I have reviewed this document as part of the Operational directorate's 
ongoing effort to review all IETF documents being processed by the IESG.  These 
comments were written with the intent of improving the operational aspects of the 
IETF drafts. Comments that are not addressed in last call may be included in AD reviews 
during the IESG review.  Document editors and WG chairs should treat these comments 
just like any other last call comments. 

This document clarifies and updates the TRILL Appointed
 Forwarder mechanism. It updates RFC 6325, updates RFC 7177, and
 obsoletes RFC 6439.

It's a complex document which requires extra reading to understand the context and the interraction with other RFCs. I believe that from an OPS-DIR perspective there are issues that need to be discussed before the document can be approved. 

The main issues with the document in its current form are: 

1. The document makes consistent changes in the way TRILL operates. It replaces TLVs and procedures, define new ones, obsoletes previous mechanisms that define VLAN mapping, and incorporates updated material from other RFCs. There is however no indication in the text about the transition between existing deployed versions of TRILL based on RFC 6439 and related protocols with the current updated mechanisms. Are these backward compatible? Do they need a simultaneous upgrade of the whole network? 

2. The document lacks a section or even minimal text concerning operational and manageability considerations.  There are several mentions in the text concerning network managers or operator actions, but there is no indication or reference to what management protocols and data models are to be used for configuration, retrieval of operational status information, or alerts. I believe that these need to be added explicitly or by reference.