Photon Netw Commun (2007) 13:19–30 DOI 10.1007/s11107-006-0012-7 ORIGINAL ARTICLE Virtual source-based minimum interference path multicast routing in optical virtual private networks Jun-Mo Jo · Suk-Jin Lee · Kyung-Dong Hong · Chun-Jai Lee · Oh-Han Kang · Sung-Un Kim Received: 19 April 2005 / Revised: 16 April 2006 / Accepted: 9 June 2006 / Published online: 27 October 2006 © Springer Science+Business Media, LLC 2006 Abstract Virtual Private Network (VPN) services over the Internet are gaining increased acceptance due to the economic benefits and flexibility. However, with diffi- culties of providing sufficient transmission capacity for value-added and mission-critical services, the Optical VPN (OVPN) deploying Dense Wavelength-Division Multiplexing (DWDM) technology has been seen as a favorable approach for realizing the future VPN ser- vices. In an OVPN, the Routing and Wavelength Assign- ment problem plays a key role for capacity utilization and therefore the Multicast Routing and Wavelength Assignment problem has been the dominant issue in a DWDM-based OVPN. In this paper, using Virtual Source (VS) nodes that have splitting and wave- length conversion capabilities, we propose a new Mul- ticast Routing and Wavelength Assignment method for multicast sessions. The algorithm combines the VS-based tree generation approach with Multi-Wavelength Mini- J.-M. Jo Tongmyong University, 535 Yongdang-Dong, Nam-Gu, Busan, 608-711, Korea e-mail: jun@tu.ac.kr S.-J. Lee · K.-D. Hong · C.-J. Lee Pukyong National University, 599-1 Daeyeon 3-Dong, Nam-Gu, Busan, 608-737, Korea e-mail: stone, omnybus, leecjcpp@pknu.ac.kr O.-H. Kang Andong National University, 388 Song-chon Dong, Andong, Kyoungbuk, 760-749, Korea e-mail: ohkang@andong.ac.kr S.-U. Kim (B ) Corresponding Author: Pukyong National University, 599-1 Daeyeon 3-Dong, Nam-Gu, Busan, 608-737, Korea e-mail: kimsu@pknu.ac.kr mum Interference Path Routing (MW-MIPR) that chooses a path that does not interfere too much with potential future multicast session requests. Keywords Multicast Routing and Wavelength Assignment · MW-MIPR · OVPN Introduction AstheInternetandopticalnetworktechnology advances, IP over Dense Wavelength-Division Multiplexing (DWDM) has been envisioned as the most promising solution for the next generation optical Internet. Espe- cially, Virtual Private Networks (VPNs) are well recog- nized as one of the critical applications of the future Internet market and have gained increased acceptance due to the economic benefits and maturing technol- ogy [1–3]. Moreover, given the increasing demand for high bandwidth services, a DWDM-based Optical VPN (OVPN) has been regarded as a favorable approach for the future VPN. One of the critical issues in OVPN is the Routing and Wavelength Assignment problem that is embossed as very important and plays a key role in improving the global efficiency for capacity utilization. In addi- tion, many applications such as television broadcast, movie broadcasts from studios, video-conferencing, live auctions, interactive distance learning, and distributed games are becoming increasingly popular. These appli- cations require point-to-multipoint connections among the nodes in the networks. As a solution of such applications, multicast provides an efficient way of disseminating data from a source to a group of destinations, so the multicast problem in