draft-ietf-sfc-nsh-28.txt   rfc8300.txt 
Service Function Chaining P. Quinn, Ed. Internet Engineering Task Force (IETF) P. Quinn, Ed.
Internet-Draft Cisco Request for Comments: 8300 Cisco
Intended status: Standards Track U. Elzur, Ed. Category: Standards Track U. Elzur, Ed.
Expires: May 7, 2018 Intel ISSN: 2070-1721 Intel
C. Pignataro, Ed. C. Pignataro, Ed.
Cisco Cisco
November 3, 2017 January 2018
Network Service Header (NSH) Network Service Header (NSH)
draft-ietf-sfc-nsh-28
Abstract Abstract
This document describes a Network Service Header (NSH) imposed on This document describes a Network Service Header (NSH) imposed on
packets or frames to realize service function paths. The NSH also packets or frames to realize Service Function Paths (SFPs). The NSH
provides a mechanism for metadata exchange along the instantiated also provides a mechanism for metadata exchange along the
service paths. The NSH is the SFC encapsulation required to support instantiated service paths. The NSH is the Service Function Chaining
the Service Function Chaining (SFC) architecture (defined in (SFC) encapsulation required to support the SFC architecture (defined
RFC7665). in RFC 7665).
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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Internet-Drafts are draft documents valid for a maximum of six months This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on May 7, 2018. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8300.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction ....................................................3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4 1.1. Applicability ..............................................4
1.2. Applicability . . . . . . . . . . . . . . . . . . . . . . 4 1.2. Requirements Language ......................................4
1.3. Definition of Terms . . . . . . . . . . . . . . . . . . . 5 1.3. Definition of Terms ........................................4
1.4. Problem Space . . . . . . . . . . . . . . . . . . . . . . 6 1.4. Problem Space ..............................................6
1.5. NSH-based Service Chaining . . . . . . . . . . . . . . . 6 1.5. NSH-Based Service Chaining .................................6
2. Network Service Header . . . . . . . . . . . . . . . . . . . 7 2. Network Service Header ..........................................7
2.1. Network Service Header Format . . . . . . . . . . . . . . 7 2.1. Network Service Header Format ..............................7
2.2. NSH Base Header . . . . . . . . . . . . . . . . . . . . . 8 2.2. NSH Base Header ............................................8
2.3. Service Path Header . . . . . . . . . . . . . . . . . . . 11 2.3. Service Path Header .......................................11
2.4. NSH MD Type 1 . . . . . . . . . . . . . . . . . . . . . . 12 2.4. NSH MD Type 1 .............................................12
2.5. NSH MD Type 2 . . . . . . . . . . . . . . . . . . . . . . 12 2.5. NSH MD Type 2 .............................................13
2.5.1. Optional Variable Length Metadata . . . . . . . . . . 13 2.5.1. Optional Variable-Length Metadata ..................13
3. NSH Actions . . . . . . . . . . . . . . . . . . . . . . . . . 14 3. NSH Actions ....................................................15
4. NSH Transport Encapsulation . . . . . . . . . . . . . . . . . 16 4. NSH Transport Encapsulation ....................................16
5. Fragmentation Considerations . . . . . . . . . . . . . . . . 17 5. Fragmentation Considerations ...................................17
6. Service Path Forwarding with NSH . . . . . . . . . . . . . . 17 6. Service Path Forwarding with NSH ...............................18
6.1. SFFs and Overlay Selection . . . . . . . . . . . . . . . 17 6.1. SFFs and Overlay Selection ................................18
6.2. Mapping the NSH to Network Topology . . . . . . . . . . . 21 6.2. Mapping the NSH to Network Topology .......................21
6.3. Service Plane Visibility . . . . . . . . . . . . . . . . 21 6.3. Service Plane Visibility ..................................21
6.4. Service Graphs . . . . . . . . . . . . . . . . . . . . . 22 6.4. Service Graphs ............................................22
7. Policy Enforcement with NSH . . . . . . . . . . . . . . . . . 22 7. Policy Enforcement with NSH ....................................22
7.1. NSH Metadata and Policy Enforcement . . . . . . . . . . . 22 7.1. NSH Metadata and Policy Enforcement .......................22
7.2. Updating/Augmenting Metadata . . . . . . . . . . . . . . 24 7.2. Updating/Augmenting Metadata ..............................24
7.3. Service Path Identifier and Metadata . . . . . . . . . . 25 7.3. Service Path Identifier and Metadata ......................25
8. Security Considerations . . . . . . . . . . . . . . . . . . . 26 8. Security Considerations ........................................26
8.1. NSH Security Considerations from Operators' Environments 27 8.1. NSH Security Considerations from Operators' Environments ..27
8.2. NSH Security Considerations from the SFC Architecture . . 28 8.2. NSH Security Considerations from the SFC Architecture .....28
8.2.1. Integrity . . . . . . . . . . . . . . . . . . . . . . 29 8.2.1. Integrity ..........................................29
8.2.2. Confidentiality . . . . . . . . . . . . . . . . . . . 31 8.2.2. Confidentiality ....................................31
9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 32 9. IANA Considerations ............................................32
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 33 9.1. NSH Parameters ............................................32
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 33 9.1.1. NSH Base Header Bits ...............................32
11.1. Network Service Header (NSH) Parameters . . . . . . . . 34 9.1.2. NSH Version ........................................32
11.1.1. NSH Base Header Bits . . . . . . . . . . . . . . . . 34 9.1.3. NSH MD Types .......................................33
11.1.2. NSH Version . . . . . . . . . . . . . . . . . . . . 34 9.1.4. NSH MD Class .......................................33
11.1.3. MD Type Registry . . . . . . . . . . . . . . . . . . 34 9.1.5. NSH IETF-Assigned Optional Variable-Length
11.1.4. MD Class Registry . . . . . . . . . . . . . . . . . 35 Metadata Types .....................................34
11.1.5. New IETF Assigned Optional Variable Length Metadata 9.1.6. NSH Next Protocol ..................................35
Type Registry . . . . . . . . . . . . . . . . . . . 36 10. NSH-Related Codepoints ........................................35
11.1.6. NSH Base Header Next Protocol . . . . . . . . . . . 36 10.1. NSH Ethertype ............................................35
11. References ....................................................36
12. NSH-Related Codepoints . . . . . . . . . . . . . . . . . . . 37 Acknowledgments ...................................................38
12.1. NSH EtherType . . . . . . . . . . . . . . . . . . . . . 37 Contributors ......................................................39
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 37 Authors' Addresses ................................................40
13.1. Normative References . . . . . . . . . . . . . . . . . . 37
13.2. Informative References . . . . . . . . . . . . . . . . . 38
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 40
1. Introduction 1. Introduction
Service functions are widely deployed and essential in many networks. Service Functions are widely deployed and essential in many networks.
These service functions provide a range of features such as security, These Service Functions provide a range of features such as security,
WAN acceleration, and server load balancing. Service functions may WAN acceleration, and server load balancing. Service Functions may
be instantiated at different points in the network infrastructure be instantiated at different points in the network infrastructure
such as the wide area network, data center, and so forth. such as the WAN, data center, and so forth.
Prior to development of the SFC architecture [RFC7665] and the Prior to development of the SFC architecture [RFC7665] and the
protocol specified in this document, current service function protocol specified in this document, current Service Function
deployment models have been relatively static and bound to topology deployment models have been relatively static and bound to topology
for insertion and policy selection. Furthermore, they do not adapt for insertion and policy selection. Furthermore, they do not adapt
well to elastic service environments enabled by virtualization. well to elastic service environments enabled by virtualization.
New data center network and cloud architectures require more flexible New data-center network and cloud architectures require more flexible
service function deployment models. Additionally, the transition to Service Function deployment models. Additionally, the transition to
virtual platforms demands an agile service insertion model that virtual platforms demands an agile service insertion model that
supports dynamic and elastic service delivery. Specifically, the supports dynamic and elastic service delivery. Specifically, the
following functions are necessary: following functions are necessary:
1. The movement of service functions and application workloads in 1. The movement of Service Functions and application workloads in
the network. the network.
2. The ability to easily bind service policy to granular 2. The ability to easily bind service policy to granular
information, such as per-subscriber state. information, such as per-subscriber state.
3. The capability to steer traffic to the requisite service 3. The capability to steer traffic to the requisite Service
function(s). Function(s).
The Network Service Header (NSH) specification defines a new data This document, the Network Service Header (NSH) specification,
plane protocol, which is an encapsulation for service function defines a new data-plane protocol, which is an encapsulation for
chains. The NSH is designed to encapsulate an original packet or SFCs. The NSH is designed to encapsulate an original packet or frame
frame, and in turn be encapsulated by an outer transport and, in turn, be encapsulated by an outer transport encapsulation
encapsulation (which is used to deliver the NSH to NSH-aware network (which is used to deliver the NSH to NSH-aware network elements), as
elements), as shown in Figure 1: shown in Figure 1:
+------------------------------+ +------------------------------+
| Transport Encapsulation | | Transport Encapsulation |
+------------------------------+ +------------------------------+
| Network Service Header (NSH) | | Network Service Header (NSH) |
+------------------------------+ +------------------------------+
| Original Packet / Frame | | Original Packet / Frame |
+------------------------------+ +------------------------------+
Figure 1: Network Service Header Encapsulation Figure 1: Network Service Header Encapsulation
The NSH is composed of the following elements: The NSH is composed of the following elements:
1. Service Function Path identification. 1. Service Function Path identification.
2. Indication of location within a Service Function Path. 2. Indication of location within a Service Function Path.
3. Optional, per packet metadata (fixed length or variable). 3. Optional, per-packet metadata (fixed-length or variable).
[RFC7665] provides an overview of a service chaining architecture [RFC7665] provides an overview of a service chaining architecture
that clearly defines the roles of the various elements and the scope that clearly defines the roles of the various elements and the scope
of a service function chaining encapsulation. Figure 3 of [RFC7665] of a SFC encapsulation. Figure 3 of [RFC7665] depicts the SFC
depicts the SFC architectural components after classification. The architectural components after classification. The NSH is the SFC
NSH is the SFC encapsulation referenced in [RFC7665]. encapsulation referenced in [RFC7665].
1.1. 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 RFC 2119 [RFC2119].
1.2. Applicability 1.1. Applicability
The NSH is designed to be easy to implement across a range of The NSH is designed to be easy to implement across a range of
devices, both physical and virtual, including hardware platforms. devices, both physical and virtual, including hardware platforms.
The intended scope of the NSH is for use within a single provider's The intended scope of the NSH is for use within a single provider's
operational domain. This deployment scope is deliberately operational domain. This deployment scope is deliberately
constrained, as explained also in [RFC7665], and limited to a single constrained, as explained also in [RFC7665], and limited to a single
network administrative domain. In this context, a "domain" is a set network administrative domain. In this context, a "domain" is a set
of network entities within a single administration. For example, a of network entities within a single administration. For example, a
network administrative domain can include a single data center, or an network administrative domain can include a single data center, or an
overlay domain using virtual connections and tunnels. A corollary is overlay domain using virtual connections and tunnels. A corollary is
that a network administrative domain has a well defined perimeter. that a network administrative domain has a well-defined perimeter.
An NSH-aware control plane is outside the scope of this document. An NSH-aware control plane is outside the scope of this document.
1.2. 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.
1.3. Definition of Terms 1.3. Definition of Terms
Byte: All references to "bytes" in this document refer to 8-bit Byte: All references to "bytes" in this document refer to 8-bit
bytes, or octets. bytes, or octets.
Classification: Defined in [RFC7665]. Classification: Defined in [RFC7665].
Classifier: Defined in [RFC7665]. Classifier: Defined in [RFC7665].
Metadata: Defined in [RFC7665]. The metadata, or context Metadata (MD): Defined in [RFC7665]. The metadata, or context
information shared between classifiers and SFs, and among SFs, is information shared between Classifiers and SFs, and among SFs, is
carried on the NSH's Context Headers. It allows summarizing a carried on the NSH's Context Headers. It allows summarizing a
classification result in the packet itself, avoiding subsequent classification result in the packet itself, avoiding subsequent
re-classifications. Examples of metadata include classification re-classifications. Examples of metadata include classification
information used for policy enforcement and network context for information used for policy enforcement and network context for
forwarding post service delivery. forwarding after service delivery.
Network Locator: Data plane address, typically IPv4 or IPv6, used to Network Locator: Data-plane address, typically IPv4 or IPv6, used to
send and receive network traffic. send and receive network traffic.
Network Node/Element: Device that forwards packets or frames based Network Node/Element: Device that forwards packets or frames based
on an outer header (i.e., transport encapsulation) information. on an outer header (i.e., transport encapsulation) information.
Network Overlay: Logical network built on top of existing network Network Overlay: Logical network built on top of an existing network
(the underlay). Packets are encapsulated or tunneled to create (the underlay). Packets are encapsulated or tunneled to create
the overlay network topology. the overlay network topology.
NSH-aware: NSH-aware means SFC-encapsulation-aware, where the NSH NSH-aware: NSH-aware means SFC-encapsulation-aware, where the NSH
provides the SFC encapsulation. This specification uses NSH-aware provides the SFC encapsulation. This specification uses NSH-aware
as a more specific term from the more generic term SFC-aware as a more specific term from the more generic term "SFC-aware"
[RFC7665]. [RFC7665].
Service Classifier: Logical entity providing classification Service Classifier: Logical entity providing classification
function. Since they are logical, classifiers may be co-resident function. Since they are logical, Classifiers may be co-resident
with SFC elements such as SFs or SFFs. Service classifiers with SFC elements such as SFs or SFFs. Service Classifiers
perform classification and impose the NSH. The initial classifier perform classification and impose the NSH. The initial Classifier
imposes the initial NSH and sends the NSH packet to the first SFF imposes the initial NSH and sends the NSH packet to the first SFF
in the path. Non-initial (i.e., subsequent) classification can in the path. Non-initial (i.e., subsequent) classification can
occur as needed and can alter, or create a new service path. occur as needed and can alter, or create a new service path.
Service Function (SF): Defined in [RFC7665]. Service Function (SF): Defined in [RFC7665].
Service Function Chain (SFC): Defined in [RFC7665]. Service Function Chain (SFC): Defined in [RFC7665].
Service Function Forwarder (SFF): Defined in [RFC7665]. Service Function Forwarder (SFF): Defined in [RFC7665].
Service Function Path (SFP): Defined in [RFC7665]. Service Function Path (SFP): Defined in [RFC7665].
Service Plane: The collection of SFFs and associated SFs creates a Service Plane: The collection of SFFs and associated SFs creates a
service-plane overlay in which all SFs and SFC Proxies reside service-plane overlay in which all SFs and SFC Proxies reside
[RFC7665]. [RFC7665].
SFC Proxy: Defined in [RFC7665]. SFC Proxy: Defined in [RFC7665].
1.4. Problem Space 1.4. Problem Space
The NSH addresses several limitations associated with service The NSH addresses several limitations associated with Service
function deployments. [RFC7498] provides a comprehensive review of Function deployments. [RFC7498] provides a comprehensive review of
those issues. those issues.
1.5. NSH-based Service Chaining 1.5. NSH-Based Service Chaining
The NSH creates a dedicated service plane; more specifically, the NSH The NSH creates a dedicated service plane; more specifically, the NSH
enables: enables:
1. Topological Independence: Service forwarding occurs within the 1. Topological Independence: Service forwarding occurs within the
service plane, so the underlying network topology does not service plane, so the underlying network topology does not
require modification. The NSH provides an identifier used to require modification. The NSH provides an identifier used to
select the network overlay for network forwarding. select the network overlay for network forwarding.
2. Service Chaining: The NSH enables service chaining per [RFC7665]. 2. Service Chaining: The NSH enables service chaining per [RFC7665].
The NSH contains path identification information needed to The NSH contains path identification information needed to
realize a service path. Furthermore, the NSH provides the realize a service path. Furthermore, the NSH provides the
ability to monitor and troubleshoot a service chain, end-to-end ability to monitor and troubleshoot a service chain, end-to-end
via service-specific OAM messages. The NSH fields can be used by via service-specific Operations, Administration, and Maintenance
administrators (via, for example, a traffic analyzer) to verify (OAM) messages. The NSH fields can be used by administrators
(account, ensure correct chaining, provide reports, etc.) the (for example, via a traffic analyzer) to verify the path
path specifics of packets being forwarded along a service path. specifics (e.g., accounting, ensuring correct chaining, providing
reports, etc.) of packets being forwarded along a service path.
3. The NSH provides a mechanism to carry shared metadata between 3. The NSH provides a mechanism to carry shared metadata between
participating entities and service functions. The semantics of participating entities and Service Functions. The semantics of
the shared metadata is communicated via a control plane, which is the shared metadata are communicated via a control plane (which
outside the scope of this document, to participating nodes. is outside the scope of this document) to participating nodes.
[I-D.ietf-sfc-control-plane] provides an example of such in Section 3.3 of [SFC-CONTROL-PLANE] provides an example of this.
Section 3.3. Examples of metadata include classification Examples of metadata include classification information used for
information used for policy enforcement and network context for policy enforcement and network context for forwarding post
forwarding post service delivery. Sharing the metadata allows service delivery. Sharing the metadata allows Service Functions
service functions to share initial and intermediate to share initial and intermediate classification results with
classification results with downstream service functions saving downstream Service Functions saving re-classification, where
re-classification, where enough information was enclosed. enough information was enclosed.
4. The NSH offers a common and standards-based header for service 4. The NSH offers a common and standards-based header for service
chaining to all network and service nodes. chaining to all network and service nodes.
5. Transport Encapsulation Agnostic: The NSH is transport 5. Transport Encapsulation Agnostic: The NSH is transport
encapsulation-independent, meaning it can be transported by a encapsulation independent: meaning it can be transported by a
variety of encapsulation protocols. An appropriate (for a given variety of encapsulation protocols. An appropriate (for a given
deployment) encapsulation protocol can be used to carry NSH- deployment) encapsulation protocol can be used to carry NSH-
encapsulated traffic. This transport encapsulation may form an encapsulated traffic. This transport encapsulation may form an
overlay network and if an existing overlay topology provides the overlay network; and if an existing overlay topology provides the
required service path connectivity, that existing overlay may be required service path connectivity, that existing overlay may be
used. used.
2. Network Service Header 2. Network Service Header
An NSH is imposed on the original packet/frame. This NSH contains An NSH is imposed on the original packet/frame. This NSH contains
service path information and optionally metadata that are added to a service path information and, optionally, metadata that are added to
packet or frame and used to create a service plane. Subsequently, an a packet or frame and used to create a service plane. Subsequently,
outer transport encapsulation is imposed on the NSH, which is used an outer transport encapsulation is imposed on the NSH, which is used
for network forwarding. for network forwarding.
A Service Classifier adds the NSH. The NSH is removed by the last A Service Classifier adds the NSH. The NSH is removed by the last
SFF in the service chain or by an SF that consumes the packet. SFF in the service chain or by an SF that consumes the packet.
2.1. Network Service Header Format 2.1. Network Service Header Format
The NSH is composed of a 4-byte Base Header, a 4-byte Service Path The NSH is composed of a 4-byte Base Header, a 4-byte Service Path
Header and optional Context Headers, as shown in Figure 2 below. Header, and optional Context Headers, as shown in Figure 2.
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Base Header | | Base Header |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Service Path Header | | Service Path Header |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
~ Context Header(s) ~ ~ Context Header(s) ~
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Network Service Header Figure 2: Network Service Header
Base header: Provides information about the service header and the Base Header: Provides information about the service header and the
payload protocol. payload protocol.
Service Path Header: Provides path identification and location within Service Path Header: Provides path identification and location
a service path. within a service path.
Context header: Carries metadata (i.e., context data) along a service Context Header: Carries metadata (i.e., context data) along a
path. service path.
2.2. NSH Base Header 2.2. NSH Base Header
Figure 3 depicts the NSH base header: Figure 3 depicts the NSH Base Header:
0 1 2 3 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 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 | |Ver|O|U| TTL | Length |U|U|U|U|MD Type| Next Protocol |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: NSH Base Header Figure 3: NSH Base Header
Base Header Field Descriptions: The field descriptions are as follows:
Version: The version field is used to ensure backward compatibility
going forward with future NSH specification updates. It MUST be set
to 0x0 by the sender, in this first revision of the NSH. If a packet
presumed to carry an NSH header is received at an SFF, and the SFF
does not understnad the version of the protocol as indicated in the
base header, the packet MUST be discarded, and the event SHOULD be
logged. Given the widespread implementation of existing hardware
that uses the first nibble after an MPLS label stack for equal-cost
multipath (ECMP) decision processing, this document reserves version
01b. This value MUST NOT be used in future versions of the protocol.
Please see [RFC7325] for further discussion of MPLS-related
forwarding requirements.
O bit: Setting this bit indicates an Operations, Administration, and Version: The Version field is used to ensure backward compatibility
Maintenance (OAM, see [RFC6291]) packet. The actual format and going forward with future NSH specification updates. It MUST be
processing of SFC OAM packets is outside the scope of this set to 0x0 by the sender, in this first revision of the NSH. If a
specification (see for example [I-D.ietf-sfc-oam-framework] for one packet presumed to carry an NSH header is received at an SFF, and
approach). the SFF does not understand the version of the protocol as
indicated in the base header, the packet MUST be discarded, and
the event SHOULD be logged. Given the widespread implementation
of existing hardware that uses the first nibble after an MPLS
label stack for Equal-Cost Multipath (ECMP) decision processing,
this document reserves version 01b. This value MUST NOT be used
in future versions of the protocol. Please see [RFC7325] for
further discussion of MPLS-related forwarding requirements.
The O bit MUST be set for OAM packets and MUST NOT be set for non-OAM O bit: Setting this bit indicates an OAM packet (see [RFC6291]).
packets. The O bit MUST NOT be modified along the SFP. The actual format and processing of SFC OAM packets is outside the
scope of this specification (for example, see [SFC-OAM-FRAMEWORK]
for one approach).
SF/SFF/SFC Proxy/Classifier implementations that do not support SFC The O bit MUST be set for OAM packets and MUST NOT be set for
OAM procedures SHOULD discard packets with O bit set, but MAY support non-OAM packets. The O bit MUST NOT be modified along the SFP.
a configurable parameter to enable forwarding received SFC OAM
packets unmodified to the next element in the chain. Forwarding OAM
packets unmodified by SFC elements that do not support SFC OAM
procedures may be acceptable for a subset of OAM functions, but can
result in unexpected outcomes for others; thus, it is recommended to
analyze the impact of forwarding an OAM packet for all OAM functions
prior to enabling this behavior. The configurable parameter MUST be
disabled by default.
TTL: Indicates the maximum SFF hops for an SFP. This field is used SF/SFF/SFC Proxy/Classifier implementations that do not support
for service plane loop detection. The initial TTL value SHOULD be SFC OAM procedures SHOULD discard packets with O bit set, but MAY
configurable via the control plane; the configured initial value can support a configurable parameter to enable forwarding received SFC
be specific to one or more SFPs. If no initial value is explicitly OAM packets unmodified to the next element in the chain.
provided, the default initial TTL value of 63 MUST be used. Each SFF Forwarding OAM packets unmodified by SFC elements that do not
involved in forwarding an NSH packet MUST decrement the TTL value by support SFC OAM procedures may be acceptable for a subset of OAM
1 prior to NSH forwarding lookup. Decrementing by 1 from an incoming functions, but it can result in unexpected outcomes for others;
value of 0 shall result in a TTL value of 63. The packet MUST NOT be thus, it is recommended to analyze the impact of forwarding an OAM
forwarded if TTL is, after decrement, 0. packet for all OAM functions prior to enabling this behavior. The
configurable parameter MUST be disabled by default.
This TTL field is the primary loop prevention mechanism. This TTL TTL: Indicates the maximum SFF hops for an SFP. This field is used
mechanism represents a robust complement to the Service Index (see for service-plane loop detection. The initial TTL value SHOULD be
Section 2.3), as the TTL is decrement by each SFF. The handling of configurable via the control plane; the configured initial value
incoming 0 TTL allows for better, although not perfect, can be specific to one or more SFPs. If no initial value is
interoperation with pre-standard implementations that do not support explicitly provided, the default initial TTL value of 63 MUST be
this TTL field. used. Each SFF involved in forwarding an NSH packet MUST
decrement the TTL value by 1 prior to NSH forwarding lookup.
Decrementing by 1 from an incoming value of 0 shall result in a
TTL value of 63. The packet MUST NOT be forwarded if TTL is,
after decrement, 0.
Length: The total length, in 4-byte words, of the NSH including the This TTL field is the primary loop-prevention mechanism. This TTL
Base Header, the Service Path Header, the Fixed Length Context Header mechanism represents a robust complement to the Service Index (see
or Variable Length Context Header(s). The length MUST be 0x6 for MD Section 2.3), as the TTL is decremented by each SFF. The handling
Type equal to 0x1, and MUST be 0x2 or greater for MD Type equal to of an incoming 0 TTL allows for better, although not perfect,
0x2. The length of the NSH header MUST be an integer multiple of 4 interoperation with pre-standard implementations that do not
bytes, thus variable length metadata is always padded out to a support this TTL field.
multiple of 4 bytes.
Unassigned bits: All other flag fields, marked U, are unassigned and Length: The total length, in 4-byte words, of the NSH including the
available for future use, see Section 11.1.1. Unassigned bits MUST Base Header, the Service Path Header, the Fixed-Length Context
be set to zero upon origination, and MUST be ignored and preserved Header, or Variable-Length Context Header(s). The length MUST be
unmodified by other NSH supporting elements. At reception, all 0x6 for MD Type 0x1, and it MUST be 0x2 or greater for MD Type
elements MUST NOT modify their actions based on these unknown bits. 0x2. The length of the Network Service Header MUST be an integer
multiple of 4 bytes; thus, variable-length metadata is always
padded out to a multiple of 4 bytes.
Metadata (MD) Type: Indicates the format of the NSH beyond the Unassigned bits: All other flag fields, marked U, are unassigned and
mandatory Base Header and the Service Path Header. MD Type defines available for future use; see Section 9.1.1. Unassigned bits MUST
the format of the metadata being carried. Please see the IANA be set to zero upon origination, and they MUST be ignored and
Considerations Section 11.1.3. preserved unmodified by other NSH supporting elements. At
reception, all elements MUST NOT modify their actions based on
these unknown bits.
This document specifies the following four MD Type values: Metadata (MD) Type: Indicates the format of the NSH beyond the
mandatory NSH Base Header and the Service Path Header. MD Type
defines the format of the metadata being carried. Please see the
IANA Considerations in Section 9.1.3.
0x0 - This is a reserved value. Implementations SHOULD silently This document specifies the following four MD Type values:
discard packets with MD Type 0x0.
0x1 - This indicates that the format of the header includes a fixed 0x0: This is a reserved value. Implementations SHOULD silently
length Context Header (see Figure 5 below). discard packets with MD Type 0x0.
0x2 - This does not mandate any headers beyond the Base Header and 0x1: This indicates that the format of the header includes a
Service Path Header, but may contain optional variable length Context Fixed-Length Context Header (see Figure 5 below).
Header(s). With MD Type 0x2, a Length of 0x2 implies there are no
Context Headers. The semantics of the variable length Context
Header(s) are not defined in this document. The format of the
optional variable length Context Headers is provided in
Section 2.5.1.
0xF - This value is reserved for experimentation and testing, as per 0x2: This does not mandate any headers beyond the Base Header and
[RFC3692]. Implementations not explicitly configured to be part of Service Path Header, but may contain optional Variable-
an experiment SHOULD silently discard packets with MD Type 0xF. Length Context Header(s). With MD Type 0x2, a length of 0x2
implies there are no Context Headers. The semantics of the
Variable-Length Context Header(s) are not defined in this
document. The format of the optional Variable-Length
Context Headers is provided in Section 2.5.1.
The format of the Base Header and the Service Path Header is 0xF: This value is reserved for experimentation and testing, as
invariant, and not affected by MD Type. per [RFC3692]. Implementations not explicitly configured to
be part of an experiment SHOULD silently discard packets
with MD Type 0xF.
The NSH MD Type 1 and MD Type 2 are described in detail in Sections The format of the Base Header and the Service Path Header is
2.4 and 2.5, respectively. NSH implementations MUST support MD types invariant and not affected by MD Type.
0x1 and 0x2 (where the length is 0x2). NSH implementations SHOULD
support MD Type 0x2 with length greater than 0x2. Devices that do
not support MD Type 0x2 with length greater than 0x2 MUST ignore any
optional context headers and process the packet without them; the
base header length field can be used to determine the original
payload offset if access to the original packet/frame is required.
This specification does not disallow the MD Type value from changing
along an SFP; however, the specification of the necessary mechanism
to allow the MD Type to change along an SFP are outside the scope of
this document and would need to be defined for that functionality to
be available. Packets with MD Type values not supported by an
implementation MUST be silently dropped.
Next Protocol: indicates the protocol type of the encapsulated data. The NSH MD Type 1 and MD Type 2 are described in detail in
The NSH does not alter the inner payload, and the semantics on the Sections 2.4 and 2.5, respectively. NSH implementations MUST
inner protocol remain unchanged due to NSH service function chaining. support MD Types 0x1 and 0x2 (where the length is 0x2). NSH
Please see the IANA Considerations section below, Section 11.1.6. implementations SHOULD support MD Type 0x2 with length greater
than 0x2. Devices that do not support MD Type 0x2 with a length
greater than 0x2 MUST ignore any optional Context Headers and
process the packet without them; the Base Header Length field can
be used to determine the original payload offset if access to the
original packet/frame is required. This specification does not
disallow the MD Type value from changing along an SFP; however,
the specification of the necessary mechanism to allow the MD Type
to change along an SFP are outside the scope of this document and
would need to be defined for that functionality to be available.
Packets with MD Type values not supported by an implementation
MUST be silently dropped.
This document defines the following Next Protocol values: Next Protocol: Indicates the protocol type of the encapsulated data.
The NSH does not alter the inner payload, and the semantics on the
inner protocol remain unchanged due to NSH SFC. Please see the
IANA Considerations in Section 9.1.6.
0x1: IPv4 This document defines the following Next Protocol values:
0x2: IPv6
0x3: Ethernet
0x4: NSH
0x5: MPLS
0xFE: Experiment 1
0xFF: Experiment 2
The functionality of hierarchical NSH using a Next Protocol value of 0x1: IPv4
0x4 NSH is outside the scope of this specification. Packets with 0x2: IPv6
Next Protocol values not supported SHOULD be silently dropped by 0x3: Ethernet
default, although an implementation MAY provide a configuration 0x4: NSH
parameter to forward them. Additionally, an implementation not 0x5: MPLS
explicitly configured for a specific experiment [RFC3692] SHOULD 0xFE: Experiment 1
silently drop packets with Next Protocol values 0xFE and 0xFF. 0xFF: Experiment 2
The functionality of hierarchical NSH using a Next Protocol value
of 0x4 (NSH) is outside the scope of this specification. Packets
with Next Protocol values not supported SHOULD be silently dropped
by default, although an implementation MAY provide a configuration
parameter to forward them. Additionally, an implementation not
explicitly configured for a specific experiment [RFC3692] SHOULD
silently drop packets with Next Protocol values 0xFE and 0xFF.
2.3. Service Path Header 2.3. Service Path Header
Figure 4 shows the format of the Service Path Header: Figure 4 shows the format of the Service Path Header:
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Service Path Identifier (SPI) | Service Index | | Service Path Identifier (SPI) | Service Index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Service Path Identifier (SPI): 24 bits Service Path Identifier (SPI): 24 bits
Service Index (SI): 8 bits Service Index (SI): 8 bits
Figure 4: NSH Service Path Header Figure 4: NSH Service Path Header
The meaning of these fields is as follows: The meaning of these fields is as follows:
Service Path Identifier (SPI): Uniquely identifies a service function Service Path Identifier (SPI): Uniquely identifies a Service Function
path. Participating nodes MUST use this identifier for Service Path (SFP). Participating nodes MUST use this identifier for SFP
Function Path selection (SFP). The initial classifier MUST set the selection. The initial Classifier MUST set the appropriate SPI for a
appropriate SPI for a given classification result. given classification result.
Service Index (SI): Provides location within the SFP. The initial Service Index (SI): Provides location within the SFP. The initial
classifier for a given SFP SHOULD set the SI to 255, however the Classifier for a given SFP SHOULD set the SI to 255; however, the
control plane MAY configure the initial value of SI as appropriate control plane MAY configure the initial value of the SI as
(i.e., taking into account the length of the service function path). appropriate (i.e., taking into account the length of the SFP). The
The Service Index MUST be decremented by a value of 1 by Service Service Index MUST be decremented by a value of 1 by Service
Functions or by SFC Proxy nodes after performing required services Functions or by SFC Proxy nodes after performing required services;
and the new decremented SI value MUST be used in the egress packet's the new decremented SI value MUST be used in the egress packet's NSH.
NSH. The initial Classifier MUST send the packet to the first SFF in The initial Classifier MUST send the packet to the first SFF in the
the identified SFP for forwarding along an SFP. If re-classification identified SFP for forwarding along an SFP. If re-classification
occurs, and that re-classification results in a new SPI, the occurs, and that re-classification results in a new SPI, the
(re)classifier is, in effect, the initial classifier for the (re-)Classifier is, in effect, the initial Classifier for the
resultant SPI. resultant SPI.
The SI is used in conjunction the with Service Path Identifier for The SI is used in conjunction with the Service Path Identifier for
Service Function Path Selection and for determining the next SFF/SF SFP selection and for determining the next SFF/SF in the path. The
in the path. The SI is also valuable when troubleshooting or SI is also valuable when troubleshooting or reporting service paths.
reporting service paths. While the TTL provides the primary SFF While the TTL provides the primary SFF-based loop prevention for this
based loop prevention for this mechanism, SI decrement by SF serves mechanism, SI decrement by SF serves as a limited loop-prevention
as a limited loop prevention mechanism. NSH packets, as described mechanism. NSH packets, as described above, are discarded when an
above, are discarded when an SFF decrements the TTL to 0. In SFF decrements the TTL to 0. In addition, an SFF that is not the
addition, an SFF which is not the terminal SFF for a Service Function terminal SFF for an SFP will discard any NSH packet with an SI of 0,
Path will discard any NSH packet with an SI of 0, as there will be no as there will be no valid next SF information.
valid next SF information.
2.4. NSH MD Type 1 2.4. NSH MD Type 1
When the Base Header specifies MD Type = 0x1, a Fixed Length Context When the Base Header specifies MD Type 0x1, a Fixed-Length Context
Header (16-bytes) MUST be present immediately following the Service Header (16-bytes) MUST be present immediately following the Service
Path Header, as per Figure 5. The value of a Fixed Length Context Path Header, as per Figure 5. The value of a Fixed-Length Context
Header that carries no metadata MUST be set to zero. Header that carries no metadata MUST be set to zero.
0 1 2 3 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 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 | |Ver|O|U| TTL | Length |U|U|U|U|MD Type| Next Protocol |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Service Path Identifier | Service Index | | Service Path Identifier | Service Index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| Fixed Length Context Header | | Fixed-Length Context Header |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: NSH MD Type=0x1 Figure 5: NSH MD Type 0x1
This specification does not make any assumptions about the content of This specification does not make any assumptions about the content of
the 16 byte Context Header that must be present when the MD Type the 16-byte Context Header that must be present when the MD Type
field is set to 1, and does not describe the structure or meaning of field is set to 1, and it does not describe the structure or meaning
the included metadata. of the included metadata.
An SFC-aware SF or SFC Proxy needs to receive the data structure and An SFC-aware SF or SFC Proxy needs to receive the data structure and
semantics first in order to process the data placed in the mandatory semantics first in order to process the data placed in the mandatory
context field. The data structure and semantics include both the context field. The data structure and semantics include both the
allocation schema and order, and the meaning of the included data. allocation schema and order as well as the meaning of the included
How an SFC-aware SF or SFC Proxy gets the data structure and data. How an SFC-aware SF or SFC Proxy gets the data structure and
semantics is outside the scope of this specification. semantics is outside the scope of this specification.
An SF or SFC Proxy that does not know the format or semantics of the An SF or SFC Proxy that does not know the format or semantics of the
Context Header for an NSH with MD Type 1 MUST discard any packet with Context Header for an NSH with MD Type 1 MUST discard any packet with
such an NSH (i.e., MUST NOT ignore the metadata that it cannot such an NSH (i.e., MUST NOT ignore the metadata that it cannot
process), and MUST log the event at least once per the SPI for which process), and MUST log the event at least once per the SPI for which
the event occurs (subject to thresholding). the event occurs (subject to thresholding).
[I-D.guichard-sfc-nsh-dc-allocation] and [NSH-DC-ALLOCATION] and [NSH-BROADBAND-ALLOCATION] provide specific
[I-D.napper-sfc-nsh-broadband-allocation] provide specific examples examples of how metadata can be allocated.
of how metadata can be allocated.
2.5. NSH MD Type 2 2.5. NSH MD Type 2
When the base header specifies MD Type = 0x2, zero or more Variable When the Base Header specifies MD Type 0x2, zero or more Variable-
Length Context Headers MAY be added, immediately following the Length Context Headers MAY be added, immediately following the
Service Path Header (see Figure 6). Therefore, Length = 0x2, Service Path Header (see Figure 6). Therefore, Length = 0x2,
indicates that only the Base Header followed by the Service Path indicates that only the Base Header and Service Path Header are
Header are present. The optional Variable Length Context Headers present (and in that order). The optional Variable-Length Context
MUST be of an integer number of 4-bytes. The base header Length Headers MUST be of an integer number of 4-bytes. The Base Header
field MUST be used to determine the offset to locate the original Length field MUST be used to determine the offset to locate the
packet or frame for SFC nodes that require access to that original packet or frame for SFC nodes that require access to that
information. information.
0 1 2 3 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 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 | |Ver|O|U| TTL | Length |U|U|U|U|MD Type| Next Protocol |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Service Path Identifier | Service Index | | Service Path Identifier | Service Index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
~ Variable Length Context Headers (opt.) ~ ~ Variable-Length Context Headers (opt.) ~
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: NSH MD Type=0x2 Figure 6: NSH MD Type 0x2
2.5.1. Optional Variable Length Metadata 2.5.1. Optional Variable-Length Metadata
The format of the optional variable length Context Headers, is as The format of the optional Variable-Length Context Headers, is as
depicted in Figure 7. depicted in Figure 7.
0 1 2 3 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 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 | | Metadata Class | Type |U| Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Variable Metadata | | Variable-Length Metadata |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: Variable Context Headers Figure 7: Variable-Length Context Headers
Metadata Class (MD Class): Defines the scope of the 'Type' field to Metadata Class (MD Class): Defines the scope of the Type field to
provide a hierarchical namespace. The IANA Considerations provide a hierarchical namespace. Section 9.1.4 defines how the
Section 11.1.4 defines how the MD Class values can be allocated to MD Class values can be allocated to standards bodies, vendors, and
standards bodies, vendors, and others. others.
Type: Indicates the explicit type of metadata being carried. The Type: Indicates the explicit type of metadata being carried. The
definition of the Type is the responsibility of the MD Class owner. definition of the Type is the responsibility of the MD Class
owner.
Unassigned bit: One unassigned bit is available for future use. This Unassigned bit: One unassigned bit is available for future use.
bit MUST NOT be set, and MUST be ignored on receipt. This bit MUST NOT be set, and it MUST be ignored on receipt.
Length: Indicates the length of the variable metadata, in bytes. In Length: Indicates the length of the variable-length metadata, in
case the metadata length is not an integer number of 4-byte words, bytes. In case the metadata length is not an integer number of
the sender MUST add pad bytes immediately following the last metadata 4-byte words, the sender MUST add pad bytes immediately following
byte to extend the metadata to an integer number of 4-byte words. the last metadata byte to extend the metadata to an integer number
The receiver MUST round up the length field to the nearest 4-byte of 4-byte words. The receiver MUST round the Length field up to
word boundary, to locate and process the next field in the packet. the nearest 4-byte-word boundary, to locate and process the next
The receiver MUST access only those bytes in the metadata indicated field in the packet. The receiver MUST access only those bytes in
by the length field (i.e., actual number of bytes) and MUST ignore the metadata indicated by the Length field (i.e., actual number of
the remaining bytes up to the nearest 4-byte word boundary. The bytes) and MUST ignore the remaining bytes up to the nearest
Length may be 0 or greater. 4-byte-word boundary. The length may be 0 or greater.
A value of 0 denotes a Context Header without a Variable Metadata A value of 0 denotes a Context Header without a Variable-Length
field. Metadata field.
This specification does not make any assumption about Context Headers This specification does not make any assumption about Context Headers
that are mandatory-to-implement or those that are mandatory-to- that are mandatory to implement or those that are mandatory to
process. These considerations are deployment-specific. However, the process. These considerations are deployment specific. However, the
control plane is entitled to instruct SFC-aware SFs with the data control plane is entitled to instruct SFC-aware SFs with the data
structure of context header together with its scoping (see e.g., structure of the Context Header together with its scoping (see e.g.,
Section 3.3.3 of [I-D.ietf-sfc-control-plane]). Section 3.3.3 of [SFC-CONTROL-PLANE]).
Upon receipt of a packet that belongs to a given SFP, if a mandatory- Upon receipt of a packet that belongs to a given SFP, if a mandatory-
to-process context header is missing in that packet, the SFC-aware SF to-process Context Header is missing in that packet, the SFC-aware SF
MUST NOT process the packet and MUST log an error at least once per MUST NOT process the packet and MUST log an error at least once per
the SPI for which the mandatory metadata is missing. the SPI for which the mandatory metadata is missing.
If multiple mandatory-to-process context headers are required for a If multiple mandatory-to-process Context Headers are required for a
given SFP, the control plane MAY instruct the SFC-aware SF with the given SFP, the control plane MAY instruct the SFC-aware SF with the
order to consume these Context Headers. If no instructions are order to consume these Context Headers. If no instructions are
provided and the SFC-aware SF will make use of or modify the specific provided and the SFC-aware SF will make use of or modify the specific
context header, then the SFC-aware SF MUST process these Context Context Header, then the SFC-aware SF MUST process these Context
Headers in the order they appear in an NSH packet. Headers in the order they appear in an NSH packet.
If multiple instances of the same metadata are included in an NSH If multiple instances of the same metadata are included in an NSH
packet, but the definition of that context header does not allow for packet, but the definition of that Context Header does not allow for
it, the SFC-aware SF MUST process the first instance and ignore it, the SFC-aware SF MUST process the first instance and ignore
subsequent instances. The SFC-aware SF MAY log or increase a counter subsequent instances. The SFC-aware SF MAY log or increase a counter
for this event. for this event.
3. NSH Actions 3. NSH Actions
NSH-aware nodes, which include service classifiers, SFFs, SFs and SFC NSH-aware nodes (which include Service Classifiers, SFFs, SFs, and
proxies, may alter the contents of the NSH headers. These nodes have SFC Proxies) may alter the contents of the NSH headers. These nodes
several possible NSH-related actions: have several possible NSH-related actions:
1. Insert or remove the NSH: These actions can occur respectively at 1. Insert or remove the NSH: These actions can occur respectively at
the start and end of a service path. Packets are classified, and the start and end of a service path. Packets are classified, and
if determined to require servicing, an NSH will be imposed. A if determined to require servicing, an NSH will be imposed. A
service classifier MUST insert an NSH at the start of an SFP. An
Service Classifier MUST insert an NSH at the start of an SFP. An
imposed NSH MUST contain both a valid Base Header and Service imposed NSH MUST contain both a valid Base Header and Service
Path Header. At the end of a service function path, an SFF MUST Path Header. At the end of an SFP, an SFF MUST remove the NSH
remove the NSH before forwarding or delivering the un- before forwarding or delivering the un-encapsulated packet.
encapsulated packet. It is therefore the last node operating on Therefore, it is the last node operating on the service header.
the service header.
Multiple logical classifiers may exist within a given service Multiple logical Classifiers may exist within a given service
path. Non-initial classifiers may re-classify data and that re- path. Non-initial Classifiers may re-classify data, and that
classification MAY result in the selection of a different Service re-classification MAY result in the selection of a different SFP.
Function Path. When the logical classifier performs re- When the logical Classifier performs re-classification that
classification that results in a change of service path, it MUST results in a change of service path, it MUST replace the existing
replace the existing NSH with a new NSH with the Base Header and NSH with a new NSH with the Base Header and Service Path Header
Service Path Header reflecting the new service path information reflecting the new service path information and MUST set the
and MUST set the initial SI. The O bit, the TTL field, as well initial SI. The O bit, the TTL field, and unassigned flags MUST
as unassigned flags, MUST be copied transparently from the old be copied transparently from the old NSH to a new NSH. Metadata
NSH to a new NSH. Metadata MAY be preserved in the new NSH. MAY be preserved in the new NSH.
2. Select service path: The Service Path Header provides service 2. Select service path: The Service Path Header provides service
path information and is used by SFFs to determine correct service path information and is used by SFFs to determine correct service
path selection. SFFs MUST use the Service Path Header for path selection. SFFs MUST use the Service Path Header for
selecting the next SF or SFF in the service path. selecting the next SF or SFF in the service path.
3. Update the NSH: SFs MUST decrement the service index by one. If 3. Update the NSH: SFs MUST decrement the service index by one. If
an SFF receives a packet with an SPI and SI that do not an SFF receives a packet with an SPI and SI that do not
correspond to a valid next hop in a valid Service Function Path, correspond to a valid next hop in a valid SFP, that packet MUST
that packet MUST be dropped by the SFF. be dropped by the SFF.
Classifiers MAY update Context Headers if new/updated context is Classifiers MAY update Context Headers if new/updated context is
available. available.
If an SFC proxy is in use (acting on behalf of an NSH-unaware If an SFC proxy is in use (acting on behalf of an NSH-unaware
service function for NSH actions), then the proxy MUST update Service Function for NSH actions), then the proxy MUST update the
Service Index and MAY update contexts. When an SFC proxy Service Index and MAY update contexts. When an SFC Proxy
receives an NSH-encapsulated packet, it MUST remove the NSH receives an NSH-encapsulated packet, it MUST remove the NSH
before forwarding it to an NSH-unaware SF. When the SFC Proxy before forwarding it to an NSH-unaware SF. When the SFC Proxy
receives a packet back from an NSH-unaware SF, it MUST re- receives a packet back from an NSH-unaware SF, it MUST
encapsulate it with the correct NSH, and MUST decrement the re-encapsulate it with the correct NSH, and it MUST decrement the
Service Index by one. Service Index by one.
4. Service policy selection: Service Functions derive policy (i.e., 4. Service policy selection: Service Functions derive policy (i.e.,
service actions such as permit or deny) selection and enforcement service actions such as permit or deny) selection and enforcement
from the NSH. Metadata shared in the NSH can provide a range of from the NSH. Metadata shared in the NSH can provide a range of
service-relevant information such as traffic classification. service-relevant information such as traffic classification.
Figure 8 maps each of the four actions above to the components in the Figure 8 maps each of the four actions above to the components in the
SFC architecture that can perform it. SFC architecture that can perform it.
+-----------+-----------------------+-------+---------------+-------+ +-----------+-----------------------+-------+---------------+-------+
| | Insert, remove, or |Forward| Update |Service| | | Insert, remove, or |Forward| Update |Service|
| | replace the NSH |the NSH| the NSH |policy | | | replace the NSH |the NSH| the NSH |policy |
| | |Packets| |sel. | | | |packets| |sel. |
|Component +-------+-------+-------+ +-------+-------+ | |Component +-------+-------+-------+ +-------+-------+ |
| | | | | |Dec. |Update | | | | | | | |Dec. |Update | |
| |Insert |Remove |Replace| |Service|Context| | | |Insert |Remove |Replace| |Service|Context| |
| | | | | |Index |Header | | | | | | | |Index |Header | |
+-----------+-------+-------+-------+-------+-------+-------+-------+ +-----------+-------+-------+-------+-------+-------+-------+-------+
| | + | | + | | | + | | | | + | | + | | | + | |
|Classifier | | | | | | | | |Classifier | | | | | | | |
+-----------+-------+-------+-------+-------+-------+-------+-------+ +-----------+-------+-------+-------+-------+-------+-------+-------+
|Service | | + | | + | | | | |Service | | + | | + | | | |
|Function | | | | | | | | |Function | | | | | | | |
skipping to change at page 17, line 21 skipping to change at page 17, line 29
Within a managed administrative domain, an operator can ensure that Within a managed administrative domain, an operator can ensure that
the underlay MTU is sufficient to carry SFC traffic without requiring the underlay MTU is sufficient to carry SFC traffic without requiring
fragmentation. Given that the intended scope of the NSH is within a fragmentation. Given that the intended scope of the NSH is within a
single provider's operational domain, that approach is sufficient. single provider's operational domain, that approach is sufficient.
However, although explicitly outside the scope of this specification, However, although explicitly outside the scope of this specification,
there might be cases where the underlay MTU is not large enough to there might be cases where the underlay MTU is not large enough to
carry the NSH traffic. Since the NSH does not provide fragmentation carry the NSH traffic. Since the NSH does not provide fragmentation
support at the service plane, the transport encapsulation protocol support at the service plane, the transport encapsulation protocol
ought to provide the requisite fragmentation handling. For instance, ought to provide the requisite fragmentation handling. For instance,
Section 9 of [I-D.ietf-rtgwg-dt-encap] provides exemplary approaches Section 9 of [RTG-ENCAP] provides exemplary approaches and guidance
and guidance for those scenarios. for those scenarios.
When the transport encapsulation protocol supports fragmentation, and When the transport encapsulation protocol supports fragmentation, and
fragmentation procedures needs to be used, such fragmentation is part fragmentation procedures needs to be used, such fragmentation is part
of the transport encapsulation logic. If, as it is common, of the transport encapsulation logic. If, as it is common,
fragmentation is performed by the endpoints of the transport fragmentation is performed by the endpoints of the transport
encapsulation, then fragmentation procedures are performed at the encapsulation, then fragmentation procedures are performed at the
sending NSH entity as part of the transport encapsulation, and sending NSH entity as part of the transport encapsulation, and
reassembly procedures are performed at the receiving NSH entity reassembly procedures are performed at the receiving NSH entity
during transport de-encapsulation handling logic. In no case would during transport de-encapsulation handling logic. In no case would
such fragmentation result in duplication of the NSH header. such fragmentation result in duplication of the NSH header.
For example, when the NSH is encapsulated in IP, IP-level For example, when the NSH is encapsulated in IP, IP-level
fragmentation coupled with Path MTU Discovery (PMTUD) (e.g., fragmentation coupled with Path MTU Discovery (PMTUD) (e.g.,
[RFC8201]) is used. Since PMTUD relies on ICMP messages, an operator [RFC8201]) is used. Since PMTUD relies on ICMP messages, an operator
should ensure ICMP packets are not blocked. When, on the other hand, should ensure ICMP packets are not blocked. When, on the other hand,
the underlay does not support fragmentation procedures, an error the underlay does not support fragmentation procedures, an error
message SHOULD be logged when dropping a packet too big. Lastly, message SHOULD be logged when dropping a packet too big. Lastly,
NSH-specific fragmentation and reassembly methods may be defined as NSH-specific fragmentation and reassembly methods may be defined as
well, but these methods are outside the scope of this document, and well, but these methods are outside the scope of this document and
subject for future work. subject for future work.
6. Service Path Forwarding with NSH 6. Service Path Forwarding with NSH
6.1. SFFs and Overlay Selection 6.1. SFFs and Overlay Selection
As described above, the NSH contains a Service Path Identifier (SPI) As described above, the NSH contains a Service Path Identifier (SPI)
and a Service Index (SI). The SPI is, as per its name, an and a Service Index (SI). The SPI is, as per its name, an
identifier. The SPI alone cannot be used to forward packets along a identifier. The SPI alone cannot be used to forward packets along a
service path. Rather the SPI provides a level of indirection between service path. Rather, the SPI provides a level of indirection
the service path/topology and the network transport encapsulation. between the service path / topology and the network transport
encapsulation. Furthermore, there is no requirement for, or
Furthermore, there is no requirement, or expectation of an SPI being expectation of, an SPI being bound to a predetermined or static
bound to a pre-determined or static network path. network path.
The Service Index provides an indication of location within a service The Service Index provides an indication of location within a service
path. The combination of SPI and SI provides the identification of a path. The combination of SPI and SI provides the identification of a
logical SF and its order within the service plane, and is used to logical SF and its order within the service plane. This combination
select the appropriate network locator(s) for overlay forwarding. is used to select the appropriate network locator(s) for overlay
The logical SF may be a single SF, or a set of eligible SFs that are forwarding. The logical SF may be a single SF or a set of eligible
equivalent. In the latter case, the SFF provides load distribution SFs that are equivalent. In the latter case, the SFF provides load
amongst the collection of SFs as needed. distribution amongst the collection of SFs as needed.
SI serves as a mechanism for detecting invalid service function SI serves as a mechanism for detecting invalid SFPs. In particular,
paths. In particular, an SI value of zero indicates that forwarding an SI value of zero indicates that forwarding is incorrect and the
is incorrect and the packet must be discarded. packet must be discarded.
This indirection -- SPI to overlay -- creates a true service plane. This indirection -- SPI to overlay -- creates a true service plane.
That is, the SFF/SF topology is constructed without impacting the That is, the SFF/SF topology is constructed without impacting the
network topology but more importantly, service plane only network topology, but, more importantly, service-plane-only
participants (i.e., most SFs) need not be part of the network overlay participants (i.e., most SFs) need not be part of the network overlay
topology and its associated infrastructure (e.g., control plane, topology and its associated infrastructure (e.g., control plane,
routing tables, etc.) SFs need to be able to return a packet to an routing tables, etc.). SFs need to be able to return a packet to an
appropriate SFF (i.e., has the requisite NSH information) when appropriate SFF (i.e., has the requisite NSH information) when
service processing is complete. This can be via the overlay or service processing is complete. This can be via the overlay or
underlay and in some cases require additional configuration on the underlay and, in some cases, can require additional configuration on
SF. As mentioned above, an existing overlay topology may be used the SF. As mentioned above, an existing overlay topology may be
provided it offers the requisite connectivity. used, provided it offers the requisite connectivity.
The mapping of SPI to transport encapsulation occurs on an SFF (as The mapping of SPI to transport encapsulation occurs on an SFF (as
discussed above, the first SFF in the path gets an NSH encapsulated discussed above, the first SFF in the path gets an NSH encapsulated
packet from the Classifier). The SFF consults the SPI/ID values to packet from the Classifier). The SFF consults the SPI/ID values to
determine the appropriate overlay transport encapsulation protocol determine the appropriate overlay transport encapsulation protocol
(several may be used within a given network) and next hop for the (several may be used within a given network) and next hop for the
requisite SF. Table 1 below depicts an example of a single next-hop requisite SF. Table 1 depicts an example of a single next-hop SPI/
SPI/SI to network overlay network locator mapping. SI-to-network overlay network locator mapping.
+------+------+---------------------+-------------------------+ +------+------+---------------------+-------------------------+
| SPI | SI | Next hop(s) | Transport Encapsulation | | SPI | SI | Next Hop(s) | Transport Encapsulation |
+------+------+---------------------+-------------------------+ +------+------+---------------------+-------------------------+
| 10 | 255 | 192.0.2.1 | VXLAN-gpe | | 10 | 255 | 192.0.2.1 | VXLAN-gpe |
| | | | | | | | | |
| 10 | 254 | 198.51.100.10 | GRE | | 10 | 254 | 198.51.100.10 | GRE |
| | | | | | | | | |
| 10 | 251 | 198.51.100.15 | GRE | | 10 | 251 | 198.51.100.15 | GRE |
| | | | | | | | | |
| 40 | 251 | 198.51.100.15 | GRE | | 40 | 251 | 198.51.100.15 | GRE |
| | | | | | | | | |
| 50 | 200 | 01:23:45:67:89:ab | Ethernet | | 50 | 200 | 01:23:45:67:89:ab | Ethernet |
| | | | | | | | | |
| 15 | 212 | Null (end of path) | None | | 15 | 212 | Null (end of path) | None |
+------+------+---------------------+-------------------------+ +------+------+---------------------+-------------------------+
Table 1: SFF NSH Mapping Example Table 1: SFF NSH Mapping Example
Additionally, further indirection is possible: the resolution of the Additionally, further indirection is possible: the resolution of the
required SF network locator may be a localized resolution on an SFF, required SF network locator may be a localized resolution on an SFF,
rather than a service function chain control plane responsibility, as rather than an SFC control plane responsibility, as per Tables 2 and
per Table 2 and Table 3 below. 3.
Please note: VXLAN-gpe and GRE in the above table refer to Please note: VXLAN-gpe and GRE in the above table refer to
[I-D.ietf-nvo3-vxlan-gpe] and [RFC2784] [RFC7676], respectively. [VXLAN-GPE] and [RFC2784] [RFC7676], respectively.
+------+-----+----------------+ +------+-----+----------------+
| SPI | SI | Next hop(s) | | SPI | SI | Next Hop(s) |
+------+-----+----------------+ +------+-----+----------------+
| 10 | 3 | SF2 | | 10 | 3 | SF2 |
| | | | | | | |
| 245 | 12 | SF34 | | 245 | 12 | SF34 |
| | | | | | | |
| 40 | 9 | SF9 | | 40 | 9 | SF9 |
+------+-----+----------------+ +------+-----+----------------+
Table 2: NSH to SF Mapping Example Table 2: NSH-to-SF Mapping Example
+------+-------------------+-------------------------+ +------+-------------------+-------------------------+
| SF | Next hop(s) | Transport Encapsulation | | SF | Next Hop(s) | Transport Encapsulation |
+------+-------------------+-------------------------+ +------+-------------------+-------------------------+
| SF2 | 192.0.2.2 | VXLAN-gpe | | SF2 | 192.0.2.2 | VXLAN-gpe |
| | | | | | | |
| SF34 | 198.51.100.34 | UDP | | SF34 | 198.51.100.34 | UDP |
| | | | | | | |
| SF9 | 2001:db8::1 | GRE | | SF9 | 2001:db8::1 | GRE |
+------+-------------------+-------------------------+ +------+-------------------+-------------------------+
Table 3: SF Locator Mapping Example Table 3: SF Locator Mapping Example
Since the SPI is a representation of the service path, the lookup may Since the SPI is a representation of the service path, the lookup may
return more than one possible next-hop within a service path for a return more than one possible next hop within a service path for a
given SF, essentially a series of weighted (equally or otherwise) given SF, essentially a series of weighted (equally or otherwise)
paths to be used (for load distribution, redundancy, or policy), see paths to be used (for load distribution, redundancy, or policy); see
Table 4. The metric depicted in Table 4 is an example to help Table 4. The metric depicted in Table 4 is an example to help
illustrated weighing SFs. In a real network, the metric will range illustrate weighing SFs. In a real network, the metric will range
from a simple preference (similar to routing next-hop), to a true from a simple preference (similar to routing next-hop) to a true
dynamic composite metric based on some service function-centric state dynamic composite metric based on the state of a Service Function
(including load, sessions state, capacity, etc.) (including load, session state, capacity, etc.).
+------+-----+--------------+---------+ +------+-----+--------------+---------+
| SPI | SI | NH | Metric | | SPI | SI | NH | Metric |
+------+-----+--------------+---------+ +------+-----+--------------+---------+
| 10 | 3 | 203.0.113.1 | 1 | | 10 | 3 | 203.0.113.1 | 1 |
| | | | | | | | | |
| | | 203.0.113.2 | 1 | | | | 203.0.113.2 | 1 |
| | | | | | | | | |
| 20 | 12 | 192.0.2.1 | 1 | | 20 | 12 | 192.0.2.1 | 1 |
| | | | | | | | | |
skipping to change at page 21, line 7 skipping to change at page 21, line 7
(encapsulation type omitted for formatting) (encapsulation type omitted for formatting)
Table 4: NSH Weighted Service Path Table 4: NSH Weighted Service Path
The information contained in Tables 1-4 may be received from the The information contained in Tables 1-4 may be received from the
control plane, but the exact mechanism is outside the scope of this control plane, but the exact mechanism is outside the scope of this
document. document.
6.2. Mapping the NSH to Network Topology 6.2. Mapping the NSH to Network Topology
As described above, the mapping of SPI to network topology may result As described above, the mapping of the SPI to network topology may
in a single path, or it might result in a more complex topology. result in a single path, or it might result in a more complex
Furthermore, the SPI to overlay mapping occurs at each SFF topology. Furthermore, the SPI-to-overlay mapping occurs at each SFF
independently. Any combination of topology selection is possible. independently. Any combination of topology selection is possible.
Please note, there is no requirement to create a new overlay topology Please note, there is no requirement to create a new overlay topology
if a suitable one already exists. NSH packets can use any (new or if a suitable one already exists. NSH packets can use any (new or
existing) overlay provided the requisite connectivity requirements existing) overlay, provided the requisite connectivity requirements
are satisfied. are satisfied.
Examples of mapping for a topology: Examples of mapping for a topology:
1. Next SF is located at SFFb with locator 2001:db8::1 1. Next SF is located at SFFb with locator 2001:db8::1
SFFa mapping: SPI=10 --> VXLAN-gpe, dst-ip: 2001:db8::1 SFFa mapping: SPI=10 --> VXLAN-gpe, dst-ip: 2001:db8::1
2. Next SF is located at SFFc with multiple network locators for 2. Next SF is located at SFFc with multiple network locators for
load distribution purposes: load-distribution purposes:
SFFb mapping: SPI=10 --> VXLAN-gpe, dst_ip:203.0.113.1, SFFb mapping: SPI=10 --> VXLAN-gpe, dst_ip:203.0.113.1,
203.0.113.2, 203.0.113.3, equal cost 203.0.113.2, 203.0.113.3, equal cost
3. Next SF is located at SFFd with two paths from SFFc, one for 3. Next SF is located at SFFd with two paths from SFFc, one for
redundancy: redundancy:
SFFc mapping: SPI=10 --> VXLAN-gpe, dst_ip:192.0.2.10 cost=10, SFFc mapping: SPI=10 --> VXLAN-gpe, dst_ip:192.0.2.10 cost=10,
203.0.113.10, cost=20 203.0.113.10, cost=20
In the above example, each SFF makes an independent decision about In the above example, each SFF makes an independent decision about
the network overlay path and policy for that path. In other words, the network overlay path and policy for that path. In other words,
skipping to change at page 21, line 47 skipping to change at page 21, line 47
paths as required. For example, the overlay path between SFFs may paths as required. For example, the overlay path between SFFs may
utilize traffic engineering, QoS marking, or ECMP, without requiring utilize traffic engineering, QoS marking, or ECMP, without requiring
complex configuration and network protocol support to be extended to complex configuration and network protocol support to be extended to
the service path explicitly. In other words, the network operates as the service path explicitly. In other words, the network operates as
expected, and evolves as required, as does the service plane. expected, and evolves as required, as does the service plane.
6.3. Service Plane Visibility 6.3. Service Plane Visibility
The SPI and SI serve an important function for visibility into the The SPI and SI serve an important function for visibility into the
service topology. An operator can determine what service path a service topology. An operator can determine what service path a
packet is "on", and its location within that path simply by viewing packet is "on" and its location within that path simply by viewing
NSH information (packet capture, IPFIX, etc.) The information can be NSH information (packet capture, IP Flow Information Export (IPFIX),
used for service scheduling and placement decisions, troubleshooting, etc.). The information can be used for service scheduling and
and compliance verification. placement decisions, troubleshooting, and compliance verification.
6.4. Service Graphs 6.4. Service Graphs
While a given realized service function path is a specific sequence While a given realized SFP is a specific sequence of Service
of service functions, the service as seen by a user can actually be a Functions, the service, as seen by a user, can actually be a
collection of service function paths, with the interconnection collection of SFPs, with the interconnection provided by Classifiers
provided by classifiers (in-service path, non-initial (in-service path, non-initial re-classification). These internal re-
reclassification). These internal reclassifiers examine the packet Classifiers examine the packet at relevant points in the network,
at relevant points in the network, and, if needed, SPI and SI are and, if needed, SPI and SI are updated (whether this update is a re-
updated (whether this update is a re-write, or the imposition of a write, or the imposition of a new NSH with new values is
new NSH with new values is implementation specific) to reflect the implementation specific) to reflect the "result" of the
"result" of the classification. These classifiers may, of course, classification. These Classifiers may, of course, also modify the
also modify the metadata associated with the packet. metadata associated with the packet.
[RFC7665], Section 2.1 describes Service Graphs in detail. Section 2.1 of [RFC7665] describes Service Graphs in detail.
7. Policy Enforcement with NSH 7. Policy Enforcement with NSH
7.1. NSH Metadata and Policy Enforcement 7.1. NSH Metadata and Policy Enforcement
As described in Section 2, NSH provides the ability to carry metadata As described in Section 2, NSH provides the ability to carry metadata
along a service path. This metadata may be derived from several along a service path. This metadata may be derived from several
sources. Common examples include: sources. Common examples include:
Network nodes/devices: Information provided by network nodes can Network nodes/devices: Information provided by network nodes can
indicate network-centric information (such as VRF or tenant) that indicate network-centric information (such as VPN Routing and
may be used by service functions or conveyed to another network Forwarding (VRF) or tenant) that may be used by Service Functions
node post service path egress. or conveyed to another network node post service path egress.
External (to the network) systems: External systems, such as External (to the network) systems: External systems, such as
orchestration systems, often contain information that is valuable orchestration systems, often contain information that is valuable
for service function policy decisions. In most cases, this for Service Function policy decisions. In most cases, this
information cannot be deduced by network nodes. For example, a information cannot be deduced by network nodes. For example, a
cloud orchestration platform placing workloads "knows" what cloud orchestration platform placing workloads "knows" what
application is being instantiated and can communicate this application is being instantiated and can communicate this
information to all NSH nodes via metadata carried in the context information to all NSH nodes via metadata carried in the Context
header(s). Header(s).
Service Functions: A classifier co-resident with Service Functions Service Functions: A Classifier co-resident with Service Functions
often perform very detailed and valuable classification. often performs very detailed and valuable classification.
Regardless of the source, metadata reflects the "result" of Regardless of the source, metadata reflects the "result" of
classification. The granularity of classification may vary. For classification. The granularity of classification may vary. For
example, a network switch, acting as a classifier, might only be able example, a network switch, acting as a Classifier, might only be able
to classify based on a 2-tuple, or based on a 5-tuple, while a to classify based on a 2-tuple, or based on a 5-tuple, while a
service function may be able to inspect application information. Service Function may be able to inspect application information.
Regardless of granularity, the classification information can be Regardless of granularity, the classification information can be
represented in the NSH. represented in the NSH.
Once the data is added to the NSH, it is carried along the service Once the data is added to the NSH, it is carried along the service
path, NSH-aware SFs receive the metadata, and can use that metadata path. NSH-aware SFs receive the metadata, and can use that metadata
for local decisions and policy enforcement. Figure 9 and Figure 10 for local decisions and policy enforcement. Figures 9 and 10
highlight the relationship between metadata and policy: highlight the relationship between metadata and policy.
+-------+ +-------+ +-------+ +-------+ +-------+ +-------+
| SFF )------->( SFF |------->| SFF | | SFF )------->( SFF |------->| SFF |
+---+---+ +---+---+ +---+---+ +---+---+ +---+---+ +---+---+
^ | | ^ | |
,-|-. ,-|-. ,-|-. ,-|-. ,-|-. ,-|-.
/ \ / \ / \ / \ / \ / \
( Class ) ( SF1 ) ( SF2 ) ( Class ) ( SF1 ) ( SF2 )
\ ify / \ / \ / \ ify / \ / \ /
`---' `---' `---' `---' `---' `---'
skipping to change at page 23, line 45 skipping to change at page 23, line 45
+---+---+ employees +---+---+ employees
| | | |
+-------+ +-------+
External External
system: system:
Employee Employee
AppZ AppZ
Figure 10: External Metadata and Policy Figure 10: External Metadata and Policy
In both of the examples above, the service functions perform policy In both of the examples above, the Service Functions perform policy
decisions based on the result of the initial classification: the SFs decisions based on the result of the initial classification: the SFs
did not need to perform re-classification; instead, they rely on a did not need to perform re-classification; instead, they rely on an
antecedent classification for local policy enforcement. antecedent classification for local policy enforcement.
Depending on the information carried in the metadata, data privacy Depending on the information carried in the metadata, data privacy
impact needs to be considered. For example, if the metadata conveys impact needs to be considered. For example, if the metadata conveys
tenant information, that information may need to be authenticated tenant information, that information may need to be authenticated
and/or encrypted between the originator and the intended recipients and/or encrypted between the originator and the intended recipients
(which may include intended SFs only); one approach to an optional (which may include intended SFs only); one approach to an optional
capability to do this is explored in [I-D.reddy-sfc-nsh-encrypt]. capability to do this is explored in [NSH-ENCRYPT]. The NSH itself
The NSH itself does not provide privacy functions, rather it relies does not provide privacy functions, rather it relies on the transport
on the transport encapsulation/overlay. An operator can select the encapsulation/overlay. An operator can select the appropriate set of
appropriate set of transport encapsulation protocols to ensure transport encapsulation protocols to ensure confidentiality (and
confidentiality (and other security) considerations are met. other security) considerations are met. Metadata privacy and
Metadata privacy and security considerations are a matter for the security considerations are a matter for the documents that define
documents that define metadata format. metadata format.
7.2. Updating/Augmenting Metadata 7.2. Updating/Augmenting Metadata
Post-initial metadata imposition (typically performed during initial Post-initial metadata imposition (typically, performed during initial
service path determination), the metadata may be augmented or service path determination), the metadata may be augmented or
updated: updated:
1. Metadata Augmentation: Information may be added to the NSH's 1. Metadata Augmentation: Information may be added to the NSH's
existing metadata, as depicted in Figure 11. For example, if the existing metadata, as depicted in Figure 11. For example, if the
initial classification returns the tenant information, a initial classification returns the tenant information, a
secondary classification (perhaps co-resident with DPI or SLB) secondary classification (perhaps co-resident with deep packet
may augment the tenant classification with application inspection (DPI) or server load balancing (SLB)) may augment the
information, and impose that new information in NSH metadata. tenant classification with application information, and impose
The tenant classification is still valid and present, but that new information in NSH metadata. The tenant classification
additional information has been added to it. is still valid and present, but additional information has been
added to it.
2. Metadata Update: Subsequent classifiers may update the initial 2. Metadata Update: Subsequent Classifiers may update the initial
classification if it is determined to be incorrect or not classification if it is determined to be incorrect or not
descriptive enough. For example, the initial classifier adds descriptive enough. For example, the initial Classifier adds
metadata that describes the traffic as "Internet" but a security metadata that describes the traffic as "Internet", but a security
service function determines that the traffic is really "attack". Service Function determines that the traffic is really "attack".
Figure 12 illustrates an example of updating metadata. Figure 12 illustrates an example of updating metadata.
+-----+ +-----+ +-----+ +-----+ +-----+ +-----+
| SFF |---------> | SFF |----------> | SFF | | SFF |---------> | SFF |----------> | SFF |
+--+--+ +--+--+ +--+--+ +--+--+ +--+--+ +--+--+
^ | | ^ | |
,---. ,---. ,---. ,---. ,---. ,---.
/ \ / \ / \ / \ / \ / \
( Class ) ( SF1 ) ( SF2 ) ( Class ) ( SF1 ) ( SF2 )
\ / \ / \ / \ / \ / \ /
skipping to change at page 25, line 49 skipping to change at page 25, line 49
7.3. Service Path Identifier and Metadata 7.3. Service Path Identifier and Metadata
Metadata information may influence the service path selection since Metadata information may influence the service path selection since
the Service Path Identifier values can represent the result of the Service Path Identifier values can represent the result of
classification. A given SPI can be defined based on classification classification. A given SPI can be defined based on classification
results (including metadata classification). The imposition of the results (including metadata classification). The imposition of the
SPI and SI results in the packet being placed on the newly specified SPI and SI results in the packet being placed on the newly specified
SFP at the position indicated by the imposed SPI and SI. SFP at the position indicated by the imposed SPI and SI.
This relationship provides the ability to create a dynamic service This relationship provides the ability to create a dynamic service
plane based on complex classification without requiring each node to plane based on complex classification, without requiring each node to
be capable of such classification, or requiring a coupling to the be capable of such classification or requiring a coupling to the
network topology. This yields service graph functionality as network topology. This yields Service Graph functionality as
described in Section 6.4. Figure 13 illustrates an example of this described in Section 6.4. Figure 13 illustrates an example of this
behavior. behavior.
+-----+ +-----+ +-----+ +-----+ +-----+ +-----+
| SFF |---------> | SFF |------+---> | SFF | | SFF |---------> | SFF |------+---> | SFF |
+--+--+ +--+--+ | +--+--+ +--+--+ +--+--+ | +--+--+
| | | | | | | |
,---. ,---. | ,---. ,---. ,---. | ,---.
/ \ / SF1 \ | / \ / \ / SF1 \ | / \
( SCL ) ( + ) | ( SF2 ) ( SCL ) ( + ) | ( SF2 )
skipping to change at page 26, line 28 skipping to change at page 26, line 28
--> DoS | --> DoS |
V V
,-+-. ,-+-.
/ \ / \
( SF10 ) ( SF10 )
\ / \ /
`---' `---'
DoS DoS
"Scrubber" "Scrubber"
Legend:
SCL = Service Classifier
Figure 13: Path ID and Metadata Figure 13: Path ID and Metadata
Specific algorithms for mapping metadata to an SPI are outside the Specific algorithms for mapping metadata to an SPI are outside the
scope of this document. scope of this document.
8. Security Considerations 8. Security Considerations
NSH security must be considered in the contexts of the SFC NSH security must be considered in the contexts of the SFC
architecture and operators' environments. One important architecture and operators' environments. One important
characteristic of NSH is that it is not an end-to-end protocol. As characteristic of NSH is that it is not an end-to-end protocol. As
opposed to a protocol that "starts" on a host, and "ends" on a server opposed to a protocol that "starts" on a host and "ends" on a server
or another host, NSH is typically imposed by a network device on or another host, NSH is typically imposed by a network device on
ingress to the SFC domain and removed at the egress of the SFC ingress to the SFC domain and removed at the egress of the SFC
domain. As such, and as with any other network-centric protocol domain. As such, and as with any other network-centric protocols
(e.g., IP Tunneling, Traffic Engineering, MPLS, or Provider (e.g., IP Tunneling, Traffic Engineering, MPLS, or Provider-
Provisioned Virtual Private Networks) there an underlying trust that Provisioned Virtual Private Networks), there is an underlying trust
the network devices responsible for imposing, removing and acting on in the network devices responsible for imposing, removing, and acting
NSH information are trusted. on NSH information.
The following sections detail an analysis and present a set of The following sections detail an analysis and present a set of
requirements and recommendations in those two areas. requirements and recommendations in those two areas.
8.1. NSH Security Considerations from Operators' Environments 8.1. NSH Security Considerations from Operators' Environments
Trusted Devices Trusted Devices
All classifiers, SFFs and SFSs (hereinafter referred to as "SFC All Classifiers, SFFs and SFs (hereinafter referred to as "SFC
devices") within an operator's environment are assumed to have devices") within an operator's environment are assumed to have
been selected, vetted, and actively maintained, therefore trusted been selected, vetted, and actively maintained; therefore, they
by that operator. This assumption differs from the oft held view are trusted by that operator. This assumption differs from the
that devices are untrusted, often refered to as zero trust model. oft held view that devices are untrusted, often referred to as the
Operators SHOULD regularly monitor (i.e. continuously audit) these "zero-trust model". Operators SHOULD regularly monitor (i.e.,
devices to help ensure complaint behavior. This trust, therefore, continuously audit) these devices to help ensure compliant
extends into NSH operations: SFC devices are not, themselves, behavior. This trust, therefore, extends into NSH operations: SFC
considered as attack vectors. This assumption, and the resultant devices are not, themselves, considered to be attack vectors.
conclusion is reasonable since this is the very basis of an This assumption, and the resultant conclusion is reasonable since
operator posture; the operator depends on this reality to this is the very basis of an operator posture; the operator
function. If these devices are not trusted, and indeed depends on this reality to function. If these devices are not
compromised, almost the entirety of the operator's standard-based trusted, and indeed are compromised, almost the entirety of the
IP and MPLS protocol suites are vulnerable, and therefore the operator's standard-based IP and MPLS protocol suites are
operation of the entire network is compromised. Although there vulnerable; therefore, the operation of the entire network is
are well documented monitoring-based methods for detecting compromised. Although there are well-documented monitoring-based
compromise, such as include continous monitoring, audit and log methods for detecting compromise (such as included continuous
review, these may not be sufficient to contain damage by a monitoring and audit and log review), these may not be sufficient
completely compromised element. to contain damage by a completely compromised element.
Methods and best practices to secure devices are also widely Methods and best practices to secure devices are also widely
documented and outside the scope of this document. documented and outside the scope of this document.
Single Domain Boundary Single Domain Boundary
As per [RFC7665], NSH is designed for use within a single As per [RFC7665], NSH is designed for use within a single
administrative domain. This scoping provides two important administrative domain. This scoping provides two important
characteristics: characteristics:
skipping to change at page 28, line 6 skipping to change at page 28, line 6
administrative domain are natively supported by the NSH given that administrative domain are natively supported by the NSH given that
the last SFF of a service path will systematically remove the NSH the last SFF of a service path will systematically remove the NSH
encapsulation before forwarding a packet exiting the service path. encapsulation before forwarding a packet exiting the service path.
The second step in such prevention is to filter the transport The second step in such prevention is to filter the transport
encapsulation protocol used by NSH at the domain edge. The encapsulation protocol used by NSH at the domain edge. The
transport encapsulation protocol MUST be filtered and MUST NOT transport encapsulation protocol MUST be filtered and MUST NOT
leave the domain edge. leave the domain edge.
Depending upon the transport encapsulation protocol used for NSH, Depending upon the transport encapsulation protocol used for NSH,
this can either be done by completely blocking the transport this can be done either by completely blocking the transport
encapsulation (e.g., if MPLS is the chosen NSH transport encapsulation (e.g., if MPLS is the chosen NSH transport
encapsulation protocol, it is therefore never allowed to leave the encapsulation protocol, it is therefore never allowed to leave the
domain) or by examining the carried protocol with the transport domain) or by examining the carried protocol with the transport
encapsulation (e.g., if VxLAN-gpe is used as the NSH transport encapsulation (e.g., if VXLAN-gpe is used as the NSH transport
encapsulation protocol, all domain edges need to filter based on encapsulation protocol, all domain edges need to filter based on
the carried protocol in the VxLAN-gpe.) the carried protocol in the VXLAN-gpe.)
The other consequence of this bounding is that ingress packets The other consequence of this bounding is that ingress packets
MUST also be filtered to prevent attackers from sending in NSH MUST also be filtered to prevent attackers from sending in NSH
packets with service path identification and metadata of their own packets with service path identification and metadata of their own
selection. The same filters as described above for both the NSH selection. The same filters as described above for both the NSH
at SFC devices and for the transport encapsulation protocol as at SFC devices and for the transport encapsulation protocol as
general edge protections MUST be applied on ingress. general edge protections MUST be applied on ingress.
In summary, packets originating outside the SFC-enabled domain In summary, packets originating outside the SFC-enabled domain
MUST be dropped if they contain an NSH. Similarly, packets MUST be dropped if they contain an NSH. Similarly, packets
exiting the SFC-enabled domain MUST be dropped if they contain an exiting the SFC-enabled domain MUST be dropped if they contain an
NSH. NSH.
ii) Mitigation of external threats ii) Mitigation of external threats
As per the trusted SFC devices points raised above, given that NSH As per the trusted SFC device points raised above, given that NSH
is scoped within an operator's domain, that operator can ensure is scoped within an operator's domain, that operator can ensure
that the environment, and its transitive properties, comply to that the environment and its transitive properties comply with
that operator's required security posture. Continuous audits for that operator's required security posture. Continuous audits for
assurance are recommended with this reliance on a fully trusted assurance are recommended with this reliance on a fully trusted
environment. The term 'continuous audits' describes a method environment. The term "continuous audits" describes a method
(automated or manual) of checking security control compliance on a (automated or manual) of checking security-control compliance on a
regular basis, at some set period of time. regular basis, at some set period of time.
8.2. NSH Security Considerations from the SFC Architecture 8.2. NSH Security Considerations from the SFC Architecture
The SFC architecture defines functional roles (e.g., SFF), as well as The SFC architecture defines functional roles (e.g., SFF), as well as
protocol element (e.g. Metadata). This section considers each role protocol elements (e.g., Metadata). This section considers each role
and element in the context of threats posed in the areas of integrity and element in the context of threats posed in the areas of integrity
and confidentiality. As with routing, the distributed computation and confidentiality. As with routing, the distributed computation
model assumes a distributed trust model. model assumes a distributed trust model.
An important consideration is that NSH contains mandatory to mute An important consideration is that NSH contains mandatory-to-mute
fields, and further, the SFC architecture describes cases where other fields, and further, the SFC architecture describes cases where other
fields in NSH change, all on a possible SFP hop-by-hop basis. This fields in NSH change, all on a possible SFP hop-by-hop basis. This
means that any cryptographic solution requires complex key means that any cryptographic solution requires complex key
distribution and lifecycle operations. distribution and life-cycle operations.
8.2.1. Integrity 8.2.1. Integrity
SFC devices SFC devices
SFC devices MAY perform various forms of verification on received SFC devices MAY perform various forms of verification on received
NSH packets such as only accepting NSH packets from expected NSH packets such as only accepting NSH packets from expected
devices, checking that NSH SPI and SI values received from devices, checking that NSH SPI and SI values received from
expected devices conform to expected values and so on. expected devices conform to expected values and so on.
Implementation of these additional checks are a local matter and Implementation of these additional checks are a local matter and,
thus out of scope of this document. thus, out of scope of this document.
NSH Base and Service Path Headers NSH Base and Service Path Headers
Attackers who can modify packets within the operator's network may Attackers who can modify packets within the operator's network may
be able to modify the service function path, path position, and / be able to modify the SFP, path position, and/or the metadata
or the metadata associated with a packet. associated with a packet.
One specific concern is an attack in which a malicious One specific concern is an attack in which a malicious
modification of the SPI/SI results in an alteration of the path to modification of the SPI/SI results in an alteration of the path to
avoid security devices. The options discussed in this section avoid security devices. The options discussed in this section
help twart that attack, and so does the use of the optional "Proof help thwart that attack, and so does the use of the optional
of Transit" method [I-D.brockners-proof-of-transit]. "Proof of Transit" method [PROOF-OF-TRANSIT].
As stated above, SFC devices are trusted; in the case where an SFC As stated above, SFC devices are trusted; in the case where an SFC
device is compromised, NSH integrity protection would be subject device is compromised, NSH integrity protection would be subject
to forging (in many cases) as well. to forging (in many cases) as well.
NSH itself does not mandate protocol-specific integrity NSH itself does not mandate protocol-specific integrity
protection. However, if an operator deems protection required, protection. However, if an operator deems protection is required,
several options are viable: several options are viable:
1. SFF/SF NSH verification 1. SFF/SF NSH verification
Although strictly speaking not integrity protection, some of Although, strictly speaking, not integrity protection, some of
the techniques mentioned above such as checking expected NSH the techniques mentioned above, such as checking expected NSH
values are received from expected SFC device(s) can provide a values are received from expected SFC device(s), can provide a
form of verification without incurring the burden of a full- form of verification without incurring the burden of a full-
fledged integrity protection deployment. fledged integrity-protection deployment.
2. Transport Security 2. Transport Security
NSH is always encapsulated by an outer transport encapsulation NSH is always encapsulated by an outer transport encapsulation
as detailed in Section 4 of this specification, and as as detailed in Section 4 of this specification, and as
depicted in Figure 1. If an operator deems cryptographic depicted in Figure 1. If an operator deems cryptographic
integrity protection necessary due to their risk analysis, integrity protection necessary due to their risk analysis,
then an outer transport encapsulation that provides such then an outer transport encapsulation that provides such
protection [RFC6071], such as IPsec, MUST be used. protection [RFC6071], such as IPsec, MUST be used.
Although the threat model and recommendations of BCP 72 Although the threat model and recommendations of Section 5 of
[RFC3552] Section 5 would normally require cryptographic data BCP 72 [RFC3552] would normally require cryptographic data
origin authentication for the header, this document does not origin authentication for the header, this document does not
mandate such mechanisms in order to reflect the operational mandate such mechanisms in order to reflect the operational
and technical realities of deployment. and technical realities of deployment.
Given that NSH is transport independent, as mentioned above, a Given that NSH is transport independent, as mentioned above, a
secure transport, such as IPsec can be used for carry NSH. secure transport, such as IPsec can be used for carry NSH.
IPsec can be used either alone, or in conjunction with other IPsec can be used either alone or in conjunction with other
transport encapsulation protocols in turn encapsulating NSH. transport encapsulation protocols, in turn, encapsulating NSH.
Operators MUST ensure the selected transport encapsulation Operators MUST ensure the selected transport encapsulation
protocol can be supported by the transport encapsulation/ protocol can be supported by the transport encapsulation/
underlay of all relevant network segments as well as SFFs, SFs underlay of all relevant network segments as well as SFFs,
and SFC proxies in the service path. SFs, and SFC Proxies in the service path.
If connectivity between SFC-enabled devices traverses the If connectivity between SFC-enabled devices traverses the
public Internet, then such connectivity MUST be secured at the public Internet, then such connectivity MUST be secured at the
transport encapsulation layer. IPsec is an example of such a transport encapsulation layer. IPsec is an example of such a
transport. transport.
3. NSH Variable Header-based Integrity 3. NSH Variable Header-Based Integrity
Lastly, NSH MD-Type 2 provides, via variable length headers, Lastly, NSH MD Type 2 provides, via variable-length headers,
the ability to append cryptographic integrity protection to the ability to append cryptographic integrity protection to
the NSH packet. The implementation of such a scheme is the NSH packet. The implementation of such a scheme is
outside the scope of this document. outside the scope of this document.
NSH metadata NSH metadata
As with the base and service path headers, if an operator deems As with the Base and Service Path Headers, if an operator deems
cryptographic integrity protection needed, then an existing, cryptographic integrity protection needed, then an existing,
standard transport protocol MUST be used since the integrity standard transport protocol MUST be used since the integrity
protection applies to entire encapsulated NSH packets. As protection applies to entire encapsulated NSH packets. As
mentioned above, a risk assessment that deems dataplane traffic mentioned above, a risk assessment that deems data-plane traffic
subject to tampering will apply not only to NSH but to the subject to tampering will apply not only to NSH but to the
transport information and therefore the use of a secure transport transport information; therefore, the use of a secure transport is
is likely needed already to protect the entire stack. likely needed already to protect the entire stack.
If an MD-Type 2 variable header integrity scheme is in place, then If an MD Type 2 variable header integrity scheme is in place, then
the integrity of the metadata can be ensured via that mechanism as the integrity of the metadata can be ensured via that mechanism as
well. well.
8.2.2. Confidentiality 8.2.2. Confidentiality
SFC devices SFC devices
SFC devices can "see" (and need to use) NSH information. SFC devices can "see" (and need to use) NSH information.
NSH base and service path headers NSH Base and Service Path Headers
SPI and other base/service path information does not typically SPI and other base / service path information does not typically
require confidentiality; however, if an operator does deem require confidentiality; however, if an operator does deem
confidentiality required, then, as with integrity, an existing confidentiality to be required, then, as with integrity, an
transport encapsulation that provides encryption MUST be utilized. existing transport encapsulation that provides encryption MUST be
utilized.
NSH metadata NSH metadata
An attacker with access to the traffic in an operator's network An attacker with access to the traffic in an operator's network
can potentially observe the metadata NSH carries with packets, can potentially observe the metadata NSH carries with packets,
potentially discovering privacy sensitive information. potentially discovering privacy-sensitive information.
Much of the metadata carried by NSH is not sensitive. It often Much of the metadata carried by NSH is not sensitive. It often
reflects information that can be derived from the underlying reflects information that can be derived from the underlying
packet or frame. Direct protection of such information is not packet or frame. Direct protection of such information is not
necessary, as the risks are simply those of carrying the necessary, as the risks are simply those of carrying the
underlying packet or frame. underlying packet or frame.
Implementers and operators MUST be aware that metadata can have Implementers and operators MUST be aware that metadata can have
privacy implications, and those implications are sometimes hard to privacy implications, and those implications are sometimes hard to
predict. Therefore, attached metadata should be limited to that predict. Therefore, attached metadata should be limited to that
skipping to change at page 31, line 48 skipping to change at page 31, line 49
done using transport encapsulation protocols with suitable done using transport encapsulation protocols with suitable
security capabilities, along the lines discussed above. If a security capabilities, along the lines discussed above. If a
security analysis deems these protections necessary, then security security analysis deems these protections necessary, then security
features in the transport encapsulation protocol (such as IPsec) features in the transport encapsulation protocol (such as IPsec)
MUST be used. MUST be used.
One useful element of providing privacy protection for sensitive One useful element of providing privacy protection for sensitive
metadata is described under the "SFC Encapsulation" area of the metadata is described under the "SFC Encapsulation" area of the
Security Considerations of [RFC7665]. Operators can and should Security Considerations of [RFC7665]. Operators can and should
use indirect identification for metadata deemed to be sensitive use indirect identification for metadata deemed to be sensitive
(such as personally identifying information) significantly (such as personally identifying information), significantly
mitigating the risk of a privacy violation. In particular, mitigating the risk of a privacy violation. In particular,
subscriber identifying information should be handled carefully, subscriber-identifying information should be handled carefully,
and in general SHOULD be obfuscated. and, in general, SHOULD be obfuscated.
For those situations where obfuscation is either inapplicable or For those situations where obfuscation is either inapplicable or
judged to be insufficient, an operator can also encrypt the judged to be insufficient, an operator can also encrypt the
metadata. An approach to an optional capability to do this was metadata. An approach to an optional capability to do this was
explored in [I-D.reddy-sfc-nsh-encrypt]. For other situations explored in [NSH-ENCRYPT]. For other situations where greater
where greater assurance is desired, optional mechanisms such as assurance is desired, optional mechanisms such as
[I-D.brockners-proof-of-transit] can be used. [PROOF-OF-TRANSIT] can be used.
9. Contributors
This WG document originated as draft-quinn-sfc-nsh; the following are
its co-authors and contributors along with their respective
affiliations at the time of WG adoption. The editors of this
document would like to thank and recognize them and their
contributions. These co-authors and contributors provided invaluable
concepts and content for this document's creation.
o Jim Guichard, Cisco Systems, Inc.
o Surendra Kumar, Cisco Systems, Inc.
o Michael Smith, Cisco Systems, Inc.
o Wim Henderickx, Alcatel-Lucent
o Tom Nadeau, Brocade
o Puneet Agarwal
o Rajeev Manur, Broadcom
o Abhishek Chauhan, Citrix
o Joel Halpern, Ericsson
o Sumandra Majee, F5
o David Melman, Marvell
o Pankaj Garg, Microsoft
o Brad McConnell, Rackspace
o Chris Wright, Red Hat, Inc.
o Kevin Glavin, Riverbed
o Hong (Cathy) Zhang, Huawei US R&D
o Louis Fourie, Huawei US R&D
o Ron Parker, Affirmed Networks
o Myo Zarny, Goldman Sachs
o Andrew Dolganow, Alcatel-Lucent
o Rex Fernando, Cisco Systems, Inc.
o Praveen Muley, Alcatel-Lucent
o Navindra Yadav, Cisco Systems, Inc.
10. Acknowledgments
The authors would like to thank Sunil Vallamkonda, Nagaraj Bagepalli,
Abhijit Patra, Peter Bosch, Darrel Lewis, Pritesh Kothari, Tal
Mizrahi and Ken Gray for their detailed review, comments and
contributions.
A special thank you goes to David Ward and Tom Edsall for their
guidance and feedback.
Additionally the authors would like to thank Larry Kreeger for his
invaluable ideas and contributions which are reflected throughout
this document.
Loa Andersson provided a thorough review and valuable comments, we
thank him for that.
Reinaldo Penno deserves a particular thank you for his architecture
and implementation work that helped guide the protocol concepts and
design.
The editors also acknowledge comprehensive reviews and respective
useful suggestions by Med Boucadair, Adrian Farrel, Juergen
Schoenwaelder, Acee Lindem, and Kathleen Moriarty.
Lastly, David Dolson has provides significant review, feedback and 9. IANA Considerations
suggestions throughout the evolution of this document. His
contributions are very much appreciated.
11. IANA Considerations 9.1. NSH Parameters
11.1. Network Service Header (NSH) Parameters
IANA is requested to create a new "Network Service Header (NSH) IANA has created a new "Network Service Header (NSH) Parameters"
Parameters" registry. The following sub-sections request new registry. The following subsections detail new registries within the
registries within the "Network Service Header (NSH) Parameters " "Network Service Header (NSH) Parameters" registry.
registry.
11.1.1. NSH Base Header Bits 9.1.1. NSH Base Header Bits
There are five unassigned bits (U bits) in the NSH Base Header, and There are five unassigned bits (U bits) in the NSH Base Header, and
one assigned bit (O bit). New bits are assigned via Standards Action one assigned bit (O bit). New bits are assigned via Standards Action
[RFC8126]. [RFC8126].
Bit 2 - O (OAM) bit Bit 2 - O (OAM) bit
Bit 3 - Unassigned Bit 3 - Unassigned
Bits 16-19 - Unassigned Bits 16-19 - Unassigned
11.1.2. NSH Version 9.1.2. NSH Version
IANA is requested to setup a registry of "NSH Version". New values IANA has set up the "NSH Version" registry. New values are assigned
are assigned via Standards Action [RFC8126]. via Standards Action [RFC8126].
Version 00b: Protocol as defined by this document. +-------------+---------------------------------+-----------+
Version 01b: Reserved. This document. | Version | Description | Reference |
Version 10b: Unassigned. +-------------+---------------------------------+-----------+
Version 11b: Unassigned. | Version 00b | Protocol as defined by RFC 8300 | RFC 8300 |
| Version 01b | Reserved | RFC 8300 |
| Version 10b | Unassigned | |
| Version 11b | Unassigned | |
+-------------+---------------------------------+-----------+
11.1.3. MD Type Registry Table 5: NSH Version
IANA is requested to set up a registry of "MD Types". These are 9.1.3. NSH MD Types
4-bit values. MD Type values 0x0, 0x1, 0x2, and 0xF are specified in
this document, see Table 5. Registry entries are assigned by using
the "IETF Review" policy defined in RFC 8126 [RFC8126].
+----------+-----------------+---------------+ IANA has set up the "NSH MD Types" registry, which contains 4-bit
| MD Type | Description | Reference | values. MD Type values 0x0, 0x1, 0x2, and 0xF are specified in this
+----------+-----------------+---------------+ document; see Table 6. Registry entries are assigned via the "IETF
| 0x0 | Reserved | This document | Review" policy defined in RFC 8126 [RFC8126].
| | | |
| 0x1 | NSH MD Type 1 | This document |
| | | |
| 0x2 | NSH MD Type 2 | This document |
| | | |
| 0x3..0xE | Unassigned | |
| | | |
| 0xF | Experimentation | This document |
+----------+-----------------+---------------+
Table 5: MD Type Values +-----------+-----------------+-----------+
| MD Type | Description | Reference |
+-----------+-----------------+-----------+
| 0x0 | Reserved | RFC 8300 |
| | | |
| 0x1 | NSH MD Type 1 | RFC 8300 |
| | | |
| 0x2 | NSH MD Type 2 | RFC 8300 |
| | | |
| 0x3 - 0xE | Unassigned | |
| | | |
| 0xF | Experimentation | RFC 8300 |
+-----------+-----------------+-----------+
11.1.4. MD Class Registry Table 6: MD Type Values
IANA is requested to set up a registry of "MD Class". These are 9.1.4. NSH MD Class
16-bit values. New allocations are to be made according to the
following policies: IANA has set up the "NSH MD Class" registry, which contains 16-bit
values. New allocations are to be made according to the following
policies:
0x0000 to 0x01ff: IETF Review 0x0000 to 0x01ff: IETF Review
0x0200 to 0xfff5: Expert Review 0x0200 to 0xfff5: Expert Review
0xfff6 to 0xfffe: Experimental
0xffff: Reserved
IANA is requested to assign the values as per Table 6:: IANA has assigned the values as follows:
+-----------+-----------------------------+------------+ +------------------+------------------------+------------+
| MD Class | Meaning | Reference | | Value | Meaning | Reference |
+-----------+-----------------------------+------------+ +------------------+------------------------+------------+
| 0x0000 | IETF Base NSH MD Class | This.I-D | | 0x0000 | IETF Base NSH MD Class | RFC 8300 |
+-----------+-----------------------------+------------+ | | | |
| 0xfff6 to 0xfffe | Experimental | RFC 8300 |
| | | |
| 0xffff | Reserved | RFC 8300 |
+------------------+------------------------+------------+
Table 6: MD Class Value Table 7: NSH MD Class
A registry for Types for the MD Class of 0x0000 is defined in A registry for Types for the MD Class of 0x0000 is defined in
Section 11.1.5. Section 9.1.5.
Designated Experts evaluating new allocation requests from the Designated Experts evaluating new allocation requests from the
"Expert Review" range should principally consider whether a new MD "Expert Review" range should principally consider whether a new MD
class is needed compared to adding MD types to an existing class. class is needed compared to adding MD Types to an existing class.
The Designated Experts should also encourage the existence of an The Designated Experts should also encourage the existence of an
associated and publicly visible registry of MD types although this associated and publicly visible registry of MD Types although this
registry need not be maintained by IANA. registry need not be maintained by IANA.
When evaluating a request for an allocation, the Expert should verify When evaluating a request for an allocation, the Expert should verify
that the allocation plan includes considerations to handle privacy that the allocation plan includes considerations to handle privacy
and security issues associated with the anticipated individual MD and security issues associated with the anticipated individual MD
Types allocated within this class. These plans should consider, when Types allocated within this class. These plans should consider, when
appropriate, alternatives such as indirection, encryption, and appropriate, alternatives such as indirection, encryption, and
limited deployment scenarios. Information that can't be directly limited-deployment scenarios. Information that can't be directly
derived from viewing the packet contents should be examined for derived from viewing the packet contents should be examined for
privacy and security implications. privacy and security implications.
11.1.5. New IETF Assigned Optional Variable Length Metadata Type 9.1.5. NSH IETF-Assigned Optional Variable-Length Metadata Types
Registry
The Type values within the IETF Base NSH MD Class, i.e., when the MD The Type values within the IETF Base NSH MD Class, i.e., when the MD
Class is set to 0x0000 (see Section 11.1.4), are the Types owned by Class is set to 0x0000 (see Section 9.1.4), are the Types owned by
the IETF. This document requests IANA to create a registry for the the IETF. Per this document, IANA has created a registry for the
Type values for the IETF Base NSH MD Class called the "IETF Assigned Type values for the IETF Base NSH MD Class called the "NSH IETF-
Optional Variable Length Metadata Type Registry", as specified in Assigned Optional Variable-Length Metadata Types" registry, as
Section 2.5.1. specified in Section 2.5.1.
The type values are assigned via Standards Action [RFC8126]. The type values are assigned via Standards Action [RFC8126].
No initial values are assigned at the creation of the registry. No initial values are assigned at the creation of the registry.
11.1.6. NSH Base Header Next Protocol 9.1.6. NSH Next Protocol
IANA is requested to set up a registry of "Next Protocol". These are IANA has set up the "NSH Next Protocol" registry, which contains
8-bit values. Next Protocol values 0, 1, 2, 3, 4 and 5 are defined 8-bit values. Next Protocol values 0, 1, 2, 3, 4, and 5 are defined
in this document (see Table 7. New values are assigned via "Expert in this document (see Table 8). New values are assigned via "Expert
Reviews" as per [RFC8126]. Review" as per [RFC8126].
+---------------+--------------+---------------+ +---------------+--------------+-----------+
| Next Protocol | Description | Reference | | Next Protocol | Description | Reference |
+---------------+--------------+---------------+ +---------------+--------------+-----------+
| 0x0 | Unassigned | | | 0x00 | Unassigned | |
| | | | | | | |
| 0x1 | IPv4 | This document | | 0x01 | IPv4 | RFC 8300 |
| | | | | | | |
| 0x2 | IPv6 | This document | | 0x02 | IPv6 | RFC 8300 |
| | | | | | | |
| 0x3 | Ethernet | This document | | 0x03 | Ethernet | RFC 8300 |
| | | | | | | |
| 0x4 | NSH | This document | | 0x04 | NSH | RFC 8300 |
| | | | | | | |
| 0x5 | MPLS | This document | | 0x05 | MPLS | RFC 8300 |
| | | | | | | |
| 0x6..0xFD | Unassigned | | | 0x06 - 0xFD | Unassigned | |
| | | | | | | |
| 0xFE | Experiment 1 | This document | | 0xFE | Experiment 1 | RFC 8300 |
| | | | | | | |
| 0xFF | Experiment 2 | This document | | 0xFF | Experiment 2 | RFC 8300 |
+---------------+--------------+---------------+ +---------------+--------------+-----------+
Table 7: NSH Base Header Next Protocol Values Table 8: NSH Base Header Next Protocol Values
Expert Review requests MUST include a single code point per request. Expert Review requests MUST include a single codepoint per request.
Designated Experts evaluating new allocation requests from this Designated Experts evaluating new allocation requests from this
registry should consider the potential scarcity of code points for an registry should consider the potential scarcity of codepoints for an
8-bit value, and check both for duplications as well as availability 8-bit value, and check both for duplications and availability of
of documentation. If the actual assignment of the Next Protocol documentation. If the actual assignment of the Next Protocol field
field allocation reaches half of the range, that is when there are allocation reaches half of the range (that is, when there are 128
128 unassigned values, IANA needs to alert the IESG. At this point, unassigned values), IANA needs to alert the IESG. At that point, a
a new more strict allocation policy SHOULD be considered. new more strict allocation policy SHOULD be considered.
12. NSH-Related Codepoints 10. NSH-Related Codepoints
12.1. NSH EtherType 10.1. NSH Ethertype
An IEEE EtherType, 0x894F, has been allocated for NSH. An IEEE Ethertype, 0x894F, has been allocated for NSH.
13. References 11. References
13.1. Normative References 11.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC7665] Halpern, J., Ed. and C. Pignataro, Ed., "Service Function [RFC7665] Halpern, J., Ed. and C. Pignataro, Ed., "Service Function
Chaining (SFC) Architecture", RFC 7665, Chaining (SFC) Architecture", RFC 7665,
DOI 10.17487/RFC7665, October 2015, DOI 10.17487/RFC7665, October 2015,
<https://www.rfc-editor.org/info/rfc7665>. <https://www.rfc-editor.org/info/rfc7665>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26, Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017, RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>. <https://www.rfc-editor.org/info/rfc8126>.
13.2. Informative References [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[I-D.brockners-proof-of-transit] 11.2. Informative References
Brockners, F., Bhandari, S., Dara, S., Pignataro, C.,
Leddy, J., Youell, S., Mozes, D., and T. Mizrahi, "Proof
of Transit", draft-brockners-proof-of-transit-04 (work in
progress), October 2017.
[I-D.guichard-sfc-nsh-dc-allocation] [NSH-BROADBAND-ALLOCATION]
Napper, J., Kumar, S., Muley, P., Henderickx, W., and M.
Boucadair, "NSH Context Header Allocation -- Broadband",
Work in Progress, draft-napper-sfc-nsh-broadband-
allocation-04, November 2017.
[NSH-DC-ALLOCATION]
Guichard, J., Smith, M., Kumar, S., Majee, S., Agarwal, Guichard, J., Smith, M., Kumar, S., Majee, S., Agarwal,
P., Glavin, K., Laribi, Y., and T. Mizrahi, "Network P., Glavin, K., Laribi, Y., and T. Mizrahi, "Network
Service Header (NSH) MD Type 1: Context Header Allocation Service Header (NSH) MD Type 1: Context Header Allocation
(Data Center)", draft-guichard-sfc-nsh-dc-allocation-07 (Data Center)", Work in Progress,
(work in progress), August 2017. draft-guichard-sfc-nsh-dc-allocation-07, August 2017.
[I-D.ietf-nvo3-vxlan-gpe]
Maino, F., Kreeger, L., and U. Elzur, "Generic Protocol
Extension for VXLAN", draft-ietf-nvo3-vxlan-gpe-05 (work
in progress), October 2017.
[I-D.ietf-rtgwg-dt-encap]
Nordmark, E., Tian, A., Gross, J., Hudson, J., Kreeger,
L., Garg, P., Thaler, P., and T. Herbert, "Encapsulation
Considerations", draft-ietf-rtgwg-dt-encap-02 (work in
progress), October 2016.
[I-D.ietf-sfc-control-plane]
Boucadair, M., "Service Function Chaining (SFC) Control
Plane Components & Requirements", draft-ietf-sfc-control-
plane-08 (work in progress), October 2016.
[I-D.ietf-sfc-oam-framework]
Aldrin, S., Pignataro, C., Kumar, N., Akiya, N., Krishnan,
R., and A. Ghanwani, "Service Function Chaining (SFC)
Operation, Administration and Maintenance (OAM)
Framework", draft-ietf-sfc-oam-framework-03 (work in
progress), September 2017.
[I-D.napper-sfc-nsh-broadband-allocation]
Napper, J., Kumar, S., Muley, P., Henderickx, W., and M.
Boucadair, "NSH Context Header Allocation -- Broadband",
draft-napper-sfc-nsh-broadband-allocation-03 (work in
progress), July 2017.
[I-D.reddy-sfc-nsh-encrypt] [NSH-ENCRYPT]
Reddy, T., Patil, P., Fluhrer, S., and P. Quinn, Reddy, T., Patil, P., Fluhrer, S., and P. Quinn,
"Authenticated and encrypted NSH service chains", draft- "Authenticated and encrypted NSH service chains", Work in
reddy-sfc-nsh-encrypt-00 (work in progress), April 2015. Progress, draft-reddy-sfc-nsh-encrypt-00, April 2015.
[PROOF-OF-TRANSIT]
Brockners, F., Bhandari, S., Dara, S., Pignataro, C.,
Leddy, J., Youell, S., Mozes, D., and T. Mizrahi, "Proof
of Transit", Work in Progress, draft-brockners-proof-
of-transit-04, October 2017.
[RFC2784] Farinacci, D., Li, T., Hanks, S., Meyer, D., and P. [RFC2784] Farinacci, D., Li, T., Hanks, S., Meyer, D., and P.
Traina, "Generic Routing Encapsulation (GRE)", RFC 2784, Traina, "Generic Routing Encapsulation (GRE)", RFC 2784,
DOI 10.17487/RFC2784, March 2000, DOI 10.17487/RFC2784, March 2000,
<https://www.rfc-editor.org/info/rfc2784>. <https://www.rfc-editor.org/info/rfc2784>.
[RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC [RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC
Text on Security Considerations", BCP 72, RFC 3552, Text on Security Considerations", BCP 72, RFC 3552,
DOI 10.17487/RFC3552, July 2003, DOI 10.17487/RFC3552, July 2003,
<https://www.rfc-editor.org/info/rfc3552>. <https://www.rfc-editor.org/info/rfc3552>.
skipping to change at page 40, line 19 skipping to change at page 38, line 14
[RFC8165] Hardie, T., "Design Considerations for Metadata [RFC8165] Hardie, T., "Design Considerations for Metadata
Insertion", RFC 8165, DOI 10.17487/RFC8165, May 2017, Insertion", RFC 8165, DOI 10.17487/RFC8165, May 2017,
<https://www.rfc-editor.org/info/rfc8165>. <https://www.rfc-editor.org/info/rfc8165>.
[RFC8201] McCann, J., Deering, S., Mogul, J., and R. Hinden, Ed., [RFC8201] McCann, J., Deering, S., Mogul, J., and R. Hinden, Ed.,
"Path MTU Discovery for IP version 6", STD 87, RFC 8201, "Path MTU Discovery for IP version 6", STD 87, RFC 8201,
DOI 10.17487/RFC8201, July 2017, DOI 10.17487/RFC8201, July 2017,
<https://www.rfc-editor.org/info/rfc8201>. <https://www.rfc-editor.org/info/rfc8201>.
[RTG-ENCAP]
Nordmark, E., Tian, A., Gross, J., Hudson, J., Kreeger,
L., Garg, P., Thaler, P., and T. Herbert, "Encapsulation
Considerations", Work in Progress,
draft-ietf-rtgwg-dt-encap-02, October 2016.
[SFC-CONTROL-PLANE]
Boucadair, M., "Service Function Chaining (SFC) Control
Plane Components & Requirements", Work in Progress,
draft-ietf-sfc-control-plane-08, October 2016.
[SFC-OAM-FRAMEWORK]
Aldrin, S., Pignataro, C., Kumar, N., Akiya, N., Krishnan,
R., and A. Ghanwani, "Service Function Chaining (SFC)
Operation, Administration and Maintenance (OAM)
Framework", Work in Progress,
draft-ietf-sfc-oam-framework-03, September 2017.
[VXLAN-GPE]
Maino, F., Kreeger, L., and U. Elzur, "Generic Protocol
Extension for VXLAN", Work in Progress,
draft-ietf-nvo3-vxlan-gpe-05, October 2017.
Acknowledgments
The authors would like to thank Sunil Vallamkonda, Nagaraj Bagepalli,
Abhijit Patra, Peter Bosch, Darrel Lewis, Pritesh Kothari, Tal
Mizrahi, and Ken Gray for their detailed reviews, comments, and
contributions.
A special thank you goes to David Ward and Tom Edsall for their
guidance and feedback.
Additionally, the authors would like to thank Larry Kreeger for his
invaluable ideas and contributions, which are reflected throughout
this document.
Loa Andersson provided a thorough review and valuable comments; we
thank him for that.
Reinaldo Penno deserves a particular thank you for his architecture
and implementation work that helped guide the protocol concepts and
design.
The editors also acknowledge comprehensive reviews and respective
useful suggestions by Med Boucadair, Adrian Farrel, Juergen
Schoenwaelder, Acee Lindem, and Kathleen Moriarty.
Lastly, David Dolson has provided significant review, feedback, and
suggestions throughout the evolution of this document. His
contributions are very much appreciated.
Contributors
This WG document originated as draft-quinn-sfc-nsh; the following are
its coauthors and contributors along with their respective
affiliations at the time of WG adoption. The editors of this
document would like to thank and recognize them and their
contributions. These coauthors and contributors provided invaluable
concepts and content for this document's creation.
o Jim Guichard, Cisco Systems, Inc.
o Surendra Kumar, Cisco Systems, Inc.
o Michael Smith, Cisco Systems, Inc.
o Wim Henderickx, Alcatel-Lucent
o Tom Nadeau, Brocade
o Puneet Agarwal
o Rajeev Manur, Broadcom
o Abhishek Chauhan, Citrix
o Joel Halpern, Ericsson
o Sumandra Majee, F5
o David Melman, Marvell
o Pankaj Garg, Microsoft
o Brad McConnell, Rackspace
o Chris Wright, Red Hat, Inc.
o Kevin Glavin, Riverbed
o Hong (Cathy) Zhang, Huawei US R&D
o Louis Fourie, Huawei US R&D
o Ron Parker, Affirmed Networks
o Myo Zarny, Goldman Sachs
o Andrew Dolganow, Alcatel-Lucent
o Rex Fernando, Cisco Systems, Inc.
o Praveen Muley, Alcatel-Lucent
o Navindra Yadav, Cisco Systems, Inc.
Authors' Addresses Authors' Addresses
Paul Quinn (editor) Paul Quinn (editor)
Cisco Systems, Inc. Cisco Systems, Inc.
Email: paulq@cisco.com Email: paulq@cisco.com
Uri Elzur (editor) Uri Elzur (editor)
Intel Intel
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