Service Function Chaining Qi Xu Internet Draft Huachun Zhou Intended status: Standards Track Taixin Li Expires: December 12, 2016 Guanglei Li Guanwen Li Beijing Jiaotong University June 11, 2016 A Coordinated Forwarding Method for Hierarchical SFC draft-xu-sfc-coordinated-forwarding-00.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." 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 December 12, 2016. Copyright Notice Copyright (c) 2016 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 Xu Expires December 12, 2016 [Page 1] Internet-Draft draft-xu-sfc-coordinated-forwarding June 2016 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. Coordinated forwardind....................................... 3 3.1. Coordinated Control Planes.............................. 4 3.2. Mapping-based forwarding method......................... 5 4. Metadata Consideration....................................... 7 5. Security Considerations...................................... 7 6. IANA Considerations ......................................... 7 7. References .................................................. 7 7.1. Normative References.................................... 7 7.2. Informative References.................................. 7 Authors' Addresses ............................................. 9 1. Introduction 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. 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. Because of hierarchical SFC supports service decomposition which means a SF chained by a SFC can be decomposed into several more refined SFs, a SF might be logical wherever it is deployed. So it is necessary to check the availability of SFs especially those logical SFs in the procedure of orchestration. Xu Expires December 12, 2016 [Page 2] Internet-Draft draft-xu-sfc-coordinated-forwarding June 2016 This document proposes that adding an interface in the SFC control plane for coordination between different SFC control planes of separate domains to achieve hierarchical service decompositions and describes a mapping-based forwarding method between multiple SFC domains for Hierarchical SFC in detail. 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-Level 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-Level network domain. I-SFC: The SFC in the Lower-Level network domain. 3. Coordinated forwardind When receiving a service request, the control plane should decide a SFC for it, select appropriate SFs of the SFC 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 subdomains. So, how Xu Expires December 12, 2016 [Page 3] Internet-Draft draft-xu-sfc-coordinated-forwarding June 2016 to guarantee the availability of logical SFs and forward SFC traffic among multiple SFC-enabled domains is an important problem. What follows in this document is going to describe how to solve aforementioned problem. 3.1. Coordinated Control Planes +----------------------+ 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. But in hierarchical SFC that SFs are distributed over multiple SFC- enabled domains that the SFC needs to pass through, it is important to provide an interface for coordination among those control planes of separate domains. 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 interface between SFC Control Planes. At the Top-level, 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 the Top-level and the Lower-levels. During the orchestration for the logical SF of a SFC in the Top-Level, the control plane of the Top-Level should send an instruction to the control plane of the corresponding Lower-Level. When the latter receives this instruction that it is likely that the Top-level receives a service request from users, Lower-Level would construct or assign an I-SFC for this "service request" which is from the Top-Level, and make a classification rules for classifier Xu Expires December 12, 2016 [Page 4] Internet-Draft draft-xu-sfc-coordinated-forwarding June 2016 in the IBN who connects the Top-Level with the Lowe-Level to match the received H-SFC with the corresponding I-SFC. 3.2. Mapping-based forwarding method This section shows an example of the processing of traffic forwarding between network domains. It is assumed that all logical SFs of H-SFC have been constructed by Lower-Level subdomains and relevant IBNs have known the classification rules. +---------------+ | SF#2 | +-----^---+-----+ | | | | | | +---------+ +---------+ +--+---v--+ +---------+ | CF #1 +----> SFF #1 +-------> SFF #2 +-------> SFF #3 +----> +---------+ +--+---^--+ +---------+ +--+---^--+ | | | | | | +-----v---+-----+ +----------------------------+ | complex SF#3 | | | | | +---------------+ | +-----v---+-----+ | | | complex SF#1 | | | +-----+------^--+ | Top-Level | | | | +------------------------------------------------------------------+ | | | | +------------------------------------------------------------------+ | | | | | +----------------+ | Lower-Level | | | | | | | | | +--+-----+ | | | | | | SFF <----------------------------------+ | | | +--------+ | | | | | | | | | | | | | | | | | | +--------+ | | +--------+ +--------+ | | | +---> CF +-------->SFF #1.1+---->SFF #1.2+--+ | | +--------+ | | +--+--^--+ +--+--^--+ | +----------------+ | | | | | | IBN | | | | | | | +--v--+--+ +--v--+--+ | | | SF#1.1 | | SF#1.2 | +----------------------------+ +--------+ +--------+ Figure 2: An example of Hierarchical SFC Xu Expires December 12, 2016 [Page 5] Internet-Draft draft-xu-sfc-coordinated-forwarding June 2016 Below is the working process: 1. The IBN receives an H-SFC encapsulated packet from a Top-Level network domain. 2. To select an appropriate I-SFC encapsulation for the packet within the Lower-Level network domain, reclassification would be performed by classifier module of the IBN according to H-SFC header information and classification rules, as the example of figure 3. Extraordinarily, the last SI of I-SFC MUST be the IBN so that the flow can go back to the H-SFC through the IBN when the I-SFC is over. +--------+--------+ +----------+----------+ | H-SFC | SF | | I-SFC | SF | +-----------------+ +-----------> +---------------------+ | 8/2 | FW | | 6/3 | EdgeFW | +--------+--------+ + +---------------------+ | | 6/2 | AppFW | | +---------------------+ | | 6/1 | IBN | +-----------> +----------+----------+ Figure 3: An example of Reclassification 3. The IBN stores the entire original H-SFC header information, as well as the mapping relation of H-SFC and I-SFC. 4. After reclassification, original H-SFC header of the packet would be replaced by the I-SFC header so that the packet could traverse the Lower-Level domain along the SFP of I-SFC. 5. When the I-SFC encapsulated packets return to the IBN at the end, the SFF module of the IBN would parse the I-SFC header of the packets to check whether the I-SFC is over. 6. For returning traffic from Lower-Level to Top-Level, IBN MUST look up the mapping relation to remove the I-SFC header and retrieve the original H-SFC header for the packets. 7. Before the packets with the original H-SFC header return to the Top-level domain, IBN MUST decrement the value of SI of the H-SFC header. If necessary, IBN would modify or consume or produce metadata according to the policy of the complex SF. Xu Expires December 12, 2016 [Page 6] Internet-Draft draft-xu-sfc-coordinated-forwarding June 2016 4. Metadata Consideration Because the IBN is regarded as a Service Function to the Top-level 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, . 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. Xu Expires December 12, 2016 [Page 7] Internet-Draft draft-xu-sfc-coordinated-forwarding June 2016 [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 December 12, 2016 [Page 8] Internet-Draft draft-xu-sfc-coordinated-forwarding June 2016 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 December 12, 2016 [Page 9]