An Architecture for a Global Internet Host Distance Estimation Service
There is an increasing need for Internet hosts to be able to quickly and efficiently learn the distance, in terms of metrics such as latency or bandwidth, between Internet hosts. For example, to select the nearest of multiple equal-content web servers. This paper explores technical issues related to the creation of a public infrastructure service to provide such information. In so doing, we suggests an architecture, called IDMaps, whereby Internet distance information is distributed over the Internet, using IP multicast groups, in the form of a virtual distance map. Systems listening to the groups can estimate the distance between any pair of IP addresses by running a spanning tree algorithm over the received distance map. We also presents the results of experiments that give preliminary evidence supporting the architecture. This work thus lays the initial foundation for future work in this new area.
The Internet Engineering Task Force (IETF) is considering the adoption of controlled-load service as a standard for relaxed real-time services on the Internet. The ability of relaxed real-time services to achieve high level of utilization and still provide acceptable quality of service depends crucially on the use of measurement-based admission control (MBAC) algorithms. MBAC algorithms admit new connections based on measured bandwidth usage of existing connections. In this paper we describe the design and implementation of an MBAC algorithm for controlled-load service on a router running FreeBSD 2.2.2 kernel. We then present an end-to-end evaluation which shows that controlled-load service, supported by an MBAC, reduces the packet loss rate and delay variation of real-time traffic while maintaining network efficiency.
A Measurement-based Admission Control Algorithms for Controlled-load Service
Controlled-Load Service provides data flows with an enhanced quality of service, in the form of low packet delay and a low probability of packet loss even under congestion. A network element providing Controlled-Load Service must use an admission control algorithm to limit the number of data flows receiving the service. In this document we describe an admission control algorithm for Controlled- Load Service. This algorithm is not intended for IETF standardization. Rather, it is presented for informational purposes only.
Measurement-based Admission Control Algorithms for Controlled-load Service: A Structural Examination
The Internet Engineering Task Force (IETF) is considering the adoption of the controlled-load service, a real-time service with very relaxed service guarantees. Measurement-based admission control algorithms (MBAC's), as opposed to the more conservative worst-case parameter-based methods, were expressly designed to achieve high levels of network utilization for such relaxed real-time services. Most researchers studying MBAC's, including ourselves, have focused primarily on the design of the admission control equations using a variety of principled and ad hoc motivations. In this paper we show that, much to our own surprise, the admission control equations developed so far in the MBAC literature give essentially the same performance. Furthermore, we observe that the equations, even though they are derived and motivated in quite different ways, have the same structural form.
Comparison of Measurement-based Admission Control Algorithms for Controlled-Load Service
We compare the performance of four admission control algorithms--one parameter-based and three measurement-based--for controlled-load service. The parameter-based admission control ensures that the sum of reserved resources is bounded by capacity. The three measurement-based algorithms are based on measured bandwidth, acceptance region, and equivalent bandwidth. We use simulation on several network scenarios to evaluate the link utilization and adherence to service commitment achieved by these four algorithms.
Many designs for integrated service networks offer a bounded delay packet delivery service to support real-time applications. To provide bounded delay service, networks must use admission control to regulate their load. Previous work on admission control mainly focused on algorithms that compute the worst case theoretical queueing delay to guarantee an absolute delay bound for all packets. In this paper we describe a measurement-based admission control algorithm for predictive service, which allows occasional delay violations. We have tested our algorithm through simulations on a wide variety of network topologies and driven with various source models, including some that exhibit long-range dependence, both in themselves and in their aggregation. Our simulation results suggest that, at least for the scenarios studied here, the measurement-based approach combined with the relaxed service commitment of predictive service enables us to achieve a high level of network utilization while still reliably meeting the delay bound.
In this paper, we characterize wide-area network applications that use the TCP transport protocol. We also describe a new way to model the wide-area traffic generated by a stub network. We believe the traffic model presented here will be useful in studying congestion control, routing algorithm, and other resource management schemes for existing and future networks.
This paper describes tcplib, a workload or source library for network simulation. We motivate the need for tools like tcplib and discusses how to incorporate it into a network simulator.