Resilient Packet Ring Networks Research Articles

Design and analysis of a resilient packet ring-based backhaul for LTE networks that reduces handover latency

This paper introduces a wireless optical integrated network architecture involving IEEE 802.17 resilient packet ring (RPR) and long-term evolution (LTE) wireless network. The primary objective of the work is to reduce handover latency when the RPR network is used for backhauling the LTE network. The proposal implements the X2 interface of the LTE network over the optical backhaul, which allows base stations of LTE to directly communicate with each other. The work further discusses about an open access network architecture where a single RPR backhaul can be used by multiple mobile service providers without compromising information security. Extensive simulations have been carried out to verify the effectiveness of the proposal. A non-preemptive priority-based queueing model has been developed to analyze the queueing delay experienced by the X2 and uplink packets. The model has been validated by simulation results.

Flood Avoidance Mechanisms for Bridged Resilient Packet Rings

Resilient Packet Ring (RPR), or the Standard IEEE 802.17, is a new IP-based network technology proposed to replace SONET/SDH in metropolitan area networks. RPR is well-adapted to handle multimedia traffic and is efficient. However, when RPR networks are bridged, inter-ring packets, or packets with the destination on a remote RPR network other than on the source network, are flooded on the source and the destination networks, and also on the path of the intermediate networks between the source and the destination networks. This decreases the available bandwidth for other traffic in those networks and is inefficient. As a result, we propose two solutions based on topology discovery, global topology discovery (GTD) and enhanced topology discovery (ETD), that prevent the flooding of inter-ring packets. GTD enables the bridges to determine the next-hop bridge for each destination. ETD enables the source node to determine a default ringlet, so that packets reach the next-hop bridge without flooding the source network. The proposed solutions were analyzed and the overhead bandwidth and stabilization time were shown to be bounded. Simulations performed showed that the proposed solutions successfully avoid flooding and achieve optimal efficiency in the intermediate and destination networks, and in the source networks with one bridge.

Non-Flooding Bridging Solutions for Resilient Packet Rings

Resilient Packet Ring (RPR) is one of the IP-based technologies that have been proposed to replace SONET/SDH in metropolitan area networks because it is well-adapted to handle diverse tra±c, including multimedia traffic, found in present-day networks. Additionally, the RPR network is used efficiently with nodes transmitting simultaneously as long as the paths of the packets do not overlap. However, when bridging RPR networks, packets are flooded on the bridged RPR network if the packet destination is on a remote network other than the source network. As a result, the network is used inefficiently, decreasing the available bandwidth for other traffic. In this paper, we propose enhanced topology discovery protocol and enhanced spanning tree protocol to prevent the flooding of packets on the bridged RPR network. Simulations were performed in order to evaluate the proposed solutions. The results show that the flooding of packets is successfully prevented and that the network is used more e±ciently as compared to the RPR

Multicasting in a WDM-upgraded Resilient Packet Ring

The recently approved IEEE 802.17 Resilient Packet Ring (RPR) network deteriorates under multicast traffic to legacy ring technologies that do not support spatial reuse. We extend our multicast approach with spatial reuse from a currently single-channel RPR to WDM-upgraded multichannel RPR networks, where each node can transmit packets on all wavelengths and receive on one wavelength, and analyze their multicast capacity. Our analysis provides a convenient method for evaluating the multicast and reception capacities of WDM-upgraded RPR networks for a wide range of uniform unicast, multicast, and broadcast traffic scenarios.

A Novel Fairness Mechanism Based on the Number of Effective Nodes for Efficient Bandwidth Allocation in the Resilient Packet Ring

Metro networks are based on SONET/SDH which uses the circuit switching technology. Circuit switching is inappropriate for the Internet traffic which is very bursty nature. Therefore, metro networks can become a bottleneck. In order to resolve this problem, the IEEE 802.17 working group has proposed the Resilient Packet Ring (RPR) technology. In order to provide fairness among stations in the RPR network, two types of RPR fairness mechanisms have been defined. However, the IEEE 802.17 RPR fairness mechanisms have the problem of inefficient use of the available bandwidth after the congestion at a node has been resolved. In'this paper, we propose an improved bandwidth allocation in which, after the congestion resolution at a node, the node estimates the number of effective nodes transmitting traffic, measures the remaining bandwidth and fairly allocates the available bandwidth to effective nodes. To show the performance of our proposed mechanism, we have performed simulation and show that the proposed mechanism gives higher bandwidth utilization than the existing RPR fairness mechanisms.

RINGOSTAR: an evolutionary performance-enhancing WDM upgrade of IEEE 802.17 resilient packet ring

To upgrade IEEE 802.17 Resilient Packet Ring networks by WDM, most previously reported approaches deploy WDM on the ring, requiring modifications of all nodes at the architecture and/or protocol level without significantly enhancing the performance of RPR apart from increased capacity and optical bypassing capability. In this article we aim at rethinking the box. Leveraging on the dark fiber infrastructure abundantly available in today's metropolitan areas, a subset of RPR nodes are interconnected by a single-hop star WDM subnetwork in a pay-as-you-grow manner. Building on RPR's destination stripping, wrapping, and steering techniques, we describe and examine two novel evolutionary performance-enhancing techniques: proxy stripping and protectoration. Our findings show that the resultant RINGOSTAR network not only dramatically increases spatial reuse, provides fairness as well as fast and efficient resilience against multiple failures but also supports both metro core's uniform and in particular metro edge's strongly hubbed traffic in a highly efficient way

SSA: simple scheduling algorithm for resilient packet ring networks

The resilient packet ring (RPR), defined under IEEE 802.17, has been proposed as a high-speed backbone technology for metropolitan area networks. RPR is introduced to mitigate the underutilisation and unfairness problems associated with the current technologies SONET and Ethernet, respectively. The key performance objectives of RPR are to achieve high bandwidth utilisation, optimum spatial reuse on the dual rings, and fairness. The RPR standard implements three traffic classes: Class A, Class B, and Class C. The RPR MAC has one queue for each traffic class. A potential performance limitation is associated with the head-of-line blocking. When the MAC uses a single FIFO to buffer frames awaiting access, a packet that is traversing through a congestion point may block transmission of other packets destined to a point before the congestion. The use of virtual destination queues (VDQs) to avoid the head-of-line blocking is introduced. Different bandwidth allocation policies are discussed to assign rates to VDQs. Finally, a bandwidth allocation policy is proposed, which would achieve the maximum utilisation at a very low complexity.

Multicasting in IEEE 802.17 resilient packet ring

By using destination stripping and shortest-path routing, the new standard IEEE 802.17 resilient packet ring (RPR) allows for spatial reuse, resulting in a significantly increased capacity compared to source-stripping legacy ring networks. We show that for multicast traffic the performance of RPR reduces to that of legacy ring networks that do not support spatial reuse. We propose a bandwidth-efficient and cost-sensitive multicast approach for RPR networks that exploits RPR's built-in topology discovery and supplementary time-to-live field to enable spatial reuse for multicast traffic. By means of analysis and simulation we investigate the proposed multicast approach in terms of transmission, multicast, and reception capacities as well as throughput efficiency for different numbers of nodes and multicast fanout under various traffic scenarios. Our findings show that for multicast traffic, the transmission capacity and multicast capacity of RPR are increased significantly, in particular for small to medium multicast group sizes, and a multicast throughput efficiency of 100% is achieved. Besides the performance gain, the proposed multicast approach is able to maintain RPR's simplicity.

Improve TCP performance with a novel adaptive queue management scheme in IEEE 802.17 RPR optical networks

Resilient Packet Ring (RPR), a novel IEEE 802-series MAC scheme over optical network for Metropontan Area Networks (MAN), provides flexible data efficient delivery and optical transmission reliability. However, RPR fairness scheme causes TCP performance degradation. In this paper, an analytical traffic model is developed to study the impact of congestion control of TCP under RPR AM fairness scheme. Basically, two possible ways may be able to improve this impact, to equip a buffer to accommodate the burst or to employ a robust active queue management (AQM). However, buffer requirement in RPR networks may be different for various network scenarios and AQM scheme should be better for RPR networks. Furthermore, our study shows that TCP works not well if queue management parameters are fixed at a value. Hence, a novel adaptive queue management scheme with RPR feedback information is proposed. Available bandwidth for each ingress-aggregated flow should be passed to its upstream nodes in RPR MAC scheme. Accordingly, queue management design parameters could be adaptively tuned to achieve better queueing behavior. Through detailed simulations in various scenarios, our proposed schemes are able to improve TCP performance obviously.

PROTECTORATION: a fast and efficient multiple-failure recovery technique for resilient packet ring using dark fiber

The two protection methods wrapping and steering used in IEEE 802.17 resilient packet ring (RPR) provide fast but very inefficient and limited network failure recovery. Due to the increased length of the backup path, RPR suffers from high traffic loss, a decreased throughput-delay performance, and the lack of resilience against multiple link and/or node failures. To achieve an improved resilience, interconnecting a subset of the ring nodes by means of a dark-fiber single-hop star wavelength division multiplexing (WDM) network is proposed. In doing so, the ring network is divided into separate domains, each being fully recoverable from a single link or node failure without losing full network connectivity. A novel hybrid fault recovery technique, termed protectoration, is proposed and examined by means of probabilistic analysis and simulation in terms of stability, channel utilization, and throughput-delay performance. The proposed protectoration technique 1) combines the fast recovery time of protection and the bandwidth efficiency of restoration, 2) provides full recovery from multiple link and node failures, 3) builds on both wrapping and steering protection methods of RPR and, thus, allows for an evolutionary upgrade of existing RPR networks, and 4) does not require the convergence of routing protocols in response to failures and, thus, improves the routing stability and network availability. Numerical investigations in this paper show that the location of failures has a strong impact on the network performance. For a given failure location, the protectoration technique is able to accommodate multiple ring failures without significant performance loss.

PID-RPR: A High Performance Bandwidth Allocation Approach for RPR Networks

Resilient Packet Ring (RPR) is a new technology currently being standardized in the IEEE 802.17 working group. The existed bandwidth allocation algorithms for RPR networks are not able to provide satisfactory solutions to meet the performance requirements. In this paper we propose one fair bandwidth allocation algorithm, termed PID-RPR, which satisfies the performance goals of RPR networks, such as fairness, high utilization and maximal spatial reuse. The algorithm is operated at each RPR node in a distributive way; the proportional, integral and differential (PID) controller is used to allocate bandwidth on the outgoing link of the node for the flows over the link in a weighted manner. To achieve the global coordination, one control packet containing every node's message runs around the ring in order to update the relevant message for all nodes on the ring. When the packet reaches one node, this node adjusts its own rate according to its own message in the control packet; in the meantime it updates other nodes' control message in the control packet. As the control packet propagates around the ring, each node can eventually adjust its sending rate to reach its fair share according to the fairness criterion, and the buffer occupancy at each node is kept within the target value. Our algorithm is of distributed nature in the sense that upstream ring nodes inject traffic at a rate according to congestion and fairness criteria downstream. The simulation results demonstrate that satisfactory performance of RPR networks can be achieved under the proposed bandwidth allocation scheme.

Distributed bandwidth allocation for resilient packet ring networks

The Resilient Packet Ring (RPR), defined under IEEE 802.17, has been proposed as a high-speed backbone technology for metropolitan area networks. RPR is introduced to mitigate the underutilization and unfairness problems associated with the current technologies, SONET and Ethernet, respectively. The key performance objectives of RPR are to achieve high bandwidth utilization, optimum spatial reuse on the dual rings, and fairness. The challenge is to design an algorithm that can react dynamically to the traffic flows in achieving these objectives. The RPR fairness algorithm is comparatively simple, but it poses some critical limitations that require further investigation and remedy. One of the major problems is that the amount of bandwidth allocated by the algorithm oscillates severely under unbalanced traffic scenarios. These oscillations are barrier to achieving spatial reuse and high bandwidth utilization. DVSR was another algorithm proposed to solve the fairness issue with no oscillation at the steady state, but at the expense of a high computational complexity O( Nlog N), where N is the number of nodes in the ring. In this paper, we propose the Distributed Bandwidth Allocation (DBA) algorithm to allocate bandwidth fairly to RPR nodes with a very low computational complexity O(1) that will converge to the exact max–min fairness in a few round trip times with no oscillation at the steady state.