Network Service Header (NSH) Metadata Type 2 Variable-Length Context Headers
draft-ietf-sfc-nsh-tlv-15
The information below is for an old version of the document that is already published as an RFC.
| Document | Type |
This is an older version of an Internet-Draft that was ultimately published as RFC 9263.
|
|
|---|---|---|---|
| Authors | Yuehua Wei , Uri Elzur , Sumandra Majee , Carlos Pignataro , Donald E. Eastlake 3rd | ||
| Last updated | 2022-08-09 (Latest revision 2022-04-20) | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Intended RFC status | Proposed Standard | ||
| Formats | |||
| Reviews | |||
| Additional resources | Mailing list discussion | ||
| Stream | WG state | Submitted to IESG for Publication | |
| Document shepherd | Greg Mirsky | ||
| Shepherd write-up | Show Last changed 2021-09-01 | ||
| IESG | IESG state | Became RFC 9263 (Proposed Standard) | |
| Action Holders |
(None)
|
||
| Consensus boilerplate | Yes | ||
| Telechat date | (None) | ||
| Responsible AD | Andrew Alston | ||
| Send notices to | gregimirsky@gmail.com | ||
| IANA | IANA review state | Version Changed - Review Needed | |
| IANA action state | RFC-Ed-Ack |
draft-ietf-sfc-nsh-tlv-15
Service Function Chaining Working Group Yuehua. Wei, Ed.
Internet-Draft ZTE Corporation
Intended status: Standards Track U. Elzur
Expires: 22 October 2022 Intel
S. Majee
Individual contributor
C. Pignataro
Cisco
D. Eastlake
Futurewei Technologies
20 April 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 (MD) with each
packet. Such Metadata can be of various Types including MD Type 2
consisting of variable length context headers. This document
specifies several such context headers that can be used within a
service function path.
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 https://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 22 October 2022.
Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
Wei, et al. Expires 22 October 2022 [Page 1]
Internet-Draft NSH MD2 Context Headers April 2022
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (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 in this document . . . . . . . . . . . . . . 3
2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Requirements Language . . . . . . . . . . . . . . . . . . 3
3. NSH MD Type 2 format . . . . . . . . . . . . . . . . . . . . 3
4. NSH MD Type 2 Context Headers . . . . . . . . . . . . . . . . 4
4.1. Forwarding Context . . . . . . . . . . . . . . . . . . . 4
4.2. Tenant Identifier . . . . . . . . . . . . . . . . . . . . 6
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
5. Security Considerations . . . . . . . . . . . . . . . . . . . 11
5.1. Forwarding Context . . . . . . . . . . . . . . . . . . . 11
5.2. Tenant Identifier . . . . . . . . . . . . . . . . . . . . 12
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
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
7.1. MD Type 2 Context Types . . . . . . . . . . . . . . . . . 13
7.2. Forwarding Context Types . . . . . . . . . . . . . . . . 14
7.3. Flow ID Context Types . . . . . . . . . . . . . . . . . . 15
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 15
8.1. Normative References . . . . . . . . . . . . . . . . . . 15
8.2. Informative References . . . . . . . . . . . . . . . . . 16
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 following key elements:
Wei, et al. Expires 22 October 2022 [Page 2]
Internet-Draft NSH MD2 Context Headers April 2022
1. Service Function Path (SFP) identification.
2. Indication of location within a Service Function Path.
3. Optional, per-packet metadata (fixed-length or 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 for use
within NSH MD Type 2. These supplement the Subscriber Identity and
Performance Policy MD Type 2 metadata 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 in this document
2.1. Terminology
This document uses the terminology defined in the SFC Architecture
[RFC7665] and the Network Service Header [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
An NSH is composed of a 4-octet Base Header, a 4-octet Service Path
Header and optional Context Headers. The Base Header identifies the
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
Wei, et al. Expires 22 October 2022 [Page 3]
Internet-Draft NSH MD2 Context Headers April 2022
Please refer to NSH [RFC8300] for a detailed header description.
When the base header specifies MD Type = 0x2, zero or more 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
3. Ingress Network Node Information
4. Ingress Node Source Interface
5. Flow ID
6. Source and/or Destination Groups
7. Policy Identifier
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 example,
VXLAN/VXLAN-GPE VNID, VRF identification, or VLAN.
Wei, et al. Expires 22 October 2022 [Page 4]
Internet-Draft NSH MD2 Context Headers April 2022
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 |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 |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 |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 |U| Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|CT=0x3 | Resv | Virtual Network Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: VNI Forwarding Context
Wei, et al. Expires 22 October 2022 [Page 5]
Internet-Draft NSH MD2 Context Headers April 2022
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 |U| Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|CT=0x4 | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Session ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: Session ID Forwarding Context
where:
Context Type (CT) is four bits-long field that defines the
interpretation of the Forwarding Context field. Please see the
IANA Considerations in Section 7.2. This document defines these
CT values:
- 0x0 - 12 bits VLAN identifier [IEEE.802.1Q_2018]. See
Figure 3.
- 0x1 - 24 bits 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 MPLS VPN label([RFC3032])([RFC4364]). See
Figure 5.
- 0x3 - 24 bits virtual network identifier (VNI)[RFC8926]. See
Figure 6.
- 0x4 - 32 bits Session ID ([RFC3931]). This is called Key in
GRE [RFC2890]. See Figure 7.
Reserved (Resv) bits in the context fields MUST be sent as zero
and ignored on receipt.
4.2. Tenant Identifier
Tenant identification is often used for segregation within a multi-
tenant environment. Orchestration system-generated tenant IDs are an
example of such data. This context header carries the value of the
Tenant identifier. [OpenDaylight-VTN] Virtual Tenant Network (VTN)
is an application that provides multi-tenant virtual network on an
SDN controller.
Wei, et al. Expires 22 October 2022 [Page 6]
Internet-Draft NSH MD2 Context Headers April 2022
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 |U| Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Tenant ID ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 8: Tenant Identifier 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
system-generated tenant identifier. The structure and semantics
of this field are specific to the operator's deployment across its
operational 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 carries a Node ID of the network node at which
the packet entered the SFC-enabled domain. This node will
necessarily be a Classifier [RFC7665]. In cases where the SPI
identifies the ingress node, this 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 |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]).
Wei, et al. Expires 22 October 2022 [Page 7]
Internet-Draft NSH MD2 Context Headers April 2022
Node ID: Represents an opaque value of the ingress network node
ID. The structure and semantics of this field are deployment
specific. For example, Node ID may be a 4 octets IPv4 address
Node ID, or a 16 octets IPv6 address Node ID, or a 6 octets MAC
address, or 8 octets MAC address (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), 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 |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 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 IPv6 Flow
Label as Flow ID, [RFC6790] defined an entropy label which is
generated based on flow information in the MPLS network is another
example of Flow ID. Absence of this 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 |U| Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|CT=0x0 | Reserved | IPv6 Flow ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Wei, et al. Expires 22 October 2022 [Page 8]
Internet-Draft NSH MD2 Context Headers April 2022
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 |U| Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|CT=0x1 | Reserved | MPLS entropy label |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 12: MPLS 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, IPv6 Flow Label in
[RFC8200] is 20-bit long. An entropy label in the MPLS network in
[RFC6790] is also 20-bit long.
Context Type (CT) is four bits-long field that defines the
interpretation of the Flow ID field. Please see the IANA
Considerations in Section 7.3. This document defines these CT
values:
- 0x0 - 20 bits IPv6 Flow Label in [RFC8200]. See Figure 11.
- 0x1 - 20 bits entropy label in the MPLS network in [RFC6790].
See Figure 12.
Reserved 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.
Wei, et al. Expires 22 October 2022 [Page 9]
Internet-Draft NSH MD2 Context Headers April 2022
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 |U| Length=8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Group |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination Group |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 13: Source/Destination Groups
If there is no group information specified for the source group or
destination group field, the field MUST be sent as zero and ignored
on receipt.
4.7. Policy Identifier
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, a database 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 |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 is a general policy ID, essentially a key to
allow Service Functions to know which policies to apply to packets.
Those policies generally will not have much to do with performance,
but rather with what specific treatment to apply. It may for example
select a URL filter data set for a URL filter, or select a video
Wei, et al. Expires 22 October 2022 [Page 10]
Internet-Draft NSH MD2 Context Headers April 2022
transcoding policy in a transcoding SF. The Performance Policy
Identifier in [RFC8979] is described there as having very specific
use, and for 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 NSH.
[I-D.ietf-sfc-nsh-integrity] specifies methods of protecting the
integrity of the NSH metadata. If the NSH includes the 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 and notify an operator.
The security and privacy considerations for the 7 types of context
header specified above are discussed below. Since 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 they could cause compromise based on the
rest of the packet. To the extent that any of these headers is
included when it would be unneeded or have no effect, they provide a
covert channel for the entity adding the 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.
Wei, et al. Expires 22 October 2022 [Page 11]
Internet-Draft NSH MD2 Context Headers April 2022
5.2. Tenant Identifier
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 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 is present in packets.
5.3. Ingress Network Node Information
The SFC-enabled domain manager normally operates the initial ingress
/ classifier node and is thus potentially aware of the information
provided by this context header. Furthermore, in many 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 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 is likely to be meaningless unless the Ingress
Network Node Information 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 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, than just the node information
header. As a result, inclusion of this context header with the node
information context header is potentially a greater threat to
security and privacy than the node information header alone but this
threat is still constrained to the SFC-enabled domain.
5.5. Flow ID
The variations of this 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.
Wei, et al. Expires 22 October 2022 [Page 12]
Internet-Draft NSH MD2 Context Headers April 2022
5.6. Source and/or Destination Groups
This 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. Thus, the presence of this 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
This 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, then the header should not be
included. If 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 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. 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.
7. IANA Considerations
7.1. MD Type 2 Context Types
IANA is requested to assign the following types (Table 1) from the
"NSH IETF-Assigned Optional Variable-Length Metadata Types" registry
available at [IANA-NSH-MD2].
Wei, et al. Expires 22 October 2022 [Page 13]
Internet-Draft NSH MD2 Context Headers April 2022
+=======+==================================+===============+
| Value | Description | Reference |
+=======+==================================+===============+
| TBA1 | Forwarding Context | This document |
+-------+----------------------------------+---------------+
| TBA2 | Tenant Identifier | This document |
+-------+----------------------------------+---------------+
| TBA3 | Ingress Network NodeID | This document |
+-------+----------------------------------+---------------+
| TBA4 | Ingress Network Interface | This document |
+-------+----------------------------------+---------------+
| TBA5 | Flow ID | This document |
+-------+----------------------------------+---------------+
| TBA6 | Source and/or Destination Groups | This document |
+-------+----------------------------------+---------------+
| TBA7 | Policy Identifier | This document |
+-------+----------------------------------+---------------+
Table 1: Type Values
7.2. Forwarding Context Types
IANA is requested to create a new sub-registry for "Forwarding
Context" context types at [IANA-NSH-MD2] as follows:
The Registration Policy is IETF Review
+=========+=========================================+===============+
| Value | Forwarding Context Header Types | Reference |
+=========+=========================================+===============+
| 0x0 | 12-bit VLAN identifier | This document |
+---------+-----------------------------------------+---------------+
| 0x1 | 24-bit double tagging identifiers | This document |
+---------+-----------------------------------------+---------------+
| 0x2 | 20-bit MPLS VPN label | This document |
+---------+-----------------------------------------+---------------+
| 0x3 | 24-bit virtual network identifier | This document |
| | (VNI) | |
+---------+-----------------------------------------+---------------+
| 0x4 | 32-bit Session ID | This document |
+---------+-----------------------------------------+---------------+
| 0x5-0xE | Unassigned | |
+---------+-----------------------------------------+---------------+
| 0xF | Reserved | This document |
+---------+-----------------------------------------+---------------+
Table 2: Forwarding Context Types
Wei, et al. Expires 22 October 2022 [Page 14]
Internet-Draft NSH MD2 Context Headers April 2022
7.3. Flow ID Context Types
IANA is requested to create a new sub-registry for "Flow ID Context"
context types at [IANA-NSH-MD2] as follows:
The Registration Policy is IETF Review
+=========+==============================+===============+
| Value | Flow ID Context Header Types | Reference |
+=========+==============================+===============+
| 0x0 | 20-bit IPv6 Flow Label | This document |
+---------+------------------------------+---------------+
| 0x1 | 20-bit entropy label in the | This document |
| | MPLS network | |
+---------+------------------------------+---------------+
| 0x2-0xE | Unassigned | |
+---------+------------------------------+---------------+
| 0xF | Reserved | This document |
+---------+------------------------------+---------------+
Table 3: Flow ID Context Types
8. References
8.1. Normative References
[I-D.ietf-sfc-nsh-integrity]
Boucadair, M., Reddy, T., and D. Wing, "Integrity
Protection for the 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>.
[IEEE.802.1Q_2018]
IEEE, "IEEE Standard for Local and Metropolitan Area
Networks--Bridges and Bridged Networks", July 2018,
<http://ieeexplore.ieee.org/servlet/
opac?punumber=8403925>.
Wei, et al. Expires 22 October 2022 [Page 15]
Internet-Draft NSH MD2 Context Headers April 2022
[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. Informative References
[IANAifType]
IANA, "IANAifType", 2021,
<https://www.iana.org/assignments/ianaiftype-mib/
ianaiftype-mib>.
[OpenDaylight]
OpenDaylight, "Group Based Policy", 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", 2021,
<https://wiki.openstack.org/wiki/GroupBasedPolicy>.
Wei, et al. Expires 22 October 2022 [Page 16]
Internet-Draft NSH MD2 Context Headers April 2022
[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>.
Authors' Addresses
Yuehua Wei (editor)
ZTE Corporation
No.50, Software Avenue
Nanjing
210012
China
Email: wei.yuehua@zte.com.cn
Wei, et al. Expires 22 October 2022 [Page 17]
Internet-Draft NSH MD2 Context Headers April 2022
Uri Elzur
Intel
Email: uri.elzur@intel.com
Sumandra Majee
Individual contributor
Email: Sum.majee@gmail.com
Carlos Pignataro
Cisco
Email: cpignata@cisco.com
Donald E. Eastlake
Futurewei Technologies
2386 Panoramic Circle
Apopka, FL 32703
United States of America
Email: d3e3e3@gmail.com
Wei, et al. Expires 22 October 2022 [Page 18]