Cisco Systems

The IETF TRILL (TRansparent Interconnection of Lots of Links) protocol provides optimal pair-wise data forwarding without configuration, 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 Routing Bridges (RBridges). TRILL supports multi-access LAN (Local Area Network) links that can have multiple end stations and RBridges attached. This document describes four aspects of the TRILL LAN Hello protocol used on such links, particularly adjacency, designated RBridge selection, and MTU (Maximum Transmission Unit) and pseudonode procedures, with state machines. There is no change for IS-IS point-to-point Hellos used on links configured as point-to-point in TRILL. Status of This Memo This is an Internet Standards Track document. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by th