S. Nelson, G. Bhanage, and
D. Raychaudhuri, " GSTAR: Generalized Storage-Aware Routing for MobilityFirst in the Future Internet Architecture," Proceedings of the 6th ACM International Workshop on Mobility in the Evolving Internet Architecture (MobiArch), Washington, DC, June 2011,
The rise of wireless, mobile devices and networks presents a unique set of challenges at the network layer. These challenges include varying levels of link quality, multi-homing, and partitions forming within networks. Since most of the interesting mobility challenges will occur relatively close to end users, it is critical for future protocols to support a flexible, robust, and unified means of exchanging data in a local area through many different types of environments. To this end, as part of the MobilityFirst project, GSTAR was developed as a generalized storage-aware intra-domain routing protocol capable of high performance in a variety of mobility-driven environments, including wired, wireless mesh, wireless ad-hoc, and DTN.
The fundamental observation of GSTAR is that the addition and utilization of in-network routing storage vastly increases the options available to routers, giving them a practical and effective means of dealing with the aforementioned challenges. Essentially, GSTAR operates on the principle that mobility-related challenges are best handled directly at the networking layer itself. GSTAR is a storage-aware, delay-tolerant link-state protocol that gives routers the freedom to temporarily store and/or replicate data in response to detected network problems. At a high level, GSTAR maintains time-sensitive information about links within its currently connected component (e.g., all nodes to which an instantaneous end-to-end path exists from the node in question) and time-insensitive information about general connection patterns between all nodes in the network. It attempts to use the time-sensitive information when possible, and fall back on the connection patterns when needed. GSTAR routes on flat, GUID-based identifiers and proactively transmits both traditional and storage-related topology information.
GSTAR proactively utilizes in-network storage to directly handle mobility challenges. The following illustrates the highlights of the protocol.
Direct, network-level handling of link quality variation, node disconnection, and network partitioning
GSTAR actively utilizes available storage in MobilityFirst routers to handle mobility challenges at the network level. Following the approach of its predecessor, CNF (cache-and-forward) routing, routers along a path will temporarily store large data units, called chunks, if link qualities further down the path are abnormally poor. This greatly helps alleviate congestion in the area and can increase overall network throughput. Furthermore, GSTAR proactively pushes chunks towards destinations, even if these destinations are currently disconnected from the network. This is accomplished through intelligent DTN-style control messaging that is integrated with traditional link-state dissemination. Finally, by exposing both fine-grained link qualities for local nodes and course-grained connection probabilities for all nodes, GSTAR can intelligently select message ferries to deliver chunks across network partitions.
Storage-aware path selection
Since chunks can be temporarily stored in MobilityFirst routers, path selection based on traditional hop-counts must be reconsidered. GSTAR utilizes a novel storage-aware path selection technique, which attempts to minimize chunk end-to-end delay by estimating both transmission- and storage-based delays. Essentially, path delays for a given chunk are computed by predicting future link qualities and storage probabilities for hops further along in the path.
Integrated hop-by-hop transport
GSTAR utilizes a connection-less, hop-by-hop transport to reliably deliver chunks through a mobility-challenged network. Each chunk is given a GUID-based destination and GSTAR will progress chunks in a store-carry-and-forward manner. This allows for opportunistic, stateless, and chatter-free communication between end-points.
Progress To Date:
GSTAR is a unification of storage-aware link-state protocols, such as CNF, and DTN protocols. Currently, a baseline protocol exists that unifies the space of MANET and DTN routing by proactively detecting and disseminating link qualities and connection probabilities. This baseline has been implemented in both simulation via NS3 and executable routing code via CLICK. Furthermore, the CLICK-based implementation can run on Linux and Android devices, and has been tested over ORBIT and the GENI network.
Prof. D. Raychaudhuri
732-932-6857 Ext. 638
ray (AT) winlab (DOT) rutgers (DOT) edu