An Efficient Multicast Routing Protocol in Wireless Mobile Networks

Providing multicast service to mobile hosts in wireless mobile networking environments is difficult due to frequent changes of mobile host location and group membership. If a conventional multicast routing protocol is used in wireless mobile networks, several problems may be experienced since existing multicast routing protocols assume static hosts when they construct the multicast delivery tree. To overcome the problems, several multicast routing protocols for mobile hosts have been proposed. Although the protocols solve several problems inherent in multicast routing proposals for static hosts, they still have problems such as non-optimal delivery path, datagram duplication, overheads resulting from frequent reconstruction of a multicast tree, etc. In this paper, we summarize these problems of multicast routing protocols and propose an efficient multicast routing protocol based on IEFT mobile IP in wireless mobile networks. The proposed protocol introduces a multicast agent, where a mobile host receives a tunneled multicast datagram from a multicast agent located in a network close to it or directly from the multicast router in the current network. While receiving a tunneled multicast datagram from a remote multicast agent, the local multicast agent may start multicast join process, which makes the multicast delivery route optimal. The proposed protocol reduces data delivery path length and decreases the amount of duplicate copies of multicast datagrams. We examined and compared the performance of the proposed protocol and existing protocols by simulation under various environments and we got an improved performance over the existing proposals.     

A Domain-Based Routing Protocol for SSM Source Mobility in Mobile IPv6 Networks

In Mobile IP, the signaling traffic overhead will be too high since the new Care-of-Address (CoA) of the mobile node (MN) is registered all the way with the home agent (HA) whenever the MN has moved into a new foreign network. To complement Mobile IP in better handling local movement, several IP micro protocols have been proposed. These protocols introduce a hierarchical mobility management scheme, which divides the mobility into micro mobility and macro mobility according to whether the host's movement is intra-domain or inter-domain. Thus, the requirements on performance and flexibility are achieved, especially for frequently moving hosts. This paper introduces a routing protocol for multicast source mobility on the basis of the hierarchical mobile management scheme, which provides a unified global architecture for both uni- and multicast routing in mobile networks. The implementation of multicast services adopts an improved SSM (Source Specific Multicast) model, which combines the advantages of the existing protocols in scalability and mobility transparency. Simulation results show that the proposed protocol has better performance than the existing routing protocols for SSM source mobility.     

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.     

On-Demand Multicast Routing Protocol in Multihop Wireless Mobile Networks

An ad hoc network is a dynamically reconfigurable wireless network with no fixed infrastructure or central administration. Each host is mobile and must act as a router. Routing and multicasting protocols in ad hoc networks are faced with the challenge of delivering data to destinations through multihop routes in the presence of node movements and topology changes. This paper presents the On-Demand Multicast Routing Protocol (ODMRP) for wireless mobile ad hoc networks. ODMRP is a mesh-based, rather than a conventional tree-based, multicast scheme and uses a forwarding group concept; only a subset of nodes forwards the multicast packets via scoped flooding. It applies on-demand procedures to dynamically build routes and maintain multicast group membership. ODMRP is well suited for ad hoc wireless networks with mobile hosts where bandwidth is limited, topology changes frequently, and power is constrained. We evaluate ODMRP performance with other multicast protocols proposed for ad hoc networks via extensive and detailed simulation.     

MobiCast: A multicast scheme for wireless networks

In this paper, we propose a multicast scheme known as MobiCast that is suitable for mobile hosts in an internetwork environment with small wireless cells. Our scheme adopts a hierarchical mobility management approach to isolate the mobility of the mobile hosts from the main multicast delivery tree. Each foreign domain has a domain foreign agent. We have simulated our scheme using the Network Simulator and the measurements show that our multicast scheme is effective in minimizing disruptions to a multicast session due to the handoffs of the mobile group member, as well as reducing packet loss when a mobile host crosses cell boundaries during a multicast session.     

Reliable and efficient multicast protocol for mobile IP networks

To provide a multicasting service, several multicast protocols for mobile hosts (MHs) have been proposed. However, all of these protocols have faults, such as non‐optimal delivery routes and data loss when hosts move to another network, resulting in insecure multicast data transmissions. Thus, this paper presents a new reliable and efficient multicast routing protocol for mobile IP networks. The proposed protocol provides a reliable multicast transmission by compensating the data loss from the previous mobile agent when a MH moves to another network. In addition, an additional function allows for direct connection to the multicast tree according to the status of agents, thereby providing a more efficient and optimal multicast path. The performance of the proposed protocol is confirmed based on simulations under various conditions. Copyright © 2008 John Wiley & Sons, Ltd.     

Multicast Handoff Agent Mechanism for All-IP Mobile Network

This paper proposes a mechanism called a Multicast Handoff Agent (MHA) to reduce handoff latency for IP multicast. The MHA acts as a proxy for the Internet Group Management Protocol (IGMP) of mobile nodes and keeps information for members of multicast groups in a cell. When a mobile node moves to other cell, the MHA immediately sends unsolicited reports without waiting for the IGMP query. In addition, our mechanism may conserve battery power since it does not need to reply to a query.The mechanism is evaluated through simulation and analysis and compared with the IGMPv2 for mobility and IGMP traffic. Simulation results show that handoff latency can be largely reduced and the IGMP control traffic can be eliminated on the wireless links during the duration of membership.     

依赖源汇聚点的组播协议

域间组播一直是大范围内部署组播时需要考虑的主要因素。依赖源汇聚点组播是一种基于Chord查找协议的简单有效的域间组播方案，方案中接收者的指定路由器（DR）使用Chord协议获得源RP地址，并加入源RP树。依赖源汇聚点的组播方案是一种域同ASM解决方案；能提供很好的容错性和可扩展性；支持主机移动组播，但不会造成三角路由问题。     

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.     

Wireless Ad Hoc Multicast Routing with Mobility Prediction

An ad hoc wireless network is an infrastructureless network composed of mobile hosts. The primary concerns in ad hoc networks are bandwidth limitations and unpredictable topology changes. Thus, efficient utilization of routing packets and immediate recovery of route breaks are critical in routing and multicasting protocols. A multicast scheme, On-Demand Multicast Routing Protocol (ODMRP), has been recently proposed for mobile ad hoc networks. ODMRP is a reactive (on-demand) protocol that delivers packets to destination(s) on a mesh topology using scoped flooding of data. We can apply a number of enhancements to improve the performance of ODMRP. In this paper, we propose a mobility prediction scheme to help select stable routes and to perform rerouting in anticipation of topology changes. We also introduce techniques to improve transmission reliability and eliminate route acquisition latency. The impact of our improvements is evaluated via simulation.     

GMZRP: Geography-aided Multicast Zone Routing Protocol in Mobile Ad Hoc Networks

This paper presents the design and evaluation of a highly efficient on-demand multicast routing protocol for mobile ad hoc networks (MANETs). The protocol, called Geography-aided Multicast Zone Routing Protocol (GMZRP), eliminates as much as possible duplicate route queries by using a simple yet effective strategy for propagating the multicast route request (MRREQ) packets. GMZRP is the first hybrid multicast protocol taking the advantages of both topological routing and geographical routing. It partitions the network coverage area into small zones and guarantees that each geographic zone is queried only once. GMZRP maintains a multicast forwarding tree at two levels of granularities, i.e., the zone granularity and the node granularity. By doing this, it can easily handle route breakage since the zone level information can help recover the link failure at the node level. The results of the performance evaluation of GMZRP using simulation show that, comparing with the well-known multicast protocol ODMRP (On-Demand Multicast Routing Protocol), GMZRP has much lower protocol overhead in terms of query packets and, meanwhile, achieves competing packet delivery ratio and shorter delivery latency.

Forwarding state scalability for multicast provisioning in IP networks

Forwarding state scalability is one of the critical issues that delay the multicast deployment in IP networks. With traditional multicast routing protocols, a forwarding tree is built for each multicast session, and each router is required to maintain a forwarding entry for each multicast session whose distribution tree passes through the router. This poses the multicast forwarding state scalability issue when the number of concurrent multicast sessions is very large. We first present a survey of existing work addressing this scalability issue for providing scalable IP multicast. Then we extend an existing multicast routing protocol, Multicast Extension to OSPF (MOSPF), to scale well with respect to the number of concurrent multicast sessions by introducing tunnel support. This extension aims to reduce the protocol overhead associated with MOSPF. Simulation results show that the extension can significantly reduce multicast forwarding state and computational overhead at routers without affecting the per-destination shortest path characteristic of a resulting tree or introducing extra control overhead.     

Efficient Resource Allocation for Wireless Multicast

In this paper, we propose a bandwidth-efficient multicast mechanism for heterogeneous wireless networks. We reduce the bandwidth cost of an Internet protocol (IP) multicast tree by adaptively selecting the cell and the wireless technology for each mobile host to join the multicast group. Our mechanism enables more mobile hosts to cluster together and leads to the use of fewer cells to save the scarce wireless bandwidth. Besides, the paths in the multicast tree connecting to the selected cells share more common links to save the wireline bandwidth. Our mechanism supports the dynamic group membership and offers mobility of group members. Moreover, our mechanism requires no modification to the current IP multicast routing protocols. We formulate the selection of the cell and the wireless technology for each mobile host in the heterogeneous wireless networks as an optimization problem. We use integer linear programming to model the problem and show that the problem is NP-hard. To solve the problem, we propose a distributed algorithm based on Lagrangean relaxation and a network protocol based on the algorithm. The simulation results show that our mechanism can effectively save the wireless and wireline bandwidth as compared to the traditional IP multicast.     

基于移动IP技术的移动办公系统设计与实现

为了解决移动用户随时随地远程接入和移动办公问题,解决传统TCP/IP协议不支持IP设备移动性问题,以及解决与数据通信的安全问题等,采用了使用移动终端自代理和基于兵符智能密码钥匙的安全机制技术,设计实现了基于移动IP技术的移动办公系统,系统实现了移动终端的跨不同网段漫游、远程接入、移动办公以及企业分支机构互联等多种功能。     

On a new multicasting approach in optical burst switched networks

We introduce a new multicasting approach, called tree-shared multicast (TS-MCAST), in order to alleviate overheads due to control packets and guard bands associated with data bursts when transporting multicast IP traffic in optical burst-switched WDM networks. We describe three tree sharing strategies and discuss implementation issues in constructing shared multicast trees for supporting TS-MCAST. Finally, we show the efficiency of TS-MCAST using simulation results.     

移动IP中的反向隧道技术

反向隧道是由移动节点（MH）到其家乡代理（HA）的隧道，始于移动节点的转交地址，终止于家乡代理。反向隧道的建立使得位于外地网络上的移动节点可以建立拓扑正确的数据包，以保证其能在设置了入口过滤路由器的外地网络上建立通信连接。     

Family ACK tree (FAT): supporting reliable multicast in mobile ad hoc networks

A new protocol, called family ACK tree (FAT), is proposed to support a reliable multicast service for mobile ad hoc networks. For each reliable multicast protocol, a recovery scheme is used to ensure end-to-end delivery of unreliable multicast packets for all group members. FAT employs a tree-based recovery mechanism that localizes ACKs and retransmissions to avoid feedback implosion. To cope with node movements, FAT constructs an ACK tree on which each node maintains reachability information to three generations of nodes on the ACK tree. When a tree is fragmented due to a departed node, the fragments are glued back to the tree using the underlying multicast routing protocol. FAT then adopts an adaptive scheme to recover missed packets that have been multicast to the group during fragmentation and are not repaired by the new reliability agent. We have conducted simulations to compare the performance of FAT with existing solutions. The results show that FAT achieves better performance for the provision of reliable service in ad hoc networks, in terms of reliability, scalability, and delivery efficiency.