Bala Rajagopalan

Mobility management in wireless ATM networks

Mobile ATM offers a common wired network infrastructure to support mobility of wireless terminals, independent of the wireless access protocol. In addition, it allows seamless migration to future wireless broadband services, such as wireless ATM, by enabling mobility of end-to-end ATM connections. In spite of the diversity in mobile networking technologies (e.g., cellular telephony, mobile-IP, packet data services, PCS), all of them require two fundamental mechanisms: location management and handoff. This article describes different schemes for augmenting a wired ATM network to support location management of mobile terminals and handoff protocols for rerouting a connection data path when the endpoint moves. A prototype implementation of mobile ATM integrating mobility support with ATM signaling and connection setup, is presented. It shows how mobile ATM may be used to provide mobility support to an IP terminal using non-ATM wireless access.

IP over optical networks: architectural aspects

The Internet transport infrastructure is moving toward a model of high-speed routers interconnected by intelligent optical core networks. A consensus is emerging in the industry on utilizing an IP-centric control plane within optical networks to support dynamic provisioning and restoration of lightpaths. At the same time, there are divergent views on how IP routers must interact with optical core networks to achieve end-to-end connectivity. This article describes the architectural alternatives for interconnecting IP routers over optical networks, considering the routing and signaling issues. Also, the application of IP-based protocols for dynamic provisioning and restoration of lightpaths, as well as the interworking of multivendor optical networks is described.

Capacity performance of dynamic provisioning in optical networks

This paper describes an architecture and analyzes the performance of dynamic provisioning of lightpaths in an optical network. In dynamic provisioning, a lightpath is set up in real-time without rearranging the working and protection routes of existing lightpaths, and without the knowledge of future lightpath provisioning events. This paper develops a general model of the physical topology of the optical network, and outlines routing approaches for dynamic provisioning of lightpaths. It analyzes via simulations the performance of dynamically provisioned unprotected, 1+1 protected and mesh-restored lightpaths. The analysis of the efficiency of network utilization of dynamic provisioning focuses on the spare capacity needed for protection, and in particular focuses on the impact of sharing of wavelength channels for mesh-restored lightpaths. The main conclusion from the performance studies is that significant capacity gains are achieved with sharing of wavelength-channels for mesh-restored lightpaths with dynamic provisioning even for sparse topologies, and even at moderate loads.

The optical network control plane: state of the standards and deployment

The notion of an optical control plane has rapidly ascended from being a mere concept to a detailed set of protocol standards developed with broad industry participation. In this article we present a brief overview of optical control plane architecture and the associated protocols. We then examine the business drivers and inhibitors behind the optical control plane effort, the current state of the standards, interoperability status, and the open issues that need to be resolved before widescale deployment of this new technology can begin.

Signaling for fast restoration in heterogeneous optical mesh networks

With the advent of optical mesh networks, certain new protection schemes have been defined. This encompasses both local span and end-to-end path protection. But the implementations of these protection schemes have so far been based on proprietary mechanisms developed by each vendor. This has made it virtually impractical to construct a heterogeneous network with interoperable mesh protection schemes. Also, while the notion of a standard IP-centric control plane for optical networks based on Generalized Multi-Protocol Label Switching (GMPLS) has gained wide acceptance, the work in this area has so far focused exclusively on connection provisioning rather than restoration. This paper defines standard, IP-based signaling protocols for restoration in optical mesh networks. These protocols focus on a new local span protection mode and end-to-end shared protection. The main requirements on these protocols are simplicity and speed. The signaling mechanisms described in this paper are complimentary to the GMPLS provisioning mechanisms.