One document matched: draft-napper-sfc-nsh-mobility-allocation-00.txt
Service Function Chaining J. Napper
Internet-Draft S. Kumar
Intended status: Informational Cisco Systems, Inc.
Expires: May 17, 2015 November 13, 2014
NSH Context Header Allocation -- Mobility
draft-napper-sfc-nsh-mobility-allocation-00
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 [quinn-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
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Table of Contents
1. Introduction
2. Definition Of Terms
3. Network Service Header (NSH) Context Headers
4. Recommended Mobility Context Allocation
5. Mobility Allocation Specifics
6. Context Allocation and Control Plane Considerations
7. Security Considerations
8. IANA Considerations
9. Acknowledgments
10. References
10.1. Normative References
10.2. Informative References
Authors' Addresses
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
and optional TLV headers as defined in [quinn-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
define any TLV headers within this context and does not address
control plane mechanisms.
2. Definition Of Terms
This document uses the terms as defined in
[ietf-sfc-problem-statement], and [ietf-sfc-arch].
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
[quinn-sfc-nsh]. An optional TLV can be signalled using the Length
field.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | TLV
~ Optional Variable Length Context Headers ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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.
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.
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
[guichard-sfc-nsh-dc-allocation]
, , and , "Network Service Header (NSH) Context Header
Allocation (Data Center)", I-D draft-guichard-sfc-nsh-dc-
allocation-00 (work in progress), August 2014.
[ietf-sfc-arch]
and , "Service Function Chaining (SFC) Architecture", I-D
draft-ietf-sfc-architecture-02 (work in progress),
September 2014.
[ietf-sfc-problem-statement]
and , "Service Function Chaining Problem Statement", I-D
draft-ietf-sfc-problem-statement-09 (work in progress),
August 2014.
[ietf-sfc-use-case-mobility]
, , , , and , "Service Function Chaining Use Cases in
Mobile Networks", I-D draft-ietf-sfc-use-case-mobility-02
(work in progress), July 2014.
[itu-e-164]
"The international public telecommunication numbering
plan", ITU-T E.164, November 2010.
[quinn-sfc-nsh]
, , , , , , , , , , , , and , "Network Service Header",
I-D draft-quinn-sfc-nsh-03 (work in progress), July 2014.
Authors' Addresses
Jeffrey Napper
Cisco Systems, Inc.
Email: jenapper@cisco.com
Surendra Kumar
Cisco Systems, Inc.
Email: smkumar@cisco.com
| PAFTECH AB 2003-2026 | 2026-04-23 22:02:40 |