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Versions: (draft-napper-sfc-nsh-mobility-allocation) 00 01 02 03 04 draft-ietf-sfc-nsh-broadband-allocation

Service Function Chaining                                      J. Napper
Internet-Draft                                                  S. Kumar
Intended status: Standards Track                     Cisco Systems, Inc.
Expires: January 20, 2018                                       P. Muley
                                                           W. Hendericks
                                                                   Nokia
                                                            M. Boucadair
                                                                  Orange
                                                           July 19, 2017


               NSH Context Header Allocation -- Broadband
              draft-napper-sfc-nsh-broadband-allocation-03

Abstract

   This document provides a recommended allocation of context headers
   for a Network Service Header (NSH) within the broadband service
   provider network context.  NSH is described in detail in
   [ietf-sfc-nsh].  This allocation is intended to support uses cases as
   defined in [ietf-sfc-use-case-mobility].

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 [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 January 20, 2018.







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Copyright Notice

   Copyright (c) 2017 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
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   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.  Definition Of Terms . . . . . . . . . . . . . . . . . . . . .   3
   3.  Network Service Header (NSH) Context Headers  . . . . . . . .   3
   4.  Recommended Context Allocation  . . . . . . . . . . . . . . .   4
     4.1.  MD Type 0x01 Allocation Specifics . . . . . . . . . . . .   4
     4.2.  MD Type 0x02 Allocation Specifics . . . . . . . . . . . .   6
   5.  Context Allocation and Control Plane Considerations . . . . .   7
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   8.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   7
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   8
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   Service function chaining provides a mechanism for network traffic to
   be steered through multiple service functions in a sequence.
   Metadata can be useful to service functions.  The Network Service
   Header (NSH) provides support for carrying shared metadata between
   service functions (and devices) either using 4 fixed-length 32-bit
   context headers or as optional TLVs as defined in [ietf-sfc-nsh].
   NSH is then encapsulated within an outer header for transport.

   This document provides a recommended default allocation scheme for
   the fixed-length context headers and for TLV types in the context of
   service chaining within fixed and mobile broadband service provider
   networks.  Supporting use cases describing the need for a metadata
   header in these contexts are described in




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   [ietf-sfc-use-case-mobility].  This draft does not address control
   plane mechanisms.

2.  Definition Of Terms

   This document uses the terms as defined in [RFC7498] and [RFC7665].

3.  Network Service Header (NSH) Context Headers

   In Service Function Chaining, the Network Service Header is composed
   of a 4-byte base header (BH1), a 4-byte service path header (SH1) and
   four mandatory 4-byte context headers (CH1-CH4) in the case of MD
   Type 0x01 and optional TLVs in the case of MD Type 0x02 as described
   in [ietf-sfc-nsh].

   The following Figure 1 shows the MD Type 0x01 mandatory context
   headers.

    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |Ver|O|C|R|R|R|R|R|R|   Length  | MD Type = 0x01| Next Protocol | BH1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          Service Path ID                      | Service Index | SH1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                Mandatory Context Header 1                     | CH1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                Mandatory Context Header 2                     | CH2
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                Mandatory Context Header 3                     | CH3
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                Mandatory Context Header 4                     | CH4
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

              Figure 1: Network Service Header - MD Type 0x01

   The following Figure 2 shows the MD Type 0x02 optional TLV header
   format.














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    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |Ver|O|C|R|R|R|R|R|R|   Length  | MD Type = 0x02| Next Protocol | BH1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          Service Path ID                      | Service Index | SH1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~              Variable Length Context Headers  (opt.)          ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

              Figure 2: Network Service Header - MD Type 0x02

4.  Recommended Context Allocation

   The following header allocations provide information to support
   service function chaining in a service provider network, for example
   as described for mobility in [ietf-sfc-use-case-mobility].

   The set of metadata headers can be delivered to service functions
   that can use the metadata within to enforce policy, communicate
   between service functions, provide subscriber information and other
   functionality.  Several of the headers are typed allowing for
   different metadata to be provided to different service functions or
   even to the same service function but on different packets within a
   flow.  Which metadata are sent to which service functions is decided
   in the SFC control plane and is thus out of the scope of this
   document.

4.1.  MD Type 0x01 Allocation Specifics

   The following Figure 3 provides a high-level description of the
   fields in the recommended allocation of the fixed context headers for
   a mobility context.

    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | R | Sub | Tag |                 Context ID                    | CH1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Sub/Endpoint ID                         ~ CH2
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   ~                   Sub/Endpoint ID (cont.)                     | CH3
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                    Service Information                        | CH4
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Figure 3: NSH Context Allocation




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   The intended use for each of the context header allocations is as
   follows:

   R  - Reserved.

   Sub  - Sub/Endpoint ID type field.  These bits determine the type of
      the 64-bit Sub/Endpoint ID field that spans CH2 and CH3.

      000  - If the Sub field is not set, then the 64-bit Sub/Endpoint
         ID field is an opaque field that can be used or ignored by
         service functions as determined by the control plane.

      001  - The Sub/Endpoint ID field contains an IMSI [itu-e-164].

      010  - The Sub/Endpoint ID field contains an MSISDN (8-15 digit)
         [itu-e-164].

      011  - The Sub/Endpoint ID field contains a 64-bit identifier that
         can be used to group flows (e.g., in Machine-to-Machine, M2M).

      100  - The Sub/Endpoint IP field contains a wireline subcriber ID
         in CH2, and CH3 contains the home identifier.

      101-111  - Reserved.

   Tag  - The Tag field indicates the type of the Service Information
      field in CH4.  Some types for this field are specified by the Tag
      field as follows:

      000  - If the Tag field is not set, then the Service Information
         field in CH4 is an opaque field that can be used or ignored by
         service functions as determined by the control plane.

      001  - The Service Information field in CH4 contains information
         related to the Access Network (AN) for the subscriber.  This is
         shown in Figure 4 for a 3GPP Radio Access Network (RAN).  Note
         that these values should correspond to those that can be
         obtained for the flow from the corresponding 3GPP PCRF (Policy
         and Charging Rules Function) component using Diameter as
         described in [TS.29.230].

    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | CAN |    QoS/DSCP   | Con |          App Id         |  Rsvd   | CH4
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

               Figure 4: Service Information RAN Allocation




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         CAN  - IP-CAN-Type for IP Connectivity Access Network (Diameter
            AVP code 1027).

         QoS  - QoS-Class-Identifier AVP (Diameter AVP code 1028) or
            Differentiated Services Code Point (DSCP) marking as
            described in [RFC2474].

         Con  - Access congestion level.  An Access Congestion level 000
            means an unknown/undefined congestion level.  An Access
            Congestion level 001 means no congestion.  For other values
            of Access Congestion level, a higher value indicates a
            higher level of congestion.

         App Id  - Application ID describing the flow type.  Allocation
            of IDs is done in the control plane and is out of the scope
            of this document.

         Rsvd  - Reserved.

      010-111  - Reserved.

   Context ID  - The Context ID field allows the Subscriber/Endpoint ID
      field to be scoped.  For example, the Context ID field could
      contain the incoming VRF, VxLAN VNID, VLAN, or policy identifier
      within which the Subscriber/Endpoint ID field is defined.

   Sub/Endpoint ID  - 64-bit length Subscriber/Endpoint identifier
      (e.g., IMSI, MSISDN, or implementation-specific Endpoint ID) of
      the corresponding subscriber/machine/application for the flow.

   Service Information  - The Service Information field is a unique
      identifier that can carry metadata specific to the flow or
      subscriber identified in the Sub/Endpoint ID field.

4.2.  MD Type 0x02 Allocation Specifics

   The following Figure 5 provides a high-level description of the
   fields in the recommended allocation of the variable length headers
   for a mobility context.

    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     TLV Class = 3GPP          |C|    Type     |R|R|R|   Len   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Data ...
   +-+-+-+-+-+-+-+-+

                         Figure 5: TLV Allocation



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   The intended use of the header is for TLVs associated with 3GPP Radio
   Access Networks as described in [TS.29.230].  This TLV can be used by
   3GPP to extend the metadata as per use cases.  Having this TLV helps
   to carry more information that does not fit within the MD Type 0x01.

   The Len field carries the total length.  Type = 0x01 is reserved.  If
   set to 0x01, the TLV carries the 4 context headers as defined in
   Section 4.1.

5.  Context Allocation and Control Plane Considerations

   This document describes an allocation scheme for both the mandatory
   context headers and optional TLV headers in the context of broadband
   service providers.  This suggested allocation of headers should be
   considered as a guideline and may vary depending on the use case.
   The control plane aspects of specifying and distributing the
   allocation scheme among different service functions within the
   Service Function Chaining environment to guarantee consistent
   semantics for the metadata is beyond the scope of this document.

6.  Security Considerations

   The header allocation recommended by this document includes numbers
   that must be distributed consistently across a Service Function
   Chaining environment.  Protocols for distributing these numbers
   securely are required in the control plane, but are out of scope of
   this document.

   Furthermore, some of the metadata carried in the headers require
   secure methods to prevent spoofing or modification by service
   function elements that may themselves be exposed to subscriber
   traffic and thus might be compromised.  This document does not
   address such security concerns.

7.  IANA Considerations

   This document requests IANA to assign a TLV class for 3GPP to be used
   for its use cases.

8.  Acknowledgments

   The authors would like to thank Jim Guichard for his assistance
   structuring the document.








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9.  References

9.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

9.2.  Informative References

   [ietf-sfc-nsh]
              Quinn, P., Elzur, U., and C. Pignataro, "Network Service
              Header", I-D draft-ietf-sfc-nsh-15 (work in progress),
              July 2017.

   [ietf-sfc-use-case-mobility]
              Haeffner, W., Napper, J., Stiemerling, M., Lopez, D., and
              J. Uttaro, "Service Function Chaining Use Cases in Mobile
              Networks", I-D draft-ietf-sfc-use-case-mobility-07 (work
              in progress), October 2016.

   [itu-e-164]
              "The international public telecommunication numbering
              plan", ITU-T E.164, November 2010.

   [RFC2474]  Nichols, K., Blake, S., Baker, F., and D. Black,
              "Definition of the Differentiated Services Field (DS
              Field) in the IPv4 and IPv6 Headers", RFC 2474,
              DOI 10.17487/RFC2474, December 1998,
              <http://www.rfc-editor.org/info/rfc2474>.

   [RFC7498]  Quinn, P., Ed. and T. Nadeau, Ed., "Problem Statement for
              Service Function Chaining", RFC 7498,
              DOI 10.17487/RFC7498, April 2015,
              <http://www.rfc-editor.org/info/rfc7498>.

   [RFC7665]  Halpern, J., Ed. and C. Pignataro, Ed., "Service Function
              Chaining (SFC) Architecture", RFC 7665,
              DOI 10.17487/RFC7665, October 2015,
              <http://www.rfc-editor.org/info/rfc7665>.

   [TS.29.230]
              "Diameter applications; 3GPP specific codes and
              identifiers", 3GPP TS 29.230 14.5.0, July 2017.






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Authors' Addresses

   Jeffrey Napper
   Cisco Systems, Inc.

   Email: jenapper@cisco.com


   Surendra Kumar
   Cisco Systems, Inc.

   Email: smkumar@cisco.com


   Praveen Muley
   Nokia

   Email: praveen.muley@nokia.com


   Wim Hendericks
   Nokia

   Email: Wim.Henderickx@nokia.com


   Mohamed Boucadair
   Orange

   Email: mohamed.boucadair@orange.com





















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