Whay Chiou Lee

Routing subject to quality of service constraints in integrated communication networks

With increasingly diverse QOS requirements, it is impractical to continue to rely on conventional routing paradigms that emphasize the search for an optimal path based on a predetermined metric, or a particular function of multiple metrics. Modern routing strategies must not only be adaptive to network changes but also offer considerable economy of scope. We consider the problem of routing in networks subject to QOS constraints. After providing an overview of prior routing work, we define various QOS constraints. We present a call architecture that may be used for QOS matching and a connection management mechanism for network resource allocation. We discuss fallback routing, and review some existing routing frameworks. We also present a new rule-based, call-by-call source routing strategy for integrated communication networks. >

Topology aggregation for hierarchical routing in ATM networks

This paper provides a tutorial for topology arregation in large hierarchical communication networks. Specifically, it examines some issues of topology aggregation for hierarchical PNNI Routing in ATM networks, presents a complex node representation, and provides some guidelines for topology aggregation. There are two main reasons for topology aggregation. First, topology information must be compressed to avoid excessive complexity in topology adevertisement. Second, the internal topology of a network may have to be hidden for security reasons. A desirable topology aggregation method must adequately represent the topology of a given network for efficient routing and netowrk resource allocation, using a compact advertised topology.

Spanning tree method for link state aggregation in large communication networks

We consider a communication network in which dynamic routing is used for establishing connections that support information transfer between end-users. Link state information is exchanged and maintained up-to-date among network nodes for path computation and network resource allocation. When the population of users is large, the amount of link state information can be overwhelming. A common solution is to use a hierarchical structure. In this paper, we present a method for aggregating link state information in a hierarchical network. We assume that each link state parameter associated with a link is symmetrical in both directions of the link. The key idea for the method is to first reduce the original subnetwork topology to a full-mesh representation that consists of a logical link for each pair of border nodes in the subnetwork, and then encode the link state information associated with the full-mesh representation with an appropriate spanning tree.

STAR: a transparent spanning tree bridge protocol with alternate routing

With increasing demand for multimedia applications, local area network (LAN) technologies are rapidly being upgraded to provide support for quality of service (QoS). In a network that consists of an interconnection of multiple LANs via bridges, the QoS of a flow depends on the length of an end-to-end forwarding path. In the IEEE 802.1D standard for bridges, a spanning tree is built among the bridges for loop-free frame forwarding. Albeit simple, this approach does not support all-pair shortest paths. In this paper, we present a novel bridge protocol, the Spanning Tree Alternate Routing (STAR) Bridge Protocol, that attempts to find and forward frames over alternate paths that are provably shorter than their corresponding tree paths. Being backward compatible to IEEE 802.1D, our bridge protocol allows cost-effective performance enhancement of an existing extended LAN by incrementally replacing a few bridges in the extended LAN by the new STAR bridges. We develop a strategy to ascertain bridge locations for maximum performance gain. Our study shows that we can significantly improve the end-to-end performance when deploying our bridge protocol.

SMOCK: A Scalable Method of Cryptographic Key Management for Mission-Critical Wireless Ad-Hoc Networks

Mission-critical networks show great potential in emergency response and/or recovery, health care, critical infrastructure monitoring, etc. Such mission-critical applications demand that security service be ldquoanywhere,rdquo ldquoanytime,rdquo and ldquoanyhow.rdquo However, it is challenging to design a key management scheme in current mission-critical networks to fulfill the required attributes of secure communications, such as data integrity, authentication, confidentiality, nonrepudiation, and service availability. In this paper, we present a self-contained public key-management scheme, a scalable method of cryptographic key management (SMOCK), which achieves almost zero communication overhead for authentication, and offers high service availability. In our scheme, a small number of cryptographic keys are stored offline at individual nodes before they are deployed in the network. To provide good scalability in terms of the number of nodes and storage space, we utilize a combinatorial design of public-private key pairs, which means nodes combine more than one key pair to encrypt and decrypt messages. We also show that SMOCK provides controllable resilience when malicious nodes compromise a limited number of nodes before key revocation and renewal.

QoS-enabled residential gateway architecture

As networking technologies penetrate wide varieties of devices for daily usage, home networks are becoming a reality. The bandwidth and always-on connectivity provided by the rapidly growing broadband technologies, such as cable and digital subscriber line (DSL), render home networking even more attractive. A residential gateway is a device that interconnects various home devices to one another as well as to the Internet. The home networks being deployed today are simple and inexpensive with the residential gateway providing only connectivity. As home networks evolve and become more widespread, emerging applications on home networks will demand additional features that require quality of service. We present an architecture of a next-generation QoS-enabled residential gateway. Such a residential gateway, in conjunction with the developments in QoS-enabled wireless LAN technologies, will usher in a new generation of home networks that are capable of supporting a wide range of applications.

Minimum equivalent subspanner algorithms for topology aggregation in ATM networks

In a hierarchical network, the process of summarizing and compressing topology information at each hierarchical level to determine the topology information to be advertised at the level above is referred to as topology aggregation. Specifically, a problem of topology aggregation is to encode a full mesh representation of a given topology with a compact auxiliary graph, such that it could be used to reconstruct the full mesh representation with little or no distortion. This paper presents some algorithms that can be used to determine, for a given topology, a minimum representation with no compromise on accuracy. The minimum representation can be used to characterize the amount of redundancy in the topology. The application of these algorithms to generate complex node representations for topology aggregation in ATM networks is discussed.

Integrated packet networks with quality of service constraints

The authors propose a QoS (quality of service) framework which strikes a balance between the quality criteria of the service providers and the quality requirement of the users. QoS is classified in terms of performance, resource, and priority constraints. The authors discuss how this framework fits into a connection-oriented fast packet environment. They also show how QoS negotiation is conducted in such a network, so that the QoS of the available network resources matches that needed by the users.<<ETX>>

Rapid Deployment of Wireless Ad Hoc Backbone Networks for Public Safety Incident Management

In this paper, we study a problem of deploying wireless ad hoc relay devices in real time by public safety first responders at an incident scene without pre-planning so that a wireless communication backbone network can be rapidly established at the scene. A collaborative deployment method is proposed to enable mobile devices carried by first responders to exchange control information and make deployment decisions based on such information. Simulation results show that the proposed method efficiently establishes a reliable ad hoc backbone network at an incident scene.

Rule-based call-by-call source routing for integrated communication networks

Routing subject to multiple quality-of-service (QOS) constraints is considered. Such a problem arises in both private corporate backbone networks and public switched networks, and will become even more prevalent in the future with the emergence of asynchronous transfer mode (ATM) networks. A rule-based call-by-call source routing strategy that makes use of routing fallbacks to accommodate users with diverse QOS requirements is proposed.<<ETX>>