Abstarct:
GOALS AND OBJECTIVES:
The goal of the project is to transmit the data to the group of the nodes in an efficient manner. The data is transmitted to the group of nodes in such a way that the burden on one node is reduced and the burden is distributed to all the nodes.
The objective is to transmit the data efficiently in terms of time and cost and also to reduce the number of Acknowledgements in transmitting the data to the group of nodes.
EXISTING SYSTEM:
Scalability is a primary issue in reliable multicast. Scalability means that the protocol should be able to work under a variety of conditions that include multiple network topologies, link speeds, and the receiver set size. It is more important to have a good understanding of how and when a protocol breaks than when it works. As the number of members in a multicast session increases, the processing time in a sender becomes extremely larger than that in a receiver. Thus, scalability requires alleviating the sender processing time and distributing the burden to the receivers. The tree-based protocols organize a sender and receivers into a hierarchical ACK tree in which the parent nodes are responsible
for reliable delivery of data to their child nodes. These protocols are proven more scalable in terms of maximum throughput and end-pointbandwidth since they can
ensure that the sender processing time is bounded by the number of the sender’s children, which remains constant in their tree hierarchy regardless of the number of receivers.
A limitation of the tree-based reliable multicast protocols is that their best performance can be achieved when the ACK tree is close to its corresponding multicast routing tree. In such a high-quality ACK tree, the underlying network-layer correlation in terms of packet loss and delay is preserved between a parent and children nodes at transport layer. For this, tree-based protocols should allow ACK trees close to the corresponding routing trees in the presence of dynamic group membership and route changes.
However, when a tree-based protocol supports a many-to many reliable multicast session, the ACK tree maintenance overhead required for high quality is likely to be considerably large. For example, RMTP supports a many-to-many session by setting up a separate ACK tree for each sender so that the best performance can be achieved. However, the tree maintenance overhead, which increases linearly with the number of senders, would not be acceptable. In order to eliminate the need to maintain an ACK tree for each source, Lorax constructs and maintains a single ACK tree for a many-to-many group. An ACK tree can be optimized if it is built based on a shared multicast routing tree. However, it cannot provide high quality ACK trees if the underlying multicast routing protocols provide per-source routing trees. These two examples show that there is a fundamental trade-off between the quality of ACK trees and the tree maintenance overhead when a globalshared routing tree is not supported.
Scalability is a focal point in reliable multicast. As the number of multicast session members increases, acknowledgmentimplosionand exposure to retransmissionbecome a serious obstacle to the scalability of a multicast protocol. A sender is imploded or overwhelmed by acknowledgments (either positive or negative) from a large number of receivers while the receivers are exposed to redundant repair packets from the sender or other receivers after successful receipt of the original packets in prior (re)transmissions. Most existing reliable multicast protocols have been designed and implemented for one to-many multicast because the current set of multicast applications typically involve a single sender such as multimedia streaming, stock quote, multicast file transfer, and software update. These applications may consist of very large number of receivers - thousands or tens of thousands.
In such large-scale one-to-many sessions, the processing time of the sender is extremely larger than the processing time of a receiver, and thus, a key factor to scalability is to alleviate the sender processing time and distribute the burden to the receivers. Tree-based protocols are proven most scalable in terms of throughput since they can ensure that the sender’s processing time is bounded by the number of its immediate children, which remain constant in the tree hierarchy regardless of the number of receivers. Unlike in one-to-many multicast, in a many-to-many reliable multicast session, eachmember can act as a sender as well as receiver, and allthe packets are delivered to and meaningful or useful to allthe session members. In large-scale multi-sender applications such as distributed virtual worlds, group members are typically not interested in all data, and thus, partitioning of group members by interest has been a noticeable trend. For example, a large virtual world is divided into multiple regions, cells, or areas because the users far apart would not likely to interact with one another. It seems that such large-scale multi-sender applications would not be supported by a single many-to-many session but rather by a combination of multiple small- or medium-scale many-to-many sessions and a few large-scale one-to many sessions. The trend is directly affected by social and human factors; there still remain another kind of multi-sender applications with little or minimal human convention.
Examples are large-scale replicated database or Web cache protocols where primary site of each item is spread in wide-area networks and each transactional data for the item is distributed to all backup sites. Large-scale distributed military simulation and peer-to-peer multicast file transfer model would require many-to-many reliable multicast with minimal human factor. Thus, even though the applications are not popular yet, it is obvious that scalability remains as a key issue in many-to-many reliable multicast.
PROPOSED SYSTEM:
In this project, we show how to achieve the high quality ACK trees while keeping the maintenance overhead reasonably low for tree-based many-to-many reliable multicast. We propose Group-Aided Multicast (GAM), which fully uses a spectrum of policies that subsumes the shared tree approach and the per-source tree approach, by introducing a ‘group’ concept into ACK tree configuration. GAM is motivated by an observation that senders close in a session share large part of the multicast routing trees, and thus can share corresponding ACK trees. Thus, if we make groups of senders and maintain one tree for each group, the maintenance overhead can be reduced as much as the number of senders without severe degradation of the quality of ACK trees. GAM builds a two-layer logical tree. At the bottom layer, collocated session members in a local ‘group’ join a ‘core’-rooted shared logical tree. At the top layer, the cores of the groups constitute per-source logical trees. Two key mechanisms are proposed to ensure high quality ACK trees generated from the hierarchy. One is a tree configuration mechanism that maintains the logical trees congruent with the underlying multicast routing trees even in the presence of dynamic group membership and route changes. The other is a group configuration mechanism that maintains a multicast session in the form of multiple distant groups in order to approximate backbone networks and regional networks of global multicast networks.
EXTERNAL INTERFACE REQUIREMENTS:
User Interface:
Only the user needs to send data. Remaining every thing can be controlled by program.
DESIGN CONSTRAINTS:
SOFTWARE CONSTRAINTS:
The system is to run on Windows 2000 server Operating System.
HARDWARE CONSTRAINTS:
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