Internet Engineering Task Force (IETF) D. Lopez

Internet Engineering Task Force (IETF) D. Lopez
Request for Comments: 9353 Telefonica I+D
Updates: 5088, 5089, 8231, 8306 Q. Wu
Category: Standards Track D. Dhody
ISSN: 2070-1721 Q. Ma
Huawei
D. King
Old Dog Consulting
January 2023

IGP Extension for Path Computation Element Communication Protocol (PCEP)
Security Capability Support in PCE Discovery (PCED)

Abstract

When a Path Computation Element (PCE) is a Label Switching Router
(LSR) or a server participating in the Interior Gateway Protocol
(IGP), its presence and path computation capabilities can be
advertised using IGP flooding. The IGP extensions for PCE Discovery
(PCED) (RFCs 5088 and 5089) define a method to advertise path
computation capabilities using IGP flooding for OSPF and IS-IS,
respectively. However, these specifications lack a method to
advertise Path Computation Element Communication Protocol (PCEP)
security (e.g., Transport Layer Security (TLS) and TCP Authentication
Option (TCP-AO)) support capability.

This document defines capability flag bits for the PCE-CAP-FLAGS sub-
TLV that can be announced as an attribute in the IGP advertisement to
distribute PCEP security support information. In addition, this
document updates RFCs 5088 and 5089 to allow advertisement of a Key
ID or KEY-CHAIN-NAME sub-TLV to support TCP-AO security capability.
This document also updates RFCs 8231 and 8306.

Status of This Memo

This is an Internet Standards Track document.

This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.

Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc9353.

Copyright Notice

Copyright (c) 2023 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) 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. Conventions Used in This Document
3. IGP Extension for PCEP Security Capability Support
3.1. Use of PCEP Security Capability Support for PCED
3.2. KEY-ID Sub-TLV
3.2.1. IS-IS
3.2.2. OSPF
3.3. KEY-CHAIN-NAME Sub-TLV
3.3.1. IS-IS
3.3.2. OSPF
4. Updates to RFCs
5. Backward Compatibility Considerations
6. Management Considerations
6.1. Control of Policy and Functions
6.2. Information and Data Model
6.3. Liveness Detection and Monitoring
6.4. Verification of Correct Operations
6.5. Requirements on Other Protocols and Functional Components
6.6. Impact on Network Operations
7. Security Considerations
8. IANA Considerations
8.1. PCE Capability Flags
8.2. PCED Sub-TLV Type Indicators
9. References
9.1. Normative References
9.2. Informative References
Acknowledgments
Authors' Addresses

1. Introduction

As described in [RFC5440], privacy and integrity are important issues
for communication using the Path Computation Element Communication
Protocol (PCEP); an attacker that intercepts a PCEP message could
obtain sensitive information related to computed paths and resources.
Authentication and integrity checks allow the receiver of a PCEP
message to know that the message genuinely comes from the node that
purports to have sent it and whether the message has been modified.

Among the possible solutions mentioned in [RFC5440], Transport Layer
Security (TLS) [RFC8446] provides support for peer authentication,
message encryption, and integrity while TCP-AO) [RFC5925] and
Cryptographic Algorithms for TCP-AO [RFC5926] offer significantly
improved security for applications using TCP. As specified in
Section 4 of [RFC8253], the PCC needs to know whether the PCE server
supports TLS or TCP-AO as a secure transport in order for a Path
Computation Client (PCC) to establish a connection with a PCE server
using TLS or TCP-AO.

[RFC5088] and [RFC5089] define a method to advertise path computation
capabilities using IGP flooding for OSPF and IS-IS, respectively.
However, these specifications lack a method to advertise PCEP
security (e.g., TLS and TCP-AO) support capability.

This document defines capability flag bits for the PCE-CAP-FLAGS sub-
TLV that can be announced as attributes in the IGP advertisement to
distribute PCEP security support information. In addition, this
document updates [RFC5088] and [RFC5089] to allow advertisement of a
KeyID or KEY-CHAIN-NAME sub-TLV to support TCP-AO security
capability.

IANA created a top-level registry titled "Path Computation Element
(PCE) Capability Flags" per [RFC5088]. This document updates
[RFC5088] and moves it to follow the heading of the "Interior Gateway
Protocol (IGP) Parameters" registry. [RFC5089] states that the IS-IS
PCE-CAP-FLAGS sub-TLV uses the same registry as OSPF. This document
updates [RFC5089] to refer to the new IGP registry. Further, this
document updates [RFC8231] where it references the registry location
as the "Open Shortest Path First v2 (OSPFv2) Parameters" registry to
the "Interior Gateway Protocol (IGP) Parameters" registry. This
document also updates [RFC8306] by changing the term "OSPF PCE
Capability Flag" to read as "Path Computation Element (PCE)
Capability Flags" and to note the corresponding registry now exists
in the "Interior Gateway Protocol (IGP) Parameters" registry.

| Note that [RFC5557] uses the term "OSPF registry" instead of
| the "IGP registry", whereas [RFC8623] and [RFC9168] use the
| term "OSPF Parameters" instead of "IGP Parameters".

| Note that the PCEP Open message exchange is another way to
| discover PCE capabilities information; however, in this
| instance, the TCP-security-related key parameters need to be
| known before the PCEP session is established and the PCEP Open
| messages are exchanged. Thus, the IGP advertisement and
| flooding mechanisms need to be leveraged for PCE discovery and
| capabilities advertisement.

2. Conventions Used in This Document

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. IGP Extension for PCEP Security Capability Support

[RFC5088] defines a PCE Discovery (PCED) TLV carried in an OSPF
Router Information Link State Advertisement (LSA) as defined in
[RFC7770] to facilitate PCED using OSPF. This document defines two
capability flag bits in the OSPF PCE Capability Flags to indicate
TCP-AO support [RFC5925] [RFC5926] and PCEP over TLS support
[RFC8253], respectively.

Similarly, [RFC5089] defines the PCED sub-TLV for use in PCED using
IS-IS. This document will use the same flag for the OSPF PCE
Capability Flags sub-TLV to allow IS-IS to indicate TCP-AO support
and PCEP over TLS support, respectively.

The IANA assignments for shared OSPF and IS-IS Security Capability
Flags are documented in Section 8.1 of this document.

3.1. Use of PCEP Security Capability Support for PCED

TCP-AO and PCEP over TLS support flag bits are advertised using IGP
flooding.

* PCE supports TCP-AO: IGP advertisement SHOULD include a TCP-AO
support flag bit.

* PCE supports TLS: IGP advertisement SHOULD include PCEP over TLS
support flag bit.

If the PCE supports multiple security mechanisms, it SHOULD include
all corresponding flag bits in its IGP advertisement.

A client's configuration MAY indicate that support for a given
security capability is required. If a client is configured to
require that its PCE server supports TCP-AO, the client MUST verify
that the TCP-AO flag bit in the PCE-CAP-FLAGS sub-TLV for a given
server is set before it opens a connection to that server.
Similarly, if the client is configured to require that its PCE server
supports TLS, the client MUST verify that the PCEP over TLS support
flag bit in the PCE-CAP-FLAGS sub-TLV for a given server is set
before it opens a connection to that server.

3.2. KEY-ID Sub-TLV

The KEY-ID sub-TLV specifies an identifier that can be used by the
PCC to identify the TCP-AO key (referred to as "KeyID" in [RFC5925]).

3.2.1. IS-IS

The KEY-ID sub-TLV MAY be present in the PCED sub-TLV carried within
the IS-IS Router CAPABILITY TLV when the capability flag bit of the
PCE-CAP-FLAGS sub-TLV in IS-IS is set to indicate TCP-AO support.

The KEY-ID sub-TLV has the following format:

Type: 6

Length: 1

KeyID: The one-octet KeyID as per [RFC5925] to uniquely identify the
Master Key Tuple (MKT).

3.2.2. OSPF

Similarly, this sub-TLV MAY be present in the PCED TLV carried within
the OSPF Router Information LSA when the capability flag bit of the
PCE-CAP-FLAGS sub-TLV in OSPF is set to indicate TCP-AO support.

The format of the KEY-ID sub-TLV is as follows:

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 6 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| KeyID | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Type: 6

Length: 4

KeyID: The one octet KeyID as per [RFC5925] to uniquely identify the
MKT.

Reserved: MUST be set to zero while sending and ignored on receipt.

3.3. KEY-CHAIN-NAME Sub-TLV

The KEY-CHAIN-NAME sub-TLV specifies a key chain name that can be
used by the PCC to identify the key chain. The key chain name could
be manually configured via command-line interface (CLI) or installed
in the YANG datastore (see [RFC8177]) at the PCC.

3.3.1. IS-IS

The KEY-CHAIN-NAME sub-TLV MAY be present in the PCED sub-TLV carried
within the IS-IS Router CAPABILITY TLV when the capability flag bit
of the PCE-CAP-FLAGS sub-TLV in IS-IS is set to indicate TCP-AO
support.

The KEY-CHAIN-NAME sub-TLV has the following format:

Type: 7

Length: Variable, encodes the length of the value field.

Key Chain Name: The Key Chain Name contains a string of 1 to 255
octets to be used to identify the key chain. It MUST be encoded
using UTF-8. A receiving entity MUST NOT interpret invalid UTF-8
sequences and ignore them. This field is not NULL terminated.
UTF-8 "Shortest Form" encoding is REQUIRED to guard against the
technical issues outlined in [UTR36].

3.3.2. OSPF

Similarly, this sub-TLV MAY be present in the PCED TLV carried within
the OSPF Router Information LSA when the capability flag bit of the
PCE-CAP-FLAGS sub-TLV in OSPF is set to indicate TCP-AO support. The
sub-TLV MUST be zero-padded so that the sub-TLV is 4-octet aligned.

The format of KEY-CHAIN-NAME sub-TLV is as follows:

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 7 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Key Chain Name //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Type: 7

Length: Variable, padding is not included in the Length field.

Key Chain Name: The Key Chain Name contains a string of 1 to 255
octets to be used to identify the key chain. It MUST be encoded
using UTF-8. A receiving entity MUST NOT interpret invalid UTF-8
sequences and ignore them. This field is not NULL terminated.
UTF-8 "Shortest Form" encoding is REQUIRED to guard against the
technical issues outlined in [UTR36]. The sub-TLV MUST be zero-
padded so that the sub-TLV is 4-octet aligned.

4. Updates to RFCs

Section 4 of [RFC5088] states that no new sub-TLVs will be added to
the PCED TLV and no new PCE information will be carried in the Router
Information LSA. This document updates [RFC5088] by allowing the two
sub-TLVs defined in this document to be carried in the PCED TLV
advertised in the Router Information LSA.

Section 4 of [RFC5089] states that no new sub-TLVs will be added to
the PCED TLV and no new PCE information will be carried in the Router
CAPABILITY TLV. This document updates [RFC5089] by allowing the two
sub-TLVs defined in this document to be carried in the PCED TLV
advertised in the Router CAPABILITY TLV.

This introduction of additional sub-TLVs should be viewed as an
exception to the policies in [RFC5088] and [RFC5089], which is
justified by the requirement to discover the PCEP security support
prior to establishing a PCEP session. The restrictions defined in
[RFC5088] and [RFC5089] should still be considered to be in place.
If new advertisements are required in the future, alternative
mechanisms such as using [RFC6823] or [LSR-OSPF-TRANSPORT-INSTANCE]
should be considered.

The registry for the PCE Capability Flags assigned in Section 8.3 of
[RFC5557], Section 8.1 of [RFC8231], Section 6.9 of [RFC8306],
Section 11.1 of [RFC8623], and Section 10.5 of [RFC9168] has changed
to the IGP Parameters "Path Computation Element (PCE) Capability
Flags" registry created in this document.

5. Backward Compatibility Considerations

An LSR that does not support the IGP PCE capability bits specified in
this document silently ignores those bits.

An LSR that does not support the KEY-ID and KEY-CHAIN-NAME sub-TLVs
specified in this document silently ignores those sub-TLVs.

IGP extensions defined in this document do not introduce any new
interoperability issues.

6. Management Considerations

Manageability considerations for PCED are addressed in Section 4.10
of [RFC4674], Section 9 of [RFC5088], and Section 9 of [RFC5089].

6.1. Control of Policy and Functions

A PCE implementation SHOULD allow the following parameters to be
configured on the PCE:

* support for TCP-AO

* the KeyID used by TCP-AO

* Key Chain Name

* support for TLS

6.2. Information and Data Model

The YANG module for PCEP [PCE-PCEP-YANG] supports PCEP security
parameters (key, key chain, and TLS).

6.3. Liveness Detection and Monitoring

Normal operations of the IGP meet the requirements for liveness
detection and monitoring.

6.4. Verification of Correct Operations

The correlation of PCEP security information advertised against
information received can be achieved by comparing the information in
the PCED sub-TLV received by the PCC with that stored at the PCE
using the PCEP YANG.

6.5. Requirements on Other Protocols and Functional Components

There are no new requirements on other protocols.

6.6. Impact on Network Operations

Frequent changes in PCEP security information advertised in the PCED
sub-TLV may have a significant impact on IGP and might destabilize
the operation of the network by causing the PCCs to reconnect
sessions with PCEs. Section 4.10.4 of [RFC4674], Section 9.6 of
[RFC5088], and Section 9.6 of [RFC5089] list techniques that are
applicable to this document as well.

7. Security Considerations

Security considerations as specified by [RFC5088] and [RFC5089] are
applicable to this document.

As described in Section 10.2 of [RFC5440], a PCEP speaker MUST
support TCP MD5 [RFC2385], so no capability advertisement is needed
to indicate support. However, as noted in [RFC6952], TCP MD5 has
been obsoleted by TCP-AO [RFC5925] because of security concerns.
TCP-AO is not widely implemented; therefore, it is RECOMMENDED that
PCEP be secured using TLS per [RFC8253] (which updates [RFC5440]).
An implementation SHOULD offer at least one of the two security
capabilities defined in this document.

The information related to PCEP security is sensitive and due care
needs to be taken by the operator. This document defines new
capability bits that are susceptible to a downgrade attack by setting
them to zero. The content of the Key-ID or KEY-CHAIN-NAME sub-TLV
can be altered to enable an on-path attack. Thus, before advertising
the PCEP security parameters by using the mechanism described in this
document, the IGP MUST be known to provide authentication and
integrity for the PCED TLV using the mechanisms defined in [RFC5304],
[RFC5310], or [RFC5709].

Moreover, as stated in the security considerations of [RFC5088] and
[RFC5089], there are no mechanisms defined in OSPF or IS-IS to
protect the confidentiality of the PCED TLV. For this reason, the
operator must ensure that no private data is carried in the TLV. For
example, the operator must ensure that KeyIDs or key chain names do
not reveal sensitive information about the network.

8. IANA Considerations

8.1. PCE Capability Flags

IANA has moved the "Path Computation Element (PCE) Capability Flags"
registry from the "Open Shortest Path First v2 (OSPFv2) Parameters"
grouping to the "Interior Gateway Protocol (IGP) Parameters"
grouping.

IANA has made the following additional assignments from the "Path
Computation Element (PCE) Capability Flags" registry:

+=====+========================+===========+
| Bit | Capability Description | Reference |
+=====+========================+===========+
| 17 | TCP-AO Support | RFC 9353 |
+-----+------------------------+-----------+
| 18 | PCEP over TLS support | RFC 9353 |
+-----+------------------------+-----------+

Table 1: Path Computation Element (PCE)
Capability Flags Registrations

The grouping is located at: <https://www.iana.org/assignments/igp-
parameters/>.

8.2. PCED Sub-TLV Type Indicators

The PCED sub-TLVs are defined in [RFC5088] and [RFC5089], but a
corresponding IANA registry was not created. IANA has created a new
registry called "PCE Discovery (PCED) Sub-TLV Type Indicators" under
the "Interior Gateway Protocol (IGP) Parameters" registry. The
registration policy for this registry is "Standards Action"
[RFC8126]. Values in this registry come from the range 0-65535.

This registry is initially populated as follows:

+=======+=================+====================+
| Value | Description | Reference |
+=======+=================+====================+
| 0 | Reserved | RFC 9353, RFC 5088 |
+-------+-----------------+--------------------+
| 1 | PCE-ADDRESS | RFC 9353, RFC 5088 |
+-------+-----------------+--------------------+
| 2 | PATH-SCOPE | RFC 9353, RFC 5088 |
+-------+-----------------+--------------------+
| 3 | PCE-DOMAIN | RFC 9353, RFC 5088 |
+-------+-----------------+--------------------+
| 4 | NEIG-PCE-DOMAIN | RFC 9353, RFC 5088 |
+-------+-----------------+--------------------+
| 5 | PCE-CAP-FLAGS | RFC 9353, RFC 5088 |
+-------+-----------------+--------------------+
| 6 | KEY-ID | RFC 9353 |
+-------+-----------------+--------------------+
| 7 | KEY-CHAIN-NAME | RFC 9353 |
+-------+-----------------+--------------------+

Table 2: Initial Contents of the PCED Sub-
TLV Type Indicators Registry

This registry is used by both the OSPF PCED TLV and the IS-IS PCED
sub-TLV.

This grouping is located at: <https://www.iana.org/assignments/igp-
parameters/>.

9. References

9.1. Normative References

[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>.

[RFC5088] Le Roux, JL., Ed., Vasseur, JP., Ed., Ikejiri, Y., and R.
Zhang, "OSPF Protocol Extensions for Path Computation
Element (PCE) Discovery", RFC 5088, DOI 10.17487/RFC5088,
January 2008, <https://www.rfc-editor.org/info/rfc5088>.

[RFC5089] Le Roux, JL., Ed., Vasseur, JP., Ed., Ikejiri, Y., and R.
Zhang, "IS-IS Protocol Extensions for Path Computation
Element (PCE) Discovery", RFC 5089, DOI 10.17487/RFC5089,
January 2008, <https://www.rfc-editor.org/info/rfc5089>.

[RFC5304] Li, T. and R. Atkinson, "IS-IS Cryptographic
Authentication", RFC 5304, DOI 10.17487/RFC5304, October
2008, <https://www.rfc-editor.org/info/rfc5304>.

[RFC5310] Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R.,
and M. Fanto, "IS-IS Generic Cryptographic
Authentication", RFC 5310, DOI 10.17487/RFC5310, February
2009, <https://www.rfc-editor.org/info/rfc5310>.

[RFC5557] Lee, Y., Le Roux, JL., King, D., and E. Oki, "Path
Computation Element Communication Protocol (PCEP)
Requirements and Protocol Extensions in Support of Global
Concurrent Optimization", RFC 5557, DOI 10.17487/RFC5557,
July 2009, <https://www.rfc-editor.org/info/rfc5557>.

[RFC5709] Bhatia, M., Manral, V., Fanto, M., White, R., Barnes, M.,
Li, T., and R. Atkinson, "OSPFv2 HMAC-SHA Cryptographic
Authentication", RFC 5709, DOI 10.17487/RFC5709, October
2009, <https://www.rfc-editor.org/info/rfc5709>.

[RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP
Authentication Option", RFC 5925, DOI 10.17487/RFC5925,
June 2010, <https://www.rfc-editor.org/info/rfc5925>.

[RFC7770] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and
S. Shaffer, "Extensions to OSPF for Advertising Optional
Router Capabilities", RFC 7770, DOI 10.17487/RFC7770,
February 2016, <https://www.rfc-editor.org/info/rfc7770>.

[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.

[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>.

[RFC8177] Lindem, A., Ed., Qu, Y., Yeung, D., Chen, I., and J.
Zhang, "YANG Data Model for Key Chains", RFC 8177,
DOI 10.17487/RFC8177, June 2017,
<https://www.rfc-editor.org/info/rfc8177>.

[RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path
Computation Element Communication Protocol (PCEP)
Extensions for Stateful PCE", RFC 8231,
DOI 10.17487/RFC8231, September 2017,
<https://www.rfc-editor.org/info/rfc8231>.

[RFC8253] Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody,
"PCEPS: Usage of TLS to Provide a Secure Transport for the
Path Computation Element Communication Protocol (PCEP)",
RFC 8253, DOI 10.17487/RFC8253, October 2017,
<https://www.rfc-editor.org/info/rfc8253>.

[RFC8306] Zhao, Q., Dhody, D., Ed., Palleti, R., and D. King,
"Extensions to the Path Computation Element Communication
Protocol (PCEP) for Point-to-Multipoint Traffic
Engineering Label Switched Paths", RFC 8306,
DOI 10.17487/RFC8306, November 2017,
<https://www.rfc-editor.org/info/rfc8306>.

[RFC8623] Palle, U., Dhody, D., Tanaka, Y., and V. Beeram, "Stateful
Path Computation Element (PCE) Protocol Extensions for
Usage with Point-to-Multipoint TE Label Switched Paths
(LSPs)", RFC 8623, DOI 10.17487/RFC8623, June 2019,
<https://www.rfc-editor.org/info/rfc8623>.

[RFC9168] Dhody, D., Farrel, A., and Z. Li, "Path Computation
Element Communication Protocol (PCEP) Extension for Flow
Specification", RFC 9168, DOI 10.17487/RFC9168, January
2022, <https://www.rfc-editor.org/info/rfc9168>.

9.2. Informative References

[LSR-OSPF-TRANSPORT-INSTANCE]
Lindem, A., Qu, Y., Roy, A., and S. Mirtorabi, "OSPF-GT
(Generalized Transport)", Work in Progress, Internet-
Draft, draft-ietf-lsr-ospf-transport-instance-04, 3
January 2023, <https://datatracker.ietf.org/doc/html/
draft-ietf-lsr-ospf-transport-instance-04>.

[PCE-PCEP-YANG]
Dhody, D., Ed., Beeram, V., Hardwick, J., and J. Tantsura,
"A YANG Data Model for Path Computation Element
Communications Protocol (PCEP)", Work in Progress,
Internet-Draft, draft-ietf-pce-pcep-yang-20, 23 October
2022, <https://datatracker.ietf.org/doc/html/draft-ietf-
pce-pcep-yang-20>.

[RFC2385] Heffernan, A., "Protection of BGP Sessions via the TCP MD5
Signature Option", RFC 2385, DOI 10.17487/RFC2385, August
1998, <https://www.rfc-editor.org/info/rfc2385>.

[RFC4674] Le Roux, J.L., Ed., "Requirements for Path Computation
Element (PCE) Discovery", RFC 4674, DOI 10.17487/RFC4674,
October 2006, <https://www.rfc-editor.org/info/rfc4674>.

[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC5440, March 2009,
<https://www.rfc-editor.org/info/rfc5440>.

[RFC5926] Lebovitz, G. and E. Rescorla, "Cryptographic Algorithms
for the TCP Authentication Option (TCP-AO)", RFC 5926,
DOI 10.17487/RFC5926, June 2010,
<https://www.rfc-editor.org/info/rfc5926>.

[RFC6823] Ginsberg, L., Previdi, S., and M. Shand, "Advertising
Generic Information in IS-IS", RFC 6823,
DOI 10.17487/RFC6823, December 2012,
<https://www.rfc-editor.org/info/rfc6823>.

[RFC6952] Jethanandani, M., Patel, K., and L. Zheng, "Analysis of
BGP, LDP, PCEP, and MSDP Issues According to the Keying
and Authentication for Routing Protocols (KARP) Design
Guide", RFC 6952, DOI 10.17487/RFC6952, May 2013,
<https://www.rfc-editor.org/info/rfc6952>.

[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>.

[UTR36] Davis, M., Ed. and M. Suignard, Ed., "Unicode Security
Considerations", Unicode Technical Report #36, August
2010, <https://www.unicode.org/unicode/reports/tr36/>.

Acknowledgments

The authors of this document would like to thank Acee Lindem, Julien
Meuric, Les Ginsberg, Ketan Talaulikar, Tom Petch, Aijun Wang, and
Adrian Farrel for the review and comments.

The authors would also like to give special thanks to Michale Wang
for his major contributions to the initial draft version.

Thanks to John Scudder for providing an excellent AD review. Thanks
to Carlos Pignataro, Yaron Sheffer, Ron Bonica, and Will (Shucheng)
LIU for directorate reviews.

Thanks to Lars Eggert, Robert Wilton, Roman Danyliw, Éric Vyncke,
Paul Wouters, Murray Kucherawy, and Warren Kumari for IESG reviews.

Authors' Addresses

Diego R. Lopez
Telefonica I+D
Spain
Email: [email protected]

Qin Wu
Huawei Technologies
Yuhua District
101 Software Avenue
Nanjing
Jiangsu, 210012
China
Email: [email protected]

Dhruv Dhody
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore 560037
Karnataka
India
Email: [email protected]

Qiufang Ma
Huawei Technologies
Yuhua District
101 Software Avenue
Nanjing
Jiangsu, 210012
China
Email: [email protected]

Daniel King
Old Dog Consulting
United Kingdom
Email: [email protected]