draft-ietf-sfc-nsh-04.txt   draft-ietf-sfc-nsh-05.txt 
Network Working Group P. Quinn, Ed. Service Function Chaining P. Quinn, Ed.
Internet-Draft Cisco Systems, Inc. Internet-Draft Cisco Systems, Inc.
Intended status: Standards Track U. Elzur, Ed. Intended status: Standards Track U. Elzur, Ed.
Expires: September 22, 2016 Intel Expires: November 27, 2016 Intel
March 21, 2016 May 26, 2016
Network Service Header Network Service Header
draft-ietf-sfc-nsh-04.txt draft-ietf-sfc-nsh-05.txt
Abstract Abstract
This draft describes a Network Service Header (NSH) inserted onto This document describes a Network Service Header (NSH) inserted onto
encapsulated packets or frames to realize service function paths. encapsulated packets or frames to realize service function paths.
NSH also provides a mechanism for metadata exchange along the NSH also provides a mechanism for metadata exchange along the
instantiated service path. NSH is the SFC encapsulation as per SFC instantiated service path. NSH is the SFC encapsulation required to
Architecture [SFC-arch] support the Service Function Chaining (SFC) Architecture (defined in
RFC7665).
1. Requirements Language 1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
Status of this Memo Status of this Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
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working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
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Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
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time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 22, 2016. This Internet-Draft will expire on November 27, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
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the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Requirements Language . . . . . . . . . . . . . . . . . . . . 2 1. Requirements Language . . . . . . . . . . . . . . . . . . . . 2
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Definition of Terms . . . . . . . . . . . . . . . . . . . 4 2.1. Definition of Terms . . . . . . . . . . . . . . . . . . . 4
2.2. Problem Space . . . . . . . . . . . . . . . . . . . . . . 7 2.2. Problem Space . . . . . . . . . . . . . . . . . . . . . . 5
2.3. NSH-based Service Chaining . . . . . . . . . . . . . . . . 8 2.3. NSH-based Service Chaining . . . . . . . . . . . . . . . . 5
3. Network Service Header . . . . . . . . . . . . . . . . . . . . 10 3. Network Service Header . . . . . . . . . . . . . . . . . . . . 7
3.1. Network Service Header Format . . . . . . . . . . . . . . 10 3.1. Network Service Header Format . . . . . . . . . . . . . . 7
3.2. NSH Base Header . . . . . . . . . . . . . . . . . . . . . 10 3.2. NSH Base Header . . . . . . . . . . . . . . . . . . . . . 7
3.3. Service Path Header . . . . . . . . . . . . . . . . . . . 12 3.3. Service Path Header . . . . . . . . . . . . . . . . . . . 9
3.4. NSH MD-type 1 . . . . . . . . . . . . . . . . . . . . . . 13 3.4. NSH MD-type 1 . . . . . . . . . . . . . . . . . . . . . . 10
3.5. NSH MD-type 2 . . . . . . . . . . . . . . . . . . . . . . 13 3.5. NSH MD-type 2 . . . . . . . . . . . . . . . . . . . . . . 10
3.5.1. Optional Variable Length Metadata . . . . . . . . . . 14 3.5.1. Optional Variable Length Metadata . . . . . . . . . . 11
4. NSH Actions . . . . . . . . . . . . . . . . . . . . . . . . . 16 4. NSH Actions . . . . . . . . . . . . . . . . . . . . . . . . . 13
5. NSH Encapsulation . . . . . . . . . . . . . . . . . . . . . . 18 5. NSH Encapsulation . . . . . . . . . . . . . . . . . . . . . . 15
6. Fragmentation Considerations . . . . . . . . . . . . . . . . . 19 6. Fragmentation Considerations . . . . . . . . . . . . . . . . . 16
7. Service Path Forwarding with NSH . . . . . . . . . . . . . . . 20 7. Service Path Forwarding with NSH . . . . . . . . . . . . . . . 17
7.1. SFFs and Overlay Selection . . . . . . . . . . . . . . . . 20 7.1. SFFs and Overlay Selection . . . . . . . . . . . . . . . . 17
7.2. Mapping NSH to Network Overlay . . . . . . . . . . . . . . 22 7.2. Mapping NSH to Network Transport . . . . . . . . . . . . . 19
7.3. Service Plane Visibility . . . . . . . . . . . . . . . . . 23 7.3. Service Plane Visibility . . . . . . . . . . . . . . . . . 20
7.4. Service Graphs . . . . . . . . . . . . . . . . . . . . . . 23 7.4. Service Graphs . . . . . . . . . . . . . . . . . . . . . . 20
8. Policy Enforcement with NSH . . . . . . . . . . . . . . . . . 26 8. Policy Enforcement with NSH . . . . . . . . . . . . . . . . . 21
8.1. NSH Metadata and Policy Enforcement . . . . . . . . . . . 26 8.1. NSH Metadata and Policy Enforcement . . . . . . . . . . . 21
8.2. Updating/Augmenting Metadata . . . . . . . . . . . . . . . 27 8.2. Updating/Augmenting Metadata . . . . . . . . . . . . . . . 22
8.3. Service Path ID and Metadata . . . . . . . . . . . . . . . 29 8.3. Service Path Identifier and Metadata . . . . . . . . . . . 24
9. NSH Encapsulation Examples . . . . . . . . . . . . . . . . . . 31 9. NSH Encapsulation Examples . . . . . . . . . . . . . . . . . . 26
9.1. GRE + NSH . . . . . . . . . . . . . . . . . . . . . . . . 31 9.1. GRE + NSH . . . . . . . . . . . . . . . . . . . . . . . . 26
9.2. VXLAN-gpe + NSH . . . . . . . . . . . . . . . . . . . . . 31 9.2. VXLAN-gpe + NSH . . . . . . . . . . . . . . . . . . . . . 26
9.3. Ethernet + NSH . . . . . . . . . . . . . . . . . . . . . . 32 9.3. Ethernet + NSH . . . . . . . . . . . . . . . . . . . . . . 27
10. Security Considerations . . . . . . . . . . . . . . . . . . . 33 10. Security Considerations . . . . . . . . . . . . . . . . . . . 28
11. Open Items for WG Discussion . . . . . . . . . . . . . . . . . 34 11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 29
12. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 35 12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 32
13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 38 13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 33
14. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 39 13.1. NSH EtherType . . . . . . . . . . . . . . . . . . . . . . 33
14.1. NSH EtherType . . . . . . . . . . . . . . . . . . . . . . 39 13.2. Network Service Header (NSH) Parameters . . . . . . . . . 33
14.2. Network Service Header (NSH) Parameters . . . . . . . . . 39 13.2.1. NSH Base Header Reserved Bits . . . . . . . . . . . . 33
14.2.1. NSH Base Header Reserved Bits . . . . . . . . . . . . 39 13.2.2. NSH Version . . . . . . . . . . . . . . . . . . . . . 33
14.2.2. MD Type Registry . . . . . . . . . . . . . . . . . . . 39 13.2.3. MD Type Registry . . . . . . . . . . . . . . . . . . . 33
14.2.3. TLV Class Registry . . . . . . . . . . . . . . . . . . 40 13.2.4. MD Class Registry . . . . . . . . . . . . . . . . . . 34
14.2.4. NSH Base Header Next Protocol . . . . . . . . . . . . 40 13.2.5. NSH Base Header Next Protocol . . . . . . . . . . . . 34
15. References . . . . . . . . . . . . . . . . . . . . . . . . . . 41 14. References . . . . . . . . . . . . . . . . . . . . . . . . . . 36
15.1. Normative References . . . . . . . . . . . . . . . . . . . 41 14.1. Normative References . . . . . . . . . . . . . . . . . . . 36
15.2. Informative References . . . . . . . . . . . . . . . . . . 41 14.2. Informative References . . . . . . . . . . . . . . . . . . 36
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 43 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 38
2. Introduction 2. 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, campus, and so forth. such as the wide area network, data center, campus, and so forth.
The current service function deployment models are relatively static, Prior to development of the SFC architecture [RFC7665] and the
and bound to topology for insertion and policy selection. protocol specified in this document, current service function
Furthermore, they do not adapt well to elastic service environments deployment models have been relatively static, and bound to topology
enabled by virtualization. for insertion and policy selection. Furthermore, they do not adapt
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 requires an agile service insertion model that virtual platforms requires an agile service insertion model that
supports dynamic and elastic service delivery; the movement of supports dynamic and elastic service delivery; the movement of
service functions and application workloads in the network and the service functions and application workloads in the network and the
ability to easily bind service policy to granular information such as ability to easily bind service policy to granular information such as
per-subscriber state and steer traffic to the requisite service per-subscriber state and steer traffic to the requisite service
function(s) are necessary. function(s) are necessary.
NSH defines a new dataplane protocol specifically for the creation of NSH defines a new service plane protocol specifically for the
dynamic service chains and is composed of the following elements: creation of dynamic service chains and is composed of the following
elements:
1. Service Function Path identification 1. Service Function Path identification
2. Transport independent service function chain 2. Transport independent service function chain
3. Per-packet network and service metadata or optional variable TLV 3. Per-packet network and service metadata or optional variable
metadata. type-length-value (TLV) metadata.
NSH is designed to be easy to implement across a range of devices, NSH is designed to be easy to implement across a range of devices,
both physical and virtual, including hardware platforms. both physical and virtual, including hardware platforms.
An NSH aware control plane is outside the scope of this document. An NSH-aware control plane is outside the scope of this document.
The SFC Architecture document [SFC-arch] provides an overview of a [RFC7665] provides an overview of a service chaining architecture
service chaining architecture that clearly defines the roles of the that clearly defines the roles of the various elements and the scope
various elements and the scope of a service function chaining of a service function chaining encapsulation. NSH is the SFC
encapsulation. NSH is the SFC encapsulation defined in that draft. encapsulation referenced in RFC7665 document.
2.1. Definition of Terms 2.1. Definition of Terms
Classification: Locally instantiated matching of traffic flows Classification: Defined in [RFC7665].
against policy for subsequent application of the required set of
network service functions. The policy may be customer/network/
service specific.
Service Function Forwarder (SFF): A service function forwarder is
responsible for forwarding traffic to one or more connected
service functions according to information carried in the NSH, as
well as handling traffic coming back from the SF. Additionally, a
service function forwarder is responsible for transporting traffic
to another SFF (in the same or different type of overlay), and
terminating the SFP.
Service Function (SF): A function that is responsible for specific
treatment of received packets. A Service Function can act at
various layers of a protocol stack (e.g., at the network layer or
other OSI layers). As a logical component, a Service Function can
be realized as a virtual element or be embedded in a physical
network element. One or more Service Functions can be embedded in
the same network element. Multiple occurrences of the Service
Function can exist in the same administrative domain.
One or more Service Functions can be involved in the delivery of
added-value services. A non-exhaustive list of abstract Service
Functions includes: firewalls, WAN and application acceleration,
Deep Packet Inspection (DPI), LI (Lawful Intercept), server load
balancing, NAT44 [RFC3022], NAT64 [RFC6146], NPTv6 [RFC6296],
HOST_ID injection, HTTP Header Enrichment functions, TCP
optimizer.
An SF may be NSH-aware, that is it receives and acts on Classifier: Defined in [RFC7665].
information in the NSH. The SF may also be NSH-unaware in which
case data forwarded to the SF does not contain NSH.
Service Function Chain (SFC): A service function chain defines an Metadata: Defined in [RFC7665].
ordered set of abstract service functions (SFs) and ordering
constraints that must be applied to packets and/or frames and/or
flows selected as a result of classification. An example of an
abstract service function is "a firewall". The implied order may
not be a linear progression as the architecture allows for SFCs
that copy to more than one branch, and also allows for cases where
there is flexibility in the order in which service functions need
to be applied. The term service chain is often used as shorthand
for service function chain.
Service Function Path (SFP): The Service Function Path is a Network Locator: dataplane address, typically IPv4 or IPv6, used to
constrained specification of where packets assigned to a certain send and receive network traffic.
service function path must go. While it may be so constrained as
to identify the exact locations, it can also be less specific.
The SFP provides a level of indirection between the fully abstract
notion of service chain as a sequence of abstract service
functions to be delivered, and the fully specified notion of
exactly which SFF/SFs the packet will visit when it actually
traverses the network. By allowing the control components to
specify this level of indirection, the operator may control the
degree of SFF/SF selection authority that is delegated to the
network.
Network Node/Element: Device that forwards packets or frames based Network Node/Element: Device that forwards packets or frames based
on outer header information. on outer header (i.e. transport) information.
Network Overlay: Logical network built on top of existing network Network Overlay: Logical network built on top of 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.
Network Service Header: provides SFP identification, and is used by
the NSH-aware functions, such as the Classifier, SFF and NSH-aware
SFs. In addition to SFP identification, the NSH may carry data
plane metadata.
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 NSH. The initial classifier perform classification and impose 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.
Network Locator: dataplane address, typically IPv4 or IPv6, used to Service Function (SF): Defined in [RFC7665].
send and receive network traffic.
NSH Proxy: Removes and inserts NSH on behalf of an NSH-unaware
service function. The proxy node removes the NSH header and
delivers the original packet/frame via a local attachment circuit
to the service function. Examples of a local attachment circuit
include, but are not limited to: VLANs, IP in IP, GRE, VXLAN.
When complete, the Service Function returns the packet to the NSH
proxy via the same or different attachment circuit. The NSH
Proxy, in turn, re-imposes NSH on the returned packets. Often, an
SFF will act as an NSH-proxy when required.
2.2. Problem Space
Network Service Header (NSH) addresses several limitations associated
with service function deployments today (i.e. prior to use of NSH).
A short reference is included below, RFC 7498 [RFC7498], provides a
more comprehensive review of the SFC Problem Statement.
1. Topological Dependencies: Network service deployments are often
coupled to network topology. Such a dependency imposes
constraints on the service delivery, potentially inhibiting the
network operator from optimally utilizing service resources, and
reduces the flexibility. This limits scale, capacity, and
redundancy across network resources.
2. Service Chain Construction: Service function chains today are Service Function Chain (SFC): Defined in [RFC7665].
most typically built through manual configuration processes.
These are slow and error prone. With the advent of newer dynamic
service deployment models, the control/management planes provide
not only connectivity state, but will also be increasingly
utilized for the creation of network services. Such a control/
management planes could be centralized, or be distributed.
3. Application of Service Policy: Service functions rely on topology Service Function Forwarder (SFF): Defined in [RFC7665].
information such as VLANs or packet (re) classification to
determine service policy selection, i.e. the service function
specific action taken. Topology information is increasingly less
viable due to scaling, tenancy and complexity reasons. The
topological information is often stale, providing the operator
with inaccurate service Function (SF) placement that can result
in suboptimal resource utilization. Furthermore topology-centric
information often does not convey adequate information to the
service functions, forcing functions to individually perform more
granular classification.
4. Per-Service (re)Classification: Classification occurs at each Service Function Path (SFP): Defined in [RFC7665].
service function independent from previously applied service
functions. More importantly, the classification functionality
often differs per service function and service functions may not
leverage the results from other service functions.
5. Common Header Format: Various proprietary methods are used to SFC Proxy: Defined in [RFC7665].
share metadata and create service paths. A standardized protocol
provides a common format for all network and service devices.
6. Limited End-to-End Service Visibility: Troubleshooting service 2.2. Problem Space
related issues is a complex process that involve both network-
specific and service-specific expertise. This is especially the
case, when service function chains span multiple DCs, or across
administrative boundaries. Furthermore, physical and virtual
environments (network and service) can be highly divergent in
terms of topology and that topological variance adds to these
challenges.
7. Transport Dependence: Service functions can and will be deployed Network Service Header (NSH) addresses several limitations associated
in networks with a range of transports requiring service with service function deployments. RFC 7498 [RFC7498] provides a
functions to support and participate in many transports (and comprehensive review of those issues.
associated control planes) or for a transport gateway function to
be present.
2.3. NSH-based Service Chaining 2.3. NSH-based Service Chaining
The NSH creates a dedicated service plane, that addresses many of the The NSH creates a dedicated service plane, more specifically, NSH
limitations highlighted in Section 2.2. More specifically, NSH
enables: enables:
1. Topological Independence: Service forwarding occurs within the 1. Topological Independence: Service forwarding occurs within the
service plane, via a network overlay, the underlying network service plane, the underlying network topology does not require
topology does not require modification. NSH provides an modification. NSH provides an identifier used to select the
identifier used to select the network overlay for network network overlay for network forwarding.
forwarding.
2. Service Chaining: NSH contains path identification information 2. Service Chaining: NSH enables Service Chaining per [RFC7665].
needed to realize a service path. Furthermore, NSH provides the NSH contains path identification information needed to realize a
ability to monitor and troubleshoot a service chain, end-to-end service path. Furthermore, NSH provides the ability to monitor
via service-specific OAM messages. The NSH fields can be used by and troubleshoot a service chain, end-to-end via service-specific
administrators (via, for example a traffic analyzer) to verify OAM messages. The NSH fields can be used by administrators (via,
(account, ensure correct chaining, provide reports, etc.) the for example a traffic analyser) to verify (account, ensure
path specifics of packets being forwarded along a service path. correct chaining, provide reports, etc.) the path specifics of
packets being forwarded along a service path.
3. NSH provides a mechanism to carry shared metadata between network 3. NSH provides a mechanism to carry shared metadata between network
devices and service function, and between service functions. The devices and service function, and between service functions. The
semantics of the shared metadata is communicated via a control semantics of the shared metadata is communicated via a control
plane to participating nodes. Examples of metadata include plane to participating nodes. Examples of metadata include
classification information used for policy enforcement and classification information used for policy enforcement and
network context for forwarding post service delivery. network context for forwarding post service delivery.
4. Classification and re-classification: sharing the metadata allows 4. Classification and re-classification: sharing the metadata allows
service functions to share initial and intermediate service functions to share initial and intermediate
classification results with downstream service functions saving classification results with downstream service functions saving
re-classification, where enough information was enclosed. re-classification, where enough information was enclosed.
5. NSH offers a common and standards based header for service 5. NSH offers a common and standards-based header for service
chaining to all network and service nodes. chaining to all network and service nodes.
6. Transport Agnostic: NSH is transport independent and is carried 6. Transport Agnostic: NSH is transport independent and is often
in an overlay, over existing underlays. If an existing overlay carried via a network transport protocol, over existing
topology provides the required service path connectivity, that underlays. This transport may form an overlay network and if an
existing overlay may be used. existing overlay topology provides the required service path
connectivity, that existing overlay may be used.
3. Network Service Header 3. Network Service Header
A Network Service Header (NSH) contains service path information and A Network Service Header (NSH) contains service path information and
optionally metadata that are added to a packet or frame and used to optionally metadata that are added to a packet or frame and used to
create a service plane. The original packets preceded by NSH, are create a service plane. The original packets preceded by NSH, are
then encapsulated in an outer header for transport. then encapsulated in an outer header for transport.
NSH is added by a Service Classifier. The NSH header is removed by A Service Classifier adds the NSH. The NSH is removed by the last
the last SFF in the chain or by a SF that consumes the packet. SFF in the service chain or by a SF that consumes the packet.
3.1. Network Service Header Format 3.1. Network Service Header Format
A NSH is composed of a 4-byte Base Header, a 4-byte Service Path An NSH is composed of a 4-byte Base Header, a 4-byte Service Path
Header and Context Headers, as shown in Figure 1 below. Header and Context Headers, as shown in Figure 1 below.
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 Headers ~ ~ Context Headers ~
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Network Service Header Figure 1: 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: provide path identification and location within Service Path Header: provide path identification and location within
a path. a service path.
Context headers: carry opaque metadata and variable length encoded Context headers: carry metadata (i.e. context data) along a service
information. path.
3.2. NSH Base Header 3.2. NSH Base Header
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|C|R|R|R|R|R|R| Length | MD Type | Next Protocol | |Ver|O|C|R|R|R|R|R|R| Length | MD Type | Next Protocol |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: NSH Base Header Figure 2: NSH Base Header
Base Header Field Descriptions: Base Header Field Descriptions:
Version: The version field is used to ensure backward compatibility Version: The version field is used to ensure backward compatibility
going forward with future NSH updates. It MUST be set to 0x0 by the going forward with future NSH updates. It MUST be set to 0x0 by the
sender, in this first revision of NSH. sender, in this first revision of NSH. Given the widespread
implementation of existing hardware that uses the first nibble after
O bit: when set to 0x1 indicates that this packet is an operations an MPLS label stack for ECMP decision processing, this document
and management (OAM) packet. The receiving SFF and SFs nodes MUST reserves version 01 and this value MUST NOT be used in future
examine the payload and take appropriate action (e.g. return status versions of the protocol.
information).
OAM message specifics and handling details are outside the scope of O bit: when set to 0x1 indicates that this packet is an Operations,
this document. Administration and Maintenance (OAM) message. The receiving SFF and
SFs nodes MUST examine the payload and take appropriate action (e.g.
return status information). OAM message specifics and handling
details are outside the scope of this document.
C bit: Indicates that a critical metadata TLV is present (see Section C bit: Indicates that a critical metadata TLV is present. This bit
3.4.2). This bit acts as an indication for hardware implementers to acts as an indication for hardware implementers to decide how to
decide how to handle the presence of a critical TLV without handle the presence of a critical TLV without necessarily needing to
necessarily needing to parse all TLVs present. The C bit MUST be set parse all TLVs present. For an MD Type of 0x1 (i.e. no variable
to 0x0 when MD Type= 0x1 and MAY be used with MD Type = 0x2 and MUST length metadata is present), the C bit MUST be set to 0x0.
be set to 0x1 if one or more critical TLVs are present.
All other flag fields are reserved for future use. Reserved bits All other flag fields are reserved for future use. Reserved bits
MUST be set to zero and MUST be ignored upon receipt. MUST be set to zero when sent and MUST be ignored upon receipt.
Length: total length, in 4-byte words, of NSH including the Base Length: total length, in 4-byte words, of NSH including the Base
Header, the Service Path Header and the optional variable TLVs. The Header, the Service Path Header and the context headers or optional
Length MUST be of value 0x6 for MD Type = 0x1 and MUST be of value variable length metadata. The Length MUST be of value 0x6 for MD
0x2 or higher for MD Type = 0x2. The NSH header length MUST be an Type equal to 0x1 and MUST be of value 0x2 or greater for MD Type
integer number of 4 bytes. The length field MUST be used to equal to 0x2. The NSH header length MUST be an integer number of 4
determine the "end" of NSH and where the original packet/frame bytes. The length field indicates the "end" of NSH and where the
begins. original packet/frame begins.
MD Type: indicates the format of NSH beyond the mandatory Base Header MD Type: indicates the format of NSH beyond the mandatory Base Header
and the Service Path Header. MD Type defines the format of the and the Service Path Header. MD Type defines the format of the
metadata being carried. A new registry will be requested from IANA metadata being carried. Please see IANA Considerations section
for the MD Type. below.
NSH defines two MD types: NSH defines two MD types:
0x1 - which indicates that the format of the header includes fixed 0x1 - which indicates that the format of the header includes fixed
length context headers (see Figure 4 below). length context headers (see Figure 4 below).
0x2 - which does not mandate any headers beyond the Base Header and 0x2 - which does not mandate any headers beyond the Base Header and
Service Path Header, and may contain optional variable length context Service Path Header, but may contain optional variable length context
information. information.
The format of the base header and the service path header is The format of the base header and the service path header is
invariant, and not affected by MD Type. invariant, and not affected by MD Type.
NSH implementations MUST support MD-Type = 0x1, and SHOULD support NSH implementations MUST support MD-Type = 0x1, and SHOULD support
MD- Type = 0x2. There exists, however, a middle ground, wherein a MD- Type = 0x2. There exists, however, a middle ground, wherein a
device will support MD-Type 1 (as per the MUST) metadata, yet device will support MD-Type 0x1 (as per the MUST) metadata, yet be
participate in the a network with MD-Type 2 metadata packets. In deployed in a network with MD-Type 0x2 metadata packets. In that
that case, the type-1 node, MUST utilize the base header length field case, the MD-Type 0x1 node, MUST utilize the base header length field
to determine the original payload offset if it requires access to the to determine the original payload offset if it requires access to the
original packet/frame. original packet/frame.
Next Protocol: indicates the protocol type of the original packet. A Next Protocol: indicates the protocol type of the original packet.
new IANA registry will be created for protocol type. Please see IANA Considerations section below.
This draft defines the following Next Protocol values: This draft defines the following Next Protocol values:
0x1 : IPv4 0x1 : IPv4
0x2 : IPv6 0x2 : IPv6
0x3 : Ethernet 0x3 : Ethernet
0x4: NSH
0x5: MPLS
0x6-0xFD: Unassigned
0xFE-0xFF: Experimental 0xFE-0xFF: Experimental
3.3. Service Path Header 3.3. Service Path Header
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 ID | Service Index | | Service Path Identifier (SPI) | Service Index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Service path ID (SPI): 24 bits Service Path Identifier (SPI): 24 bits
Service index (SI): 8 bits Service Index (SI): 8 bits
Figure 3: NSH Service Path Header Figure 3: NSH Service Path Header
Service Path Identifier (SPI): identifies a service path. Service Path Identifier (SPI): identifies a service path.
Participating nodes MUST use this identifier for Service Function Participating nodes MUST use this identifier for Service Function
Path selection. Path selection.
Service Index (SI): provides location within the SFP. The first Service Index (SI): provides location within the SFP. The first
Classifier (i.e. at the boundary of the NSH domain)in the NSH Service classifier (i.e. at the boundary of the NSH domain) in the NSH
Function Path, SHOULD set the SI to 255, however the control plane Service Function Path, SHOULD set the SI to 255, however the control
MAY configure the initial value of SI as appropriate (i.e. taking plane MAY configure the initial value of SI as appropriate (i.e.
into account the length of the service function path). A Classifier taking into account the length of the service function path). A
MUST send the packet to the first SFF in the chain. Service index Classifier MUST send the packet to the first SFF in the chain.
MUST be decremented by service functions or proxy nodes after Service index MUST be decremented by service functions or proxy nodes
performing required services and the new decremented SI value MUST be after performing required services and the new decremented SI value
reflected in the egress NSH packet. SI MAY be used in conjunction MUST be used in the egress NSH packet. SI SHOULD be used in
with Service Path ID for Service Function Path selection. Service conjunction with Service Path Identifier for Service Function Path
Index (SI) is also valuable when troubleshooting/reporting service selection. Service Index (SI) is also valuable when troubleshooting/
paths. In addition to indicating the location within a Service reporting service paths. In addition to indicating the location
Function Path, SI can be used for loop detection. within a Service Function Path, SI can be used for service plane loop
detection.
3.4. NSH MD-type 1 3.4. NSH MD-type 1
When the Base Header specifies MD Type = 0x1, four Context Header, When the Base Header specifies MD Type = 0x1, four Context Headers,
4-byte each, MUST be added immediately following the Service Path 4-byte each, MUST be added immediately following the Service Path
Header, as per Figure 4. Context Headers that carry no metadata MUST Header, as per Figure 4. Context Headers that carry no metadata MUST
be set to zero. be set to zero.
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|C|R|R|R|R|R|R| Length | MD-type=0x1 | Next Protocol | |Ver|O|C|R|R|R|R|R|R| Length | MD-type=0x1 | Next Protocol |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Service Path ID | Service Index | | Service Path Identifer | Service Index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mandatory Context Header | | Mandatory Context Header |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mandatory Context Header | | Mandatory Context Header |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mandatory Context Header | | Mandatory Context Header |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mandatory Context Header | | Mandatory Context Header |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: NSH MD-type=0x1 Figure 4: NSH MD-type=0x1
Draft-dc [dcalloc] and draft-mobility [moballoc] provide specific [dcalloc] and [broadalloc] provide specific examples of how metadata
examples of how metadata can be allocated. can be allocated.
3.5. NSH MD-type 2 3.5. 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. Therefore, Length = 0x2, indicates that only Service Path Header. Therefore, Length = 0x2, indicates that only
the Base Header followed by the Service Path Header are present. The the Base Header followed by the Service Path Header are present. The
optional Variable Length Context Headers MUST be of an integer number optional Variable Length Context Headers MUST be of an integer number
of 4-bytes. The base header length field MUST be used to determine of 4-bytes. The base header length field MUST be used to determine
the offset to locate the original packet or frame for SFC nodes that the offset to locate the original packet or frame for SFC nodes that
require access to that information. require access to that information.
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|C|R|R|R|R|R|R| Length | MD-type=0x2 | Next Protocol | |Ver|O|C|R|R|R|R|R|R| Length | MD-type=0x2 | Next Protocol |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Service Path ID | Service Index | | Service Path Identifier | Service Index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
~ Variable Length Context Headers (opt.) ~ ~ Variable Length Context Headers (opt.) ~
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: NSH MD-type=0x2 Figure 5: NSH MD-type=0x2
3.5.1. Optional Variable Length Metadata 3.5.1. 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
described below. described below.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Class |C| Type |R|R|R| Len | | Metadata Class |C| Type |R|R|R| Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Variable Metadata | | Variable Metadata |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: Variable Context Headers Figure 6: Variable Context Headers
TLV Class: describes the scope of the "Type" field. In some cases, Metadata Class (MD Class): describes the scope of the "Type" field.
the TLV Class will identify a specific vendor, in others, the TLV In some cases, the MD Class will identify a specific vendor, in
Class will identify specific standards body allocated types. A new others, the MD Class will identify specific standards body allocated
IANA registry will be created for TLV Class type. types. Please see IANA Considerations section below.
Type: the specific type of information being carried, within the Type: the specific type of information being carried, within the
scope of a given TLV Class. Value allocation is the responsibility scope of a given MD Class. Value allocation is the responsibility of
of the TLV Class owner. the MD Class owner.
Encoding the criticality of the TLV within the Type field is Encoding the criticality of the TLV within the Type field is
consistent with IPv6 option types: the most significant bit of the consistent with IPv6 option types: the most significant bit of the
Type field indicates whether the TLV is mandatory for the receiver to Type field indicates whether the TLV is mandatory for the receiver to
understand/process. This effectively allocates Type values 0 to 127 understand/process. This effectively allocates Type values 0 to 127
for non-critical options and Type values 128 to 255 for critical for non-critical options and Type values 128 to 255 for critical
options. Figure 7 below illustrates the placement of the Critical options. Figure 7 below illustrates the placement of the Critical
bit within the Type field. bit within the Type field.
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|C| Type | |C| Type |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Figure 7: Critical Bit Placement Within the TLV Type Field Figure 7: Critical Bit Placement Within the TLV Type Field
If a receiver receives an encapsulated packet containing a TLV with If an NSH-aware node receives an encapsulated packet containing a TLV
the Critical bit set to 0x1 in the Type field and it does not with the Critical bit set to 0x1 in the Type field and it does not
understand how to process the Type, it MUST drop the packet. Transit understand how to process the Type, it MUST drop the packet. Transit
devices MUST NOT drop packets based on the setting of this bit. devices (i.e. network nodes that do not participate in the service
plane) MUST NOT drop packets based on the setting of this bit.
Reserved bits: three reserved bit are present for future use. The Reserved bits: three reserved bit are present for future use. The
reserved bits MUST be set to 0x0. reserved bits MUST be set to 0x0.
Length: Length of the variable metadata, in 4-byte words. A value of Length: Length of the variable metadata, in 4-byte words. A value of
0x0 or higher can be used. A value of 0x0 denotes a TLV header 0x0 or higher can be used. A value of 0x0 denotes a TLV header
without a Variable Metadata field. without a Variable Metadata field.
4. NSH Actions 4. NSH Actions
NSH-aware nodes are the only nodes that MAY alter the content of the NSH-aware nodes are the only nodes that MAY alter the content of the
NSH headers. NSH-aware nodes include: service classifiers, SFF, SF NSH headers. NSH-aware nodes include: service classifiers, SFF, SF
and NSH proxies. These nodes have several possible header related and SFC proxies. These nodes have several possible header related
actions: actions:
1. Insert or remove NSH: These actions can occur at the start and 1. Insert or remove NSH: These actions can occur at the start and
end respectively of a service path. Packets are classified, and end respectively of a service path. Packets are classified, and
if determined to require servicing, NSH will be imposed. A if determined to require servicing, NSH will be imposed. A
service classifier MUST insert NSH at the start of an SFP. An service classifier MUST insert NSH at the start of an SFP. An
imposed NSH MUST contain valid Base Header and Service Path imposed NSH MUST contain valid Base Header and Service Path
Header. At the end of a service function path, a SFF, MUST be Header. At the end of a service function path, a SFF, MUST be
the last node operating on the service header and MUST remove it. the last node operating on the service header and MUST remove it.
skipping to change at page 16, line 34 skipping to change at page 13, line 34
a change of service path, it MUST remove the existing NSH and a change of service path, it MUST remove the existing NSH and
MUST impose a new NSH with the Base Header and Service Path MUST impose a new NSH with the Base Header and Service Path
Header reflecting the new service path information and set the Header reflecting the new service path information and set the
initial SI. Metadata MAY be preserved in the new NSH. initial SI. Metadata 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
chain information and is used by SFFs to determine correct chain information and is used by SFFs to determine correct
service path selection. SFFs MUST use the Service Path Header service path selection. SFFs MUST use the Service Path Header
for selecting the next SF or SFF in the service path. for selecting the next SF or SFF in the service path.
3. Update a Service Path Header: NSH aware service functions (SF) 3. Update a Service Path Header: NSH-aware service functions (SF)
MUST decrement the service index. A service index = 0x0 MUST decrement the service index. If an SFF receives a packet
indicates that a packet MUST be dropped by the SFF. with SI equal to 0x0, that packet MUST be dropped by the SFF.
Classifier(s) MAY update Context Headers if new/updated context Classifier(s) MAY update Context Headers if new/updated context
is available. is available.
If an NSH proxy (see Section 7) is in use (acting on behalf of a If an SFC proxy is in use (acting on behalf of a non-NSH-aware
non-NSH-aware service function for NSH actions), then the proxy service function for NSH actions), then the proxy MUST update
MUST update Service Index and MAY update contexts. When an NSH Service Index and MAY update contexts. When an SFC proxy
proxy receives an NSH-encapsulated packet, it MUST remove the NSH receives an NSH-encapsulated packet, it MUST remove the NSH
headers before forwarding it to an NSH unaware SF. When the NSH headers before forwarding it to an NSH unaware SF. When the SFC
Proxy receives a packet back from an NSH unaware SF, it MUST re- Proxy receives a packet back from an NSH unaware SF, it MUST re-
encapsulate it with the correct NSH, and MUST also decrement the encapsulates it with the correct NSH, and MUST decrement the
Service Index. Service Index.
4. Service policy selection: Service Function instances derive 4. Service policy selection: Service Function instances derive
policy (i.e. service actions such as permit or deny) selection policy (i.e. service actions such as permit or deny) selection
and enforcement from the service header. Metadata shared in the and enforcement from the service header. Metadata shared in the
service header can provide a range of service-relevant service header can provide a range of service-relevant
information such as traffic classification. Service functions information such as traffic classification. Service functions
SHOULD use NSH to select local service policy. SHOULD use NSH to select local service policy.
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
skipping to change at page 17, line 30 skipping to change at page 14, line 30
| | | | | Dec. |Update | | | | | | | Dec. |Update | |
| | Insert | Remove | |Service |Context| | | | Insert | Remove | |Service |Context| |
| | | | | Index |Header | | | | | | | Index |Header | |
+----------------+--------+--------+-------+--------+-------+---------+ +----------------+--------+--------+-------+--------+-------+---------+
| | + | + | | | + | | | | + | + | | | + | |
|Classifier | | | | | | | |Classifier | | | | | | |
+--------------- +--------+--------+-------+--------+-------+---------+ +--------------- +--------+--------+-------+--------+-------+---------+
|Service Function| | + | + | | | | |Service Function| | + | + | | | |
|Forwarder(SFF) | | | | | | | |Forwarder(SFF) | | | | | | |
+--------------- +--------+--------+-------+--------+-------+---------+ +--------------- +--------+--------+-------+--------+-------+---------+
|Service | | | | + | | + | |Service | | | | + | + | + |
|Function (SF) | | | | | | | |Function (SF) | | | | | | |
+--------------- +--------+--------+-------+--------+-------+---------+ +--------------- +--------+--------+-------+--------+-------+---------+
|NSH Proxy | + | + | | + | | | |SFC Proxy | + | + | | + | | |
+----------------+--------+--------+-------+--------+-------+---------+ +----------------+--------+--------+-------+--------+-------+---------+
Figure 8: NSH Action and Role Mapping Figure 8: NSH Action and Role Mapping
5. NSH Encapsulation 5. NSH Encapsulation
Once NSH is added to a packet, an outer encapsulation is used to Once NSH is added to a packet, an outer encapsulation is used to
forward the original packet and the associated metadata to the start forward the original packet and the associated metadata to the start
of a service chain. The encapsulation serves two purposes: of a service chain. The encapsulation serves two purposes:
skipping to change at page 19, line 10 skipping to change at page 16, line 10
indicated via protocol type or other indicator in the outer indicated via protocol type or other indicator in the outer
encapsulation. encapsulation.
See Section 9 for NSH encapsulation examples. See Section 9 for NSH encapsulation examples.
6. Fragmentation Considerations 6. Fragmentation Considerations
NSH and the associated transport header are "added" to the NSH and the associated transport header are "added" to the
encapsulated packet/frame. This additional information increases the encapsulated packet/frame. This additional information increases the
size of the packet. In order the ensure proper forwarding of NSH size of the packet. In order the ensure proper forwarding of NSH
data, several options for handling fragmentation and re-assembly packets, several options for handling fragmentation and re-assembly
exist: exist:
1. Jumbo Frames, when supported, enable the transport of NSH and 1. Jumbo Frames, when supported, enable the transport of NSH and
associated transport packets without requiring fragmentation. associated transport packets without requiring fragmentation.
2. Path MTU Discovery [RFC1191]"describes a technique for 2. and [RFC1191][RFC1981] describe a technique for dynamically
dynamically discovering the maximum transmission unit (MTU) of an discovering the maximum transmission unit (MTU) of an arbitrary
arbitrary internet path" and can be utilized to ensure the the internet path" and can be utilized to ensure the required packet
required packet size is used. size is used.
3. [RFC6830] describes two schemes for fragmentation and re-assembly 3. Use the fragmentation provided by the network transport/overlay.
in section 5.4. One example can be found in [RFC6830], section 5.4.
7. Service Path Forwarding with NSH 7. Service Path Forwarding with NSH
7.1. SFFs and Overlay Selection 7.1. SFFs and Overlay Selection
As described above, NSH contains a Service Path Identifier (SPI) and As described above, NSH contains a Service Path Identifier (SPI) and
a Service Index (SI). The SPI is, as per its name, an identifier. a Service Index (SI). The SPI is, as per its name, an identifier.
The SPI alone cannot be used to forward packets along a service path. The SPI alone cannot be used to forward packets along a service path.
Rather the SPI provide a level of indirection between the service Rather the SPI provide a level of indirection between the service
path/topology and the network transport. Furthermore, there is no path/topology and the network transport. Furthermore, there is no
skipping to change at page 20, line 25 skipping to change at page 17, line 25
or static network path. or static 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, and is used to
select the appropriate network locator(s) for overlay forwarding. select the appropriate network locator(s) for overlay forwarding.
The logical SF may be a single SF, or a set of eligible SFs that are The logical SF may be a single SF, or a set of eligible SFs that are
equivalent. In the latter case, the SFF provides load distribution equivalent. In the latter case, the SFF provides load distribution
amongst the collection of SFs as needed. amongst the collection of SFs as needed.
SI may also serve as a mechanism for loop detection within a service SI can also serve as a mechanism for loop detection within a service
path since each SF in the path decrements the index; an Service Index path since each SF in the path decrements the index; an Service Index
of 0 indicates that a loop occurred and packet must be discarded. of 0 indicates that a loop occurred and the packet must be discarded.
This indirection -- path ID to overlay -- creates a true service This indirection -- path ID to overlay -- creates a true service
plane. That is the SFF/SF topology is constructed without impacting plane. That is the SFF/SF topology is constructed without impacting
the network topology but more importantly service plane only the 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.). As mentioned above, an existing overlay routing tables, etc.). As mentioned above, an existing overlay
topology may be used provided it offers the requisite connectivity. topology may be used provided it offers the requisite connectivity.
The mapping of SPI to transport occurs on an SFF (as discussed above, The mapping of SPI to transport occurs on an SFF (as discussed above,
the first SFF in the path gets a NSH encapsulated packet from the the first SFF in the path gets a NSH encapsulated packet from the
Classifier). The SFF consults the SPI/ID values to determine the Classifier). The SFF consults the SPI/ID values to determine the
appropriate overlay transport protocol (several may be used within a appropriate overlay transport protocol (several may be used within a
given network) and next hop for the requisite SF. Figure 9 below given network) and next hop for the requisite SF. Figure 9 below
depicts a simple, single next-hop SPI/SI to network overlay network depicts an example of a single next-hop SPI/SI to network overlay
locator mapping. network locator mapping.
+-------------------------------------------------------+ +-------------------------------------------------------+
| SPI | SI | NH | Transport | | SPI | SI | NH | Transport |
+-------------------------------------------------------+ +-------------------------------------------------------+
| 10 | 255 | 1.1.1.1 | VXLAN-gpe | | 10 | 255 | 192.0.2.1 | VXLAN-gpe |
| 10 | 254 | 2.2.2.2 | nvGRE | | 10 | 254 | 198.51.100.10 | GRE |
| 10 | 251 | 10.1.2.3 | GRE | | 10 | 251 | 198.51.100.15 | GRE |
| 40 | 251 | 10.1.2.3 | 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 |
+-------------------------------------------------------+ +-------------------------------------------------------+
Figure 9: SFF NSH Mapping Example Figure 9: 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 a service function chain control plane responsibility, as
per figures 10 and 11 below. per figures 10 and 11 below.
Please note: VXLAN-gpe and GRE in the above table refer to
[VXLAN-gpe] and [RFC2784], respectively.
+-------------------+ +-------------------+
| SPI | SI | NH | | SPI | SI | NH |
+-------------------+ +-------------------+
| 10 | 3 | SF2 | | 10 | 3 | SF2 |
| 245 | 12 | SF34 | | 245 | 12 | SF34 |
| 40 | 9 | SF9 | | 40 | 9 | SF9 |
+-------------------+ +-------------------+
Figure 10: NSH to SF Mapping Example Figure 10: NSH to SF Mapping Example
+-----------------------------------+ +----------------------------------------+
| SF | NH | Transport | | SF | NH | Transport |
+-----------------------------------| +----------------------------------------|
| SF2 | 10.1.1.1 | VXLAN-gpe | | SF2 | 192.0.2.2 | VXLAN-gpe |
| SF34| 192.168.1.1 | UDP | | SF34| 198.51.100.34 | UDP |
| SF9 | 1.1.1.1 | GRE | | SF9 | 2001:db8::1 | GRE |
+-----------------------------------+ +--------------------------+-------------
=
Figure 11: SF Locator Mapping Example Figure 11: 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)
overlay links to be used (for load distribution, redundancy or paths to be used (for load distribution, redundancy or policy), see
policy), see Figure 12. The metric depicted in Figure 12 is an Figure 12. The metric depicted in Figure 12 is an example to help
example to help illustrated weighing SFs. In a real network, the illustrated weighing SFs. In a real network, the metric will range
metric will range from a simple preference (similar to routing next- from a simple preference (similar to routing next- hop), to a true
hop), to a true dynamic composite metric based on some service dynamic composite metric based on some service function-centric state
function-centric state (including load, sessions state, capacity, (including load, sessions state, capacity, etc.)
etc.)
+----------------------------------+ +----------------------------------+
| SPI | SI | NH | Metric | | SPI | SI | NH | Metric |
+----------------------------------+ +----------------------------------+
| 10 | 3 | 10.1.1.1 | 1 | | 10 | 3 | 203.0.113.1 | 1 |
| | | 10.1.1.2 | 1 | | | | 203.0.113.2 | 1 |
| | | | | | | | | |
| 20 | 12 | 192.168.1.1 | 1 | | 20 | 12 | 192.0.2.1 | 1 |
| | | 10.2.2.2 | 1 | | | | 203.0.113.4 | 1 |
| | | | | | | | | |
| 30 | 7 | 10.2.2.3 | 10 | | 30 | 7 | 192.0.2.10 | 10 |
| | | 10.3.3.3 | 5 | | | | 198.51.100.1| 5 |
+----------------------------------+ +----------------------------------+
(encap type omitted for formatting) (encapsulation type omitted for formatting)
Figure 12: NSH Weighted Service Path Figure 12: NSH Weighted Service Path
7.2. Mapping NSH to Network Overlay 7.2. Mapping NSH to Network Transport
As described above, the mapping of SPI to network topology may result As described above, the mapping of SPI to network topology may result
in a single overlay path, or it might result in a more complex in a single path, or it might result in a more complex topology.
topology. Furthermore, the SPI to overlay mapping occurs at each SFF 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 existing. NSH packets can use any (new or if a suitable one already existing. 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 10.1.1.1 1. Next SF is located at SFFb with locator 192.0.2.1
SFFa mapping: SPI=10 --> VXLAN-gpe, dst-ip: 10.1.1.1 SFFa mapping: SPI=10 --> VXLAN-gpe, dst-ip: 192.0.2.1
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:10.2.2.1, 10.2.2.2, SFFb mapping: SPI=10 --> VXLAN-gpe, dst_ip:203.0.113.1,
10.2.2.3, equal cost 203.0.113.2, 203.0.113.3, equal cost
3. Next SF is located at SFFd with two paths to 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:10.1.1.1 cost=10, SFFc mapping: SPI=10 --> VXLAN-gpe, dst_ip:192.0.2.10 cost=10,
10.1.1.2, 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,
there is no a priori mandate about how to forward packets in the there is no a priori mandate about how to forward packets in the
network (only the order of services that must be traversed). network (only the order of services that must be traversed).
The network operator retains the ability to engineer the overlay The network operator retains the ability to engineer the network
paths as required. For example, the overlay path between service paths as required. For example, the overlay path between SFFs may
functions forwarders may utilize traffic engineering, QoS marking, or utilize traffic engineering, QoS marking, or ECMP, without requiring
ECMP, without requiring complex configuration and network protocol complex configuration and network protocol support to be extended to
support to be extended to the service path explicitly. In other the service path explicitly. In other words, the network operates as
words, the network operates as expected, and evolves as required, as expected, and evolves as required, as does the service plane.
does the service function plane.
7.3. Service Plane Visibility 7.3. 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
the NSH information (packet capture, IPFIX, etc.). The information the NSH information (packet capture, IPFIX, etc.). The information
can be used for service scheduling and placement decisions, can be used for service scheduling and placement decisions,
troubleshooting and compliance verification. troubleshooting and compliance verification.
7.4. Service Graphs 7.4. Service Graphs
In some cases, a service path is exactly that -- a linear list of While a given realized service function path is a specific sequence
service functions that must be traversed. However, the "path" is of service functions, the service as seen by a user can actually be a
actually a directed graph. Furthermore, within a given service collection of service function paths, with the interconnection
topology several directed graphs may exist with packets moving provided by classifiers (in-service path, non-initial
between graphs based on non-initial classification (in Figure 13, co- reclassification). These internal reclassifiers examine the packet
located with the SFs). at relevant points in the network, and rewrite the SPI and SI to
reflect the results of the reclassification. (These classifiers may
,---. ,---. ,---. also of course modify the metadata associated with the packet.)
/ \ / \ / \ RFC7665, section 2.1 describes Service Graphs in detail.
( SF2 +------+ SF7 +--------+ SF3 )
,------\ / \ / /-+ /
; |---' `---'\ / `-+-'
| : \ /
| \ /---:---
,-+-. `. ,---. / :
/ \ '---+ \/ \
( SF1 ) ( SF6 ) \
\ / \ +--. :
`---' `---' `-. ,-+-.
`+ \
( SF4 )
\ /
`---'
Figure 13: Service Graph Example
The SPI/SI combination provides a simple representation of a directed
graph, the SPI represents a graph ID; and the SI a node ID. The
service topology formed by SPI/SI support cycles, weighting, and
alternate topology selection, all within the service plane. The
realization of the network topology occurs as described above: SPI/ID
mapping to an appropriate transport and associated next network hops.
NSH-aware services receive the entire header, including the SPI/SI.
An non-initial logical classifier (in many deployment, this
classifier will be co-resident with a SF) can now, based on local
policy, alter the SPI, which in turn effects both the service graph,
and in turn the selection of overlay at the SFF. The figure below
depicts the policy associated with the graph in Figure 13 above.
Note: this illustrates multiple graphs and their representation; it
does not depict the use of metadata within a single service function
graph.
SF1:
SPI: 10
NH: SF2
SF2:
Class: Bad
SPI: 20
NH: SF6
Class: Good
SPI: 30
NH: SF7
SF6:
Class: Employee
SPI: 21
NH: SF4
Class: Guest
SPI: 22
NH: SF3
SF7:
Class: Employee
SPI: 31
NH: SF4
Class: Guest
SPI: 32
NH: SF3
Figure 14: Service Graphs Using SPI
This example above does not show the mapping of the service topology
to the network overlay topology. As discussed in the sections above,
the overlay selection occurs as per network policy.
8. Policy Enforcement with NSH 8. Policy Enforcement with NSH
8.1. NSH Metadata and Policy Enforcement 8.1. NSH Metadata and Policy Enforcement
As described in Section 3, NSH provides the ability to carry metadata As described in Section 3, 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
skipping to change at page 27, line 17 skipping to change at page 22, line 17
+---^---+ +---|---+ +---|---+ +---^---+ +---|---+ +---|---+
,-|-. ,-|-. ,-|-. ,-|-. ,-|-. ,-|-.
/ \ / \ / \ / \ / \ / \
( Class ) SF1 ) ( SF2 ) ( Class ) SF1 ) ( SF2 )
\ ify / \ / \ / \ ify / \ / \ /
`---' `---' `---' `---' `---' `---'
5-tuple: Permit Inspect 5-tuple: Permit Inspect
Tenant A Tenant A AppY Tenant A Tenant A AppY
AppY AppY
Figure 15: Metadata and Policy Figure 13: Metadata and Policy
+-----+ +-----+ +-----+ +-----+ +-----+ +-----+
| SFF |---------> | SFF |----------> | SFF | | SFF |---------> | SFF |----------> | SFF |
+--+--+ +--+--+ +--+--+ +--+--+ +--+--+ +--+--+
^ | | ^ | |
,-+-. ,-+-. ,-+-. ,-+-. ,-+-. ,-+-.
/ \ / \ / \ / \ / \ / \
( Class ) ( SF1 ) ( SF2 ) ( Class ) ( SF1 ) ( SF2 )
\ ify / \ / \ / \ ify / \ / \ /
`-+-' `---' `---' `-+-' `---' `---'
| Permit Deny AppZ | Permit Deny AppZ
+---+---+ employees +---+---+ employees
| | | |
+-------+ +-------+
external external
system: system:
Employee Employee
AppZ AppZ
Figure 16: External Metadata and Policy Figure 14: 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, rather they rely on a did not need to perform re-classification, rather they rely on a
antecedent classification for local policy enforcement. antecedent classification for local policy enforcement.
8.2. Updating/Augmenting Metadata 8.2. Updating/Augmenting Metadata
Post-initial metadata imposition (typically performed during initial Post-initial metadata imposition (typically performed during initial
service path determination), metadata may be augmented or updated: service path determination), metadata may be augmented or updated:
skipping to change at page 28, line 38 skipping to change at page 23, line 38
\ / \ / \ / \ / \ / \ /
`-+-' `---' `---' `-+-' `---' `---'
| Inspect Deny | Inspect Deny
+---+---+ employees employee+ +---+---+ employees employee+
| | Class=AppZ appZ | | Class=AppZ appZ
+-------+ +-------+
external external
system: system:
Employee Employee
Figure 17: Metadata Augmentation Figure 15: Metadata Augmentation
+-----+ +-----+ +-----+ +-----+ +-----+ +-----+
| SFF |---------> | SFF |----------> | SFF | | SFF |---------> | SFF |----------> | SFF |
+--+--+ +--+--+ +--+--+ +--+--+ +--+--+ +--+--+
^ | | ^ | |
,---. ,---. ,---. ,---. ,---. ,---.
/ \ / \ / \ / \ / \ / \
( Class ) ( SF1 ) ( SF2 ) ( Class ) ( SF1 ) ( SF2 )
\ / \ / \ / \ / \ / \ /
`---' `---' `---' `---' `---' `---'
5-tuple: Inspect Deny 5-tuple: Inspect Deny
Tenant A Tenant A attack Tenant A Tenant A attack
--> attack --> attack
Figure 18: Metadata Update Figure 16: Metadata Update
8.3. Service Path ID and Metadata 8.3. 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 can represent the result of the Service Path Identifier can represent the result of
classification. A given SPI can represent all or some of the classification. A given SPI can represent all or some of the
metadata, and be updated based on metadata classification results. metadata, and be updated based on metadata classification results.
This relationship provides the ability to create a dynamic services 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 7.4. Figure 19 illustrates an example of this described in Section 7.4. Figure 19 illustrates an example of this
behavior. behavior.
+-----+ +-----+ +-----+ +-----+ +-----+ +-----+
| SFF |---------> | SFF |------+---> | SFF | | SFF |---------> | SFF |------+---> | SFF |
+--+--+ +--+--+ | +--+--+ +--+--+ +--+--+ | +--+--+
| | | | | | | |
skipping to change at page 30, line 26 skipping to change at page 25, line 26
--> DoS | --> DoS |
V V
,-+-. ,-+-.
/ \ / \
( SF10 ) ( SF10 )
\ / \ /
`---' `---'
DoS DoS
"Scrubber" "Scrubber"
Figure 19: Path ID and Metadata Figure 17: 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 draft. scope of this document.
9. NSH Encapsulation Examples 9. NSH Encapsulation Examples
9.1. GRE + NSH 9.1. GRE + NSH
IPv4 Packet: IPv4 Packet:
+----------+--------------------+--------------------+ +----------+--------------------+--------------------+
|L2 header | L3 header, proto=47|GRE header,PT=0x894F| |L2 header | L3 header, proto=47|GRE header,PT=0x894F|
+----------+--------------------+--------------------+ +----------+--------------------+--------------------+
--------------+----------------+ --------------+----------------+
skipping to change at page 31, line 25 skipping to change at page 26, line 25
--------------+----------------+ --------------+----------------+
L2 Frame: L2 Frame:
+----------+--------------------+--------------------+ +----------+--------------------+--------------------+
|L2 header | L3 header, proto=47|GRE header,PT=0x894F| |L2 header | L3 header, proto=47|GRE header,PT=0x894F|
+----------+--------------------+--------------------+ +----------+--------------------+--------------------+
---------------+---------------+ ---------------+---------------+
NSH, NP=0x3 |original frame | NSH, NP=0x3 |original frame |
---------------+---------------+ ---------------+---------------+
Figure 20: GRE + NSH Figure 18: GRE + NSH
9.2. VXLAN-gpe + NSH 9.2. VXLAN-gpe + NSH
IPv4 Packet: IPv4 Packet:
+----------+------------------------+---------------------+ +----------+------------------------+---------------------+
|L2 header | IP + UDP dst port=4790 |VXLAN-gpe NP=0x4(NSH)| |L2 header | IP + UDP dst port=4790 |VXLAN-gpe NP=0x4(NSH)|
+----------+------------------------+---------------------+ +----------+------------------------+---------------------+
--------------+----------------+ --------------+----------------+
NSH, NP=0x1 |original packet | NSH, NP=0x1 |original packet |
--------------+----------------+ --------------+----------------+
L2 Frame: L2 Frame:
+----------+------------------------+---------------------+ +----------+------------------------+---------------------+
|L2 header | IP + UDP dst port=4790 |VXLAN-gpe NP=0x4(NSH)| |L2 header | IP + UDP dst port=4790 |VXLAN-gpe NP=0x4(NSH)|
+----------+------------------------+---------------------+ +----------+------------------------+---------------------+
---------------+---------------+ ---------------+---------------+
NSH,NP=0x3 |original frame | NSH,NP=0x3 |original frame |
---------------+---------------+ ---------------+---------------+
Figure 21: VXLAN-gpe + NSH Figure 19: VXLAN-gpe + NSH
9.3. Ethernet + NSH 9.3. Ethernet + NSH
IPv4 Packet: IPv4 Packet:
+-------------------------------+---------------+--------------------+ +-------------------------------+---------------+--------------------+
|Outer Ethernet, ET=0x894F | NSH, NP = 0x1 | original IP Packet | |Outer Ethernet, ET=0x894F | NSH, NP = 0x1 | original IP Packet |
+-------------------------------+---------------+--------------------+ +-------------------------------+---------------+--------------------+
L2 Frame: L2 Frame:
+-------------------------------+---------------+----------------+ +-------------------------------+---------------+----------------+
|Outer Ethernet, ET=0x894F | NSH, NP = 0x3 | original frame | |Outer Ethernet, ET=0x894F | NSH, NP = 0x3 | original frame |
+-------------------------------+---------------+----------------+ +-------------------------------+---------------+----------------+
Figure 22: Ethernet + NSH Figure 20: Ethernet + NSH
10. Security Considerations 10. Security Considerations
As with many other protocols, NSH data can be spoofed or otherwise As with many other protocols, NSH data can be spoofed or otherwise
modified. In many deployments, NSH will be used in a controlled modified. In many deployments, NSH will be used in a controlled
environment, with trusted devices (e.g. a data center) thus environment, with trusted devices (e.g. a data center) thus
mitigating the risk of unauthorized header manipulation. mitigating the risk of unauthorized header manipulation.
NSH is always encapsulated in a transport protocol and therefore, NSH is always encapsulated in a transport protocol and therefore,
when required, existing security protocols that provide authenticity when required, existing security protocols that provide authenticity
(e.g. RFC 2119 [RFC6071]) can be used. (e.g. RFC 2119 [RFC6071]) can be used.
Similarly if confidentiality is required, existing encryption Similarly if confidentiality is required, existing encryption
protocols can be used in conjunction with encapsulated NSH. protocols can be used in conjunction with encapsulated NSH.
Further security considerations are discussed in [nsh-sec]. Further security considerations are discussed in [nsh-sec].
11. Open Items for WG Discussion 11. Contributors
1. MD type 1 metadata semantics specifics
2. Bypass bit in NSH.
3. Rendered Service Path ID (RSPID).
12. Contributors
This WG document originated as draft-quinn-sfc-nsh and had the This WG document originated as draft-quinn-sfc-nsh and had the
following co-authors and contributors. The editors of this document following co-authors and contributors. The editors of this document
would like to thank and recognize them and their contributions. would like to thank and recognize them and their contributions.
These co-authors and contributors provided invaluable concepts and These co-authors and contributors provided invaluable concepts and
content for this document's creation. content for this document's creation.
Surendra Kumar Surendra Kumar
Cisco Systems Cisco Systems
smkumar@cisco.com smkumar@cisco.com
skipping to change at page 36, line 25 skipping to change at page 30, line 25
Sumandra Majee Sumandra Majee
F5 F5
S.Majee@f5.com S.Majee@f5.com
David Melman David Melman
Marvell Marvell
davidme@marvell.com davidme@marvell.com
Pankaj Garg Pankaj Garg
Microsoft Microsoft
Garg.Pankaj@microsoft.com pankajg@microsoft.com
Brad McConnell Brad McConnell
Rackspace Rackspace
bmcconne@rackspace.com bmcconne@rackspace.com
Chris Wright Chris Wright
Red Hat Inc. Red Hat Inc.
chrisw@redhat.com chrisw@redhat.com
Kevin Glavin Kevin Glavin
skipping to change at page 38, line 5 skipping to change at page 32, line 5
louis.fourie@huawei.com louis.fourie@huawei.com
Ron Parker Ron Parker
Affirmed Networks Affirmed Networks
ron_parker@affirmednetworks.com ron_parker@affirmednetworks.com
Myo Zarny Myo Zarny
Goldman Sachs Goldman Sachs
myo.zarny@gs.com myo.zarny@gs.com
13. Acknowledgments 12. Acknowledgments
The authors would like to thank Nagaraj Bagepalli, Abhijit Patra, The authors would like to thank Nagaraj Bagepalli, Abhijit Patra,
Peter Bosch, Darrel Lewis, Pritesh Kothari, Tal Mizrahi and Ken Gray Peter Bosch, Darrel Lewis, Pritesh Kothari, Tal Mizrahi and Ken Gray
for their detailed review, comments and contributions. for their detailed review, comments and contributions.
A special thank you goes to David Ward and Tom Edsall for their A special thank you goes to David Ward and Tom Edsall for their
guidance and feedback. guidance and feedback.
Additionally the authors would like to thank Carlos Pignataro and Additionally the authors would like to thank Carlos Pignataro and
Larry Kreeger for their invaluable ideas and contributions which are Larry Kreeger for their invaluable ideas and contributions which are
reflected throughout this draft. reflected throughout this document.
Loa Andersson provided a thorough review and valuable comments, we
thank him for that.
Lastly, Reinaldo Penno deserves a particular thank you for his Lastly, Reinaldo Penno deserves a particular thank you for his
architecture and implementation work that helped guide the protocol architecture and implementation work that helped guide the protocol
concepts and design. concepts and design.
14. IANA Considerations 13. IANA Considerations
14.1. NSH EtherType 13.1. NSH EtherType
An IEEE EtherType, 0x894F, has been allocated for NSH. An IEEE EtherType, 0x894F, has been allocated for NSH.
14.2. Network Service Header (NSH) Parameters 13.2. Network Service Header (NSH) Parameters
IANA is requested to create a new "Network Service Header (NSH) IANA is requested to create a new "Network Service Header (NSH)
Parameters" registry. The following sub-sections request new Parameters" registry. The following sub-sections request new
registries within the "Network Service Header (NSH) Parameters " registries within the "Network Service Header (NSH) Parameters "
registry. registry.
14.2.1. NSH Base Header Reserved Bits 13.2.1. NSH Base Header Reserved Bits
There are ten bits at the beginning of the NSH Base Header. New bits There are ten bits at the beginning of the NSH Base Header. New bits
are assigned via Standards Action [RFC5226]. are assigned via Standards Action [RFC5226].
Bits 0-1 - Version Bits 0-1 - Version
Bit 2 - OAM (O bit) Bit 2 - OAM (O bit)
Bits 2-9 - Reserved Bit 3 - Critical TLV (C bit)
Bits 4-9 - Reserved
14.2.2. MD Type Registry 13.2.2. NSH Version
IANA is requested to setup a registry of "NSH Version". New values
are assigned via Standards Action [RFC5226].
Version 00: This protocol version. This document.
Version 01: Reserved. This document.
Version 10: Unassigned.
Version 11: Unassigned.
13.2.3. MD Type Registry
IANA is requested to set up a registry of "MD Types". These are IANA is requested to set up a registry of "MD Types". These are
8-bit values. MD Type values 0, 1, 2, 254, and 255 are specified in 8-bit values. MD Type values 0, 1, 2, 254, and 255 are specified in
this document. Registry entries are assigned by using the "IETF this document. Registry entries are assigned by using the "IETF
Review" policy defined in RFC 5226 [RFC5226]. Review" policy defined in RFC 5226 [RFC5226].
+---------+--------------+---------------+ +---------+--------------+---------------+
| MD Type | Description | Reference | | MD Type | Description | Reference |
+---------+--------------+---------------+ +---------+--------------+---------------+
| 0 | Reserved | This document | | 0 | Reserved | This document |
skipping to change at page 40, line 5 skipping to change at page 34, line 23
| | | | | | | |
| 3..253 | Unassigned | | | 3..253 | Unassigned | |
| | | | | | | |
| 254 | Experiment 1 | This document | | 254 | Experiment 1 | This document |
| | | | | | | |
| 255 | Experiment 2 | This document | | 255 | Experiment 2 | This document |
+---------+--------------+---------------+ +---------+--------------+---------------+
Table 1 Table 1
14.2.3. TLV Class Registry 13.2.4. MD Class Registry
IANA is requested to set up a registry of "TLV Types". These are 16- IANA is requested to set up a registry of "MD Class". These are 16-
bit values. Registry entries are assigned by using the "IETF Review" bit values. Registry entries are assigned by using the "IETF Review"
policy defined in RFC 5226 [RFC5226]. policy defined in RFC 5226 [RFC5226]. TLV Classes defined by this
document are listed below. New values are assigned via Standards
Action [RFC5226].
0x0000 to 0x01ff: IETF Consensus
0x0200 to 0x7fff: Expert Review
0xfff6 to 0xfffe: Experimental
0xffff: Reserved
14.2.4. NSH Base Header Next Protocol 13.2.5. NSH Base Header Next Protocol
IANA is requested to set up a registry of "Next Protocol". These are IANA is requested to set up a registry of "Next Protocol". These are
8-bit values. Next Protocol values 0, 1, 2 and 3 are defined in this 8-bit values. Next Protocol values 0, 1, 2, 3, 4 and 5 are defined
draft. New values are assigned via Standards Action [RFC5226]. in this draft. New values are assigned via Standards Action
[RFC5226].
+---------------+--------------+---------------+ +---------------+--------------+---------------+
| Next Protocol | Description | Reference | | Next Protocol | Description | Reference |
+---------------+--------------+---------------+ +---------------+--------------+---------------+
| 0 | Reserved | This document | | 0 | Reserved | This document |
| | | | | | | |
| 1 | IPv4 | This document | | 1 | IPv4 | This document |
| | | | | | | |
| 2 | IPv6 | This document | | 2 | IPv6 | This document |
| | | | | | | |
| 3 | Ethernet | This document | | 3 | Ethernet | This document |
| | | | | | | |
| 4..253 | Unassigned | | | 4 | NSH | This document |
| | | |
| 5 | MPLS | This document |
| | | |
| 6..253 | Unassigned | |
| | | | | | | |
| 254 | Experiment 1 | This document | | 254 | Experiment 1 | This document |
| | | | | | | |
| 255 | Experiment 2 | This document | | 255 | Experiment 2 | This document |
+---------------+--------------+---------------+ +---------------+--------------+---------------+
Table 2 Table 2
15. References 14. References
15.1. Normative References
[RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791, 14.1. Normative References
DOI 10.17487/RFC0791, September 1981,
<http://www.rfc-editor.org/info/rfc791>.
[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, DOI 10.17487/ Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/
RFC2119, March 1997, RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <http://www.rfc-editor.org/info/rfc2119>.
15.2. Informative References [RFC7498] Quinn, P., Ed. and T. Nadeau, Ed., "Problem Statement for
Service Function Chaining", RFC 7498, DOI 10.17487/
RFC7498, April 2015,
<http://www.rfc-editor.org/info/rfc7498>.
[RFC7665] Halpern, J., Ed. and C. Pignataro, Ed., "Service Function
Chaining (SFC) Architecture", RFC 7665, DOI 10.17487/
RFC7665, October 2015,
<http://www.rfc-editor.org/info/rfc7665>.
14.2. Informative References
[RFC1191] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191, [RFC1191] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191,
DOI 10.17487/RFC1191, November 1990, DOI 10.17487/RFC1191, November 1990,
<http://www.rfc-editor.org/info/rfc1191>. <http://www.rfc-editor.org/info/rfc1191>.
[RFC1981] McCann, J., Deering, S., and J. Mogul, "Path MTU Discovery
for IP version 6", RFC 1981, DOI 10.17487/RFC1981,
August 1996, <http://www.rfc-editor.org/info/rfc1981>.
[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,
<http://www.rfc-editor.org/info/rfc2784>. <http://www.rfc-editor.org/info/rfc2784>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226, IANA Considerations Section in RFCs", BCP 26, RFC 5226,
DOI 10.17487/RFC5226, May 2008, DOI 10.17487/RFC5226, May 2008,
<http://www.rfc-editor.org/info/rfc5226>. <http://www.rfc-editor.org/info/rfc5226>.
[RFC6071] Frankel, S. and S. Krishnan, "IP Security (IPsec) and [RFC6071] Frankel, S. and S. Krishnan, "IP Security (IPsec) and
Internet Key Exchange (IKE) Document Roadmap", RFC 6071, Internet Key Exchange (IKE) Document Roadmap", RFC 6071,
DOI 10.17487/RFC6071, February 2011, DOI 10.17487/RFC6071, February 2011,
<http://www.rfc-editor.org/info/rfc6071>. <http://www.rfc-editor.org/info/rfc6071>.
[RFC6830] Farinacci, D., Fuller, V., Meyer, D., and D. Lewis, "The [RFC6830] Farinacci, D., Fuller, V., Meyer, D., and D. Lewis, "The
Locator/ID Separation Protocol (LISP)", RFC 6830, Locator/ID Separation Protocol (LISP)", RFC 6830,
DOI 10.17487/RFC6830, January 2013, DOI 10.17487/RFC6830, January 2013,
<http://www.rfc-editor.org/info/rfc6830>. <http://www.rfc-editor.org/info/rfc6830>.
[RFC7498] Quinn, P., Ed. and T. Nadeau, Ed., "Problem Statement for
Service Function Chaining", RFC 7498, DOI 10.17487/
RFC7498, April 2015,
<http://www.rfc-editor.org/info/rfc7498>.
[SFC-arch]
Quinn, P., Ed. and J. Halpern, Ed., "Service Function
Chaining (SFC) Architecture", 2014,
<http://datatracker.ietf.org/doc/draft-quinn-sfc-arch>.
[VXLAN-gpe] [VXLAN-gpe]
Quinn, P., Manur, R., Agarwal, P., Kreeger, L., Lewis, D., Quinn, P., Manur, R., Agarwal, P., Kreeger, L., Lewis, D.,
Maino, F., Smith, M., Yong, L., Xu, X., Elzur, U., Garg, Maino, F., Smith, M., Yong, L., Xu, X., Elzur, U., Garg,
P., and D. Melman, "Generic Protocol Extension for VXLAN", P., and D. Melman, "Generic Protocol Extension for VXLAN",
<https://datatracker.ietf.org/doc/ <https://datatracker.ietf.org/doc/
draft-ietf-nvo3-vxlan-gpe/>. draft-ietf-nvo3-vxlan-gpe/>.
[dcalloc] Guichard, J., Smith, M., and S. Kumar, "Network Service [broadalloc]
Napper, J., Kumar, S., Muley, P., and W. Hendericks, "NSH
Context Header Allocation -- Mobility", 2016, <https://
datatracker.ietf.org/doc/
draft-napper-sfc-nsh-broadband-allocation/>.
[dcalloc] Guichard, J., Smith, M., and et al., "Network Service
Header (NSH) Context Header Allocation (Data Center)", Header (NSH) Context Header Allocation (Data Center)",
2014, <https://datatracker.ietf.org/doc/ 2016, <https://datatracker.ietf.org/doc/
draft-guichard-sfc-nsh-dc-allocation/>. draft-guichard-sfc-nsh-dc-allocation/>.
[moballoc]
Napper, J. and S. Kumar, "NSH Context Header Allocation --
Mobility", 2014, <https://datatracker.ietf.org/doc/
draft-napper-sfc-nsh-mobility-allocation/>.
[nsh-sec] Reddy, T., Migault, D., Pignataro, C., Quinn, P., and C. [nsh-sec] Reddy, T., Migault, D., Pignataro, C., Quinn, P., and C.
Inacio, "NSH Security and Privacy requirements", 2016, <ht Inacio, "NSH Security and Privacy requirements", 2016, <ht
tps://datatracker.ietf.org/doc/ tps://datatracker.ietf.org/doc/
draft-reddy-sfc-nsh-security-req/>. draft-reddy-sfc-nsh-security-req/>.
Authors' Addresses Authors' Addresses
Paul Quinn (editor) Paul Quinn (editor)
Cisco Systems, Inc. Cisco Systems, Inc.
 End of changes. 119 change blocks. 
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