Narayanan Natarajan

PECAN: policy-enabled configuration across networks

The Internet is growing to the point of needing more serious, scalable management infrastructure. Telecommunications companies and Internet service providers alike face the pressures of upgrading and provisioning their networks while constraining their infrastructure costs to maintain profitability and to stay competitive in an industry that is financially stressed with tight profit margins. In order to be financially successful in this environment, service providers will have to support a variety of services and applications on a combined packet infrastructure, carrying increased varieties of traffic with different performance characteristics and predictable levels of managed quality of service (QoS). Multi-protocol label switching (MPLS) traffic engineering enables service providers to engineer their networks to provide such QoS; however, this task brings along with it a plethora of management challenges. We discuss these management challenges and our experience with the design and implementation of a policy-based management system, PECAN, for managing MPLS networks. PECAN provides the ability for a network operator to define high-level policies that control the operation of the management system. These high-level policies control admission of traffic into the network based on the QoS guarantees required; placement of traffic flows on MPLS traffic engineered paths; and the feedback loop between network fault/performance monitoring and reconfiguration of the network to alleviate the effects of any observed problems.

Efficient assignment of multicast groups to publish-subscribe information topics in tactical networks

A key challenge in a network-centric tactical environment is disseminating information related to sensors, situational awareness, and command and control to the appropriate receivers in a timely, reliable and efficient fashion. IP multicast is the transport mechanism used for information dissemination. It is typically the case in tactical networks that the number of IP multicast addresses available for use is limited and it becomes necessary to assign multiple information topics to each multicast address. This necessitates use of an efficient assignment algorithm during network planning to minimize the dissemination of unwanted information in order to decrease the unnecessary use of network resources and reduce the information load on the receiving nodes. This paper describes an efficient algorithm for assigning information topics to multicast groups taking into consideration the overlapping information needs of subscriber nodes and network bandwidth that will be consumed in the dissemination of each topic based on its size and frequency of publication. The assignment algorithm supports unique requirements of tactical networks: for an information topic, the subscribers may not be related by echelon hierarchy and the criticality of information may vary with subscribers. The assignment algorithm uses the simulated annealing technique to compute an optimal address assignment.

Planning and Management of Dynamic Publish-Subscribe Communications in Tactical Networks using Multicast Groups

A challenge in planning and managing publish-subscribe (pub-sub) communications in tactical environments is making efficient use of IP multicast services with limited multicast address space, i.e., optimally associating pub-sub topics with multicast groups to minimize reception of unsubscribed information at receiver nodes and sending of duplicate information at sender nodes. To address this challenge, this paper proposes a scheme for assigning multiple pub-sub topics to each multicast group intelligently such that members of each multicast group have overlapping information needs to a maximum extent. Experimental results show that the proposed scheme is quite efficient and the efficiency increases with the size of available multicast address pool. The proposed scheme is set in the context of a two-tier information dissemination system architecture for tactical networks consisting of a central planner in a single node, and a dissemination executive in every node. The central planner generates and disseminates the multicast address plan for pub-sub topics to other nodes. The dissemination executive at each node subscribes or publishes information to multicast groups in accordance with the plan and provides pub-sub services to applications in the node.

Network architecture for mission critical communications using LEO satellites

Use of Low Earth Orbit (LEO) satellite networks is a promising approach for global mission communications in view of their low delay and bit error characteristics. This paper describes the network architecture for an LEO environment where payloads have severe size, weight, and power (SWaP) constraints. In this architecture, payloads perform adaptive Layer 2 switching using routes computed by the central network operations center in the ground. Routes are computed considering traffic bandwidth, priority, and duration requirements, and time deterministic network topology changes. If necessary, lower priority traffic is preempted to accommodate higher priority traffic. Based on the routes computed for different snapshots, the planning system generates forwarding rules for payloads and uploads them via management centers that are deployed in different geographical locations in the ground. The architecture employs a distributed management scheme that reduces latency of critical management data such as alarms while avoiding the use of crosslinks for noncritical management communication.

A network management prototype for information delivery and planning with quality of service guarantees

This paper describes two resource management algorithms that have been implemented in a network management system called MetaNet that supports information delivery and planning with quality of service (QoS) guarantees for military applications. The first algorithm deals with provisioning QoS for end-to-end communication services, called MetaNet Channels, with immediate/advance resource reservation and priority based resource preemption. The second algorithm processes queries on bandwidth available over a given time interval for potential channels between two hosts that may be in different networks. The paper also describes results from a set of experiments that were performed to assess the performance and scalability of the QoS provisioning algorithm implemented in a prototype MetaNet system.

Adaptive Dynamic Traffic Engineering for DiffServ-Enabled MPLS Networks

The current practice in traffic engineering for multi-protocol label switching (MPLS) networks is to use expected traffic matrix and service level agreements (SLA) policies as input, and compute a set of label switched paths (LSPs) that satisfy the requested requirements. However, mismatch between traffic forecast and actual load including distribution among differentiated services (DiffServ) classes is unavoidable in dynamic network environments. This may cause overload and unbalanced utilization of LSPs. Furthermore, network failures may occur causing the failure of LSPs and possibly their planned backups; even in the case of dynamic backups, the MPLS network may not be able to establish backup paths because of resource shortages. Consequently, there is a critical need for adaptive dynamic traffic engineering. In this paper, we propose two novel schemes to realize such adaptive dynamic traffic engineering. A traffic rearrangement scheme that executes when changes on link bandwidth partitions among DiffServ classes are needed to alleviate the overload situations and a traffic restoration scheme that kicks into action whenever the MPLS network fails to restore failed LSPs upon network failures

MetaNet: A Distributed Network Management System for Information Delivery and Planning with Quality of Service Guarantees

MetaNet is a network management system that provides end-to-end communication services with QoS and communication planning support for mission critical applications. It supports immediate and advance resource reservation, and provides information on immediate and future available communication capacity taking into account network configuration and traffic. MetaNet supports these services over multiple heterogeneous networks. The MetaNet consists of a number of PoPs (Point of Presence); each PoP is associated with one or more communication networks. PoPs realize the functionality within their networks and coordinate with each other to realize the end-to-end functionality. Associated with each network is an Adapter that hides from the PoP the network technology specific QoS model and mechanisms.

Secure Content Based Routing in Tactical Mobile Ad Hoc Networks

Information superiority in future network centric warfare requires bandwidth efficient data dissemination to the right person at the right time with high assurance. This paper presents a secure content based routing approach for information dissemination in tactical networks. In this approach, subscription is expressed in terms of information items. This approach is more general and flexible than dissemination based on multicast addresses, and avoids the problem of pre-deployment multicast address planning for dynamic engagement situations in battle fields. To be bandwidth efficient, the proposed approach establishes routing paths taking into account overlapping information needs of different nodes. Secure dissemination is founded on a novel concept that separates the concerns of key management for trusted communication (entitlement grouping) from that of disseminating only specific information items that are of interest to recipients (dissemination grouping). The proposed approach provides an integrated scheme that facilitates entitlement based key management for protecting contents in packet payloads and content markup in packet headers for content based routing. The content markup enables intermediate forwarding nodes to employ efficient bandwidth utilization techniques without examining packet contents, thus reducing security vulnerabilities