The goal of admission control is to support the quality-of-service demands of real-time applications via resource reservation. We introduce a new approach to measurement-based admission control for multiclass networks with link sharing. We employ adaptive and measurement-based maximal rate envelopes of the aggregate traffic flow to provide a general and accurate traffic characterization that captures its temporal correlation as well as the available statistical multiplexing gain. In estimating the applications' future performance, we introduce the notion of a schedulability confidence level which describes the uncertainty of the measurement-based "prediction" and reflects temporal variations in the measured envelope. We then devise techniques to control loss probability for a buffered multiplexer servicing heterogeneous and bursty traffic flows, even in the regime of a moderate number of traffic flows, which is important in link-sharing environments. Finally, we have developed an implementation of the scheme on a prototype router and performed a testbed measurement study, which together with extensive trace-driven simulations illustrates the effectiveness of the approach in practical scenarios.

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Measurement-based admission control with aggregate traffic envelopes

Allocating resources for multimedia traffic flows with real-time performance requirements is an important challenge for future packet networks. However, in large-scale networks, individually managing each traffic flow on each of its traversed routers has fundamental scalability limitations, in both the control plane's requirements for signaling, state management, and admission control, and the data plane's requirements for per-flow scheduling mechanisms. In this paper, we develop a scalable architecture and algorithm for quality-of-service management termed egress admission control. In our approach, resource management and admission control are performed only at egress routers, without any coordination among backbone nodes or per-flow management. Our key technique is to develop a framework for admission control under a general "black box" model, which allows for cross traffic that cannot be directly measured, and scheduling policies that may be ill-described across many network nodes. By monitoring and controlling egress routers' class-based arrival and service envelopes, we show how network services can be provisioned via scalable control at the network edge. We illustrate the performance of our approach with a set of simulation experiments using highly bursty traffic flows and find that despite our use of distributed admission control, our approach is able to accurately control the system's admissible region under a wide range of conditions.

Scalable services via egress admission control

According to a disclosed embodiment, a communication device comprises an air interface module which is synchronized in time with a universal time source such as Global Positioning System ('GPS'). The communication device further comprises a network time server which is synchronized with the universal time source. The communication device further comprises an address server configured to provide an address of the network time server to a CPU included in the communication device. The CPU is configured to synchronize time with the network time server and provide the synchronized time to a network interface. The network interface is configured to communicate the synchronized time to a user computer. For example, the user computer can run Network Time Protocol, NTP, to facilitate updating the system clock of the user computer using the synchronized time.

Apparatus and system for maintaining accurate time in a wireless environment

Appropriate determinations in a series of tests, which transition from more passive tests to more active tests, control the admission of data streams onto a network data path. More passive tests can include promiscuous mode and packet-pair tests. When the results of more passive tests indicate a reduce likelihood of a data stream causing a network data path to transition into a congested state, the network data path can be actively probed to make a more precise determination on the likelihood of congestion. A train of diagnostic data packets is transmitted at a diagnostic data transfer rate having a significantly reduced chance of causing congestion. A train of target data packets is transmitted at a requested application transfer data rate. The number of target data packets received within a specified delay threshold is compared to the number of diagnostic data packets receive with the delay threshold.

Controlling admission of data streams onto a network based on end-to-end measurements

A method for synchronizing a time architecture of a mobile network that includes a plurality of network components, each having a time subsystem clock that is updated using a network time protocol (NTP) program The method includes operating the components in a hierarchical fashion and booting up all the network components such that execution of a NTP sub-program for making small incremental changes to the each component time subsystem clock is delayed Additionally, the method includes iteratively executing a NTP sub-program for making large changes to each component time system clock until each component time sub-system clock establishes an initial synchronization with a parent component time sub-system clock Furthermore, the method includes iteratively executing the NTP sub-program for making small incremental changes once initial synchronization is established such that each component time sub-system clock maintains synchronization with the parent component time sub-system clock

Mobile network time distribution

While the IntServ solution to Internet QoS can achieve a strong service model that guarantees flow throughputs and loss rates, it places excessive burdens on high-speed core routers to signal, schedule, and manage state for individual flows. Alternatively, the DiffServ solution achieves scalability via aggregate control, yet cannot ensure a particular QoS to individual flows. To simultaneously achieve scalability and a strong service model, we have designed and implemented a novel architecture and admission control algorithm termed Egress Admission Control. In our approach, the available service on a network path is passively monitored, and admission control is performed only at egress nodes, incorporating the effects of cross traffic with implicit measurements rather than with explicit signaling. In this paper, we describe our implementation of the scheme on a network of prototype routers enhanced with ingress-egress path monitoring and edge admission control. We report the results of testbed experiments and demonstrate the feasibility of an edge-based architecture for providing IntServ-like services in a scalable way.

Anders Skoe

Papers

Design and Implementation of Scalable Admission Control

Design and implementation of scalable edge-based admission control