Unicast Routing Protocol Research Articles

ANSI: A swarm intelligence-based unicast routing protocol for hybrid ad hoc networks

We present a hybrid routing protocol for both pure and hybrid ad hoc networks which uses the mechanisms of swarm intelligence to select next hops. Our protocol, Ad hoc Networking with Swarm Intelligence (ANSI), is a congestion-aware routing protocol, which, owing to the self-organizing mechanisms of swarm intelligence, is able to collect more information about the local network and make more effective routing decisions than traditional MANET protocols. Once routes are found, ANSI maintains routes along a path from source to destination effectively by using swarm intelligence techniques, and is able to gauge the slow deterioration of a link and restore a path along newer links as and when necessary. ANSI is thus more responsive to topological fluctuations. ANSI is designed to work over hybrid ad hoc networks: ad hoc networks which consist of both lower-capability, mobile wireless devices and higher-capability, wireless devices which may or may not be mobile. In addition, ANSI works with multiple interfaces and with both wired and wireless interfaces.Our simulation study compared ANSI with AODV on both hybrid and pure ad hoc network scenarios using both TCP and UDP data flows. The results show that ANSI is able to achieve better results (in terms of packet delivery, number of packets sent, end-to-end delay, and jitter) as compared to AODV in most simulation scenarios. In addition, ANSI achieves this performance with fewer route errors as compared to AODV. Lastly, ANSI is able to perform more consistently, considering the lower variation (measured as the width of the confidence intervals) of the observed values in the results of the experiments. We show that ANSI's performance is aided by both its superior handling of routing information and also its congestion awareness properties, though we see that congestion awareness in ANSI comes at a price.

Mobile IPv6-based ad hoc networks: its development and application

The Internet protocol version 6 (IPv6)-enabled network architecture has recently attracted much attention. In this paper, we address the issue of connecting mobile ad hoc networks (MANETs) to global IPv6 networks, while supporting IPv6 mobility. Specifically, we propose a self-organizing, self-addressing, self-routing IPv6-enabled MANET infrastructure, referred to as IPv6-based MANET. The proposed self-organization addressing protocol automatically organizes nodes into tree architecture and configures their global IPv6 addresses. Novel unicast and multicast routing protocols, based on longest prefix matching and soft state routing cache, are specially designed for the IPv6-based MANET. Mobile IPv6 is also supported such that a mobile node can move from one MANET to another. Moreover, a peer-to-peer (P2P) information sharing system is also designed over the proposed IPv6-based MANET. We have implemented a prototyping system to demonstrate the feasibility and efficiency of the IPv6-based MANET and the P2P information sharing system. Simulations are also conducted to show the efficiency of the proposed routing protocols.

QoS routing for wireless ad hoc networks: problems, algorithms, and protocols

QoS routing plays an important role for providing QoS in wireless ad hoc networks. The goals of QoS routing are in general twofold: selecting routes with satisfied QoS requirement(s), and achieving global efficiency in resource utilization. In this article we first discuss some key design considerations in providing QoS routing support, and present a review of previous work addressing the issue of route selection subject to QoS constraint(s). We then devise an on-demand delay-constrained unicast routing protocol. Various strategies are employed in the protocol to reduce the communication overhead in acquiring cost-effective delay-constrained routes. Simulation results are used to verify our expectation of the high performance of the devised protocol. Finally, we discuss some possible future directions for providing efficient QoS routing support in wireless ad hoc networks.

MULTICAST STATE DISTRIBUTION BY JOINS USING MULTIPLE SHORTEST PATHS

The lack of resources in routers will become a crucial issue with the deployment of state storing protocols. In particular, single or any source multicast protocols will most probably take over large amounts of resources for maintaining multicast tree information. The aim of this paper is to study the possibility and benefit of using multiple shortest paths in order for a new member to reach a multicast tree. Such a mechanism would not reduce the overall amount of state information in the network but it would distribute this amount more evenly among all routers. The idea is to use alternate shortest paths provided by the underlying unicast routing protocol to avoid saturated routers, that is, routers that can not or do not want to store any more multicast state information. As the simulation results are very sensitive to the topology, we have used subgraphs of an Internet map. We have then simulated our multipath join mechanism and have found that depending on the tree size, the use of our mechanism can increase successful join attempts by up to 55% when the network is half saturated.

Domain Constrained Multicast: A New Approach for IP Multicast Routing

One of major reasons why IP multicast has not been well deployed is the complexity of IP multicast routing. Since existing IP multicast routing protocols have been designed independently of IP unicast routing protocols, a router must maintain routing tables for both IP mutlicast and unicast routing. This is, in particular, a big burden for an inter-domain router. In addition, by using existing IP multicast routing protocols, we cannot realize an application that a sending host outside the designated domain sends IP multicast packets only towards the designated domain. To resolve above issues, we propose a new architecture for IP multicast, which is called Domain Constrained Multicast (DCM). In this architecture, IP multicast packets are forwarded to a border router of the designated domain using IP unicast routing. And then, IP multicast packets are delivered inside the designated domain using IP multicast. We propose an address format when realizing the DCM architecture using IPv6. We describe the extension of the DCM architecture for applying it to inter-domain IP multicast routing. Finally, we have compared the DCM architecture for inter-domain routing, with existing inter-domain IP multicast routing protocols such as MSDP and BGMP.

Time-stable geocast for ad hoc networks and its application with virtual warning signs

Virtual warning signs allow to increase road safety. Like real traffic or warning signs, they are attached to a certain geographical position or area. When a vehicle enters this area, the virtual warning sign is displayed for the driver. In contrast to real traffic signs they allow faster adaptation to the current road and traffic situation like icy roads or accident warnings. For the realization of virtual warning signs, geocasting is a promising approach. Existing geocast solutions lack the time-stability required for realizing virtual warning signs, which we call abiding geocast. An abiding geocast solution delivers a message either periodically or on demand, everytime a new vehicle enters the warning sign area. This article introduces the virtual warning sign idea and discusses the design space, three reasonable solutions and simulation results for abiding geocast in an ad hoc network. The first approach is an infrastructure-based server solution to store the messages. The second is an infrastructure-less approach that maybe more suitable for an ad hoc network. A node inside the geocast destination region is elected to act temporarily as a server for geocast messages. The last approach works infrastructure-less, too, by complementing the exchange of neighbor information necessary for many geographic unicast routing protocols with geocast information. In simulations we compare the delivery ratio and the resulting network load of the three approaches.

A distributed QoS-Aware multicast routing protocol

This paper discusses the multicast routing problem with QoS constraints, and describes a network model that is suitable to research such routing problem. The paper mainly presents a distributed QoS-aware multicast routing protocol (QMRP). The QMRP can operate on top of the unicast routing protocol. It only requires the local state information of the link (or the node), but does not require any global network state to be maintained. The QMRP can significantly reduce the overhead for constructing a multicast tree with QoS constraints. In QMRP, a multicast group member can join or leave the multicast session dynamically, which can support dynamic membership. The protocol can search multiple feasible tree branches, and select the optimal or near-optimal branch for connecting the new receiver to the multicast tree if it exists. In this paper, the proof of correctness and complexity analysis of the QMRP are given, and the performance measures of the protocol are evaluated using simulation. The study shows that QMRP provides an available approach to multicast routing with QoS constraints and dynamic membership support.

Position-based multicast routing for mobile Ad-hoc networks

In this paper we present Position-Based Multicast (PBM), a multicast routing algorithm for mobile ad-hoc networks which does neither require the maintenance of a distribution structure (e.g., a tree or a mesh) nor resorts to flooding of data packets. Instead a forwarding node uses information about the positions of the destinations and its own neighbors to determine the next hops that the packet should be forwarded to and is thus very well suited for highly dynamic networks. PBM is a generalization of existing position-based unicast routing protocols such as face-2 or GPSR. The key contributions of PBM are rules for the splitting of multicast packets and a repair strategy for situations where there exists no direct neighbor that makes progress toward one or more destinations. The characteristics of PBM are evaluated in detail by means of simulation.

A QoS-guaranteed multicast routing protocol

With the rapid development of high-performance networking technology, multicast routing with quality of service (QoS) constraints has continued to be a very important research issue in the fields of the networks and distributed systems. This paper discusses the multicast routing problem with QoS constraints such as delay, delay jitter, bandwidth and packet loss metrics, and describes a network model that is suitable to search such routing problem. The paper mainly presents a QoS-guaranteed multicast routing protocol (QGMRP). The QGMRP can operate on top of the unicast routing protocol. The QGMRP can significantly reduce the overhead for constructing a multicast tree with QoS constraints. In QGMRP, a multicast group member can join or leave the multicast session dynamically. The protocol can search multiple feasible tree branches, and select the optimal or near-optimal branch for connecting the new receiver to the multicast tree if it exists. In this paper, the proof of correctness and complexity analysis of the QGMRP are given, and the performance measures of the protocol are evaluated using simulation. The study shows that QGMRP provides an available approach to multicast routing with QoS constraints.

Anycasting-based protocol for geocast service in mobile ad hoc networks

Geocasting is a variation on the notion of multicasting. Geocasting is useful for sending messages to nodes in a specified geographical region. This region is called the geocast region. This paper presents a protocol, named GeoTORA, for geocasting in mobile ad hoc networks. The proposed GeoTORA protocol combines anycasting with local flooding to implement geocasting. Thus, GeoTORA requires two phases for geocasting. First, it performs anycasting from a source to any node in the geocast region, by modifying the Temporally-Ordered Routing Algorithm (TORA) (unicast) routing protocol. Subsequently, localized flooding within the geocast region is performed to deliver the messages to nodes within the geocast region. This integration of TORA and local flooding can significantly reduce the overhead of geocast delivery, while maintaining reasonably high accuracy.

QMBF: a QoS-aware multicast routing protocol

Many multicast applications, such as video-on-demand and tele-education, desire quality of service (QoS) support from the underlying network. Recently, many QoS-based multicast protocols have been proposed to meet this requirement. However, few of them can achieve high success ratios while maintaining good scalability. In this paper, we propose a new QoS-aware multicast protocol based on a bounded flooding technique (QMBF). In this protocol, every network node maintains the knowledge of a local network cell (LNC) topology as well as QoS state information (collected from the bounded flooding messages). QMBF utilizes this knowledge to increase the probability and accuracy of finding a feasible branch which connects a new member to an existing multicast tree. The protocol exploits two approaches to find feasible branches: repeatedly computing partial feasible branches using the LNC information and searching multiple paths. The design of QMBF allows it to operate on top of any unicast routing protocol or cooperate with a QoS-based unicast routing protocol. Results obtained using NS-2 simulator demonstrate high success ratio for locating feasible branches for multicast paths.

AMRoute: ad hoc multicast routing protocol

The Ad hoc Multicast Routing protocol (AMRoute) presents a novel approach for robust IP Multicast in mobile ad hoc networks by exploiting user-multicast trees and dynamic logical cores. It creates a bidirectional, shared tree for data distribution using only group senders and receivers as tree nodes. Unicast tunnels are used as tree links to connect neighbors on the user-multicast tree. Thus, AMRoute does not need to be supported by network nodes that are not interested/capable of multicast, and group state cost is incurred only by group senders and receivers. Also, the use of tunnels as tree links implies that tree structure does not need to change even in case of a dynamic network topology, which reduces the signaling traffic and packet loss. Thus AMRoute does not need to track network dynamics; the underlying unicast protocol is solely responsible for this function. AMRoute does not require a specific unicast routing protocol; therefore, it can operate seamlessly over separate domains with different unicast protocols. Certain tree nodes are designated by AMRoute as logical cores, and are responsible for initiating and managing the signaling component of AMRoute, such as detection of group members and tree setup. Logical cores differ significantly from those in CBT and PIM-SM, since they are not a central point for data distribution and can migrate dynamically among member nodes. Simulation results (using ns-2) demonstrate that AMRoute signaling traffic remains at relatively low level for typical group sizes. The results also indicate that group members receive a high proportion of data multicast by senders, even in the case of a highly dynamic network.

A flexible multicast routing protocol for group communication

Multicast routing, once dominated by a single routing protocol, is becoming increasingly diverse. It is generally agreed that at least three routing protocols, PIM, DVMRP, and CBT will be widely deployed and must interoperate. This signals a shift from the Mbone as one large domain to a collection of administrative domains where each domain selects its own multicast routing protocol. This paper proposes another multicast routing protocol, Conference Steiner Multicast (CSM), that is suited for domains that implement OSPF as the unicast routing protocol. CSM is targeted towards (sparse) multicast conferencing and online discussion groups. Characteristics of such discussion groups include any member being a speaker or listener and dynamic changes in the group membership. CSM is futhermore well suited for domains with mobile hosts because its basic architecture can support a mobile environment. CSM is based on the use of a shared, heuristic Steiner minimal tree for interconnecting group members. A key component of the design is that it dynamically and reliably shifts to a different tree as changes warrant. CSM supports rudimentary entry control for security and permits application assistance over routing decisions (termed Application Assisted Routing). This paper describes the architecture of CSM as well as a prototype implementation. Several CSM routers have been interconnected to form a Multicast Steiner Backbone (Msbone). Standard applications such as vat, vic, and wb [V. Jacobson, Multimedia Conferencing on the Internet, Tutorial 4, ACM SIG-COMM 94, August 1994] have been modified to run on Msbone. CSM is designed to connect to the Mbone via interoperation with DVMRP, and as interoperation standards develop it should be capable of implementing these standards.

The request reply family of group routing protocols

We present a family of group routing protocols for a network of processes. The task of these protocols is to route data messages to each member of a process group. To this end, a tree of processes is constructed in the network, ensuring that each group member is included in the tree. No processing or storage overhead is required for processes not included in the tree. The overhead of processes in the tree consists solely of the periodic exchange of request/reply messages with their parent. To choose the processes that constitute the tree, we take advantage of the existing unicast routing protocol in the network. In addition, our family of group routing protocols distinguishes itself from other group routing protocols in three ways. First, the protocols are proven correct. Second, the protocols preserve the integrity of the group tree as it adapts to changes in the unicast routing tables, even in the presence of temporary unicast routing loops. Third, data messages are propagated along the entire group tree, even while the tree adapts to changes in the unicast routing tables.

Building shared trees using a one-to-many joining mechanism

This paper presents a new approach for building shared trees which have the capability of providing multiple routes from the joining node onto an existing tree. The approach follows a design parameter of CBT and PIM in that it operates independently of any unicast routing protocol. However, a paradigm shift is introduced such that trees are built in an on-demand basis through the use of a one-to-many joining mechanism. In addition, the paper presents optimisations of the new mechanism to help constrain its impact in the case where many receivers exist for a given multicast group.

Group routing without group routing tables: an exercise in protocol design

We present a group routing protocol for a network of processes. The task of the protocol is to route data messages to each member of a process group. To this end, a tree of processes is constructed in the network, ensuring that each group member is included in the tree. To build this tree, the group routing protocol relies upon the local unicast routing tables of each process. Thus, group routing is accomplished by composing two protocols: an underlying unicast routing protocol, whose detailed behavior is unknown but its basic properties are given, and a protocol that builds a group tree based upon the unicast routing tables. The group routing protocol is developed in three steps. First, a simple protocol is obtained, and is proven correct. Then, the protocol is refined twice. Each refined protocol improves upon its predecessor by satisfying all of the predecessor's properties plus some additional stronger properties. The final protocol has the property of adapting the group tree to changes in the unicast routing tables without compromising the integrity of the group tree, even in the presence of unicast routing loops.

The PIM architecture for wide-area multicast routing

The purpose of multicast routing is to reduce the communication costs for applications that send the same data to multiple recipients. Existing multicast routing mechanisms were intended for use within regions where a group is widely represented or bandwidth is universally plentiful. When group members, and senders to those group members, are distributed sparsely across a wide area, these schemes are not efficient; data packets or membership report information are occasionally sent over many links that do not lead to receivers or senders, respectively. We have developed a multicast routing architecture that efficiently establishes distribution trees across wide area internets, where many groups will be sparsely represented. Efficiency is measured in terms of the router state, control message processing, and data packet processing, required across the entire network in order to deliver data packets to the members of the group. Our protocol independent multicast (PIM) architecture: (a) maintains the traditional IP multicast service model of receiver-initiated membership, (b) supports both shared and source-specific (shortest-path) distribution trees, (c) is not dependent on a specific unicast routing protocol, and (d) uses soft-state mechanisms to adapt to underlying network conditions and group dynamics. The robustness, flexibility, and scaling properties of this architecture make it well-suited to large heterogeneous internetworks.

A reservation-based multicast (RBM) routing protocol for mobile networks: initial route construction phase

We propose a combined multicast routing, resource reservation and admission control protocol, termed Reservation-Based Multicast (RBM), that borrows the “Rendez-vous Point” or “Core” concept from multicast routing algorithms proposed for the Internet, but which is intended for operation in mobile networks and routes hierarchically-encoded data streams based on user-specified fidelity requirements, real-time delivery thresholds and prevailing network bandwidth constraints. The protocol exhibits the fully distributed operation and receiver-initiated orientation of these proposed algorithms; but, unlike them, the protocol is tightly coupled to a class of underlying, distributed, unicast routing protocols thereby facilitating operation in a dynamic topology. This paper focuses on the initial route construction phase, assumed to occur during a static “snapshot” of the dynamic topology, and is therefore applicable to fixed networks as well, e.g. the Internet.

An architecture for wide-area multicast routing

Existing multicast routing mechanisms were intended for use within regions where a group is widely represented or bandwidth is universally plentiful. When group members, and senders to those group members, are distributed sparsely across a wide area, these schemes are not efficient; data packets or membership report information are occasionally sent over many links that do not lead to receivers or senders, respectively. We have developed a multicast routing architecture that efficiently establishes distribution trees across wide area internets, where many groups will be sparsely represented. Efficiency is measured in terms of the state, control message processing, and data packet processing, required across the entire network in order to deliver data packets to the members of the group. Our Protocol Independent Multicast (PIM) architecture: (a) maintains the traditional IP multicast service model of receiver-initiated membership; (b) can be configured to adapt to different multicast group and network characteristics; (c) is not dependent on a specific unicast routing protocol; and (d) uses soft-state mechanisms to adapt to underlying network conditions and group dynamics. The robustness, flexibility, and scaling properties of this architecture make it well suited to large heterogeneous inter-networks.