Internet DRAFT - draft-napper-sfc-nsh-mobility-allocation
draft-napper-sfc-nsh-mobility-allocation
Service Function Chaining J. Napper
Internet-Draft S. Kumar
Intended status: Informational Cisco Systems, Inc.
Expires: May 7, 2016 P. Muley
W. Hendericks
Alcatel-Lucent
November 4, 2015
NSH Context Header Allocation -- Mobility
draft-napper-sfc-nsh-mobility-allocation-02
Abstract
This document provides a recommended allocation of the mandatory
fixed context headers for a Network Service Header (NSH) within the
mobility 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.
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This Internet-Draft will expire on May 7, 2016.
Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Definition Of Terms . . . . . . . . . . . . . . . . . . . . . 2
3. Network Service Header (NSH) Context Headers . . . . . . . . 3
4. Recommended Mobility Context Allocation . . . . . . . . . . . 3
5. Broadband Allocation Specifics . . . . . . . . . . . . . . . 4
6. Context Allocation and Control Plane Considerations . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . 6
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
10.1. Normative References . . . . . . . . . . . . . . . . . . 6
10.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
Service function chaining provides a mechanism for network traffic to
be forced through multiple service functions in a sequence. Metadata
can be useful to service functions. Network Service Headers (NSH)
provides support for carrying shared metadata between service
functions (and devices) using 4 fixed-length 32-bit context headers
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 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 [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].
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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) as described in
[ietf-sfc-nsh].
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
4. Recommended Mobility Context Allocation
The following context header allocation provides information to
support service function chaining in a mobile service provider
network as described in [ietf-sfc-use-case-mobility].
The set of context 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 context 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.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| R | Sub | Tag | Context ID | CH1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub/Endpoint ID ~ CH2
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Sub/Endpoint ID (cont.) | CH3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ServiceTag | CH4
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: NSH Mobility Context Allocation
Figure 2 provides a high-level description of the fields in the
recommended allocation of the fixed context headers for a mobility
context.
5. Broadband Allocation Specifics
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.
Tag - The Tag field indicates the type of the ServiceTag field in
CH4.
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/App 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. This
field is typed by the value of the Sub field as follows:
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].
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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).
100-111 - Reserved.
ServiceTag - A ServiceTag is a unique identifier that can carry
metadata specific to the flow or subscriber identified in the Sub/
App ID field. Some types for this field are specified by the Tag
field as follows:
000 - If the Tag field is not set, then the ServiceTag field in
CH4 is an opaque field that can be used or ignored by service
functions as determined by the control plane.
001 - The ServiceTag field in CH4 contains information related to
the Radio Access Network (RAN) for the subscriber as follows in
Figure 3. 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 |U| Con | App Id | Rsvd | CH4
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Service Tag RAN Allocation
CAN - IP-CAN-Type (Diameter AVP code 1027).
QoS - QoS-Class-Identifier AVP (Diameter AVP code 1028).
U - QoS-Upgrade AVP (Diameter AVP code 1030).
Con - Congestion level.
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.
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6. Context Allocation and Control Plane Considerations
This document describes an allocation scheme for the mandatory
context headers in the context of mobile service providers. This
suggested allocation of context 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.
7. Security Considerations
The context 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 context 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.
8. IANA Considerations
This document has no actions for IANA.
9. Acknowledgments
The authors would like to thank Jim Guichard for his assistance
structuring the document.
10. References
10.1. 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>.
10.2. Informative References
[ietf-sfc-nsh]
Quinn, P. and U. Elzur, "Network Service Header", I-D
draft-ietf-sfc-nsh-01 (work in progress), July 2015.
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[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-05 (work
in progress), January 2015.
[itu-e-164]
"The international public telecommunication numbering
plan", ITU-T E.164, November 2010.
[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 13.2.0, September 2015.
Authors' Addresses
Jeffrey Napper
Cisco Systems, Inc.
Email: jenapper@cisco.com
Surendra Kumar
Cisco Systems, Inc.
Email: smkumar@cisco.com
Praveen Muley
Alcatel-Lucent
Email: praveen.muley@alcatel-lucent.com
Wim Hendericks
Alcatel-Lucent
Email: Wim.Henderickx@alcatel-lucent.com
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