Service Function Chaining Working Group Yuehua.
Internet Engineering Task Force (IETF) Y. Wei, Ed.
Internet-Draft
Request for Comments: 9263 ZTE Corporation
Intended status:
Category: Standards Track U. Elzur
Expires: 22 October 2022
ISSN: 2070-1721 Intel
S. Majee
Individual contributor Contributor
C. Pignataro
Cisco
D. Eastlake 3rd
Futurewei Technologies
20 April
August 2022
Network Service Header (NSH) Metadata Type 2 Variable-Length Context
Headers
draft-ietf-sfc-nsh-tlv-15
Abstract
Service Function Chaining (SFC) uses the Network Service Header (NSH)
(RFC 8300) to steer and provide context Metadata metadata (MD) with each
packet. Such Metadata metadata can be of various Types types, including MD Type 2 2,
consisting of variable length context headers. Variable-Length Context Headers. This document
specifies several such context headers Context Headers that can be used within a
service function path.
Service Function Path (SFP).
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 an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list It represents the consensus of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid the IETF community. It has
received public review and has been approved for a maximum publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of six months RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be updated, replaced, or obsoleted by other documents obtained 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 22 October 2022.
https://www.rfc-editor.org/info/rfc9263.
Copyright Notice
Copyright (c) 2022 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 (https://trustee.ietf.org/
license-info)
(https://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 Revised BSD License text as described in Section 4.e of the
Trust Legal Provisions and are provided without warranty as described
in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used Used in this document . . . . . . . . . . . . . . 3 This Document
2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Requirements Language . . . . . . . . . . . . . . . . . . 3
3. NSH MD Type 2 format . . . . . . . . . . . . . . . . . . . . 3 Format
4. NSH MD Type 2 Context Headers . . . . . . . . . . . . . . . . 4
4.1. Forwarding Context . . . . . . . . . . . . . . . . . . . 4
4.2. Tenant Identifier . . . . . . . . . . . . . . . . . . . . 6 ID
4.3. Ingress Network Node Information . . . . . . . . . . . . 7
4.4. Ingress Network Source Interface . . . . . . . . . . . . 8
4.5. Flow ID . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.6. Source and/or Destination Groups . . . . . . . . . . . . 9
4.7. Policy Identifier . . . . . . . . . . . . . . . . . . . . 10 ID
5. Security Considerations . . . . . . . . . . . . . . . . . . . 11
5.1. Forwarding Context . . . . . . . . . . . . . . . . . . . 11
5.2. Tenant Identifier . . . . . . . . . . . . . . . . . . . . 12 ID
5.3. Ingress Network Node Information . . . . . . . . . . . . 12
5.4. Ingress Node Source Interface . . . . . . . . . . . . . . 12
5.5. Flow ID . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.6. Source and/or Destination Groups . . . . . . . . . . . . 13
5.7. Policy Identifier . . . . . . . . . . . . . . . . . . . . 13 ID
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
7.1.
6.1. MD Type 2 Context Types . . . . . . . . . . . . . . . . . 13
7.2.
6.2. Forwarding Context Types . . . . . . . . . . . . . . . . 14
7.3.
6.3. Flow ID Context Types . . . . . . . . . . . . . . . . . . 15
8.
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 15
8.1.
7.1. Normative References . . . . . . . . . . . . . . . . . . 15
8.2.
7.2. Informative References . . . . . . . . . . . . . . . . . 16
Acknowledgments
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17
1. Introduction
The Network Service Header (NSH) [RFC8300] is the Service Function
Chaining (SFC) encapsulation that supports the SFC architecture
[RFC7665]. As such, the NSH provides the following key elements:
1. Service Function Path (SFP) identification. identification
2. Indication indication of location within a Service Function Path. an SFP
3. Optional, optional, per-packet metadata (fixed-length or variable-length). variable-length)
[RFC8300] further defines two metadata formats (MD Types): 1 and 2.
MD Type 1 defines the fixed-length, 16-octet long metadata, whereas MD
Type 2 defines a variable-length context format for metadata. This
document defines several common metadata context headers Context Headers for use
within NSH MD Type 2. These supplement the Subscriber Identity Identifier and
Performance Policy MD Type 2 metadata context headers Context Headers specified in
[RFC8979].
This document does not address metadata usage, updating/chaining of
metadata, or other SFP functions. Those topics are described in
[RFC8300].
2. Conventions used Used in this document This Document
2.1. Terminology
This document uses the terminology defined in the SFC Architecture architecture
[RFC7665] and the Network Service Header NSH [RFC8300].
2.2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. NSH MD Type 2 format Format
An NSH is composed of a 4-octet Base Header, a 4-octet Service Path
Header
Header, and optional Context Headers. The Base Header identifies the
MD-Type
MD Type in use:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Ver|O|U| TTL | Length |U|U|U|U|MD Type| Next Protocol |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: NSH Base Header
Please refer to the NSH [RFC8300] for a detailed header description.
When the base header Base Header specifies MD Type = 0x2, zero or more Variable Variable-
Length Context Headers MAY be added, immediately following the
Service Path Header. Figure 2 below depicts the format of the
Context Header as defined in Section 2.5.1 of [RFC8300].
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metadata Class | Type |U| Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Variable-Length Metadata |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: NSH Variable-Length Context Headers
4. NSH MD Type 2 Context Headers
[RFC8300] specifies Metadata Class 0x0000 as IETF Base NSH MD Class.
In this document, metadata types are defined for the IETF Base NSH MD
Class. The Context Headers specified in the subsections below are as
follows:
1. Forwarding Context
2. Tenant Identifier ID
3. Ingress Network Node Information
4. Ingress Node Source Interface
5. Flow ID
6. Source and/or Destination Groups
7. Policy Identifier ID
4.1. Forwarding Context
This metadata context carries a network forwarding context, used for
segregation and forwarding scope. Forwarding context can take
several forms depending on the network environment. For environment, for example,
VXLAN/VXLAN-GPE VNID, VRF
Virtual eXtensible Local Area Network (VXLAN) / Generic Protocol
Extension for VXLAN (VXLAN-GPE) Virtual Network Identifier (VNID),
VPN Routing and Forwarding (VRF) identification, or VLAN.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metadata Class = 0x0000 | Type = TBA1 0x04 |U| Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|CT=0x0 | Reserved | VLAN ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: VLAN Forwarding Context
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metadata Class = 0x0000 | Type = TBA1 0x04 |U| Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|CT=0x1 |Resv | Service VLAN ID | Customer VLAN ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: QinQ Forwarding Context
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metadata Class = 0x0000 | Type = TBA1 0x04 |U| Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|CT=0x2 | Reserved | MPLS VPN Label |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: MPLS VPN Forwarding Context
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metadata Class = 0x0000 | Type = TBA1 0x04 |U| Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|CT=0x3 | Resv | Virtual Network Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: VNI Forwarding Context
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metadata Class = 0x0000 | Type = TBA1 0x04 |U| Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|CT=0x4 | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Session ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: Session ID Forwarding Context
where:
The fields are described as follows:
Context Type (CT) is four bits-long (CT): This 4-bit field that defines the interpretation
of the Forwarding Context field. Please see the IANA Considerations
considerations in Section 7.2. 6.2. This document defines these CT
values:
- 0x0 - 12 bits
0x0: 12-bit VLAN identifier [IEEE.802.1Q_2018]. See Figure 3.
- 0x1 - 24 bits
0x1: 24-bit double tagging identifiers. A service VLAN tag
followed by a customer VLAN tag [IEEE.802.1Q_2018]. The two
VLAN IDs are concatenated and appear in the same order that
they appeared in the payload. See Figure 4.
- 0x2 - 20 bits
0x2: 20-bit MPLS VPN label([RFC3032])([RFC4364]). label [RFC3032] [RFC4364]. See Figure 5.
- 0x3 - 24 bits
0x3: 24-bit virtual network identifier (VNI)[RFC8926]. (VNI) [RFC8926]. See
Figure 6.
- 0x4 - 32 bits
0x4: 32-bit Session ID ([RFC3931]). [RFC3931]. This is called Key in GRE
[RFC2890]. See Figure 7.
Reserved (Resv) (Resv): These bits in the context fields MUST be sent as
zero and ignored on receipt.
4.2. Tenant Identifier ID
Tenant identification is often used for segregation within a multi-
tenant environment. Orchestration system-generated tenant Tenant IDs are an
example of such data. This context header Context Header carries the value of the
Tenant identifier. [OpenDaylight-VTN] ID. Virtual Tenant Network (VTN) [OpenDaylight-VTN] is an
application that provides multi-tenant virtual network networks on an
SDN a
Software-Defined Networking (SDN) controller.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metadata Class = 0x0000 | Type = TBA2 0x05 |U| Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Tenant ID ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 8: Tenant Identifier ID List
The fields are described as follows:
Length: Indicates the length of the Tenant ID in octets (see
Section 2.5.1 of [RFC8300]).
Tenant ID: Represents an opaque value pointing to Orchestration orchestration
system-generated tenant identifier. Tenant ID. The structure and semantics of this
field are specific to the operator's deployment across its
operational domain, domain and are specified and assigned by an
orchestration function. The specifics of that orchestration-based
assignment are outside the scope of this document.
4.3. Ingress Network Node Information
This context header Context Header carries a Node ID of the network node at which
the packet entered the SFC-enabled domain. This node will
necessarily be a Classifier classifier [RFC7665]. In cases where the SPI Service
Path Identifier (SPI) identifies the ingress node, this context header Context
Header is superfluous.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metadata Class = 0x0000 | Type = TBA3 0x06 |U| Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Node ID ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 9: Ingress Network Node ID
The fields are described as follows:
Length: Indicates the length of the Node ID in octets (see
Section 2.5.1 of [RFC8300]).
Node ID: Represents an opaque value of the ingress network node Node ID.
The structure and semantics of this field are deployment specific.
For example, Node ID may be a 4 octets 4-octet IPv4 address Node ID, or a 16 octets
16-octet IPv6 address Node ID, or a 6 octets 6-octet MAC address, or 8 octets an 8-octet
MAC address (EUI-64), (64-bit Extended Unique Identifier (EUI-64)), etc.
4.4. Ingress Network Source Interface
This context identifies the ingress interface of the ingress network
node. The l2vlan (135), l3ipvlan (136), ipForward (142), and mpls
(166) in [IANAifType] are examples of source interfaces.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metadata Class = 0x0000 | Type = TBA4 0x07 |U| Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Source Interface ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 10: Ingress Network Source Interface
The fields are described as follows:
Length: Indicates the length of the Source Interface in octets (see
Section 2.5.1 of [RFC8300]).
Source Interface: Represents an opaque value of the identifier of
the ingress interface of the ingress network node.
4.5. Flow ID
Flow ID provides a field in the NSH MD Type 2 to label packets belonging
to the same flow. For example, [RFC8200] defined defines IPv6 Flow Label as
Flow ID, ID. Another example of Flow ID is how [RFC6790] defined defines an
entropy label which that is generated based on flow information in the MPLS network is another
example of Flow ID.
network. Absence of this field, field or a value of zero denotes that
packets have not been labeled with a Flow ID.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metadata Class = 0x0000 | Type = TBA5 0x08 |U| Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|CT=0x0 | Reserved | IPv6 Flow ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 11: IPv6 Flow ID
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metadata Class = 0x0000 | Type = TBA5 0x08 |U| Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|CT=0x1 | Reserved | MPLS entropy label |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 12: MPLS entropy label Entropy Label
The fields are described as follows:
Length: Indicates the length of the Flow ID in octets (see
Section 2.5.1 of [RFC8300]). For example, the IPv6 Flow Label in
[RFC8200] is 20-bit 20 bits long. An entropy label in the MPLS network
in [RFC6790] is also 20-bit 20 bits long.
Context Type (CT) is four bits-long (CT): This 4-bit field that defines the interpretation
of the Flow ID field. Please see the IANA
Considerations considerations in
Section 7.3. 6.3. This document defines these CT values:
- 0x0 - 20 bits
0x0: 20-bit IPv6 Flow Label in [RFC8200]. See Figure 11.
- 0x1 - 20 bits
0x1: 20-bit entropy label in the MPLS network in [RFC6790]. See
Figure 12.
Reserved
Reserved: These bits in the context fields MUST be sent as zero and
ignored on receipt.
4.6. Source and/or Destination Groups
Intent-based systems can use this data to express the logical
grouping of source and/or destination objects. [OpenStack] and
[OpenDaylight] provide examples of such a system. Each is expressed
as a 32-bit opaque object.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metadata Class = 0x0000 | Type = TBA6 0x09 |U| Length=8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Group |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination Group |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 13: Source/Destination Groups
If there is no group information specified for the source group Source Group or
destination group
Destination Group field, the field MUST be sent as zero and ignored
on receipt.
4.7. Policy Identifier ID
Traffic handling policies are often referred to by a system-generated
identifier, which is then used by the devices to look up the policy's
content locally. For example, this identifier could be an index to
an array, a lookup key, or a database Id. ID. The identifier allows
enforcement agents or services to look up the content of their part
of the policy.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metadata Class = 0x0000 | Type = TBA7 0x0A |U| Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Policy ID ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 14: Policy ID
The fields are described as follows:
Length: Indicates the length of the Policy ID in octets (see
Section 2.5.1 of [RFC8300]).
Policy ID: Represents an opaque value of the Policy ID.
This policy identifier Policy ID is a general policy Policy ID, essentially a key to allow
Service Functions (SFs) to know which policies to apply to packets.
Those policies generally will not have much to do with performance, performance
but rather with what specific treatment to apply. It may may, for example
example, select a URL filter data set for a URL filter, filter or select a
video transcoding policy in a transcoding SF. The Performance Policy
Identifier
ID in [RFC8979] is described there as having very specific
use, and use and,
for example example, says that fully controlled SFPs would not use it. The
Policy ID in this document is for cases not covered by [RFC8979].
5. Security Considerations
A misbehaving node from within the SFC-enabled domain may alter the
content of the Context Headers, which may lead to service disruption.
Such an attack is not unique to the Context Headers defined in this
document. Measures discussed in Section 8 of [RFC8300] describes the
general security considerations for protecting the NSH.
[I-D.ietf-sfc-nsh-integrity] [RFC9145]
specifies methods of protecting the integrity of the NSH metadata.
If the NSH includes the MAC Message Authentication Code (MAC) and
Encrypted Metadata Context Header [RFC9145], the authentication of
the packet MUST be verified before using any data. If the
verification fails, the receiver MUST stop processing the variable
length context headers Variable-
Length Context Headers and notify an operator.
The security and privacy considerations for the 7 types of context
header Context
Headers specified above are discussed below. Since NSH ignorant NSH-ignorant SFs
will never see the NSH, then even if they are malign, they cannot
compromise security or privacy based on the NSH or any of these
context headers, although
Context Headers; however, they could cause compromise based on the
rest of the packet. To the extent that any of these headers is are
included when it they would be unneeded or have no effect, they provide
a covert channel for the entity adding the context header Context Header to
communicate a limited amount of arbitrary information to downstream
entities within the SFC-enabled domain.
5.1. Forwarding Context
All of the Forwarding Context variants specified in this document
(those with CT values between 0 and 4) merely repeat a field that is
available in the packet encapsulated by the NSH. These variants
repeat that field in the NSH for convenience. Thus, there are no
special security or privacy considerations in these cases. Any
future new values of CT for the Forwarding Context must specify the
security and privacy considerations for those extensions.
5.2. Tenant Identifier ID
The Tenant ID indicates the tenant to which traffic belongs and might
be used to tie together and correlate packets for a tenant that some
monitoring function could not otherwise group group, especially if other
possible identifiers were being randomized. As such, it may reduce
security by facilitating traffic analysis but only within the SFC-
enabled domain where this context header Context Header is present in packets.
5.3. Ingress Network Node Information
The SFC-enabled domain manager normally operates the initial ingress
/ ingress/
classifier node and is thus potentially aware of the information
provided by this context header. Context Header. Furthermore, in many cases cases, the SPI
that will be present in the NSH identifies or closely constrains the
ingress node. Also, in most cases, it is anticipated that many
entities will be sending packets into an SFC-enabled domain through
the same ingress node. Thus, under most circumstances, this context
header Context
Header is expected to weaken security and privacy to only a minor
extent and only within the SFC-enabled domain.
5.4. Ingress Node Source Interface
This context header Context Header is likely to be meaningless unless the Ingress
Network Node Information context header Context Header is also present. When that
node information header is present, this source interface header
provides a more fine-grained view of the source by identifying not
just the initial ingress / classifier ingress/classifier node but also the port of that
node on which the data arrived. Thus, it is more likely to identify
a specific source entity or at least to more tightly constrain the
set of possible source entities, entities than just the node information
header. As a result, inclusion of this context header Context Header with the node
information context header Context Header is potentially a greater threat to
security and privacy than the node information header alone alone, but this
threat is still constrained to the SFC-enabled domain.
5.5. Flow ID
The variations of this context header Context Header specified in this document
simply repeat fields already available in the packet and thus have no
special security or privacy considerations. Any future new values of
CT for the Flow ID must specify the security and privacy
considerations for those extensions.
5.6. Source and/or Destination Groups
This context header Context Header provides additional information that might help
identify the source and/or destination of packets. Depending on the
granularity of the groups, it could either (1) distinguish packets as
part of flows from and/or to objects where those flows could not
otherwise be easily distinguished but appear to be part of one or
fewer flows or (2) group packet flows that are from and/or to an
object where those flows could not otherwise be easily grouped for
analysis or whatever. another purpose. Thus, the presence of this context header Context
Header with non-zero source and/or destination groups can, within the
SFC-enabled domain, erode security and privacy to an extent that
depends on the details of the grouping.
5.7. Policy Identifier ID
This context header Context Header carries an identifier that nodes in the SFC-
enabled domain can use to look up policy to potentially influence
their actions with regard to the packet carrying this header. If
there are no such action decisions, decisions regarding their actions, then the header
should not be included. If there are such decisions, the information
on which they are to be based needs to be included somewhere in the
packet. There is no reason for inclusion in this context header Context Header to
have any security or privacy considerations that would not apply to
any other plaintext way of including such information. It may
provide additional information to help identify a flow of data for
analysis.
6.
7. IANA Considerations
7.1.
6.1. MD Type 2 Context Types
IANA is requested to assign has assigned the following types (Table 1) from the "NSH IETF-Assigned IETF-
Assigned Optional Variable-Length Metadata Types" registry available
at [IANA-NSH-MD2].
+=======+==================================+===============+
+=======+==================================+===========+
| Value | Description | Reference |
+=======+==================================+===============+
+=======+==================================+===========+
| TBA1 0x04 | Forwarding Context | This document RFC 9263 |
+-------+----------------------------------+---------------+
+-------+----------------------------------+-----------+
| TBA2 0x05 | Tenant Identifier ID | This document RFC 9263 |
+-------+----------------------------------+---------------+
+-------+----------------------------------+-----------+
| TBA3 0x06 | Ingress Network NodeID Node ID | This document RFC 9263 |
+-------+----------------------------------+---------------+
+-------+----------------------------------+-----------+
| TBA4 0x07 | Ingress Network Interface | This document RFC 9263 |
+-------+----------------------------------+---------------+
+-------+----------------------------------+-----------+
| TBA5 0x08 | Flow ID | This document RFC 9263 |
+-------+----------------------------------+---------------+
+-------+----------------------------------+-----------+
| TBA6 0x09 | Source and/or Destination Groups | This document RFC 9263 |
+-------+----------------------------------+---------------+
+-------+----------------------------------+-----------+
| TBA7 0x0A | Policy Identifier ID | This document RFC 9263 |
+-------+----------------------------------+---------------+
+-------+----------------------------------+-----------+
Table 1: Type Values
7.2.
6.2. Forwarding Context Types
IANA is requested to create has created a new sub-registry subregistry for "Forwarding
Context" context types Context Types" at
[IANA-NSH-MD2] as follows: follows.
The Registration Policy registration policy is IETF Review
+=========+=========================================+===============+ Review.
+=========+=========================================+===========+
| Value | Forwarding Context Header Types Description | Reference |
+=========+=========================================+===============+
+=========+=========================================+===========+
| 0x0 | 12-bit VLAN identifier | This document RFC 9263 |
+---------+-----------------------------------------+---------------+
+---------+-----------------------------------------+-----------+
| 0x1 | 24-bit double tagging identifiers | This document RFC 9263 |
+---------+-----------------------------------------+---------------+
+---------+-----------------------------------------+-----------+
| 0x2 | 20-bit MPLS VPN label | This document RFC 9263 |
+---------+-----------------------------------------+---------------+
+---------+-----------------------------------------+-----------+
| 0x3 | 24-bit virtual network identifier | This document |
| | (VNI) | RFC 9263 |
+---------+-----------------------------------------+---------------+
+---------+-----------------------------------------+-----------+
| 0x4 | 32-bit Session ID | This document RFC 9263 |
+---------+-----------------------------------------+---------------+
+---------+-----------------------------------------+-----------+
| 0x5-0xE | Unassigned | |
+---------+-----------------------------------------+---------------+
+---------+-----------------------------------------+-----------+
| 0xF | Reserved | This document RFC 9263 |
+---------+-----------------------------------------+---------------+
+---------+-----------------------------------------+-----------+
Table 2: Forwarding Context Types
7.3.
6.3. Flow ID Context Types
IANA is requested to create has created a new sub-registry subregistry for "Flow ID Context"
context types Context Types" at
[IANA-NSH-MD2] as follows: follows.
The Registration Policy registration policy is IETF Review
+=========+==============================+===============+ Review.
+=========+==========================================+===========+
| Value | Flow ID Context Header Types Description | Reference |
+=========+==============================+===============+
+=========+==========================================+===========+
| 0x0 | 20-bit IPv6 Flow Label | This document RFC 9263 |
+---------+------------------------------+---------------+
+---------+------------------------------------------+-----------+
| 0x1 | 20-bit entropy label in the | This document |
| | MPLS network | RFC 9263 |
+---------+------------------------------+---------------+
+---------+------------------------------------------+-----------+
| 0x2-0xE | Unassigned | |
+---------+------------------------------+---------------+
+---------+------------------------------------------+-----------+
| 0xF | Reserved | This document RFC 9263 |
+---------+------------------------------+---------------+
+---------+------------------------------------------+-----------+
Table 3: Flow ID Context Types
8.
7. References
8.1.
7.1. Normative References
[I-D.ietf-sfc-nsh-integrity]
Boucadair, M., Reddy, T., and D. Wing, "Integrity
Protection for the Network
[IANA-NSH-MD2]
IANA, "Network Service Header (NSH) and
Encryption of Sensitive Context Headers", Work in
Progress, Internet-Draft, draft-ietf-sfc-nsh-integrity-09,
20 September 2021, <https://www.ietf.org/archive/id/draft-
ietf-sfc-nsh-integrity-09.txt>.
[IANA-NSH-MD2]
IANA, "NSH IETF-Assigned Optional Variable-Length Metadata
Types", <https://www.iana.org/assignments/nsh/
nsh.xhtml#optional-variable-length-metadata-types>. Parameters",
<https://www.iana.org/assignments/nsh>.
[IEEE.802.1Q_2018]
IEEE, "IEEE Standard for Local and Metropolitan Area
Networks--Bridges
Network -- Bridges and Bridged Networks", July 2018,
<http://ieeexplore.ieee.org/servlet/
opac?punumber=8403925>.
<https://ieeexplore.ieee.org/document/8403927>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC3931] Lau, J., Ed., Townsley, M., Ed., and I. Goyret, Ed.,
"Layer Two Tunneling Protocol - Version 3 (L2TPv3)",
RFC 3931, DOI 10.17487/RFC3931, March 2005,
<https://www.rfc-editor.org/info/rfc3931>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8300] Quinn, P., Ed., Elzur, U., Ed., and C. Pignataro, Ed.,
"Network Service Header (NSH)", RFC 8300,
DOI 10.17487/RFC8300, January 2018,
<https://www.rfc-editor.org/info/rfc8300>.
[RFC9145] Boucadair, M., Reddy.K, T., and D. Wing, "Integrity
Protection for the Network Service Header (NSH) and
Encryption of Sensitive Context Headers", RFC 9145,
DOI 10.17487/RFC9145, December 2021,
<https://www.rfc-editor.org/info/rfc9145>.
8.2.
7.2. Informative References
[IANAifType]
IANA, "IANAifType", "IANAifType-MIB DEFINITIONS", 2021,
<https://www.iana.org/assignments/ianaiftype-mib/
ianaiftype-mib>.
[OpenDaylight]
OpenDaylight, "Group Based Policy", Policy User Guide", 2021,
<https://docs.opendaylight.org/en/stable-fluorine/user-
guide/group-based-policy-user-
guide.html?highlight=group%20policy#>.
[OpenDaylight-VTN]
OpenDaylight, "OpenDaylight VTN", 2021, <https://nexus.ope
ndaylight.org/content/sites/site/org.opendaylight.docs/mas
ter/userguide/manuals/userguide/bk-user-guide/
content/_vtn.html>.
[OpenStack]
OpenStack, "Group Based Policy", "GroupBasedPolicy", 2021,
<https://wiki.openstack.org/wiki/GroupBasedPolicy>.
[RFC2890] Dommety, G., "Key and Sequence Number Extensions to GRE",
RFC 2890, DOI 10.17487/RFC2890, September 2000,
<https://www.rfc-editor.org/info/rfc2890>.
[RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y.,
Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack
Encoding", RFC 3032, DOI 10.17487/RFC3032, January 2001,
<https://www.rfc-editor.org/info/rfc3032>.
[RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February
2006, <https://www.rfc-editor.org/info/rfc4364>.
[RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and
L. Yong, "The Use of Entropy Labels in MPLS Forwarding",
RFC 6790, DOI 10.17487/RFC6790, November 2012,
<https://www.rfc-editor.org/info/rfc6790>.
[RFC7665] Halpern, J., Ed. and C. Pignataro, Ed., "Service Function
Chaining (SFC) Architecture", RFC 7665,
DOI 10.17487/RFC7665, October 2015,
<https://www.rfc-editor.org/info/rfc7665>.
[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017,
<https://www.rfc-editor.org/info/rfc8200>.
[RFC8926] Gross, J., Ed., Ganga, I., Ed., and T. Sridhar, Ed.,
"Geneve: Generic Network Virtualization Encapsulation",
RFC 8926, DOI 10.17487/RFC8926, November 2020,
<https://www.rfc-editor.org/info/rfc8926>.
[RFC8979] Sarikaya, B., von Hugo, D., and M. Boucadair, "Subscriber
and Performance Policy Identifier Context Headers in the
Network Service Header (NSH)", RFC 8979,
DOI 10.17487/RFC8979, February 2021,
<https://www.rfc-editor.org/info/rfc8979>.
Acknowledgments
The authors would like to thank Paul Quinn, Behcet Sarikaya, Dirk von
Hugo, Mohamed Boucadair, Gregory Mirsky, and Joel Halpern for
providing invaluable concepts and content for this document.
Authors' Addresses
Yuehua Wei (editor)
ZTE Corporation
No.50, Software Avenue
Nanjing
210012
China
Email: wei.yuehua@zte.com.cn
Uri Elzur
Intel
Email: uri.elzur@intel.com
Sumandra Majee
Individual contributor Contributor
Email: Sum.majee@gmail.com
Carlos Pignataro
Cisco
Email: cpignata@cisco.com
Donald E. Eastlake Eastlake, 3rd
Futurewei Technologies
2386 Panoramic Circle
Apopka, FL 32703
United States of America
Phone: +1-508-333-2270
Email: d3e3e3@gmail.com