Technical Summary:
The TRILL base protocol supports labeling of TRILL Data packets
with up to 4K IDs. However, there are applications that require
more fine-grained labeling of data for configurable isolation based
on different tenants, service instances, or the like. This document
updates TRILL by specifying an optional extension that supports an
additional 2**24 labels, called fine-grained labels (FGLs).
Provisions for mixed networks of TRILL switches that do and do not
support FGLs are provided.
Working Group Summary:
The two primary points of discussion in the WG were how to encode
fine grained labels and how to handled mixed networks.
Early versions of FGL, for maximum backwards compatibility with the
TRILL base protocol, made a non-standard use of an Ethertype
assigned to another group as part of FGL encoding, but this ws not
allowed by the asignee of that Ethertype. So the encoding was
changed to use a new Ethertype allocated for TRILL FGL. After
discussion, the consensus of the working group was to use
an encoding structure optimized for support by existing fast path
silicon, although this is not the most compact encoding.
For handling mixed networks, the problem to be solved was how to
avoid giving an FGL TRILL Data packet to a TRILL switch not
supporting FGL that might mishandle it. The WG decision was to
avoid methods that would require silicon changes or additional
shortest path calculation, yet have the protocol be robust against
mixtures of old and new TRILL switches.
Document Quality:
The document has been reviewed by participants from the TRILL
vendors that appear to plan to implement this specification.
The document shepherd has reviewed the document in its most recent
form.
Personnel:
Erik Nordmark is the Document Shepherd.
Ted Lemon is the Responsible Area Director.
IANA Note
You will definitely want to process all the IANA considerations
for draft-ietf-isis-rfc6326bis before attempting to make sense
of the IANA considerations in this document.