[secdir] SECDIR review of draft-ietf-mpls-retire-ach-tlv-02

[Alexey Melnikov <[e-mail]>]

I reviewed this document as part of the security directorate's ongoing 
effort to review all IETF documents being processed by the IESG.  These 
comments were written primarily for the benefit of the security area 
directors.  Document editors and WG chairs should treat these comments 
just like any other last call comments.

This document updates RFC 5586 by retiring ACH TLVs (an MPLS 
extensibility mechanism) and removing the associated IANA registry.

The Security Considerations section states that by removing an unused 
feature of MPLS security of implementations is improved. I tend to 
agree, simplicity is a good thing.

It also states that the removed feature can be used to secure messages 
on the G-ACh in a generic way, but that no such mechanism was proposed 
so far. I think this is a fair comment.

I think the Security Considerations section is quite reasonable for this 
document. I don't have any issues with this document.