Charles U. Martel

The distribution of large data sets from a centralized node to several destination sites is frequently required by many data-intensive networking applications; this distribution can be efficiently achieved by the means of multicasting. Multicasting has been typically considered for on-demand applications and services, e.g., video-on-demand, IPTV, etc., which usually require start of data transmission immediately. We consider that multicast sessions can be provisioned starting with flexible times and that the multicast client can specify a maximum allowed time by which all data needs to be delivered to destinations. This is true for e-Science and high-performance applications, in which data distribution is not necessarily immediate. In this paper, we study the problem of provisioning dynamic multicast data-distribution requests (MDDRs) with flexible scheduling over optical WDM networks. We consider the practical case of fractional-capacity multicast sessions that require less than the entire wavelength capacity (nodes are equipped with multicast-capable opaque switches). We devise provisioning methods based on the multicast tree (or light-tree) distribution model. In our first approach (named Rand), we generate multiple randomized alternate trees on which we try to provision the multicast session and then assign wavelengths and schedule the session. In our second approach (named AllSlots), we dynamically generate light-trees depending on the network state. In our next approach (named Break), when provisioning an entire tree fails, we try to “break” the tree into time-independent subtrees. We also study the impact of allowing data to be buffered at intermediary nodes and then transmitted toward destinations (method named Buffer) and consider an approach that partitions the data sets. Finally, we study the impact of the switch architecture on our provisioning by restricting our approaches to full-wavelength MDDRs.

Telecommunication networks spanning large areas are subject to various failures, such as natural disasters, operation errors, and malicious attacks. Disaster failures (DFs) are those, which can lead to a large-area malfunction and degrade the performance of a backbone telecom mesh network. A survivable network provisioning scheme that can recognize and address multiple levels of network failures, including DFs, is desirable for the future Internet. We study the characteristics of multiple failures in telecom mesh networks, such as optical wavelength-division-multiplexed (WDM) networks. In particular, we devise a novel provisioning scheme for telecom mesh networks, which can efficiently exploit the network connectivity using multiple paths. Three provisioning states are defined, in response to single-link failure (SF), multiple-link failure (MF), and DF. We integrate the conventional primary-backup method with reprovisioning and degraded service (i.e., a reduced level of service versus no service at all) into a state-transition model to handle different levels of failures. A predefined level of service is guaranteed for premium customers even if the service cannot be fully recovered. Multinode failures within the same shared risk group (SRG) and failures on destination node are also considered in our study. Our results show that: 1) connection-dropping probability due to a node failure can be significantly reduced with a small extra cost in SF protection; 2) for single-node failure, our algorithm achieves better performance than the shortest vertex-disjoint algorithm; and 3) remote-site data replication is effective to protect against destination-node failures.

With the increasing diversity of applications supported over optical networks, new service guarantees must be offered to network customers. Among the emerging data-intensive applications are those which require their data to be transferred before a predefined deadline. We call these deadline-driven requests (DDRs). In such applications, data-transfer finish time (which must be accomplished before the deadline) is the key service guarantee that the customer wants. In fact, the amount of bandwidth allocated to transfer a request is not a concern for the customer as long as its service deadline is met. Hence, the service provider can choose the bandwidth (transmission rate) to provision the request. In this case, even though DDRs impose a deadline constraint, they provide scheduling flexibility for the service provider since it can choose the transmission rate while achieving two objectives: 1) satisfying the guaranteed deadline; and 2) optimizing the network's resource utilization. We investigate the problem of provisioning DDRs with flexible transmission rates in wavelength-division multiplexing (WDM) mesh networks, although this approach is generalizable to other networks also. We investigate several (fixed and adaptive to network state) bandwidth-allocation policies and study the benefit of allowing dynamic bandwidth adjustment, which is found to generally improve network performance. We show that the performance of the bandwidth-allocation algorithms depends on the DDR traffic distribution and on the node architecture and its parameters. In addition, we develop a mathematical formulation for our problem as a mixed integer linear program (MILP), which allows choosing flexible transmission rates and provides a lower bound for our provisioning algorithms.

We investigate the problem of provisioning deadline-driven requests with flexible transmission rates in WDM mesh networks. We analyze the network's performance and cost for different node architectures and for different traffic distributions.

Many researchers have considered security policy management, including how to configure policies manually and even how to automatically generate security policies based on security requirements. Both can be error prone, especially when properties of the network topology change, because security requirements are usually not bound to any particular route path. Our DETER lab emulation results show that conflicts could be caused by these factors. Therefore, a systematic way to validate the correctness of the security policies is essential. This paper presents an approach, CLID (conflict and looping identification and detection), to verify whether a set of security policies (e.g. IPSec/VPN tunnels) satisfy the given security requirements, without causing any conflicts. This approach utilizes the definition of a security policy lo include network routing data as well as traffic selector information, thus it works for general network topologies. We also analyze and justify the correctness of the approach. The paper concludes with our simulation results and addresses future work.

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We gratefully acknowledge support from the NSF ITR Program, Grant No. 0085961. Integrity critical databases, such as financial information used in high-value decisions, are frequently published over the Internet. Publishers of such data must satisfy