SFC Working Group A. Malis Internet-Draft S. Bryant Intended status: Informational Huawei Technologies Expires: December 21, 2018 J. Halpern Ericsson June 19, 2018 MPLS Encapsulation for SFC NSH draft-malis-mpls-sfc-encapsulation-00 Abstract This document describes how to use a Service Function Forwarder (SFF) Label (similar to a pseudowire label or VPN label) to indicate the presence of a Service Function Chaining (SFC) Network Service Header (NSH) between an MPLS label stack and the packet payload. This allows SFC packets using the NSH to be forwarded between SFFs over an MPLS network, and the selection between multiple SFFs in the destination node. 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 https://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 December 21, 2018. Copyright Notice Copyright (c) 2018 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 (https://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 Malis, et al. Expires December 21, 2018 [Page 1] Internet-Draft MPLSforSFC June 2018 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 . . . . . . . . . . . . . . . . . . . . . . . . 2 2. MPLS Encapsulation . . . . . . . . . . . . . . . . . . . . . 2 3. SFF Label . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3 5. Security considerations . . . . . . . . . . . . . . . . . . . 3 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 7.1. Normative References . . . . . . . . . . . . . . . . . . 4 7.2. Informative References . . . . . . . . . . . . . . . . . 4 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 1. Introduction As discussed in [RFC8300], a number of encapsulations for the Service Function Chaining (SFC) Network Service Header (NSH) already exist, such as in Ethernet, GRE [RFC2784], and VXLAN-GPE [I-D.ietf-nvo3-vxlan-gpe]. This document describes an MPLS encapsulation for the NSH, and also describes how to use an Service Function Forwarder (SFF) [RFC7665] Label to indicate the presence of the NSH header in the MPLS packet payload. This allows SFC packets using the NSH to be forwarded between SFFs over an MPLS network, and the selection between multiple SFFs in the destination node. SFF Labels are similar to other labels at the bottom of an MPLS label stack that denote the contents of the MPLS payload being other than globally routed IP, such as a layer 2 pseudowire, an IP packet that is routed in a VPN context with a private address, or an Ethernet virtual private wire service. This informational document follows well-established MPLS procedures and does not require any actions by IANA or any new protocol elements. 2. MPLS Encapsulation The encapsulation is simply a standard MPLS label stack [RFC3032] with the SFF Label at the bottom of the stack, followed by a NSH as defined by [RFC8300] and the NSH payload. As discussed by [RFC4928] and [RFC7325], there are Equal Cost Multipath (ECMP) considerations for payloads carried by MPLS. Many Malis, et al. Expires December 21, 2018 [Page 2] Internet-Draft MPLSforSFC June 2018 existing routers use deep packet inspection to examine the payload of an MPLS packet, and if the first nibble of the payload is equal to 0x4 or 0x6, these routers assume that the payload is IPv4 or IPv6 respectively, and perform ECMP load balancing on the MPLS packets. For SFC, this is undesirable for several reasons. First of all, NSH is not IPv4 and IPv6, and the presumed contents of the TCP/IP five- tuple used for load balancing would be incorrect. Also, as discussed in [RFC8300], ECMP in general is undesirable for SFC and should be avoided. For this reason, the NSH Base Header was carefully constructed so that the NSH could not look like IPv4 or IPv6 based on its first nibble. See Section 2.2 of [RFC8300] for further details. 3. SFF Label Much like a pseudowire label, an SFF Label is allocated by the downstream receiver of the NSH header from its per-platform label space. If a receiving node supports more than one SFF (i.e, more than one SFC forwarding instance), then the SFF Label can be used select the proper SFF, by having the receiving advertise more than one SFF Label to its upstream sending nodes as appropriate. The method used by the downstream receiving node to advertise SFF Labels to the upstream sending node is currently out of scope of this document. That said, a number of methods are possible, such as via a protocol exchange, or via a centralized controller that manages both the sender and the receiver via NETCONF/YANG, BGP, PCEP, etc. These are meant as possible examples and not to constrain the future definition of such advertisement methods. 4. IANA Considerations This document does not request any actions from IANA. Editorial note to RFC Editor: This section may be removed at your discretion. 5. Security considerations This document describes a method for transporting SFC packets using the NSH over MPLS. It follows well-established MPLS procedures and does not define any new protocol elements or allocate any new code points. It is operationally equivalent to other existing NSH encapsulations as defined in [RFC8300]. As such, it should have no effect on SFC security as already discussed in Section 8 of [RFC8300]. Malis, et al. Expires December 21, 2018 [Page 3] Internet-Draft MPLSforSFC June 2018 6. Acknowledgements Thanks to Jim Guichard for his review and comments. 7. References 7.1. Normative References [RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y., Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack Encoding", RFC 3032, DOI 10.17487/RFC3032, January 2001, . [RFC8300] Quinn, P., Ed., Elzur, U., Ed., and C. Pignataro, Ed., "Network Service Header (NSH)", RFC 8300, DOI 10.17487/RFC8300, January 2018, . 7.2. Informative References [I-D.ietf-nvo3-vxlan-gpe] Maino, F., Kreeger, L., and U. Elzur, "Generic Protocol Extension for VXLAN", draft-ietf-nvo3-vxlan-gpe-06 (work in progress), April 2018. [RFC2784] Farinacci, D., Li, T., Hanks, S., Meyer, D., and P. Traina, "Generic Routing Encapsulation (GRE)", RFC 2784, DOI 10.17487/RFC2784, March 2000, . [RFC4928] Swallow, G., Bryant, S., and L. Andersson, "Avoiding Equal Cost Multipath Treatment in MPLS Networks", BCP 128, RFC 4928, DOI 10.17487/RFC4928, June 2007, . [RFC7325] Villamizar, C., Ed., Kompella, K., Amante, S., Malis, A., and C. Pignataro, "MPLS Forwarding Compliance and Performance Requirements", RFC 7325, DOI 10.17487/RFC7325, August 2014, . [RFC7665] Halpern, J., Ed. and C. Pignataro, Ed., "Service Function Chaining (SFC) Architecture", RFC 7665, DOI 10.17487/RFC7665, October 2015, . Malis, et al. Expires December 21, 2018 [Page 4] Internet-Draft MPLSforSFC June 2018 Authors' Addresses Andrew G. Malis Huawei Technologies Email: agmalis@gmail.com Stewart Bryant Huawei Technologies Email: stewart.bryant@gmail.com Joel M. Halpern Ericsson Email: joel.halpern@ericsson.com Malis, et al. Expires December 21, 2018 [Page 5]