service function chain W. Meng Internet-Draft C. Wang Intended status: Standards Track ZTE Corporation Expires: April 10, 2016 October 8, 2015 Redundancy Mechanism for Service Function Chains draft-meng-sfc-chain-redundancy-02 Abstract This document discusses about hot standby analysis of service function instances (SFIs) under different scenarios. The document provides requirement and use cases and also describes the suitable scenarios that each solution may be deployed in. 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 10, 2016. Copyright Notice Copyright (c) 2015 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. Meng & Wang Expires April 10, 2016 [Page 1] Internet-Draft service chain Redundancy October 2015 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Convention and Terminology . . . . . . . . . . . . . . . . . . 4 3. Redundancy Mechanisms . . . . . . . . . . . . . . . . . . . . 5 3.1. Homogeneous Backup . . . . . . . . . . . . . . . . . . . . 5 3.2. Heterogeneous Backup . . . . . . . . . . . . . . . . . . . 5 3.3. Internal Backup . . . . . . . . . . . . . . . . . . . . . 6 3.4. External Backup . . . . . . . . . . . . . . . . . . . . . 6 4. Redirect Service Function Paths . . . . . . . . . . . . . . . 8 5. Control Plane Considerations . . . . . . . . . . . . . . . . . 9 6. Data Plane Considerations . . . . . . . . . . . . . . . . . . 10 7. Load Balancing Considerations . . . . . . . . . . . . . . . . 11 8. Normative References . . . . . . . . . . . . . . . . . . . . . 12 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13 Meng & Wang Expires April 10, 2016 [Page 2] Internet-Draft service chain Redundancy October 2015 1. Introduction The object of Service Function Chains (SFC) is trying to unload services from nodes in traditional network and deal with such services through service function chains. As a result of this, redundancy of service function instances needs to be standardize, rather than maintain as an internal mechanism in a traditional network device. Many SFs might be located in large-scale networks, such as ISP networks or enterprise ones, where exist a large number of customers. In each service function, these customers which is served by a single service function instance (SFI) may experience service degradation in case of the presence of the single point of exceptional failure. Therefore, redundancy of the SFI will be strongly desired in order to deliver highly available services. This memo describes some use cases of redundancy among SFIs under typical scenarios. Meng & Wang Expires April 10, 2016 [Page 3] Internet-Draft service chain Redundancy October 2015 2. Convention and Terminology 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 [RFC2119]. The terms about SFC are defined in [I-D.ietf-sfc-problem-statement] and [I-D.ietf-sfc-architecture]. Meng & Wang Expires April 10, 2016 [Page 4] Internet-Draft service chain Redundancy October 2015 3. Redundancy Mechanisms As illustrated in Figure 1, two SFIs (SFI1 and SFI1') are deployed for redundancy purposes. This is the reference architecture for the mechanisms we describe in this memo. ,---. / \ --------( SFI1 |- \ / \ `-^-' \ ,---. | \-- / \-------> Master Service Function Path Backup --> | ( SFI2 ) ,-v-. .... \ /.......> Backup Service Function Path / \ . `---' ........( SFI1' ). \ / `---' Figure 1: Reference Model 3.1. Homogeneous Backup Figure 2 illustrates a homogeneous backup cases. In this scenario, each of those master SFIs will have a corresponding backup SFI. ,---. ,---. ,---. / \ / \ / \ ( SFI1 | ( SFI2 | ( SFI3 | \ / \ / \ / `-^-' `-^-' `-^-' | | | | | | | | | ,-v-. ,-v-. ,-v-. / \ / \ / \ ( SFI1' ) ( SFI2' ) ( SFI3' ) \ / \ / \ / `---' `---' `---' Figure 2: Homogeneous Backup Model 3.2. Heterogeneous Backup Figure 3 illustrates a heterogeneous backup cases. In this scenario, each of those master SFIs might have more than one corresponding backup SFIs. Meng & Wang Expires April 10, 2016 [Page 5] Internet-Draft service chain Redundancy October 2015 ,---. ,---. / \ / \ ( SFI1 | ( SFI2 | \ / / \ / \ `-^-' / `---' \ | | | | | | | | | ,-v-. ,-v-. ,-v-. / \ / \ / \ ( SFI1' ) ( SFI2' ) ( SFI2'') \ / \ / \ / `---' `---' `---' Figure 3: Heterogeneous Backup Model 3.3. Internal Backup Figure 4 illustrates a internal backup cases. In this scenario, both sides of backup are located in a same Service Function Node. +----------------------------------------+ | ,---. ,---. ,---. | | / \ / \ / \ | | ( SFI1 <---> SFI1' | ( SFI2 | | <-- Service Function Node | \ / \ / \ / | | `---' `---' `---' | +----------------------------------------+ Figure 4: Internal Backup Model 3.4. External Backup Figure 5 illustrates a external backup cases. In this scenario, each side of backup is located in its own Service Function Node. Meng & Wang Expires April 10, 2016 [Page 6] Internet-Draft service chain Redundancy October 2015 +---------------------------------------+ | ,---. ,---. ,---. | | / \ / \ / \ | | ( SFI1 | ( SFI2 | ( SFI3 | | <-- Service Function Node 1 | \ / \ / \ / | | `-^-' `-^-' `-^-' | +-------|-----------|-----------|-------+ | | | <------- Network +-------|-----------|-----------|-------+ | ,-v-. ,-v-. ,-v-. | | / \ / \ / \ | | ( SFI1' | ( SFI2' | ( SFI3' | | <-- Service Function Node 2 | \ / \ / \ / | | `---' `---' `---' | +---------------------------------------+ Figure 5: External Backup Model Meng & Wang Expires April 10, 2016 [Page 7] Internet-Draft service chain Redundancy October 2015 4. Redirect Service Function Paths As described in [ietf-sfc-architecture], a Service Function Path is the instantiation of the defined SFC. In case of planned maintenance operations or exceptional failure of Service Function Node, The SFP MUST be changed to prevent disrupting the normal traffic. Meng & Wang Expires April 10, 2016 [Page 8] Internet-Draft service chain Redundancy October 2015 5. Control Plane Considerations TBD Meng & Wang Expires April 10, 2016 [Page 9] Internet-Draft service chain Redundancy October 2015 6. Data Plane Considerations TBD Meng & Wang Expires April 10, 2016 [Page 10] Internet-Draft service chain Redundancy October 2015 7. Load Balancing Considerations TBD Meng & Wang Expires April 10, 2016 [Page 11] Internet-Draft service chain Redundancy October 2015 8. Normative 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-problem-statement] Quinn, P. and T. Nadeau, "Service Function Chaining Problem Statement", draft-ietf-sfc-problem-statement-13 (work in progress), February 2015. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/ RFC2119, March 1997, . [RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson, "Remote Authentication Dial In User Service (RADIUS)", RFC 2865, DOI 10.17487/RFC2865, June 2000, . Meng & Wang Expires April 10, 2016 [Page 12] Internet-Draft service chain Redundancy October 2015 Authors' Addresses Wei Meng ZTE Corporation No.50 Software Avenue, Yuhuatai District Nanjing China Email: meng.wei2@zte.com.cn,vally.meng@gmail.com Cui Wang ZTE Corporation No.50 Software Avenue, Yuhuatai District Nanjing China Email: wang.cui1@zte.com.cn Meng & Wang Expires April 10, 2016 [Page 13]