Mobility Support for Next-Generation Internet Signaling Protocols

Internet signaling protocols establish, maintain and remove state along the data path. Next-generation signaling protocols design must meet the scaling requirements imposed by the various tasks of the Internet signaling applications, such as resource reservation and middlebox configuration, and to meet the demand for general functionality in signaling protocols, including strong security, reliability, congestion control, support for various signaling purposes and message sizes, and efficient support for mobility. This paper presents a generic signaling architecture, the Cross-Application Signaling Protocol (CASP) and describes how it supports efficient and secure signaling in IP mobility scenarios. In this approach, the signaling functionality is splitted into two layers: a generic messaging layer which provides the generic functionality for message delivery, and a client layer consisting of a next-hop discovery client and any number of client protocols which perform the actual signaling tasks. The essential mechanisms required to support mobility are: (1) a session identifier uniquely selected by the initiator and effective discovery of the cross-over node; (2) a branch identifier incrementally assigned for the new branch and efficient release of state in the abandoned branch; (3) ensuring discovery messages are delivered exactly following the path that mobile IP packets are encapsulated; (4) effective hop-by-hop authentication and reauthorization provided by the messaging layer, non hop-by-hop security for signaling clients and denial-of-service protection in the discovery client.