management for each service function is required and synchronized with the same kind of service function when creating a back-up SFP - State synchronization can be handled by the direct communication between two same kind service functions + When a critical event occurs, the back-up SFP can be invoked and replace the current SFP. + The information about new SFP (back-up) is updated to all corresponding SFFs. Expires April 20,2016 [Page 7] Internet-Draft Oct 20, 2015 4. Security Considerations TBD. 5. IANA Considerations TBD. 6. References 6.1. Normative References [RFC7498] Quinn, P. and T. Nadeau, "Problem Statement for Service Function Chaining", RFC 7498, April 2015. 6.2. Informative References [I-D.ietf-sfc-architecture] Halpern, J. and C. Pignataro, "Service Function Chaining (SFC) Architecture", draft-ietf-sfc-architecture-11 (work in progress), July 2015. [I-D.ietf-sfc-control-plane] H. Li, Q. Wu, O. Huang, etc. al., "Service Function Chaining (SFC) Control Plane Components & Requirements", draft-ietf-sfc-control-plane-00, Aug 2015 Expires April 20,2016 [Page 8] Internet-Draft Oct 20, 2015 Authors' Addresses Truong-Xuan Do Soongsil University 4F Hyungnam Engineering Bldg. 424, (156-743) 511 Sangdo-Dong, Dongjak-Gu, Seoul, Korea Phone: +82 10 4473 6869 Email: xuan@dcn.ssu.ac.kr Younghan Kim Soongsil University 4F Hyungnam Engineering Bldg. 424, (156-743) 511 Sangdo-Dong, Dongjak-Gu, Seoul, Korea Phone: +82-2-820-0904 Email: younghak@ssu.ac.kr Expires April 20,2016 [Page 9]