Network Working Group A. Beliveau Internet-Draft Ericsson Intended status: Standards Track October 16, 2013 Expires: April 19, 2014 Service Function Chaining Architecture draft-beliveau-sfc-architecture-00 Abstract This document describes an architecture for Service Function Chaining. It addresses operational aspects of Service Function Chaining such administration of Service Function Chains, network and forwarding principles. It also covers architectural principles to support scale-in and scale-out of Service Functions. 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]. 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 19, 2014. Copyright Notice Copyright (c) 2013 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 Beliveau Expires April 19, 2014 [Page 1] Internet-Draft SFC architecture October 2013 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 . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Architecture principles . . . . . . . . . . . . . . . . . . . 4 3.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 4 3.2. Service Function Chain . . . . . . . . . . . . . . . . . . 4 3.3. Service Chaining Infrastructure . . . . . . . . . . . . . 5 3.4. Service Function scaling . . . . . . . . . . . . . . . . . 7 3.5. Service Function Classification . . . . . . . . . . . . . 7 3.6. Service Chaining Controller . . . . . . . . . . . . . . . 7 4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 8 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 6. Security Considerations . . . . . . . . . . . . . . . . . . . 8 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9 7.1. Normative References . . . . . . . . . . . . . . . . . . . 9 7.2. Informative References . . . . . . . . . . . . . . . . . . 9 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 10 Beliveau Expires April 19, 2014 [Page 2] Internet-Draft SFC architecture October 2013 1. Introduction This document describes an architecture for Service Function Chaining (SFC). It describes components and architecture principles to provide Service Function Chaining in a network. 2. Terminology This document makes use of the following terms: Service Function(SF): An application or service which performs specific treatments when packets traverses it. A non-exhaustive list of Service Functions include: firewall (e.g.,[RFC6092]), DPI (Deep Packet Inspection), NAT44 [RFC3022], NAT64 [RFC6146], HOST_ID injection, HTTP Header Enrichment function, load-balancer, etc. The exact definition of each Service Function is specifc to each Service Function provider. Service Function Identity(SF-ID): A unique identifier which represents each SF in a network. SF-ID is unique within each SFC network and does not need to be globally unique. Even if multiple instances of the same Service Function are available in an SFC network, the same SF-ID is used to identify the Service Function. Service Function Locator(SF-Loc): A unique name or address which identifies each Service Function. When multiple instances of the same Service Function are available in an SFC network, each instance has its own Service Function Locator. Service Function Chain (SFC): An ordered list of SF which should be traversed. Service Function Chain Identity (SC-ID): A unique identifier which represents each SFC in a network. SC-ID is unique within each SFC network and does not need to be globally unique. Service Function Chain Enforcement Point (SCEP): A node which is able to guarantee that a list of SF will be traversed in a specific order for flows which are associated with such SF chain. Service Chaining Infrastructure Network (SC-IN): is formed by a one or more SCEP nodes connected together. Service Chaining Classification Function (SC-CL): A logical function part of a SCEP node. SC-CL is mandatory to execute when packets enter the SC-IN (ingress). Beliveau Expires April 19, 2014 [Page 3] Internet-Draft SFC architecture October 2013 Service Chaining Forwarding Function (SC-FWD): A logical function part of a SCEP node. It is responsible for forwarding packets to SF, forwarding packets to other SCEP nodes and to remove SC-IN specific information from packets when exiting (egress) SC-IN. SC-FWD is mandatory in all SCEP nodes. Service Function Path: Specific path taken by packets through SC-IN. Service Function Path includes specific SCEP nodes and SF nodes traversed by an individual flow. 3. Architecture principles 3.1. Introduction The concept of Service Function Chaining consists of applying a number of Service Functions in a specific order. The proposed architecture for Service Function Chaining ties together four different mechanisms to guarantee the execution of Service Functions in a specifc order. Those four separate mechanisms are: o A mechanism to specify a Service Function Chain (SFC) as an ordered list of Service Functions. o A mechanism to deliver packets between SF instances in the specified order: Service Chaining Infrastructure (SC-IN). o A mechanism to specify which packets should be associated with a specific Service Function Chain: SFC classification. o A mechanism to support scaling in/out the number of instances of each SF. 3.2. Service Function Chain A Service Function Chain (SFC) consists of an ordered list of Service Function (SF). Each SF is defined by an identifier which is unique within an administrative domain (SF-ID). No IANA registry is required to store the identity of SFs. Multiple Service Function Chains can exist in the same administrative domain. Each Service Function Chain (SFC) is defined by an identifier which is unique within an administrative domain (SC-ID). No IANA registry is required to store the identity of Service Function Chains. Beliveau Expires April 19, 2014 [Page 4] Internet-Draft SFC architecture October 2013 As no information about topology, SF classification or SF scaling is represented in the SF chain definition therefore, Service Function Chains are independent from changes in topology, classification or scaling instances of a Service Function. Here is a some examples of Service Function Chains: +----------+ +----------+ +----------+ +----------+ | Load | | Web | | Fire | | | SFC-ID=1 | Balancer |--| Proxy |--| wall |--| NAT44 | | SF-ID=1 | | SF-ID=2 | | SF-ID=3 | | SF-ID=4 | +----------+ +----------+ +----------+ +----------+ +----------+ +----------+ +----------+ | | | Header | | Fire | SFC-ID=2 | DPI |--| enrichm. |--| wall | | SF-ID=6 | | SF-ID=5 | | SF-ID=3 | +----------+ +----------+ +----------+ Figure 1: Service Function Chain examples 3.3. Service Chaining Infrastructure The Service Chaining Infrastructure (SC-IN) consists of Service Chaining Enforcement Points (SCEP) and Service Functions interconnected as a network. An SCEP node contains a forwarding function (SC-FWD) and optionally a classification function (SC-CL). Service Chaining Infrastructure (SC-IN) is illustrated in Figure 2. Beliveau Expires April 19, 2014 [Page 5] Internet-Draft SFC architecture October 2013 +..................................................................+ . +------------+ +------------+ +------------+ +------------+ . . | Service | | Service | | Service | | Service | . . |Function(SF)| |Function(SF)| |Function(SF)| |Function(SF)| . . +------------+ +------------+ +------------+ +------------+ . . \ / \ / . . \ / \ / . . \ / \ / . . +------------+ +------------+ . . | SCEP | | SCEP | . . | (SC-FWD) | | (SC-FWD) | . . +------------+ +------------+ . . \ / . . \ / . . \ .--. / . . +------------+ \ ( )-. / +------------+ . . |SCEP-Ingress| .' ' | SCEP-Egress| . . |(SC-CL,FWD) |-------( Network )------| (SC-FWD) | . . +------------+ ( -' +------------+ . . / '-( ) \ . . / '---' \ . . / Service Chaining Infrastructure \ . +......../..............................................\..........+ / \ .--. .--. ( )-. ( )-. .' Ingress' .' Egress ' ( Network ) ( Network ) ( -' ( -' '-( ) '-( ) '---' '---' Figure 2: Service Chaining Infrastructure SCEP can directly reach other SCEP nodes within the SC-IN. Service Functions (SF) are directly connected to an SCEP. To enforce the execution of SF in the specified order, Service Functions (SF) cannot communicate directly between eachother without going through an SCEP. One or many SFs can be attached to the same SCEP. When entering an SC-IN, an ingress SCEP which contains an SC-CL will map packets into a specific Service Function Path. Once this mapping is done, the SC-FWD will determine the locator for the next SF on the Service Function Path and forward the packet to the SF to be invoked. Beliveau Expires April 19, 2014 [Page 6] Internet-Draft SFC architecture October 2013 3.4. Service Function scaling Multiple instances of the same Service Function can exist in the SC-IN. Each new instances of a SF, when created, will be attached to an SCEP in the SC-IN and a unique locator (SF-Loc) will be allocated to it. When instances of a Service Function needs to be removed, the Service Function Controller will ensure that no packet can be forwarded to the instance of Service Function to be removed. Once done, the Service Function instance can be removed. 3.5. Service Function Classification In order to direct specific packets to follow a certain Service Function Path, SC-CL will analyse the packet headers and determine which Service Function Path should be followed. A Service Function Path is a list of Service Function locators (SF-Loc) for the specific instances of SF which constitutes a SFC. Once the Service Function Path is determined, the Service Chaining Forwarding function (SC-FWD) will determine the next Service Function and forward the traffic to it. 3.6. Service Chaining Controller The Service Function Chaining Controller is responsible to configure SCEP nodes in the Service Chaining Infrastructure. It is the controller which ties together Service Function Chains/Paths, the topology of the Service Chaining Infrastructure, the locating information of SF instances as they are being scaled in/out and Service Chaining Classification rules. It is responsible to guarantee the consistency of the configuration of SCEP across the SC-IN. Service Chaining Controller is illustrated in Figure 3. Beliveau Expires April 19, 2014 [Page 7] Internet-Draft SFC architecture October 2013 +-----------------+ | Service | | Chaining |..................... | Controller | . +-----------------+ . . . . +..................................................................+ . . . . . . . +------------+ . . . . | SCEP | . . . . | (SC-FWD) | . . . . +------------+ . . . . \ . . . . \ . . . . \ .--. . . . +------------+ \ ( )-. +------------+ . . |SCEP-Ingress| .' ' | SCEP-Egress| . . |(SC-CL,FWD) |-------( Network )------| (SC-FWD) | . . +------------+ ( -' +------------+ . . '-( ) . . '---' . . Service Chaining Infrastructure . +..................................................................+ Figure 3: Service Chaining Controller 4. Acknowledgements This template was derived from an initial version written by Pekka Savola and contributed by him to the xml2rfc project. 5. IANA Considerations This document has no IANA actions. 6. Security Considerations SFC must address at least the following security considerations: o Secure and authenticate communication between controller and SCEP nodes o Authenticate communication between SF and SCEP node. Beliveau Expires April 19, 2014 [Page 8] Internet-Draft SFC architecture October 2013 o Isolate SC-IN network when infrastructure is shared with nodes which are not SCEP nodes. o Protect interface at border of SC-IN (ingress/egress SCEP) against fraudulent usage. o Protect SFC specific protocol/metadata information against fraudulent usage. o When an SCEP participate in multiple networks, isolation between them. o Protect interface between SF and SCEP node against fraudulent usage. 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. [RFC3022] Srisuresh, P. and K. Egevang, "Traditional IP Network Address Translator (Traditional NAT)", RFC 3022, January 2001. [RFC6092] Woodyatt, J., "Recommended Simple Security Capabilities in Customer Premises Equipment (CPE) for Providing Residential IPv6 Internet Service", RFC 6092, January 2011. [RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful NAT64: Network Address and Protocol Translation from IPv6 Clients to IPv4 Servers", RFC 6146, April 2011. 7.2. Informative References [I-D.boucadair-sfc-framework] Boucadair, M., Jacquenet, C., Parker, R., Lopez, D., Guichard, J., and C. Pignataro, "Service Function Chaining: Framework & Architecture", draft-boucadair-sfc-framework-00 (work in progress), October 2013. [I-D.boucadair-sfc-requirements] Boucadair, M., Jacquenet, C., Jiang, Y., Parker, R., and C. Pignataro, "Requirements for Service Function Beliveau Expires April 19, 2014 [Page 9] Internet-Draft SFC architecture October 2013 Chaining", draft-boucadair-sfc-requirements-00 (work in progress), October 2013. [I-D.quinn-sfc-problem-statement] Quinn, P., Guichard, J., Surendra, S., Agarwal, P., Manur, R., Chauhan, A., Leymann, N., Boucadair, M., Jacquenet, C., Smith, M., Yadav, N., Nadeau, T., Gray, K., McConnell, B., and K. Kevin, "Service Function Chaining Problem Statement", draft-quinn-sfc-problem-statement-00 (work in progress), October 2013. Author's Address Andre Beliveau Ericsson 8400 Decarie Blvd. Town of Mount Royal, QC Canada Phone: +1 514 345 2708 Email: andre.beliveau@ericsson.com Beliveau Expires April 19, 2014 [Page 10]