IGP extension for PCEP security capability support in the PCE discovery
draft-wu-lsr-pce-discovery-security-support-00

Abstract

When a Path Computation Element (PCE) is a Label Switching Router (LSR) participating in the Interior Gateway Protocol (IGP), or even a server participating in IGP, its presence and path computation capabilities can be advertised using IGP flooding. The IGP extensions for PCE discovery (RFC 5088 and RFC 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 PCEP security (e.g., Transport Layer Security(TLS),TCP Authentication Option (TCP-AO)) support capability.

This document proposes new capability flag bits for PCE-CAP-FLAGS sub-TLV that can be announced as attribute in the IGP advertisement to distribute PCEP security support information.

Status of This Memo

This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.

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This Internet-Draft will expire on February 24, 2019.

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1. Introduction

As described in [RFC5440], PCEP communication privacy is one importance issue, as an attacker that intercepts a Path Computation Element (PCE) message could obtain sensitive information related to computed paths and resources.

Among the possible solutions mentioned in these documents, Transport Layer Security (TLS) [RFC5246] provides support for peer authentication, and message encryption and integrity while TCP Authentication Option (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], in order for a Path Computation Client(PCC) to begin a connection with a PCE server using TLS or TCP-AO, PCC SHOULD know whether PCE server supports TLS or TCP-AO as a secure transport.

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

This document proposes new capability flag bits for PCE-CAP-FLAGS sub-TLV that can be announced as attributes in the IGP advertisement (defined in [RFC5088] and [RFC5089]) to distribute PCEP security support information.

2. Conventions used in this document

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC2119.

3. IGP extension for PCEP security capability support

The PCE-CAP-FLAGS sub-TLV is defined in section 4.5 of [RFC5088] and [RFC5089] as an optional sub-TLV used to advertise PCE capabilities. In this section, we extend the PCE-CAP-FLAGS sub-TLV to include the capability and indications that are described for PCEP security (e.g., TLS) support in the current document.

   o  TYPE: 5
   o  LENGTH: Multiple of 4
   o  VALUE: This contains an array of units of 32 bit flags with
      the most significant bit as 0. Each bit represents one PCE 
      capability.

In the PCE-CAP-FLAGS sub-TLV defined in [RFC5088] and [RFC5089], nine capability flags defined in [RFC5088] (as per [RFC4657]) and two capability flags defined [RFC5557], [RFC6006] are included and follows the following format:

     Bit         Capability Description
     xx            TCP AO Support
     xx            PCEP over TLS support

and the processing rule of these flag bits are defined in [RFC5088] and [RFC5089]. In this document, we define two new capability flag bits that indicate TCP Authentication Option (TCP-AO) support, PCEP over TLS support respectively as follows:

3.1. Use of PCEP security capability support for PCE discovery

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

• PCE supports TCP-AO: IGP advertisement SHOULD include TCP-AO support flag bit.
• PCE supports TLS: IGP advertisement SHOULD include PCEP over TLS support flag bit.

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

If the client is looking for connecting with PCE server with TCP-AO support, the client MUST check if TCP-AO support flag bit in the PCE- CAP-FLAGS sub-TLV is set. If not, the client SHOULD NOT consider this PCE. If the client is looking for connecting with PCE server using TLS, the client MUST check if PCEP over TLS support flag bit in the PCE-CAP-FLAGS sub-TLV is set. If not, the client SHOULD NOT consider this PCE.

4. Backward Compatibility Consideration

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

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

5. Management Considerations

A configuration option may be provided for advertising and withdrawing PCE security capability via IGP.

6. Security Considerations

This document raises no new security issues beyond those described in [RFC5088] and [RFC5089].

7. IANA Considerations

IANA is requested to allocate a new bit in "PCE Security Capability Flags" registry for PCEP Security support capability.

     Bit           Meaning                 Reference 
     xx            TCP-AO Support          [This.I.D] 
     xx            PCEP over TLS support   [This.I.D] 

8. References

8.1. Normative References

8.2. Informative References

Appendix A. Appendix A: No MD5 Capability Support

To be compliant with Section 10.2 of RFC5440, this document doesn't consider to add capability for TCP-MD5. Therefore by default, PCEP Speaker in communication supports capability for TCP-MD5 (See section 10.2,[RFC5440]). A method to advertise TCP-MD5 Capability support using IGP flooding is not required. If the client is looking for connecting with PCE server with other Security capability support (e.g., TLS support) than TCP-MD5, the client MUST check if flag bit in the PCE- CAP-FLAGS sub-TLV for specific capability is set (See section 3.1).

Authors' Addresses

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 PCE discovery
• 4. Backward Compatibility Consideration
• 5. Management Considerations
• 6. Security Considerations
• 7. IANA Considerations
• 8. References
• 8.1. Normative References
• 8.2. Informative References
• Appendix A. Appendix A: No MD5 Capability Support
• Authors' Addresses