PCEPS: Usage of TLS to Provide a Secure Transport for the Path Computation Element Communication Protocol (PCEP)
draft-ietf-pce-pceps-18

I think that the document should explain why this does STARTTLS and not e.g another port (which would be more downgrade resistant) 
Obviously this is in addition to the DISCUSS held by EKR.

This document needs a significant editorial pass. I found a number of
writing errors, e.g., "Securing via TLS of an existing PCEP session is
not permitted,"

S 1.
   defining their application in depth.  Moreover, [RFC6952] remarks the
   importance of ensuring PCEP communication privacy, especially when

The term here is "confidentiality"

S 3.2.
The whole description of how you can race StartTLS iff you know you
are TLS only is really hard to understand until you get to the
diagrams. I would write something like:

   The PCC initiates the use of TLS by sending a StartTLS message
   The PCE agrees to the use of TLS by responding with its own
   StartTLS message. If the PCE is configured to only do TLS, it
   may send the StartTLS message immediately upon TCP connection
   establishment; otherwise it MUST wait for the PCC's first
   message to see whether it is an Open or StartTLS message.



S 3.4.
          +  Implementations SHOULD indicate their trusted CAs.  For TLS
             1.2, this is done using [RFC5246], Section 7.4.4,
             "certificate_authorities" (server side) and [RFC6066],
             Section 6 "Trusted CA Indication" (client side).

Do common stacks do this? I know NSS does not.


   To support TLS re-negotiation both peers MUST support the mechanism
   described in [RFC5746].  Any attempt to initiate a TLS handshake to
   establish new cryptographic parameters not aligned with [RFC5746]
   SHALL be considered a TLS negotiation failure.

Is there a reason to allow renegotiation at all?


S 3.5
   [I-D.ietf-pce-stateful-sync-optimizations] specify a Speaker Entity
   Identifier TLV (SPEAKER-ENTITY-ID), as an optional TLV that MAY be
   included in the OPEN Object.  It contains a unique identifier for the
   node that does not change during the lifetime of the PCEP speaker.
   An implementation would thus expose the speaker entity identifier as
   part of the X509v3 certificate, so that an implementation could use
   this identifier for the peer identification trust model.

This seems underspecified. Is there an OID assigned?


S 4.1.
   DANE [RFC6698] defines a secure method to associate the certificate
   that is obtained from a TLS server with a domain name using DNS,
   i.e., using the TLSA DNS resource record (RR) to associate a TLS
   server certificate or public key with the domain name where the
   record is found, thus forming a "TLSA certificate association".  The
   DNS information needs to be protected by DNS Security (DNSSEC).  A
   PCC willing to apply DANE to verify server identity MUST conform to
   the rules defined in section 4 of [RFC6698].  The server's domain
   name must be authorized separately, as TLSA does not provide any
   useful authorization guarantees.

This is also underspecified. Which DANE types are you suggesting you
use?


S  7.
   Some TLS ciphersuites only provide integrity validation of their
   payload, and provide no encryption.  This specification does not
   forbid the use of such ciphersuites, but administrators must weight
   carefully the risk of relevant internal data leakage that can occur
   in such a case, as explicitly stated by [RFC6952].

Why don't you forbid it?

One high level comment:

As already mentioned by the gen-art review (Thanks Dale for the detailed review!), for me the text was for a long time while reading not clear on who starts the TLS negotiation. In think there is a statement missing that a speaker/PCE that supports PCEPS and receives a StartTLS message MUST reply with a StartTLS message and further the PCC MUST initiation the TLS after reception of a StartTLS message from the PCC.

More minor/editorial comments:

1) There are two cases where the behavior of speakers that do not support PCEPS is specified, which is a bit non-sensical given that not support probably means it does not follow this spec:
 OLD
"If the PCEP speaker that does not support PCEPS, receives a StartTLS
   message, it MUST behave according to the existing error mechanism
   described in section 6.2 of [RFC5440] (in case message is received
   prior to an Open message) or section 6.9 of [RFC5440] (for the case
   of reception of unknown message)."
NEW
"If the PCEP speaker that does not support PCEPS, receives a StartTLS
   message, it will behave according to the existing error mechanism
   described in section 6.2 of [RFC5440] (in case message is received
   prior to an Open message) or section 6.9 of [RFC5440] (for the case
   of reception of unknown message)."
and
OLD
"A PCEP speaker that does not support PCEPS or has learned the peer
   willingness to reestablish session without TLS, can send the Open
   message directly, as per [RFC5440]."
NEW
"A PCEP speaker that does not support PCEPS sends the Open message directly, as per [RFC5440].
 A PCEP speaker that supports PCEPS but has previously already learned the peer
   willingness to reestablish session without TLS, MAY send the Open
   message directly, as per [RFC5440]."

2) As already mentioned in the gen-art review, I also think there should be more text on what a host should do that uses StartTLS but gets an error back. This is defined previously in the document but given there is an own section here, I would just recommend to re-iterate there. In other words please add the proposed text!

3) Why is this a MUST?
sec 8.1 "A PCE or PCC implementation MUST allow configuring the PCEP security
   via TLS capabilities as described in this document."
 Wouldn't a SHOULD be enough/better? Meaning that when PCEPS is implemented and turned on by default, I don't necessarily have to provide a knob to turn it off?

4) Also related to the previous point
sec 8.2 "An implementation SHOULD allow the operator to configure the PCEPS
   capability and various TLS related parameters, ..."
Probably this part of sentence should not be normative given this part is (differently) specified in the previous section.

Thanks for taking care of my DISCUSS points.