An apparatus for transmitting a file with enhanced transmission security through a network includes a file-splitting processor that splits the file into a plurality of message segments and addresses the plurality of message segments to a plurality of addresses assigned to a receiving host. The apparatus includes a message segment transmitter for transmitting the plurality of message segments to the receiving host.

Camouflage of network traffic to resist attack

A system for the assessment of network performance criteria, and applying this criteria to the classification of network addresses into appropriate ranges, using these ranges to consolidate performance measurements for the associated addresses, and applying these metrics toward the optimization of the network towards performance or policy objectives.

Method and apparatus for the assessment and optimization of network traffic

In light of the slow deployment of IP Multicast technology on the global Internet and the explosive popularity of peer-to-peer (P2P) file-sharing applications, there has been a flurry of research activities investigating the feasibility of implementing multicasting capability at the application layer, referred to as Application Layer Multicasting (ALM), and numerous algorithms and protocols have been proposed. This article aims to provide researchers in the field with an understanding of ALM protocols by identifying significant characteristics, from both application requirements and networking points of view, and by using those characteristics as a basis for organizing the protocols into an integrated and well-structured format. Current trends and directions for further research are also presented. This article surveys the literature over the period 1995?2005 on different application layer multicasting approaches.

A survey of application-layer multicast protocols

Virtual machines can greatly simplify wide-area distributed computing by lowering the level of abstraction to the benefit of both resource providers and users. Networking, however, can be a challenge because remote sites are loath to provide connectivity to any machine attached to the site network by outsiders. In response, we have developed a simple and efficient layer two virtual network tool that in effect connects the virtual machine to the home network of the user, making the connectivity problem identical to that faced by the user when connecting any new machine to his own network. We describe this tool and evaluate its performance in LAN and WAN environments. Next, we describe our plans to enhance it to become an adaptive virtual network that will dynamically modify its topology and routing rules in response to the offered traffic load of the virtual machines it supports and to the load of the underlying network. We formalize the adaptation problem induced by this scheme and take initial steps to solving it. The virtual network will also be able to use underlying resource reservation mechanisms on behalf of virtual machines. Both adaptation and reservation will work with existing, unmodified applications and operating systems.

/pdf/towards-virtual-networks-for-virtual-machine-grid-computing-2jodfbknau.pdf

Towards virtual networks for virtual machine grid computing

A method for re-routing communications based on link quality includes establishing a first wireless communication link with a mobile station. The first wireless communication link is included in a first communication path used for communications between the mobile station and a destination device. The method also includes monitoring, from the mobile station, the link quality of the first wireless link and determining, at the mobile station, that the link quality of the first communication link has decreased below a low link quality threshold. The method further includes routing, using a router at the mobile station, communications between the mobile station and the destination device to a second communication path that includes a second wireless communication link to the mobile station. The second communication path is selected by the router based on one or more metrics.

System and method for re-routing communications based on wireless communication link quality

This paper presents algorithms, heuristics and lower bounds for an optimal sharing of network resources among several multicast groups that coexist in the network. Group (i.e., many-to-many) multicasting is a demanding service since any member can become a sender independently from the others. We consider a shared tree as the backbone of a group multicasting session. Considering each multicast session in isolation and independently may cause congestion on some links and reduce network utilization. Thus, we define the multicast packing problem in which the network tries to accommodate simultaneously all the multicast groups while trying to avoid bottlenecks on the links for higher throughput (i.e., minimize the maximum link sharing among multicast groups). Minimization of maximum congestion is achieved at the expense of increasing the size of some multicast trees which in turn impacts the delay. This trade-off is addressed by adding a penalty term to the objective function of the optimal packing formulation. The penalty term is a function of the amount of dilation from the size of the optimal tree obtained for each group multicast independently from the others (i.e., in isolation). Since the mathematical programming formulation for the optimization problem is computationally intractable, we resort to suboptimal solutions with heuristics. Our heuristic method aims to reduce the sharing of a link while ensuring that the size of multicast trees will never exceed /spl alpha/OPT/sup k/ where OPT/sup k/ is the size of the optimum tree for multicast group k in isolation. Optimum multicast tree for each group (in isolation) is computed by using cutting-plane inequalities and the branch-and-cut algorithm. In order to evaluate the performance of our approximation, we derive lower bounds on the problem. Our first lower bound on the maximum congestion is a theoretical one and puts a cap on the following two constructive lower bounds. The lower bounds and the heuristic method are implemented and it is shown that the maximum congestion obtained by the heuristic method is quite close to the constructive lower bounds.

The multicast packing problem

A virtual private network (VPN) aims to emulate the services provided by a private network over the shared Internet. The endpoints of a VPN are connected using abstractions such as virtual channels (VCs) of ATM or label switched paths (LSPs) of MPLS technologies. Reliability of an end-to-end VPN connection depends on the reliability of the links and nodes in the fixed path that it traverses in the network. In order to ensure service quality and availability in a VPN, seamless recovery from failures is essential. This work considers the problem of fast recovery in the recently proposed VPN hose model. In the hose model, bandwidth is reserved for traffic aggregates instead of pairwise specifications to allow any traffic pattern among the VPN endpoints. This work assumes that the VPN endpoints are connected using a tree structure and, at any time, at most one tree link can fail (i.e., single link failure model). A restoration algorithm must select a set of backup edges and allocate necessary bandwidth on them in advance, so that the traffic disrupted by failure of a primary edge can be re-routed via backup paths. We aim at designing an optimal restoration algorithm to minimize the total bandwidth reserved on the backup edges. This problem is a variant of optimal graph augmentation problem which is NP-complete. Thus, we present a polynomial-time approximation algorithm that guarantees a solution which is at most 16 times of the optimum. The algorithm is based on designing two reductions to convert the original problem to one of adding minimum cost edges to the VPN tree so that the resulting graph is 2-connected, which can be solved in polynomial time using known algorithms. The two reductions introduce approximation factors of 8 and 2, respectively, thus resulting in a 16-approximation algorithm with polynomial time complexity.

http://www.cs.rpi.edu/~yener/PAPERS/QoS/infocom02-restoration.pdf

Restoration algorithms for virtual private networks in the hose model

In this paper, a new hierarchical multihop routing algorithm and its performance evaluation is presented for fully dynamic wireless networks. The routing algorithm operates on a virtual topology obtained by partitioning the routing information for mobile terminals and mobile base stations into a hierarchical, distributed database. Based on the virtual topology, each mobile base station stores a fraction of the routing information to balance the complexity of the location-update and the path-finding operations. Mobility of the network entities changes the load distribution and causes processing and memory bottlenecks in some parts of the network. However, since the network routing elements are also mobile, their movement can be used to distribute the load. Thus, new load balancing schemes are introduced to distribute the routing overhead uniformly among the mobile base stations. The performance of the hierarchical multihop routing algorithm is investigated through simulations. It is shown that the routing protocol can cope with high mobility and deliver packets to the destinations successfully.

Virtual Topology Based Routing Protocol for Multihop Dynamic Wireless Networks

A wireless telecommunications network is disclosed in which all of the facilities (e.g., wireless switching centers, base stations, etc.) are mobile, and, therefore, are capable of being moved while the system provides wireless telecommunications service to one or more wireless terminals. In particular, the present invention is advantageous in that any or all of the various facilities can move relative to each other without the need to suspend the provision of service. An illustrative embodiment of the present invention comprises: a plurality of base stations in a hierarchical network, wherein: each of the base stations comprises the identity of its filial base stations, if any, and wirelessly communicates with its filial base stations; and each of the base stations comprises the identity of its lineal base stations, if any.

Wireless telecommunications network whose facilities are mobile and whose topology is dynamic

A method for mapping a network, in accordance with the present invention, includes providing distance measurements between tracers in the network, determining routes along which the distance measurements are made, and creating a system of equations which links the distance measurements between the nodes with a sum of the delays between the nodes which comprise the routes. Additional information is extracted about distances of subpaths of the routes to provide additional details to a map of the network. The additional information provides a capability of estimation of distances between nodes without tracers.

Bulent Yener

Papers

The multicast packing problem

Restoration algorithms for virtual private networks in the hose model

Virtual Topology Based Routing Protocol for Multihop Dynamic Wireless Networks

Wireless telecommunications network whose facilities are mobile and whose topology is dynamic

Method and apparatus for network mapping using end-to-end delay measurements