by Chao, Chi-Shih; Natu, Maitreya; Sethi, Adarshpal S.

To ensure high availability of telephone services, there is considerable interest in network management activities to develop competent fault management mechanisms. In this paper we investigate, examine, and try to adapt the current active probing technologies to fault isolation and problem determination of telecommunication networks. The unfitness, issues, and difficulties while adopting these IP-networking probing methods into fault isolation of telecommunication networks are addressed and elaborated. For achieving our goal, call-forwarding which is a dedicated function (or feature) in telecommunication networks is utilized to overcome the unfitness and difficulties while applying probing technologies to fault isolation of telecommunication networks. Numerous experiments with different probe sets, probe stations, total probe lengths, network topologies, and probing algorithms are conducted and analyzed to validate our strategy. From the results of our experiments, we can find that phone call-forwarding can not only facilitate the fault isolation with the existing active probing techniques, but also increase the system flexibility on the installation of probe stations. Meanwhile, on the basis of our experimental results, several practical suggestions are also provided for system implementation.

DOI: 10.1007/s10922-007-9076-7
Online Date: 9/19/2007
Print publication date: 6/1/2008
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by Liotta, Antonio; Tyrode-Goilo, Daniel H.; Oredope, Adetola

Virtual Private Networks (VPNs) are normally used for secured communications over the Internet. The VPNs have evolved significantly over the years, leading to a range of open-source and proprietary solutions. In Converged, all-IP networks terminal mobility introduces, however, new challenges that have so far been addressed only partially and via proprietary solutions. In this article we assess the level of maturity, the viability and performance achieved in mobile VPNs, based merely on open-source software. Our prototype MVPN is obtained by integrating IPv6, Mobile IPv6 and IPsec, i.e., the protocols that 3GPP envisions for all-IP, mobile and fixed networks. We perform a series of tests on a multi-access wireless network (WLAN, GPRS and UMTS), aimed at identifying the issues arising when mobility management (vertical and horizontal handover) is combined with different levels of network security. Tests led to the discovery of various results such as the flushing of routing tables in MIPv6 during handover. Our performance analysis is complemented with lessons learnt and recommendations.

DOI: 10.1007/s10922-007-9075-8
Online Date: 9/12/2007
Print publication date: 6/1/2008
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