SFC Y. Wei, Ed.
Internet-Draft ZTE Corporation
Intended status: Standards Track U. Elzur
Expires: November 21, 2020 Intel
S. Majee
Caber systems inc
May 20, 2020

Network Service Header Metadata Type 2 Variable-Length Context Headers
draft-ietf-sfc-nsh-tlv-03

Abstract

This draft describes Network Service Header (NSH) Metadata (MD) Type 2 variable-length context headers that can be used within a service function path.

Status of This Memo

This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.

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This Internet-Draft will expire on November 21, 2020.

Copyright Notice

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Table of Contents

1. Introduction

Network Service Header (NSH) [RFC8300] is the Service Function Chaining (SFC) encapsulation required to support the SFC architecture. As such, NSH provides following key elements:

  1. Service Function Path identification.
  2. Indication of location within a Service Function Path.
  3. Optional, per-packet metadata (fixed-length or variable).

[RFC8300] further defines two metadata formats (MD Types): 1 and 2. MD Type 1 defines fixed length, 16 bytes-long metadata, whereas MD Type 2 defines a variable-length context format for metadata. This draft defines some common metadata contexts for use with NSH MD Type 2.

This draft does not address metadata usage, updating/chaining of metadata or other SFP functions. Those topics are described in [RFC8300].

2. Conventions used in this document

2.1. Terminology

This document uses the terminology defined in the SFC Architecture [RFC7665]and the Network Service Header [RFC8300]

2.2. Requirements Language

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

3. NSH MD Type 2 format 

    
 0                   1                   2                   3
 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|U|    TTL    |   Length  |U|U|U|U|MD Type| Next Protocol |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 1: NSH Base Header

A NSH is composed of a 4-byte Base Header, a 4-byte Service Path Header and Context Headers. The Base Header identifies the MD-Type in use: [RFC8300] for a detailed header description. 

    
     0                   1                   2                   3
     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Metadata Class       |      Type     |U|    Length   |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                   Variable-Length Metadata                    |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 2: NSH Variable-Length Context Headers

When the base header specifies MD Type = 0x2, zero or more Variable Length Context Headers MAY be added, immediately following the Service Path Header. Therefore, Length = 0x2 indicates that only the Base Header followed by the Service Path Header is present. The number, indicated in the Length field, of optional Variable Length Context Headers MUST be of an integer indicating length in 4-bytes words Figure 2 below depicts the format of the Context Header as defined in Section 2.5.1 of [RFC8300].

4. NSH MD Type 2 Context Headers

In [RFC8300] defined that Metadata Class 0x0000 as IETF Base NSH MD Class. In this draft, metadata types are defined for the IETF Base NSH MD Class.

4.1. Forwarding Context 

    
    0                   1                   2                   3
    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Metadata Class = 0x0000    |  Type = TBA1  |U|  Length = 8 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   CT  |             Reserved                                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Tenant ID                                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 3: Forwarding Context

This metadata context carries a network forwarding context, used for segregation and forwarding scope. Forwarding context can take several forms depending on the network environment. For example, VXLAN/VXLAN-GPE VNID, VRF identification or VLAN.

where:

4.2. Tenant Identifier 

    0                   1                   2                   3
    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Metadata Class = 0x0000    |  Type = 0x02  |U|  Length=12  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  TT   |             Reserved                                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         Tenant ID                             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         Tenant ID                             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 4: Tenant Identifier List

Tenant identification is often used for segregation within a multi-tenant environment. Orchestration system-generated tenant IDs are an example of such data. This context header carries both the format and value of the Tenant identifier.

where:

4.3. Content Type 

    
    0                   1                   2                   3
    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Metadata Class = 0x0000    |  Type = TBA3  |U|  Length = 4 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Content Type                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 5: Content Type

Provides explicit information about the content being carried, for example, type of video or content value for billing purposes.

4.4. Ingress Network Node Information 

    
    0                   1                   2                   3
    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Metadata Class = 0x0000    |  Type = TBA4  |U|  Length = 8 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Node ID                                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 6: Ingress Network Node ID

This context carries Node ID of the ingress network node.

4.5. Ingress Network Source Interface 

    
    0                   1                   2                   3
    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Metadata Class = 0x0000    |  Type = TBA5  |U|  Length = 8 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Source Interface/Port                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 7: Ingress Network Source Interface

This context carries the ingress interface of the ingress network node.

4.6. Flow ID 

    
    0                   1                   2                   3
    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Metadata Class = 0x0000    |  Type = TBA6  |U|  Length = 4 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Flow ID                                   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 8: Flow ID

Flow ID provides a representation of the flow. Akin, but not identical to the usage described in [RFC6437].

4.7. Source and/or Destination Groups 

    
    0                   1                   2                   3
    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Metadata Class = 0x0000    |  Type = TBA7  |U|  Length=12  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  GT   |                Reserved                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Source Group                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Dest Group                             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 9: End Point Group

Intent-based systems can use this data to express the logical grouping of source and/or destination objects. [GROUPBASEDPOLICY] and [GROUPPOLICY] provide examples of such a system.

where:

4.8. Universal Resource Identifier 

    
    0                   1                   2                   3
    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Metadata Class = 0x0000    |  Type = TBA8  |U|  Length=var |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  UT   |                URI                                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   ~                        URI                                    ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 10: Universal Resource Identifier

where

4.9. Policy Identifier (POLICY_ID) 

    
    0                   1                   2                   3
    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Metadata Class = 0x0000    |  Type = TBA9  |U|  Length=var |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     POLICY_ID                                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   ~                     POLICY_ID                                  ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 11: POLICY_ID

The policy is often referred by a system-generated identifier which is then used by the devices to lookup the content of the policy locally. For example, this identifier could be an index to an array, a lookup key, a database Id. The identifier allows enforcement agents or services to lookup up the content of their part of the policy quite efficiently.

5. Security Considerations

[RFC8300] describes the requisite security considerations for protecting NSH metadata.

6. Acknowledgments

The authors would like to thank Paul Quinn, Behcet Sarikaya, Dirk von Hugo, Mohamed Boucadair, Carlos Pignataro and Gregory Mirsky for providing invaluable concepts and content for this document.

7. IANA Considerations

This document requests IANA to assign the following types from the "NSH IETF- Assigned Optional Variable-Length Metadata Types" (0x0000 IETF Base NSH MD Class) registry available at [IANA-NSH-MD2]

This document defines the following new values (Table 1)in the Network Service Header (NSH) metadata context Type registry:

Type Values
Value Description Reference
TBA1 Forwarding Context This document
TBA2 Tenant Identifier This document
TBA3 Content Type This document
TBA4 Ingress Network NodeID This document
TBA5 Ingress Network Interface This document
TBA6 Flow ID This document
TBA7 Source and/or Destination Groups This document
TBA8 Universal Resource Identifier This document
TBA9 Policy Identifier This document

7.1. Forwarding Context Types

IANA is requested to create and maintain a new sub registry for "Forwarding Context" context types at [IANA-NSH-MD2].

Fowarding Context Types
Value Context Types Reference
0x0 24-bits VXLAN/LISP virtual network identifier (VNI) This document
0x1 20-bits MPLS VPN label This document
0x2 12-bit VLAN identifier This document
0x3-0x9 Unassigned IETF Review
0xA-0xE Expert Review IETF Review
0xF Reserved This document

7.2. Tenant Identifier Types

IANA is requested to create and maintain a new sub registry for "Tenant Identifier" context types at [IANA-NSH-MD2], with the following initial allocation:

Tenant Identifier Types
Value Tenant Identifier Types Reference
0x0 32 bits-long Tenant ID This document
0x1 64 bits-long Tenant ID This document

7.3. Group Types

IANA is requested to create and maintain a new sub registry for "Group" context types at [IANA-NSH-MD2], with the following initial allocation:

Group Types
Value Group Types Reference
0x0 Reserved This document
0x1 Group Based Policy (GBP) end point group (EPG) This document
0x2-0xE Unassigned IETF Review
0xF Reserved This document

7.4. URI Types

IANA is requested to create and maintain a new sub registry for "Group" context types at [IANA-NSH-MD2], with the following initial allocation:

URI Types
Value URI Types Reference
0x0 Reserved This document
0x1 URI in standard string format as defined in [RFC3986] This document
0x2 URI represented in a compacted hash format This document
0x3-0xE Unassigned IETF Review
0xF Reserved This document

8. References

8.1. Normative References

[IANA-NSH-MD2] IANA, "NSH IETF-Assigned Optional Variable-Length Metadata Types"
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997.
[RFC3986] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, DOI 10.17487/RFC3986, January 2005.
[RFC7665] Halpern, J. and C. Pignataro, "Service Function Chaining (SFC) Architecture", RFC 7665, DOI 10.17487/RFC7665, October 2015.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017.
[RFC8300] Quinn, P., Elzur, U. and C. Pignataro, "Network Service Header (NSH)", RFC 8300, DOI 10.17487/RFC8300, January 2018.

8.2. Informative References

[GROUPBASEDPOLICY] OpenStack, "Group Based Policy", 2014.
[GROUPPOLICY] OpenDaylight, "Group Policy", 2014.
[RFC6437] Amante, S., Carpenter, B., Jiang, S. and J. Rajahalme, "IPv6 Flow Label Specification", RFC 6437, DOI 10.17487/RFC6437, November 2011.

Authors' Addresses

Yuehua (Corona) Wei (editor) ZTE Corporation No.50, Software Avenue Nanjing, 210012 China EMail: wei.yuehua@zte.com.cn
Uri Elzur Intel EMail: uri.elzur@intel.com
Sumandra Majee Caber systems inc EMail: Sum.majee@gmail.com