Service Function Chaining Qi Xu Internet Draft Huachun Zhou Intended status: Informational Taixin Li Expires: April 2018 Guanglei Li Guanwen Li Beijing Jiaotong University October 11, 2017 A Method for Service Orchestration in hSFC draft-xu-sfc-hierarchical-orchestration-01.txt 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." 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Code Components extracted from this document must include Simplified BSD License text as described in Xu Expires April 11, 2018 [Page 1] Internet-Draft draft-xu-sfc-hierarchical-orchestration October 2017 Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Abstract Hierarchical SFC is a network architecture for implementing SFC the chain with an ordered set of service functions which could be deployed in multiple geographically dispersed networks. How to forward traffic between networks in Hierarchical SFC is what the draft wants to present. This document proposes a mapping-based forwarding method with coordinated orchestration by the translation of H-SFC and I-SFC to forward traffic between networks in Hierarchical SFC. Table of Contents 1. Introduction ................................................ 2 1.1. Assumptions ............................................ 3 1.2. Requirements Language .................................. 3 2. Terminology ................................................. 3 3. Hierarchical Service Orchestration .......................... 3 3.1. East-west interface..................................... 4 3.1.1. C5: Interface between SFC Control Planes........... 4 3.1.2. Interface between SFC Control Planes and IBN....... 5 3.2. Hierarchical service orchestration ..................... 5 4. Metadata Consideration ...................................... 5 5. Security Considerations ..................................... 5 6. IANA Considerations ......................................... 5 7. References .................................................. 5 7.1. Normative References ................................... 5 7.2. Informative References ................................. 6 Authors' Addresses ............................................. 7 1. Introduction Hierarchical SFC is a network architecture for supporting service function chains across multiple geographically dispersed networks. Hierarchical SFC is described in detail in [I.D. dolson-sfc- hierarchical] and [I.D.ao-sfc-for-dc-interconnect], and is not repeated here. In hSFC, SFs in top-domain can be logical and composed of several more refined SFs in sub-domain. Therefore, it is necessary to check the availability of those logical SFs in the procedure of orchestration. Xu Expires April 11, 2018 [Page 2] Internet-Draft draft-xu-sfc-hierarchical-orchestration October 2017 This document proposes that adding an east-west interface for coordination among different control planes of separate SFC-enabled domains so to supporting hierarchical service orchestration. 1.1. Assumptions The following assumptions are made: o A Hierarchical SFC-enabled network has multiple level network domains. Each domain has their own control plane and data plane. o Control planes of different domain can work coordinately, but they are independent or non-transparent to each other. For example, Top-domain network domain just uses logical SFs, but don't care how to construct a corresponding SFC for these logical SFs in Lower-Level network domains. 1.2. Requirements Language 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]. 2. Terminology The reader should be familiar with the terms contained in [RFC7665], [I-D.ietf-sfc-control-plane], [I-D.dolson-sfc-hierarchical] and [I- D.ao-sfc-for-dc-interconnect]. H-SFC: The SFC in the Top-domain network domain. I-SFC: The SFC in the Lower-Level network domain. 3. Hierarchical Service Orchestration When receiving a service request, the control plane should decide a SFC for it, select appropriate SF instances and make a SFP for the SFC. Furthermore, a classification policy which binds the flow with the request to a given SFC should be told to classifiers so that the flow can pass through relevant SFs along the SFP. But in hierarchical SFC, SFs might be logical which means it can be decomposed to several less abstract, more refined SFs. Besides, logical SFs always represent SFCs in SFC-enabled sub-domains. So, how to guarantee the availability of logical SFs and forward SFC traffic among multiple SFC-enabled domains is an important problem. Xu Expires April 11, 2018 [Page 3] Internet-Draft draft-xu-sfc-hierarchical-orchestration October 2017 3.1. East-west interface +----------------------+ C5 | SFC Control Plane +----> | | +---+----+----+----+---+ | | | | | | | v | | v C4 | v C3 v C2 C1 Figure 1: Interfaces of SFC Control Plane [I-D.ietf-sfc-control-plane] presents a reference architecture of the SFC control plane, including 4 kinds of interfaces between the SFC control plane and various SFC data plane elements. In hierarchical SFC that SFs are distributed over multiple SFC- enabled domains that the SFC needs to pass through, the control plane also should be hierarchical. As we know, each control plane is responsible for managing a single SFC-enabled domain. Then, each SFC control plane should gather and update information of local domain real-timely. Due to there is no formal control hierarchy scheme, this document attempts to propose a simple Hierarchical Control Plane Scheme for Hierarchical SFC architecture. Figure 1 shows the interface reference points of the SFC control plane architecture. C1 is the interface between SFC Control Plane and SFC Classifier; C2 is the interface between SFC Control Plane and SFF; C3 is the interface between SFC Control Plane and SFC-aware SFs; C4 is the interface between SFC Control Plane and SFC Proxy; C5 this document proposes is the east-west interface between SFC Control Planes for supporting coordination among those control planes of separate domains. 3.1.1. C5: Interface between SFC Control Planes As [I-D.ietf-sfc-hierarchical] said the IBN acts as a SFC-aware SF in the Top-Level domain and as a classifier in the Lower-Level domain. At the Top-domain, the SFs that compose an SFC might be logical which means they are actually SFCs composed by more refined SFs in the Lower-Levels. To setup these logical SFs, it needs coordinated orchestration between the control planes of Top-domain and Lower- domains. Xu Expires April 11, 2018 [Page 4] Internet-Draft draft-xu-sfc-hierarchical-orchestration October 2017 3.1.2. Interface between SFC Control Planes and IBN Due to IBN behaves as an SF to Top-domain, it is controlled by interface C3 or C4. Besides, IBN acts as a classifier and a SFF of end-of-chains to Lower-Level domain, it exchanges information with control plane of Lower-Level domain through interface C1 and C2. 3.2. Hierarchical service orchestration During the orchestration for logical SFs of service chains in the Top-domain, the control plane of the Top-domain should send an instruction to control plane of the corresponding Lower-domain. When the latter receives this instruction, it is likely that the Top- domain receives service requests from users. Then Lower-Level would construct or assign an I-SFC for this "service request", and make a classification rule for the classifier of the IBN. 4. Metadata Consideration Because the IBN is regarded as a Service Function to the Top-domain domain, it should provide the ability to handle the metadata in the NSH header if necessary. For example, it is common that checking the liveness of the service function of a service function path before the traffic selected by a Classifier traverse the network along a SFC which has been describe in [I-D.penno-sfc-trace-03]. Therefore, the IBN must be able to add its identifying information at the end of the existing NSH headers as a Service Function. 5. Security Considerations TBD. 6. IANA Considerations TBD. 7. References 7.1. Normative References [RFC7665] Halpern, J., Ed. and C. Pignataro, Ed., "Service Function Chaining (SFC) Architecture", RFC 7665, DOI 10.17487/RFC7665, October 2015, . Xu Expires April 11, 2018 [Page 5] Internet-Draft draft-xu-sfc-hierarchical-orchestration October 2017 7.2. Informative References [I-D.dolson-sfc-hierarchical] Dolson, D., Homma, S., Lopez, D., Boucadair, M., D.Liu, and Ao, T., "Hierarchical Service Function Chaining", draft-dolson-sfc-hierarchical-05 (work in progress), March 2016. [I-D.ao-sfc-for-dc-interconnect] Ao, T. and W. Bo, "Hierarchical SFC for DC Interconnection", draft-ao-sfc-for-dc-interconnect-01(work in progress), October 2015. [I-D.ietf-sfc-dc-use-cases] Komma, S., Tufail, M., Majee, S., Captari, C., and S.Homma, "Service Function Chaining Use Cases In Data Centers", draft-ietf-sfc-dc-use-cases-04 (work in progress), January 2016. [I-D.ietf-sfc-control-plane] Boucadair, M., Ed., "Service Function Chaining (SFC) Control Plane Components & Requirements", draft-ietf-sfc- control-plane-06 (work in progress), May 2016. [I-D.unify-sfc-control-plane-exp] Szabo, R., Sonkoly, B., "A Multi-Domain Multi-Technology SFC Control Plane Experiment: A UNIFYed", draft-unify-sfc- control-plane-exp-00 (work in progress), March 2016. [1] Sahhaf, Sahel, et al. "Network service chaining with optimized network function embedding supporting service decompositions." Computer Networks (2015): 492-505. Xu Expires April 11, 2018 [Page 6] Internet-Draft draft-xu-sfc-hierarchical-orchestration October 2017 Authors' Addresses Qi Xu Beijing Jiaotong University Beijing 100044 P.R. China Email: 15111046@bjtu.edu.cn Huachun Zhou Beijing Jiaotong University Beijing 100044 P.R. China Email: hchzhou@bjtu.edu.cn Taixin Li Beijing Jiaotong University Beijing 100044 P.R. China Email: 14111040@bjtu.edu.cn Guanglei Li Beijing Jiaotong University Beijing 100044 P.R. China Email: 15111035@bjtu.edu.cn Guanwen Li Beijing Jiaotong University Beijing 100044 P.R. China Email: 14120079@bjtu.edu.cn Xu Expires April 11, 2018 [Page 7]