Network Working Group B. Sarikaya
Internet-Draft Huawei
Intended status: Informational M. Boucadair
Expires: January 8, 2017 Orange
D. von Hugo
Telekom Innovation Laboratories
July 7, 2016
Road to the Standardization for Service Function Chaining Metadata Type
1 and Type 2
draft-sarikaya-sfc-sfctlvs-00.txt
Abstract
With the definition of service function chain data plane protocol
there comes the need to define the context data needed in the service
function chain use cases. This document gives an account of all
context data defined so far as Network Service Header metadata Type 1
and Type 2 context headers. Next, the document discusses the various
options that can be made in standardizing these TLVs.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Context Metadata Definitions . . . . . . . . . . . . . . . . 2
3. The Road to Standardization . . . . . . . . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
7.1. Normative References . . . . . . . . . . . . . . . . . . 6
7.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
Network Service Header (NSH) [I-D.ietf-sfc-nsh] is the Service
Function Chaining (SFC) data plane protocol. The SFC architecture is
defined in [RFC7665].
NSH has the function of carrying context data in the form of context
header. NSH metadata type 2 carries the optional variable length
context header.
Many context headers were proposed by many documents. In this
document we survey existing drafts that propose new context metadata
and then discuss different options that can be taken to standardize
this work.
The reader should be familiar with the terms defined in [RFC7665] and
[I-D.ietf-sfc-nsh].
2. Context Metadata Definitions
[I-D.quinn-sfc-nsh-tlv] defines NSH metadata Type 2 TLVs such as
forwarding context, subscriber/user info, tenant, application ID,
content type, ingress network information, flow ID, source and/or
destination groups, universal resource identifier (URI).
Some of these TLVs are defined in other documents, like App ID,
Context ID in [I-D.napper-sfc-nsh-broadband-allocation]. Also for
Application ID, even though the document references
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[I-D.penno-sfc-appid], [I-D.penno-sfc-appid] seems to mean
Classification Engine ID and Selector ID for the Application ID.
The purpose of [I-D.quinn-sfc-nsh-tlv] is to document syntactic
structure of the TLVs. No other additional information about the
metadata processing is within the scope of this document. The
document mentions no use cases in which the TLVs defined are needed.
An implementer will need to refer to other documents to understand
the exact behavior for handling those contexts.
[I-D.napper-sfc-nsh-mobility-allocation] addresses the use cases
defined in [I-D.ietf-sfc-use-case-mobility]. For this purpose a
single TLV is defined called NSH mobility context allocation TLV.
This TLV is meta data Type 1 and defines endpoint ID, e.g. for IMSI
or MSISDN with 64-bit length and ServiceTag, a 64-bit field
containing flow or subscriber identified by the endpoint ID field
identifying IP-CAN type, QoS class, congestion level, etc. This
document does not define any meta data Type 2.
[I-D.napper-sfc-nsh-broadband-allocation] also supports use cases in
[I-D.ietf-sfc-use-case-mobility] but seems to address the needs of
fixed network as well as mobile networks.
This document updates the meta data Type 1 TLV defined in
[I-D.napper-sfc-nsh-mobility-allocation] for the wireline subscriber.
In addition, it defines a meta data Type 2 TLV to be associated with
3GPP registry. The intent here is to offer this TLV for the use of
3GPP to extend the meta data to meet the needs of 3GPP use cases.
However, it was not stated if 3GPP requested such an allocation.
[I-D.wang-sfc-nsh-ns-allocation] addresses the use cases for network
security defined in [I-D.wang-sfc-ns-use-cases].
It defines a recommended security context allocation as a meta data
Type 1 TLV. It is intended to define session ID, tenant ID,
destination/ source class for the logical classification of the
destination/ source of the traffic, destination/ source score which
contains security classification results for communicating immediate
actions and accumulated verdicts to downstream Service Functions.
[I-D.wang-sfc-nsh-ns-allocation] also mentions that the security
context allocation, although defined as Type 1, it may also form a
MD-Type 2 metadata TLV, possibly implying that the sizes of data such
as session/ tenant ID, etc. may need to become longer. As a result,
they may need to become variable length data as in Type 2 meta data
TLVs.
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[] addresses use cases that
require revealing host and/ or subscriber related information to
upstream SFs as well as extreme low latency service and ultra-high
reliability applications use cases.
From the analysed use cases, there comes the need to come up with
definition of host, subscriber, slice identifier and service
identifier SFC meta data Type 2 TLVs. Apart from defining these
TLVs, the document gives details of post processing in various nodes
such as ingress/egress border nodes, SFC-aware Service Functions and
Proxies. Such post processing is defined as normative behavior.
Since host and subscriber identifiers may reveal private information
about the host and/or the subscriber, the document also defines
normative behavior needed to protect the privacy of the hosts and
subscribers in an operator network.
[] is unique among the documents
discussed in this document because it defines the post processing
normative behavior related to the host and subscriber identifier meta
data Type 2 TLVs. Also the use cases are defined in the same
document not as a separate document as in the other cases.
[I-D.penno-sfc-packet] addresses the problem of sending packets in
the reverse direction to the source of the current in-process packet/
flow. It defines SF Reverse Packet Request as Type 1 metadata TLV.
This is defined as Version 1 (as opposed to Version 0 of NSH MD-type
1 in [I-D.ietf-sfc-nsh]) with OAM Protocol replacing the next
protocol field and with Reverse Packet Request added to the end of
mandatory context header octets for SFC as an additional 4-octet for
OAM.
This document also proposes 5 new metadata on service-path
invariants, service-path default, bidirectional clonable,
unidirectional clonable and service-function-mastered metadata.
Their structure specifics are not specified.
[I-D.penno-sfc-packet] gives a detailed explaination of the use of
the metadata defined, all the semantic information, pre and post
processing details at various nodes.
[I-D.vallamkonda-sfc-metadata-model] does not define any Type 1 or
Type 2 meta data TLVs, viewing such meta data as conveying
preprocessing information about the packet, this document attempts to
formally defines the post processing information. To that end, it
defines a vocabulary and information model for metadata. The
document gives metadata information model example definitions for
routing domain, IP endpoint, flow and traffic policy indication.
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3. The Road to Standardization
Some options are discussed below for progressing NSH TLVs:
1. List the structure of meta data in one single document. The
document is not supposed to contain any post processing
information. [I-D.quinn-sfc-nsh-tlv] attempts this choice for
Type 2 TLVs. Currently there is no such document for Type 1
TLVs. Note that in this case it is not clear how the post
processing normative behavior will be specified for the TLVs.
One option is to keep such information in separate document. If
such a strategy is adopted then the advantages obtained from
documenting all TLVs in one document disappears because the
implementers would need to consult many documents instead of only
one.
2. Specify an exhaustive list of TLVs in one single document: this
approach allows avoiding dependency on other document.
3. All documents defining new meta data Type 1 and Type 2 TLVs are
treated individually for standardization. This approach has the
advantage of keeping all meta data Type 1 and Type 2 TLVs in
separate and dedicated documents together with all the
information that the implementers may need. This could be a
strong positive especially if we consider the fact that the meta
data are being defined for very many use cases and scenarios. It
is unlikely that one implementer would need to implement a large
number of these TLVs, thereby defeating the need for combining
them in a single document.
4. Together with choice 1 above, while combining all TLVs in one
document, it could be possible to keep post processing
information related to the meta data can be considered
individually for standardization.
5. Together with choice 2 above, Type 1 TLVs can combined in one
document but all Type 2 TLVs can be considered individually in
separate dedicated documents.
4. IANA Considerations
None.
5. Security Considerations
This document does not introduce any security issues.
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6. Acknowledgements
TBD.
7. References
7.1. Normative References
[I-D.ietf-sfc-nsh]
Quinn, P. and U. Elzur, "Network Service Header", draft-
ietf-sfc-nsh-05 (work in progress), May 2016.
[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>.
[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>.
7.2. Informative References
[I-D.ietf-sfc-use-case-mobility]
Haeffner, W., Napper, J., Stiemerling, M., Lopez, D., and
J. Uttaro, "Service Function Chaining Use Cases in Mobile
Networks", draft-ietf-sfc-use-case-mobility-06 (work in
progress), April 2016.
[I-D.liu-sfc-use-cases]
Will, W., Li, H., Huang, O., Boucadair, M., Leymann, N.,
Qiao, F., Qiong, Q., Pham, C., Huang, C., Zhu, J., and P.
He, "Service Function Chaining (SFC) General Use Cases",
draft-liu-sfc-use-cases-08 (work in progress), September
2014.
[I-D.napper-sfc-nsh-broadband-allocation]
Napper, J., Surendra, S., Muley, P., and W. Henderickx,
"NSH Context Header Allocation -- Broadband", draft-
napper-sfc-nsh-broadband-allocation-00 (work in progress),
March 2016.
[I-D.napper-sfc-nsh-mobility-allocation]
Napper, J., Surendra, S., Muley, P., and W. Henderickx,
"NSH Context Header Allocation -- Mobility", draft-napper-
sfc-nsh-mobility-allocation-02 (work in progress),
November 2015.
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[I-D.penno-sfc-appid]
Penno, R., Claise, B., Pignataro, C., and C. Fontaine,
"Using Application Identification in Services Function
Chaining Metadata", draft-penno-sfc-appid-04 (work in
progress), June 2016.
[I-D.penno-sfc-packet]
Penno, R., Pignataro, C., Yen, C., Wang, E., Leung, K.,
and D. Dolson, "Packet Generation in Service Function
Chains", draft-penno-sfc-packet-03 (work in progress),
April 2016.
[I-D.quinn-sfc-nsh-tlv]
Quinn, P., Elzur, U., Majee, S., and J. Halpern, "Network
Service Header TLVs", draft-quinn-sfc-nsh-tlv-01 (work in
progress), April 2016.
[]
Boucadair, M., Hugo, D., and B. Sarikaya, "Service
Function Chaining Service, Subscriber and Host
Identification Use Cases and Metadata", draft-sarikaya-
sfc-hostid-serviceheader-03 (work in progress), July 2016.
[I-D.vallamkonda-sfc-metadata-model]
sunilvk@f5.com, s. and D. Dolson, "Information Model for
SFC Metadata", draft-vallamkonda-sfc-metadata-model-00
(work in progress), January 2016.
[I-D.wang-sfc-ns-use-cases]
Wang, E., Leung, K., Felix, J., and J. Iyer, "Service
Function Chaining Use Cases for Network Security", draft-
wang-sfc-ns-use-cases-01 (work in progress), March 2016.
[I-D.wang-sfc-nsh-ns-allocation]
Wang, E. and K. Leung, "Network Service Header (NSH)
Context Header Allocation (Network Security)", draft-wang-
sfc-nsh-ns-allocation-00 (work in progress), May 2016.
Authors' Addresses
Behcet Sarikaya
Huawei
5340 Legacy Dr.
Plano, TX 75024
Email: sarikaya@ieee.org
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Mohamed Boucadair
Orange
Rennes 3500, France
Email: mohamed.boucadair@orange.com
Dirk von Hugo
Telekom Innovation Laboratories
Deutsche-Telekom-Allee 7
D-64295 Darmstadt
Germany
Email: Dirk.von-Hugo@telekom.de
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