Shepherd writeup

Essay format shepherd writeup for draft-ietf-sfc-nsh-18

The writeup is being prepared by one of the working group co-chairs, Joel Halpern.   It is prepared for consideration by the community, the IESG, and the responsible AD, Alia Atlas.

This document describes a Network Service Header (NSH) inserted onto packets or frames to realize service function paths.  NSH also provides a mechanism for metadata exchange along the instantiated service path. NSH is the SFC encapsulation required to support the Service Function Chaining (SFC) Architecture (defined in RFC7665).

The working group is requesting that this packet format and handling information be published as a Proposed Standard RFC.  It defines an interoperable mechanism to achieve the stated goals.

The working group has had many discussions on this document.  Many individuals from many companies have helped bring together this solution.  Over the last 9 months significant effort has gone into fixing issues raised by earlier reviews.  While there is still some disagreement (such as on the fact that the WG selected TTL mechanism is a compromise with some accepted imperfections), all technical limitations are identified in the document and dealt with in fashions acceptable to the rough consensus of the working group.

There are multiple implementations of this work, some from open source and some proprietary.

As required by IETF process, all front page editors have explicitly confirmed that there is no undisclosed relevant IPR.

This document does normatively reference and build upon RFC 7665, which is an informational RFC published by the working group.