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Current Research Topic

MARA: Maximum Alternative Routing Algorithm

Multipath routing has been considered that it can improve the communication network in termes of the reliability (failure recovery) and the available bandwidth. Past works, however, did not provide sufficient number of multipaths. This work provides MARA, a new multipath routing algorithm that produces a number of multipaths. MARA calculates routes using every link in the network (for a destination). It runs in a sub-one second time for moderate sized networks.

Y. Ohara, S. Imahori, R. Van Meter, "MARA: Maximum Alternative Routing Algorithm," IEEE INFOCOM 2009, April 2009 (Rio de Janeiro, Brazil) [pdf]

Drouting architecture

We propose a new routing architecture that can leverages the many alternative paths produced by MARA. It is called Drouting architecture. Drouting architecture enables the use of many multipaths, by a really simple way. It enables to switch the communication path stochastically, by only changing of the random packet tag. Routers map packet tags to nexthops deterministically, so enables also not to change paths (e.g. for a TCP session). Drouting architecture achieves high probability of failure avoidance, with scalability. It is further expected that Drouting architecture enables ad-hoc "QoS routing" and employment of "network optimization".

Y. Ohara, H. Kusumoto, O. Nakamura, and J. Murai, “Drouting architecture: Improvement of failure avoidance capability using multipath routing.” IEICE Transactions, vol. 91-B, no. 5, pp. 1403–1415, 2008. [link]

Y. Ohara, “Routing Architecture for the Dependable Internet,” Ph.D. dissertation, Keio University, 2008. [pdf]

SimRouting

Simple simulation, analysis, and evaluation of routing algorithms and routing systems were tough tasks because past network simulators mainly targets on the simulation of complex (multi-layered) protocol operation. A new simulation tool, SimRouting, takes Graph theoretic way, disregards the details such as protocol header overhead, and targets to evaluate routing systems easily. Evaluation of MARA and Drouting architecture was conducted using the SimRouting.

Network Optimization on Drouting architecture

Drouting architecture reserves rooms to load balance the traffic on multipath routes. Dynamic programming, along with the Drouting architecture, is expected to enable off-line network optimization as a simple, reasonable, straightforward approach.

Past

Route Flapping Effects on OSPF

This work investigated the effects of oscillating network events to OSPF. It showed that the communication path can excessively be unstable, even though there is an alternative stable path. Also in this work, BGP route flap damping technology is applied to avoid this problem, and showed significant improvements. This work was summarized in the SAINT 2003 workshop paper.

Y. Ohara, M. Bhatia, N. Osamu, and J. Murai. Route Flapping Effects on OSPF. In Proceedings of the 2003 Symposium on Applications and the Internet Workshops, 2003. [pdf]

OSPFv3 Implementation on GNU Zebra

Due to lack of open OSPFv3 implementation managing native IPv6 Network was hard task. We implemented an open OSPFv3 implementation from early days in GNU Zebra. It accelerated many vendors to provide interoperable OSPFv3 implementations.

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