Anycast Group Research Articles

A Cognitive Anycast Routing Method for Delay-Tolerant Networks

A cognitive networking approach to the anycast routing problem for delay-tolerant networking (DTN) is proposed. The method is suitable for the space–ground and other domains where communications are recurrently challenged by diverse link impairments, including long propagation delays, communication asymmetry, and lengthy disruptions. The proposed method delivers data bundles achieving low delays by avoiding, whenever possible, link congestion and long wait times for contacts to become active, and without the need of duplicating data bundles. Network gateways use a spiking neural network (SNN) to decide the optimal outbound link for each bundle. The SNN is regularly updated to reflect the expected cost of the routing decisions, which helps to fine-tune future decisions. The method is decentralized and selects both the anycast group member to be used as the sink and the path to reach that node. A series of experiments were carried out on a network testbed to evaluate the method. The results demonstrate its performance advantage over unicast routing, as anycast routing is not yet supported by the current DTN standard (Contact Graph Routing). The proposed approach yields improved performance for space applications that require as-fast-as-possible data returns.

Anycast-Based Content-Centric MANET

In this paper, we propose an ancyast-based content-centric MANET (ACCM) to reduce the content acquisition cost and to improve the content acquisition success rate. In ACCM, providers form an anycast group and a consumer can acquire the desired contents from the nearest anycast member in the unicast way. ACCM depends on addresses to return the requested contents to a consumer, so the content acquisition failure caused by reverse-path disruptions is avoided. Finally, ACCM is analyzed and evaluated, and the data show that it reduces the content acquisition cost and improves the success rate.

Modeling and Analyzing Anycast and Geocast Routing in Wireless Mesh Networks

Wireless technology has become an essential part of this era’s human life and has the capability of connecting virtually to any place within the universe. A mesh network is a self healing wireless network, built through a number of distributed and redundant nodes to support variety of applications and provide reliability. Similarly, anycasting is an important service that might be used for a variety of applications. In this paper we have studied anycast routing in the wireless mesh networks and the anycast traffic from the gateway to the mesh network having multiple anycast groups. We have also studied the geocast traffic in which the packets reach to the group head via unicast traffic and then are broadcasted inside the group. Moreover, we have studied the intergroup communication between different anycast groups. The review of the related literature shows that no one has considered anycasting and geocasting from gateway to the mesh network while considering the multiple anycast groups and intergroup communication. The network is modeled, simulated and analyzed for its various parameters using OMNET++ simulator.

Design and Implementation of AIRF: A Anycast-Based Integrated Routing Framework for WSNs

In wireless sensor networks (WSNs), asynchronous sleep wake scheduling protocols can significantly reduce energy consumption without incurring the communication overhead. However, the savings could come at a significant cost in delay performance. In this paper, we consider anycast-based integrated routing framework (AIRF) to reduce the cost in delay performance of communications in multihop WSNs. Without tight time synchronization or known geographic information, AIRF provides low-delay cost route. We implement a low-overhead AIRF module in TinyOS kernel by modifying BLIP protocol stack, i.e., the Berkeley Low-power IP stack; as demonstrated, this implementation can be incorporated into existing routing protocols with the least effort. We describe in detail the format of AIRF message, the dynamic updating process of mapping record information, and anycast data flow under TinyOS. And then, we present the anycast group management system. Finally, we analyze the application performance of AIRF in balancing network load, network lifetime, and delay performance.

A novel gateway load-balance algorithm for wireless mesh network

Wireless mesh network (WMN) is mainly used to obtain Internet access, so most of the traffic converges to the gateways. Due to the nature characteristic of WMN traffic model, the gateways unavoidably become the bottleneck of the whole network. An anycast-based gateway load balance method is proposed in this paper. All the gateway nodes are abstracted as an anycast group and the clients can adaptively select the best gateway node for Internet access through effective anycast mechanism. Simulation results show that the algorithm can effectively achieve the goal of load balance among gateways.

A Reliable Transmission Protocol for ZigBee-Based Wireless Patient Monitoring

Patient monitoring systems are gaining their importance as the fast-growing global elderly population increases demands for caretaking. These systems use wireless technologies to transmit vital signs for medical evaluation. In a multihop ZigBee network, the existing systems usually use broadcast or multicast schemes to increase the reliability of signals transmission; however, both the schemes lead to significantly higher network traffic and end-to-end transmission delay. In this paper, we present a reliable transmission protocol based on anycast routing for wireless patient monitoring. Our scheme automatically selects the closest data receiver in an anycast group as a destination to reduce the transmission latency as well as the control overhead. The new protocol also shortens the latency of path recovery by initiating route recovery from the intermediate routers of the original path. On the basis of a reliable transmission scheme, we implement a ZigBee device for fall monitoring, which integrates fall detection, indoor positioning, and ECG monitoring. When the triaxial accelerometer of the device detects a fall, the current position of the patient is transmitted to an emergency center through a ZigBee network. In order to clarify the situation of the fallen patient, 4-s ECG signals are also transmitted. Our transmission scheme ensures the successful transmission of these critical messages. The experimental results show that our scheme is fast and reliable. We also demonstrate that our devices can seamlessly integrate with the next generation technology of wireless wide area network, worldwide interoperability for microwave access, to achieve real-time patient monitoring.

Design and Implementation of an Anycast Services Discovery in Mobile Ad Hoc Networks

Anycasting is a network service that selects the best one of service providers in an anycast group as a destination. While anycasting offers better service flexibility in mobile ad hoc networks (MANETs), it also incurs new problems. In MANETs, every node can move arbitrarily, and the routes from mobile nodes to their service providers would vary. Therefore, anycast service discovery in MANETs usually relies on network-layer message broadcasting, which leads to large traffic overhead for the scarce bandwidth of MANETs. In this work, we present a traffic-control scheme for anycast service discovery in MANETs. Our scheme can reduce the volume of query messages and the reply messages. In addition to basic anycasting, our scheme also supports k-anycast service that requests for k anycast service providers in each service instance. With k-anycast service, the fault tolerance and service flexibility of our scheme can be improved. Experimental results demonstrate that our scheme is efficient and feasible for MANETs.

Analysis of an anycast based overlay system for scalable service discovery and execution

Support for anycast in the IP network layer allows one source node to contact a single member out of a group of destination nodes configured with the same IP address. Due to the stateless nature of the IP protocol, subsequent packets from the same source node targeted at the same anycast group may arrive at different group members. Consequently, native IP anycast cannot be applied directly to support distributed session-based services. For this reason, an anycast overlay architecture combining the transparency offered by native anycast with support for stateful communications has been proposed. In this paper, we investigate the operational impact of deploying this overlay architecture. Performance evaluation of a data plane prototype implementation for an anycast overlay node shows that high throughput and small latency can be achieved. Additionally, we show how threshold-based update triggering, in combination with an appropriate inter-proxy update strategy, delivers control plane accuracy with minimal network overhead.

AAPP: An Anycast Based AODV Routing Protocol for Peer to Peer Services in MANET

The study of Peer-to-Peer (P2P) network and Mobile Ad hoc Network (MANET) are currently two hotspots in distributed domain. We propose a novel anycast based AODV routing protocol which is a simple and efficient routing protocol designed especially for MANET for P2P applications called AAPP (an Anycast based AODV routing protocol for Peer to Peer services in MANET). AAPP integrate DHT protocol operating in a logical namespace and MANET routing protocol operating in a physical namespace. The key idea of the integration is to bring the Chord protocol to the network layer of MANETs via a one-to-one mapping between the service keys of the mobile nodes providing services and their anycast groupIDs in the namespace. The object of our design is to construct a new type of anycast based AODV model for P2P services, especially for discovery service, information administration service, file sharing service, and communication security. It is assumed that the number of anycast groups is steady in a MANET, so we consider the instance that a node joins or leaves an anycast group. When a mobile node attains a service, such as a file and a particular data, it can share its resource to other nodes and becomes a mobile peer. Whenever a mobile node joins or leaves an anycast group, it originates a request packet and sends it to the network layer. The anycast groupID is updated correspondingly, and broadcasts the information about updating information. In this paper, we have designed an anycast based protocol for P2P application in mobile wireless ad hoc networks based on on-demand routing protocols AODV. We have tested the packets' delivery fraction, average end-to end delay of data packets, and normalized the routing protocol performance of anycast protocols by simulation with OPNET on different traffic models, node mobility models, and connection models. With our novel anycast protocol AAPP, the traffic load can be balanced thus, reducing the transmission delay and increase the route utilization which is better for P2P application. That all the members in one anycast group share one anycast address enables them to take the same priority in the routing searching process. Therefore, this approach can provide the transmission path with the shortest length. With scattering of the anycast server in the geographical area, the traffic load is obviously distributed in the network. All these properties can help to improve the performance of the network.

Density-Based Anycast: A Robust Routing Strategy for Wireless Ad Hoc Networks

Existing anycast routing protocols solely route packets to the closest group member. In this paper, we introduce density-based anycast routing, a new anycast routing paradigm particularly suitable for wireless ad hoc networks. Instead of routing packets merely on proximity information to the closest member, density-based anycast routing considers the number of available anycast group members for its routing decision. We present a unified model based on potential fields that allows for instantiation of pure proximity-based, pure density-based, as well as hybrid routing strategies. We implement anycast using this model and simulate the performance of the different approaches for mobile as well as static ad hoc networks with frequent link failures. Our results show that the best performance lies in a tradeoff between proximity and density. In this combined routing strategy, the packet delivery ratio is considerably higher and the path length remains almost as low than with traditional shortest-path anycast routing.

Design and implementation of Anycast communication model in IPv6

AbstractThe existing designs for providing Anycast services are either to confine each Anycast group to a preconfigured topological region or to distribute members of Anycast groups over global regions. The former brings an Anycast scalability problem and the latter causes the routing tables to grow proportionally to the number of all global Anycast groups in the entire Internet. Therefore, both of the above designs restrict and hinder the application and development of Anycast services. A new kind of Anycast communication model is proposed in this paper which solves some existing problems, such as scalability and communication errors between clients and servers. In this paper, the Anycast communication model is analyzed in depth and discussed, and the experimental data of this Anycast communication model demonstrate its feasibility and validity.

A scheme for solving Anycast scalability in IPv6

AbstractThe existing designs for providing Anycast services are either to confine Anycast groups to a preconfigured topological region or to distribute Anycast groups globally across the whole Internet. The latter causes routing tables to grow proportionally to the number of global Anycast groups in the entire Internet and both of the above designs restrict and hinder the application and development of Anycast services. A new kind of Anycast communication scheme is proposed in this paper. This scheme adopts a novel Anycast address structure which can achieve a dynamic Anycast group while allowing Anycast members to freely leave and join the Anycast group without geographical restriction and it effectively solves the expanding explosion of the Anycast routing table. In addition, this scheme can evenly disperse Anycast request messages from clients across the Anycast servers of one Anycast group, thus achieving load balance. This paper analyzes the communication scheme in depth and discusses its feasibility and validity. The experimental data in IPv6 simulation demonstrate that the TRT (Total Response Time) of one Anycast service (e.g., file downloading) acquired through this communication scheme is shorter by 15% than that through the existing Anycast communication scheme. Copyright © 2007 John Wiley & Sons, Ltd.

Enabling service adaptability with versatile anycast

AbstractWe present versatile anycast, which allows a service running on a varying collection of nodes scattered over a wide‐area network to present itself to the clients as one running on a single node. Providing a single logical address enables the client‐side software to preserve the traditional service access model based on single access points. At the same time, the dynamic composition of anycast groups implemented by versatile anycast enables the server‐side service infrastructure to evolve and adapt to changing network conditions. We implement versatile anycast using Mobile IPv6, which decouples the logical addresses of mobile nodes from their physical location. We exploit that decoupling to implement logical service addresses that are not bound to any physical nodes, and employ standard MIPv6 mechanisms to dynamically map each such address onto individual service nodes. Our solution enables a service to transparently hand off clients among the service nodes at the network level while preserving optimal routing between the clients and the service nodes. We demonstrate that the overhead of versatile anycasting is very low. In particular, the client‐perceived handoff time is shown to be a linear function of the latencies among the client and the service nodes participating in the handoff. Copyright © 2007 John Wiley & Sons, Ltd.

Analysis and discussion of Anycast scalability in IPv6

AbstractThe existing designs for providing Anycast services are either to confine Anycast groups to a preconfigured topological region or to globally distribute Anycast groups across the whole Internet. The latter causes the routing tables to grow proportionally to the number of global Anycast groups in the entire Internet and both of the above designs restrict and hinder the application and development of Anycast services. In this paper a new kind of Anycast communication model is proposed on the basis of Anycast tree technology. Since this model adopts a dynamic Anycast group, allowing Anycast members to freely leave and join the Anycast group, it radically solves the existing scalability problem. In addition, this model accomplishes the distributed maintenance and transaction of Anycast service requests and information on the Anycast tree; thus it performs load balance. This paper analyzes and discusses the feasibility and validity of the communication model; the experimental data in IPv6 simulation demonstrate that the total response time of one Anycast service (e.g., file downloading) acquired through this communication model is shorter by 15% than that through the current communication model. Copyright © 2007 John Wiley & Sons, Ltd.

Towards a global IP anycast service

IP anycast, with its innate ability to find nearby resources in a robust and efficient fashion, has long been considered an important means of service discovery. The growth of P2P applications presents appealing new uses for IP anycast. Unfortunately, IP anycast suffers from serious problems: it is very hard to deploy globally, it scales poorly by the number of anycast groups, and it lacks important features like load-balancing. As a result, its use is limited to a few critical infrastructure services such as DNS root servers. The primary contribution of this paper is a new IP anycast architecture, PIAS, that overcomes these problems while largely maintaining the strengths of IP anycast. PIAS makes use of a proxy overlay that advertises IP anycast addresses on behalf of group members and tunnels anycast packets to those members. The paper presents a detailed design of PIAS and evaluates its scalability and efficiency through simulation. We also present preliminary measurement results on anycasted DNS root servers that suggest that IP anycast provides good affinity. Finally, we describe how PIAS supports two important P2P and overlay applications.

On the use of anycast in DNS

We present the initial results from our evaluation study on the performance implications of anycast in DNS, using four anycast servers deployed at top-level DNS zones. Our results show that 15% to 55% of the queries sent to an anycast group, are answered by the topologically closest server and at least 10% of the queries experience an additional delay in the order of 100ms. While increased availability is one of the supposed advantages of anycast, we found that outages can last up to multiple minutes, mainly due to slow BGP convergence. On the other hand, the number of outages observed was fairly small, suggesting that anycast provides a generally stable service.

Multi-shared-trees based multicast routing control protocol using anycast selection

A novel internet multicast routing protocol is presented to possess efficiency and effectiveness for multicast packet routing with short delay, high throughput, resource utilization and scalability for a single multicast group g. The protocol has two features: (1) Multiple Shared-Trees (MST) are configured to provide efficient, dynamic and quality multicast routing; (2) Anycasting approach is applied by forming the tree roots into an anycast group so that the multicast packets can be anycast to the nearest node at one of the shared trees to achieve the best routing service for the packets. The performance of the MST protocol is analyzed through extensive simulations and compared with well-known source tree and shared-tree routing.

Delay Control and Parallel Admission Algorithms for Real-Time Anycast Flow

An anycast flow is a flow that can be connected to any one of the members in a group of designated (replicated) servers (called anycast group). In this paper, we derive a set of formulas for calculating the end-to-end delay bound for the anycast flows and present novel admission control algorithms for anycast flows with real-time constraints. Given such an anycast group, our algorithms can effectively select the paths for anycast flows' admission and connection based on the least end-to-end delay bounds evaluated. We also present a parallel admission control algorithm that can effectively calculate the available paths with a short delay bound for different destinations in the anycast group so that a best path with the shortest delay bound can be chosen.

The hopcount to an anycast group

AbstractThe probability density function of the number of hops to the most nearby member of the anycast group consisting of m members (e.g. servers) is analysed. The results are applied to compute a performance measure η of the efficiency of anycast over unicast and to the server placement problem. The server placement problem asks for the number of (replicated) servers m needed such that any user in the network is not more than j hops away from a server of the anycast group with a certain prescribed probability. Two types of shortest path trees are investigated: the regular k‐ary tree and the irregular uniform recursive tree. Since these two types of trees indicate that the performance measure η ≈ 1 − a log m where the real number a depends on the details of the tree, it suggests that for trees in real networks (as the Internet) a same logarithmic law applies. An order calculus on exponentially growing tree further supplies evidence for the conjecture that η ≈ 1 − a log m for small m. Copyright © 2004 John Wiley & Sons, Ltd.

IP anycast point-to-(any) point communication

The Internet supports three communication paradigms. The first, unicast, is the point-to-point flow of packets between a single source (client) and destination (server) host. Web browsing and file Me transfer are unicast applications. The next, multicast, is the point-to-multipoint flow of packets between a single source host and one or more destination hosts. Broadcast-style videoconferencing, for example, employs IP multicast. Anycast is the point-to-point flow of packets between a single client and the nearest destination server identified by an anycast address. The idea behind anycast is that a client wants to send packets to any one of several possible servers offering a particular service or application but does not really care which one. Any number of servers can be assigned a single anycast address within an anycast group. A client sends packets to an anycast server by placing the anycast address in the packet header. Routers then attempt to deliver the packet to a server with the matching anycast address.