Routing Bridges (RBridges): Appointed Forwarders

The IETF TRILL (TRansparent Interconnection of Lots of Links) protocol provides least cost pair-wise data forwarding without configuration in multi-hop networks with arbitrary topology, safe forwarding even during periods of temporary loops, and support for multipathing of both unicast and multicast traffic. TRILL accomplishes this by using IS-IS (Intermediate System to Intermediate System) link state routing and by encapsulating traffic using a header that includes a hop count. Devices that implement TRILL are called "RBridges" (Routing Bridges). TRILL supports multi-access LAN (Local Area Network) links that can have multiple end stations and RBridges attached. Where multiple RBridges are attached to a link, native traffic to and from end stations on that link is handled by a subset of those RBridges called "Appointed Forwarders", with the intent that native traffic in each VLAN (Virtual LAN) be handled by at most one RBridge. The purpose of this document is to improve the documentation of the Appointed Forwarder mechanism; thus, it updates RFC 6325. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.