Network Working Group P. Quinn, Ed.
Internet-Draft Cisco Systems, Inc.
Intended status: Standards Track U. Elzur, Ed.
Expires: January 24, 2016 Intel
July 23, 2015
Network Service Header
draft-ietf-sfc-nsh-01.txt
Abstract
This draft describes a Network Service Header (NSH) inserted onto
encapsulated packets or frames to realize service function paths.
NSH also provides a mechanism for metadata exchange along the
instantiated service path. NSH is the SFC encapsulation as per SFC
Architecture [SFC-arch]
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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].
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 24, 2016.
Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
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Table of Contents
1. Requirements Language . . . . . . . . . . . . . . . . . . . . 2
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Definition of Terms . . . . . . . . . . . . . . . . . . . 4
2.2. Problem Space . . . . . . . . . . . . . . . . . . . . . . 7
2.3. NSH-based Service Chaining . . . . . . . . . . . . . . . . 8
3. Network Service Header . . . . . . . . . . . . . . . . . . . . 10
3.1. Network Service Header Format . . . . . . . . . . . . . . 10
3.2. NSH Base Header . . . . . . . . . . . . . . . . . . . . . 10
3.3. Service Path Header . . . . . . . . . . . . . . . . . . . 12
3.4. NSH MD-type 1 . . . . . . . . . . . . . . . . . . . . . . 13
3.5. NSH MD-type 2 . . . . . . . . . . . . . . . . . . . . . . 13
3.5.1. Optional Variable Length Metadata . . . . . . . . . . 14
4. NSH Actions . . . . . . . . . . . . . . . . . . . . . . . . . 16
5. NSH Encapsulation . . . . . . . . . . . . . . . . . . . . . . 18
6. Fragmentation Considerations . . . . . . . . . . . . . . . . . 19
7. Service Path Forwarding with NSH . . . . . . . . . . . . . . . 20
7.1. SFFs and Overlay Selection . . . . . . . . . . . . . . . . 20
7.2. Mapping NSH to Network Overlay . . . . . . . . . . . . . . 22
7.3. Service Plane Visibility . . . . . . . . . . . . . . . . . 23
7.4. Service Graphs . . . . . . . . . . . . . . . . . . . . . . 23
8. Policy Enforcement with NSH . . . . . . . . . . . . . . . . . 26
8.1. NSH Metadata and Policy Enforcement . . . . . . . . . . . 26
8.2. Updating/Augmenting Metadata . . . . . . . . . . . . . . . 27
8.3. Service Path ID and Metadata . . . . . . . . . . . . . . . 29
9. NSH Encapsulation Examples . . . . . . . . . . . . . . . . . . 31
9.1. GRE + NSH . . . . . . . . . . . . . . . . . . . . . . . . 31
9.2. VXLAN-gpe + NSH . . . . . . . . . . . . . . . . . . . . . 31
9.3. Ethernet + NSH . . . . . . . . . . . . . . . . . . . . . . 32
10. Security Considerations . . . . . . . . . . . . . . . . . . . 33
11. Open Items for WG Discussion . . . . . . . . . . . . . . . . . 34
12. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 35
13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 38
14. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 39
14.1. NSH EtherType . . . . . . . . . . . . . . . . . . . . . . 39
14.2. Network Service Header (NSH) Parameters . . . . . . . . . 39
14.2.1. NSH Base Header Reserved Bits . . . . . . . . . . . . 39
14.2.2. MD Type Registry . . . . . . . . . . . . . . . . . . . 39
14.2.3. TLV Class Registry . . . . . . . . . . . . . . . . . . 40
14.2.4. NSH Base Header Next Protocol . . . . . . . . . . . . 40
15. References . . . . . . . . . . . . . . . . . . . . . . . . . . 41
15.1. Normative References . . . . . . . . . . . . . . . . . . . 41
15.2. Informative References . . . . . . . . . . . . . . . . . . 41
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 43
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2. Introduction
Service functions are widely deployed and essential in many networks.
These service functions provide a range of features such as security,
WAN acceleration, and server load balancing. Service functions may
be instantiated at different points in the network infrastructure
such as the wide area network, data center, campus, and so forth.
The current service function deployment models are relatively static,
and bound to topology 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
service function deployment models. Additionally, the transition to
virtual platforms requires an agile service insertion model that
supports dynamic and elastic service delivery; the movement of
service functions and application workloads in the network and the
ability to easily bind service policy to granular information such as
per-subscriber state and steer traffic to the requisite service
function(s) are necessary.
NSH defines a new dataplane protocol specifically for the creation of
dynamic service chains and is composed of the following elements:
1. Service Function Path identification
2. Transport independent service function chain
3. Per-packet network and service metadata or optional variable TLV
metadata.
NSH is designed to be easy to implement across a range of devices,
both physical and virtual, including hardware platforms.
An NSH aware control plane is outside the scope of this document.
The SFC Architecture document [SFC-arch] provides an overview of a
service chaining architecture that clearly defines the roles of the
various elements and the scope of a service function chaining
encapsulation. NSH is the SFC encapsulation defined in that draft.
2.1. Definition of Terms
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Classification: Locally instantiated matching of traffic flows
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
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
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.
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Service Function Path (SFP): The Service Function Path is a
constrained specification of where packets assigned to a certain
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
on outer header information.
Network Overlay: Logical network built on top of existing network
(the underlay). Packets are encapsulated or tunneled to create
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 function that performs classification
and imposes an NSH. The initial classifier imposes the initial
NSH and sends the NSH packet to the first SFF in the path. Non-
initial (i.e. subsequent) classification can occur as needed and
can alter, or create a new service path.
Network Locator: dataplane address, typically IPv4 or IPv6, used to
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.
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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
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
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 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
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
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
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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
in networks with a range of transports requiring service
functions to support and participate in many transports (and
associated control planes) or for a transport gateway function to
be present.
2.3. NSH-based Service Chaining
The NSH creates a dedicated service plane, that addresses many of the
limitations highlighted in Section 2.2. More specifically, NSH
enables:
1. Topological Independence: Service forwarding occurs within the
service plane, via a network overlay, the underlying network
topology does not require modification. NSH provides an
identifier used to select the network overlay for network
forwarding.
2. Service Chaining: NSH contains path identification information
needed to realize a service path. Furthermore, NSH provides the
ability to monitor and troubleshoot a service chain, end-to-end
via service-specific OAM messages. The NSH fields can be used by
administrators (via, for example a traffic analyzer) to verify
(account, ensure 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
devices and service function, and between service functions. The
semantics of the shared metadata is communicated via a control
plane to participating nodes. Examples of metadata include
classification information used for policy enforcement and
network context for forwarding post service delivery.
4. Classification and re-classification: sharing the metadata allows
service functions to share initial and intermediate
classification results with downstream service functions saving
re-classification, where enough information was enclosed.
5. NSH offers a common and standards based header for service
chaining to all network and service nodes.
6. Transport Agnostic: NSH is transport independent and is carried
in an overlay, over existing underlays. If an existing overlay
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topology provides the required service path connectivity, that
existing overlay may be used.
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3. Network Service Header
A Network Service Header (NSH) contains service path information and
optionally metadata that are added to a packet or frame and used to
create a service plane. The original packets preceded by NSH, are
then encapsulated in an outer header for transport.
NSH is added by a Service Classifier. The NSH header is removed by
the last SFF in the chain or by a SF that consumes the packet.
3.1. Network Service Header Format
A NSH is composed of a 4-byte Base Header, a 4-byte Service Path
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Base Header |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Service Path Header |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Context Headers ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Network Service Header
Base header: provides information about the service header and the
payload protocol.
Service Path Header: provide path identification and location within
a path.
Context headers: carry opaque metadata and variable length encoded
information.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Ver|O|C|R|R|R|R|R|R| Length | MD Type | Next Protocol |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Figure 2: NSH Base Header
Base Header Field Descriptions:
Version: The version field is used to ensure backward compatibility
going forward with future NSH updates. It MUST be set to 0x0 by the
sender, in this first revision of NSH.
O bit: when set to 0x1 indicates that this packet is an operations
and management (OAM) packet. 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
3.4.2). This bit acts as an indication for hardware implementers to
decide how to handle the presence of a critical TLV without
necessarily needing to parse all TLVs present. The C bit MUST be set
to 0x0 when MD Type= 0x01 and MAY be used with MD Type = 0x2 and MUST
be set to 0x1 if one or more critical TLVs are present.
All other flag fields are reserved.
Length: total length, in 4-byte words, of NSH including the Base
Header, the Service Path Header and the optional variable TLVs. The
Length MUST be of value 0x6 for MD Type = 0x1 and MUST be of value
0x2 or higher for MD Type = 0x2. The NSH header length MUST be an
integer number of 4 bytes.
MD Type: indicates the format of NSH beyond the mandatory Base Header
and the Service Path Header. MD Type defines the format of the
metadata being carried. A new registry will be requested from IANA
for the MD Type.
NSH defines two MD types:
0x1 - which indicates that the format of the header includes fixed
length context headers (see Figure 4 below).
0x2 - which does not mandate any headers beyond the Base Header and
Service Path Header, and may contain optional variable length context
information.
The format of the base header and the service path header is
invariant, and not affected by MD Type.
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NSH implementations MUST support MD-Type = 0x1, and SHOULD support
MD- Type = 0x2.
Next Protocol: indicates the protocol type of the original packet. A
new IANA registry will be created for protocol type.
This draft defines the following Next Protocol values:
0x1 : IPv4
0x2 : IPv6
0x3 : Ethernet
0x253: Experimental
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Service Path ID | Service Index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Service path ID (SPI): 24 bits
Service index (SI): 8 bits
Figure 3: NSH Service Path Header
Service Path Identifier (SPI): identifies a service path.
Participating nodes MUST use this identifier for Service Function
Path selection.
Service Index (SI): provides location within the SFP. The first
Classifier (i.e. at the boundary of the NSH domain)in the NSH Service
Function Path, SHOULD set the SI to 255, however the control plane
MAY configure the initial value of SI as appropriate (i.e. taking
into account the length of the service function path). A Classifier
MUST send the packet to the first SFF in the chain. Service index
MUST be decremented by service functions or proxy nodes after
performing required services and the new decremented SI value MUST be
reflected in the egress NSH packet. SI MAY be used in conjunction
with Service Path ID for Service Function Path selection. Service
Index (SI) is also valuable when troubleshooting/reporting service
paths. In addition to indicating the location within a Service
Function Path, SI can be used for loop detection.
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3.4. NSH MD-type 1
When the Base Header specifies MD Type = 0x1, four Context Header,
4-byte each, MUST be added immediately following the Service Path
Header, as per Figure 4. Context Headers that carry no metadata MUST
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Ver|O|C|R|R|R|R|R|R| Length | MD-type=0x1 | Next Protocol |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Service Path ID | Service Index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mandatory Context Header |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mandatory Context Header |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mandatory Context Header |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mandatory Context Header |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: NSH MD-type=0x1
Draft-dc [dcalloc] and draft-mobility [moballoc] provide specific
examples of how metadata can be allocated.
3.5. NSH MD-type 2
When the base header specifies MD Type= 0x2, zero or more Variable
Length Context Headers MAY be added, immediately following the
Service Path Header. Therefore, Length = 0x2, indicates that only
the Base Header followed by the Service Path Header are present. The
optional Variable Length Context Headers MUST be of an integer number
of 4-bytes.
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0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Ver|O|C|R|R|R|R|R|R| Length | MD-type=0x2 | Next Protocol |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Service Path ID | Service Index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Variable Length Context Headers (opt.) ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: NSH MD-type=0x2
3.5.1. Optional Variable Length Metadata
The format of the optional variable length context headers, is as
described below.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Class |C| Type |R|R|R| Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Variable Metadata |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: Variable Context Headers
TLV Class: describes the scope of the "Type" field. In some cases,
the TLV Class will identify a specific vendor, in others, the TLV
Class will identify specific standards body allocated types. A new
IANA registry will be created for TLV Class type.
Type: the specific type of information being carried, within the
scope of a given TLV Class. Value allocation is the responsibility
of the TLV Class owner.
Encoding the criticality of the TLV within the Type field is
consistent with IPv6 option types: the most significant bit of the
Type field indicates whether the TLV is mandatory for the receiver to
understand/process. This effectively allocates Type values 0 to 127
for non-critical options and Type values 128 to 255 for critical
options. Figure 7 below illustrates the placement of the Critical
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bit within the Type field.
+-+-+-+-+-+-+-+-+
|C| Type |
+-+-+-+-+-+-+-+-+
Figure 7: Critical Bit Placement Within the TLV Type Field
If a receiver receives an encapsulated packet containing a TLV 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
devices MUST NOT drop packets based on the setting of this bit.
Reserved bits: three reserved bit are present for future use. The
reserved bits MUST be set to 0x0.
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
without a Variable Metadata field.
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4. NSH Actions
NSH-aware nodes are the only nodes that MAY alter the content of the
NSH headers. NSH-aware nodes include: service classifiers, SFF, SF
and NSH proxies. These nodes have several possible header related
actions:
1. Insert or remove NSH: These actions can occur at the start and
end respectively of a service path. Packets are classified, and
if determined to require servicing, NSH will be imposed. A
service classifier MUST insert NSH at the start of an SFP. An
imposed NSH MUST contain valid Base Header and Service Path
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.
Multiple logical classifiers may exist within a given service
path. Non-initial classifiers may re-classify data and that re-
classification MAY result in a new Service Function Path. When
the logical classifier performs re-classification that results in
a change of service path, it MUST remove the existing NSH and
MUST impose a new NSH with the Base Header and Service Path
Header reflecting the new service path information and set the SI
to 255. Metadata MAY be preserved in the new NSH.
2. Select service path: The Service Path Header provides service
chain information and is used by SFFs to determine correct
service path selection. SFFs MUST use the Service Path Header
for selecting the next SF or SFF in the service path.
3. Update a Service Path Header: NSH aware service functions (SF)
MUST decrement the service index. A service index = 0x0
indicates that a packet MUST be dropped by the SFF.
Classifier(s) MAY update Context Headers if new/updated context
is available.
If an NSH proxy (see Section 7) is in use (acting on behalf of a
non-NSH-aware service function for NSH actions), then the proxy
MUST update Service Index and MAY update contexts. When an NSH
proxy receives an NSH-encapsulated packet, it MUST remove the NSH
headers before forwarding it to an NSH unaware SF. When the NSH
Proxy receives a packet back from an NSH unaware SF, it MUST re-
encapsulate it with the correct NSH, and MUST also decrement the
Service Index.
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4. Service policy selection: Service Function instances derive
policy (i.e. service actions such as permit or deny) selection
and enforcement from the service header. Metadata shared in the
service header can provide a range of service-relevant
information such as traffic classification. Service functions
SHOULD use NSH to select local service policy.
Figure 8 maps each of the four actions above to the components in the
SFC architecture that can perform it.
+---------------+------------------+-------+----------------+---------+
| | Insert |Select | Update |Service |
| | or remove NSH |Service| NSH |policy |
| | |Function| |selection|
| Component +--------+--------+Path +----------------+ |
| | | | | Dec. |Update | |
| | Insert | Remove | |Service |Context| |
| | | | | Index |Header | |
+----------------+--------+--------+-------+--------+-------+---------+
| | + | + | | | + | |
|Classifier | | | | | | |
+--------------- +--------+--------+-------+--------+-------+---------+
|Service Function| | + | + | | | |
|Forwarder(SFF) | | | | | | |
+--------------- +--------+--------+-------+--------+-------+---------+
|Service | | | | + | | + |
|Function (SF) | | | | | | |
+--------------- +--------+--------+-------+--------+-------+---------+
|NSH Proxy | + | + | | + | | |
+----------------+--------+--------+-------+--------+-------+---------+
Figure 8: NSH Action and Role Mapping
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5. NSH Encapsulation
Once NSH is added to a packet, an outer encapsulation is used to
forward the original packet and the associated metadata to the start
of a service chain. The encapsulation serves two purposes:
1. Creates a topologically independent services plane. Packets are
forwarded to the required services without changing the
underlying network topology
2. Transit network nodes simply forward the encapsulated packets as
is.
The service header is independent of the encapsulation used and is
encapsulated in existing transports. The presence of NSH is
indicated via protocol type or other indicator in the outer
encapsulation.
See Section 9 for NSH encapsulation examples.
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6. Fragmentation Considerations
Work in progress: discussion of jumbo frames and PMTUD implications.
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7. Service Path Forwarding with NSH
7.1. SFFs and Overlay Selection
As described above, NSH contains a Service Path Identifier (SPI) 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 service path.
Rather the SPI provide a level of indirection between the service
path/topology and the network transport. Furthermore, there is no
requirement, or expectation of an SPI being bound to a pre-determined
or static network path.
The Service Index provides an indication of location within a service
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
select the appropriate network locator(s) for overlay forwarding.
The logical SF may be a single SF, or a set of SFs that are
equivalent. In the latter case, the SFF provides load distribution
amongst the collection of SFs as needed. SI may also serve as a
mechanism for loop detection within a service 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.
This indirection -- path ID to overlay -- creates a true service
plane. That is the SFF/SF topology is constructed without impacting
the network topology but more importantly service plane only
participants (i.e. most SFs) need not be part of the network overlay
topology and its associated infrastructure (e.g. control plane,
routing tables, etc.). As mentioned above, an existing overlay
topology may be used provided it offers the requisite connectivity.
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
Classifier). The SFF consults the SPI/ID values to determine the
appropriate overlay transport protocol (several may be used within a
given network) and next hop for the requisite SF. Figure 9 below
depicts a simple, single next-hop SPI/SI to network overlay network
locator mapping.
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+-------------------------------------------------------+
| SPI | SI | NH | Transport |
+-------------------------------------------------------+
| 10 | 255 | 1.1.1.1 | VXLAN-gpe |
| 10 | 254 | 2.2.2.2 | nvGRE |
| 10 | 251 | 10.1.2.3 | GRE |
| 40 | 251 | 10.1.2.3 | GRE |
| 50 | 200 | 01:23:45:67:89:ab | Ethernet |
| 15 | 212 | Null (end of path) | None |
+-------------------------------------------------------+
Figure 9: SFF NSH Mapping Example
Additionally, further indirection is possible: the resolution of the
required SF network locator may be a localized resolution on an SFF,
rather than a service function chain control plane responsibility, as
per figures 10 and 11 below.
+-------------------+
| SPI | SI | NH |
+-------------------+
| 10 | 3 | SF2 |
| 245 | 12 | SF34 |
| 40 | 9 | SF9 |
+-------------------+
Figure 10: NSH to SF Mapping Example
+-----------------------------------+
| SF | NH | Transport |
+-----------------------------------|
| SF2 | 10.1.1.1 | VXLAN-gpe |
| SF34| 192.168.1.1 | UDP |
| SF9 | 1.1.1.1 | GRE |
+-----------------------------------+
Figure 11: SF Locator Mapping Example
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
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given SF, essentially a series of weighted (equally or otherwise)
overlay links to be used (for load distribution, redundancy or
policy), see Figure 12. The metric depicted in Figure 12 is an
example to help illustrated weighing SFs. In a real network, the
metric will range from a simple preference (similar to routing next-
hop), to a true dynamic composite metric based on some service
function-centric state (including load, sessions state, capacity,
etc.)
+----------------------------------+
| SPI | SI | NH | Metric |
+----------------------------------+
| 10 | 3 | 10.1.1.1 | 1 |
| | | 10.1.1.2 | 1 |
| | | | |
| 20 | 12 | 192.168.1.1 | 1 |
| | | 10.2.2.2 | 1 |
| | | | |
| 30 | 7 | 10.2.2.3 | 10 |
| | | 10.3.3.3 | 5 |
+----------------------------------+
(encap type omitted for formatting)
Figure 12: NSH Weighted Service Path
7.2. Mapping NSH to Network Overlay
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
topology. Furthermore, the SPIx to overlay mapping occurs at each
SFF independently. Any combination of topology selection is
possible. 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 existing) overlay provided the requisite connectivity
requirements are satisfied.
Examples of mapping for a topology:
1. Next SF is located at SFFb with locator 10.1.1.1
SFFa mapping: SPI=10 --> VXLAN-gpe, dst-ip: 10.1.1.1
2. Next SF is located at SFFc with multiple network locators for
load distribution purposes:
SFFb mapping: SPI=10 --> VXLAN-gpe, dst_ip:10.2.2.1, 10.2.2.2,
10.2.2.3, equal cost
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3. Next SF is located at SFFd with two paths to SFFc, one for
redundancy:
SFFc mapping: SPI=10 --> VXLAN-gpe, dst_ip:10.1.1.1 cost=10,
10.1.1.2, cost=20
In the above example, each SFF makes an independent decision about
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
network (only the order of services that must be traversed).
The network operator retains the ability to engineer the overlay
paths as required. For example, the overlay path between service
functions forwarders may utilize traffic engineering, QoS marking, or
ECMP, without requiring complex configuration and network protocol
support to be extended to the service path explicitly. In other
words, the network operates as expected, and evolves as required, as
does the service function plane.
7.3. Service Plane Visibility
The SPI and SI serve an important function for visibility into the
service topology. An operator can determine what service path a
packet is "on", and its location within that path simply by viewing
the NSH information (packet capture, IPFIX, etc.). The information
can be used for service scheduling and placement decisions,
troubleshooting and compliance verification.
7.4. Service Graphs
In some cases, a service path is exactly that -- a linear list of
service functions that must be traversed. However, the "path" is
actually a directed graph. Furthermore, within a given service
topology several directed graphs may exist with packets moving
between graphs based on non-initial classification (in Figure 13, co-
located with the SFs).
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,---. ,---. ,---.
/ \ / \ / \
( 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.
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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.
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8. Policy Enforcement with NSH
8.1. NSH Metadata and Policy Enforcement
As described in Section 3, NSH provides the ability to carry metadata
along a service path. This metadata may be derived from several
sources, common examples include:
Network nodes/devices: Information provided by network nodes can
indicate network-centric information (such as VRF or tenant) that
may be used by service functions, or conveyed to another network
node post service path egress.
External (to the network) systems: External systems, such as
orchestration systems, often contain information that is valuable
for service function policy decisions. In most cases, this
information cannot be deduced by network nodes. For example, a
cloud orchestration platform placing workloads "knows" what
application is being instantiated and can communicate this
information to all NSH nodes via metadata carried in the context
header(s).
Service Functions: A classifier co-resident with Service Functions
often perform very detailed and valuable classification. In some
cases they may terminate, and be able to inspect encrypted
traffic.
Regardless of the source, metadata reflects the "result" of
classification. The granularity of classification may vary. For
example, a network switch, acting as a classifier, might only be able
to classify based on a 5-tuple, whereas, a service function may be
able to inspect application information. Regardless of granularity,
the classification information can be represented in NSH.
Once the data is added to NSH, it is carried along the service path,
NSH-aware SFs receive the metadata, and can use that metadata for
local decisions and policy enforcement. The following two examples
highlight the relationship between metadata and policy:
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+-------+ +-------+ +-------+
| SFF )------->( SFF |------->| SFF |
+---^---+ +---|---+ +---|---+
,-|-. ,-|-. ,-|-.
/ \ / \ / \
( Class ) SF1 ) ( SF2 )
\ ify / \ / \ /
`---' `---' `---'
5-tuple: Permit Inspect
Tenant A Tenant A AppY
AppY
Figure 15: Metadata and Policy
+-----+ +-----+ +-----+
| SFF |---------> | SFF |----------> | SFF |
+--+--+ +--+--+ +--+--+
^ | |
,-+-. ,-+-. ,-+-.
/ \ / \ / \
( Class ) ( SF1 ) ( SF2 )
\ ify / \ / \ /
`-+-' `---' `---'
| Permit Deny AppZ
+---+---+ employees
| |
+-------+
external
system:
Employee
AppZ
Figure 16: External Metadata and Policy
In both of the examples above, the service functions perform policy
decisions based on the result of the initial classification: the SFs
did not need to perform re-classification, rather they rely on a
antecedent classification for local policy enforcement.
8.2. Updating/Augmenting Metadata
Post-initial metadata imposition (typically performed during initial
service path determination), metadata may be augmented or updated:
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1. Metadata Augmentation: Information may be added to NSH's existing
metadata, as depicted in Figure 17. For example, if the initial
classification returns the tenant information, a secondary
classification (perhaps co-resident with DPI or SLB) may augment
the tenant classification with application information, and
impose that new information in the NSH metadata. The tenant
classification is still valid and present, but additional
information has been added to it.
2. Metadata Update: Subsequent classifiers may update the initial
classification if it is determined to be incorrect or not
descriptive enough. For example, the initial classifier adds
metadata that describes the traffic as "internet" but a security
service function determines that the traffic is really "attack".
Figure 18 illustrates an example of updating metadata.
+-----+ +-----+ +-----+
| SFF |---------> | SFF |----------> | SFF |
+--+--+ +--+--+ +--+--+
^ | |
,---. ,---. ,---.
/ \ / \ / \
( Class ) ( SF1 ) ( SF2 )
\ / \ / \ /
`-+-' `---' `---'
| Inspect Deny
+---+---+ employees employee+
| | Class=AppZ appZ
+-------+
external
system:
Employee
Figure 17: Metadata Augmentation
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+-----+ +-----+ +-----+
| SFF |---------> | SFF |----------> | SFF |
+--+--+ +--+--+ +--+--+
^ | |
,---. ,---. ,---.
/ \ / \ / \
( Class ) ( SF1 ) ( SF2 )
\ / \ / \ /
`---' `---' `---'
5-tuple: Inspect Deny
Tenant A Tenant A attack
--> attack
Figure 18: Metadata Update
8.3. Service Path ID and Metadata
Metadata information may influence the service path selection since
the Service Path Identifier can represent the result of
classification. A given SPI can represent all or some of the
metadata, and be updated based on metadata classification results.
This relationship provides the ability to create a dynamic services
plane based on complex classification without requiring each node to
be capable of such classification, or requiring a coupling to the
network topology. This yields service graph functionality as
described in Section 7.4. Figure 19 illustrates an example of this
behavior.
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+-----+ +-----+ +-----+
| SFF |---------> | SFF |------+---> | SFF |
+--+--+ +--+--+ | +--+--+
| | | |
,---. ,---. | ,---.
/ \ / \ | / \
( SCL ) ( SF1 ) | ( SF2 )
\ / \ / | \ /
`---' `---' +-----+ `---'
5-tuple: Inspect | SFF | Original
Tenant A Tenant A +--+--+ next SF
--> DoS |
V
,-+-.
/ \
( SF10 )
\ /
`---'
DoS
"Scrubber"
Figure 19: Path ID and Metadata
Specific algorithms for mapping metadata to an SPI are outside the
scope of this draft.
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9. NSH Encapsulation Examples
9.1. GRE + NSH
IPv4 Packet:
+----------+--------------------+--------------------+
|L2 header | L3 header, proto=47|GRE header,PT=0x894F|
+----------+--------------------+--------------------+
--------------+----------------+
NSH, NP=0x1 |original packet |
--------------+----------------+
L2 Frame:
+----------+--------------------+--------------------+
|L2 header | L3 header, proto=47|GRE header,PT=0x894F|
+----------+--------------------+--------------------+
---------------+---------------+
NSH, NP=0x3 |original frame |
---------------+---------------+
Figure 20: GRE + NSH
9.2. VXLAN-gpe + NSH
IPv4 Packet:
+----------+------------------------+---------------------+
|L2 header | IP + UDP dst port=4790 |VXLAN-gpe NP=0x4(NSH)|
+----------+------------------------+---------------------+
--------------+----------------+
NSH, NP=0x1 |original packet |
--------------+----------------+
L2 Frame:
+----------+------------------------+---------------------+
|L2 header | IP + UDP dst port=4790 |VXLAN-gpe NP=0x4(NSH)|
+----------+------------------------+---------------------+
---------------+---------------+
NSH,NP=0x3 |original frame |
---------------+---------------+
Figure 21: VXLAN-gpe + NSH
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9.3. Ethernet + NSH
IPv4 Packet:
+-------------------------------+---------------+--------------------+
|Outer Ethernet, ET=0x894F | NSH, NP = 0x1 | original IP Packet |
+-------------------------------+---------------+--------------------+
L2 Frame:
+-------------------------------+---------------+----------------+
|Outer Ethernet, ET=0x894F | NSH, NP = 0x3 | original frame |
+-------------------------------+---------------+----------------+
Figure 22: Ethernet + NSH
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10. Security Considerations
As with many other protocols, NSH data can be spoofed or otherwise
modified. In many deployments, NSH will be used in a controlled
environment, with trusted devices (e.g. a data center) thus
mitigating the risk of unauthorized header manipulation.
NSH is always encapsulated in a transport protocol and therefore,
when required, existing security protocols that provide authenticity
(e.g. RFC 2119 [RFC6071]) can be used.
Similarly if confidentiality is required, existing encryption
protocols can be used in conjunction with encapsulated NSH.
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11. Open Items for WG Discussion
1. MD type 1 metadata semantics specifics
2. Bypass bit in NSH.
3. Rendered Service Path ID (RSPID).
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12. Contributors
This WG document originated as draft-quinn-sfc-nsh and had the
following co-authors and contributors. 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.
Surendra Kumar
Cisco Systems
smkumar@cisco.com
Michael Smith
Cisco Systems
michsmit@cisco.com
Jim Guichard
Cisco Systems
jguichar@cisco.com
Rex Fernando
Cisco Systems
Email: rex@cisco.com
Navindra Yadav
Cisco Systems
Email: nyadav@cisco.com
Wim Henderickx
Alcatel-Lucent
wim.henderickx@alcatel-lucent.com
Andrew Dolganow
Alcaltel-Lucent
Email: andrew.dolganow@alcatel-lucent.com
Praveen Muley
Alcaltel-Lucent
Email: praveen.muley@alcatel-lucent.com
Tom Nadeau
Brocade
tnadeau@lucidvision.com
Puneet Agarwal
puneet@acm.org
Rajeev Manur
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Broadcom
rmanur@broadcom.com
Abhishek Chauhan
Citrix
Abhishek.Chauhan@citrix.com
Joel Halpern
Ericsson
joel.halpern@ericsson.com
Sumandra Majee
F5
S.Majee@f5.com
David Melman
Marvell
davidme@marvell.com
Pankaj Garg
Microsoft
Garg.Pankaj@microsoft.com
Brad McConnell
Rackspace
bmcconne@rackspace.com
Chris Wright
Red Hat Inc.
chrisw@redhat.com
Kevin Glavin
Riverbed
kevin.glavin@riverbed.com
Hong (Cathy) Zhang
Huawei US R&D
cathy.h.zhang@huawei.com
Louis Fourie
Huawei US R&D
louis.fourie@huawei.com
Ron Parker
Affirmed Networks
ron_parker@affirmednetworks.com
Myo Zarny
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Goldman Sachs
myo.zarny@gs.com
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13. Acknowledgments
The authors would like to thank 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 Carlos Pignataro and
Larry Kreeger for their invaluable ideas and contributions which are
reflected throughout this draft.
Lastly, Reinaldo Penno deserves a particular thank you for his
architecture and implementation work that helped guide the protocol
concepts and design.
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14. IANA Considerations
14.1. NSH EtherType
An IEEE EtherType, 0x894F, has been allocated for NSH.
14.2. Network Service Header (NSH) Parameters
IANA is requested to create a new "Network Service Header (NSH)
Parameters" registry. The following sub-sections request new
registries within the "Network Service Header (NSH) Parameters "
registry.
14.2.1. NSH Base Header Reserved Bits
There are ten bits at the beginning of the NSH Base Header. New bits
are assigned via Standards Action [RFC5226].
Bits 0-1 - Version
Bit 2 - OAM (O bit)
Bits 2-9 - Reserved
14.2.2. MD Type Registry
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
this document. Registry entries are assigned by using the "IETF
Review" policy defined in RFC 5226 [RFC5226].
+---------+--------------+---------------+
| MD Type | Description | Reference |
+---------+--------------+---------------+
| 0 | Reserved | This document |
| | | |
| 1 | NSH | This document |
| | | |
| 2 | NSH | This document |
| | | |
| 3..253 | Unassigned | |
| | | |
| 254 | Experiment 1 | This document |
| | | |
| 255 | Experiment 2 | This document |
+---------+--------------+---------------+
Table 1
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14.2.3. TLV Class Registry
IANA is requested to set up a registry of "TLV Types". These are 16-
bit values. Registry entries are assigned by using the "IETF Review"
policy defined in RFC 5226 [RFC5226].
14.2.4. NSH Base Header Next Protocol
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
draft. New values are assigned via Standards Action [RFC5226].
+---------------+-------------+---------------+
| Next Protocol | Description | Reference |
+---------------+-------------+---------------+
| 0 | Reserved | This document |
| | | |
| 1 | IPv4 | This document |
| | | |
| 2 | IPv6 | This document |
| | | |
| 3 | Ethernet | This document |
| | | |
| 4..253 | Unassigned | |
+---------------+-------------+---------------+
Table 2
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15. References
15.1. Normative References
[RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791,
DOI 10.17487/RFC0791, September 1981,
<http://www.rfc-editor.org/info/rfc791>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/
RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
15.2. Informative References
[RFC2784] Farinacci, D., Li, T., Hanks, S., Meyer, D., and P.
Traina, "Generic Routing Encapsulation (GRE)", RFC 2784,
DOI 10.17487/RFC2784, March 2000,
<http://www.rfc-editor.org/info/rfc2784>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
DOI 10.17487/RFC5226, May 2008,
<http://www.rfc-editor.org/info/rfc5226>.
[RFC6071] Frankel, S. and S. Krishnan, "IP Security (IPsec) and
Internet Key Exchange (IKE) Document Roadmap", RFC 6071,
DOI 10.17487/RFC6071, February 2011,
<http://www.rfc-editor.org/info/rfc6071>.
[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]
Quinn, P., Manur, R., Agarwal, P., Kreeger, L., Lewis, D.,
Maino, F., Smith, M., Yong, L., Xu, X., Elzur, U., Garg,
P., and D. Melman, "Generic Protocol Extension for VXLAN",
<https://datatracker.ietf.org/doc/
draft-ietf-nvo3-vxlan-gpe/>.
[dcalloc] Guichard, J., Smith, M., and S. Kumar, "Network Service
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Header (NSH) Context Header Allocation (Data Center)",
2014, <https://datatracker.ietf.org/doc/
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/>.
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Authors' Addresses
Paul Quinn (editor)
Cisco Systems, Inc.
Email: paulq@cisco.com
Uri Elzur (editor)
Intel
Email: uri.elzur@intel.com
Quinn & Elzur Expires January 24, 2016 [Page 43]
