One document matched: draft-napper-sfc-nsh-mobility-allocation-01.txt
Differences from draft-napper-sfc-nsh-mobility-allocation-00.txt
Service Function Chaining J. Napper
Internet-Draft S. Kumar
Intended status: Informational Cisco Systems, Inc.
Expires: November 17, 2015 May 16, 2015
NSH Context Header Allocation -- Mobility
draft-napper-sfc-nsh-mobility-allocation-01
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.
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 November 17, 2015.
Copyright Notice
Copyright (c) 2015 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
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publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
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described in the Simplified BSD License.
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. Mobility Allocation Specifics . . . . . . . . . . . . . . . . 4
6. Context Allocation and Control Plane Considerations . . . . . 4
7. Security Considerations . . . . . . . . . . . . . . . . . . . 5
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 5
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
10.1. Normative References . . . . . . . . . . . . . . . . . . 5
10.2. Informative References . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
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)
povides 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 mobile service provider networks. Supporting use cases
describing the need for a metadata header in this context 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
[ietf-sfc-arch].
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flow Cookie | CH1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserv |TenTy| Tenant ID | CH2
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub/App ID ~ CH3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Sub/App ID (cont.) | CH4
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: NSH Mobility Context Allocation
5. Mobility Allocation Specifics
The intended use for each of the context header allocations is as
follows:
Flow Cookie - unique value with respect to the Subscriber/
Application Identifier field that can be used to identify a packet
or flow even if the encapsulated packet changes (e.g., when a flow
is terminated at a proxy).
Reserv - Reserved.
TenTy - Tenant Type represents type of Tenant Identifier field
(e.g., vlan, vxlan, vrf, mpls, etc.).
Tenant ID - value encoded according to Tenant Type field
corresponding to encapsulated packet (e.g., ingress VRF id). The
Tenant ID field allows the Base Header (BH1) and Service Headers
(SH) to be tenant independent.
Sub/App ID - 64-bit length Subscriber/Application identifier (e.g.,
IMSI [itu-e-164], MSISDN (8-15 digit) [itu-e-164], or
implementation-specific Application ID) of the corresponding
subscriber/application for the flow.
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.
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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, March 1997.
10.2. Informative References
[RFC7498] Quinn, P. and T. Nadeau, "Problem Statement for Service
Function Chaining", RFC 7498, April 2015.
[guichard-sfc-nsh-dc-allocation]
Guichard, J., Smith, M., Kumar, S., Majee, S., Agarwal,
P., Glavin, K., and Y. Laribi, "Network Service Header
(NSH) Context Header Allocation (Data Center)", I-D draft-
guichard-sfc-nsh-dc-allocation-01 (work in progress),
December 2014.
[ietf-sfc-arch]
Halpern, J. and C. Pignataro, "Service Function Chaining
(SFC) Architecture", I-D draft-ietf-sfc-architecture-08
(work in progress), May 2015.
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[ietf-sfc-nsh]
Quinn, P. and U. Elzur, "Network Service Header", I-D
draft-ietf-sfc-nsh-00 (work in progress), March 2015.
[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-03 (work
in progress), January 2015.
[itu-e-164]
"The international public telecommunication numbering
plan", ITU-T E.164, November 2010.
Authors' Addresses
Jeffrey Napper
Cisco Systems, Inc.
Email: jenapper@cisco.com
Surendra Kumar
Cisco Systems, Inc.
Email: smkumar@cisco.com
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