Mesh Based Multicast Routing in MANET: Stable Link Based Approach

The group-oriented services are one of the primary application classes that are addressed by mobile ad hoc networks (MANETs) in recent years. To support such services, multicast routing is used. Thus, there is a need to design stable and reliable multicast routing protocols for MANETs to ensure better packet delivery ratio, lower delays and reduced control overheads. In this paper, we propose a mesh based multicast routing scheme that finds stable multicast path from source to receivers. The multicast mesh is constructed by using route request and route reply packets with the help of multicast routing information cache and link stability database maintained at every node. The stable paths are found based on selection of stable forwarding nodes that have high stability of link connectivity. The link stability is computed by using the parameters such as received power, distance between neighboring nodes and the link quality assessed using bit errors in a packet. The proposed scheme is simulated over a large number of MANET nodes with wide range of mobility and the performance is evaluated. It is observed that proposed scheme produces better packet delivery ratio, less control overheads and reduced packet delay compared to on-demand multicast routing protocol (ODMRP).

Proposed System:-

The tree management algorithm of HBH uses three control messages to construct an SPT. messages are periodically sent to the source by the receivers. The source periodically produces messages that are multicast to the receivers. As the messages travels in the tree, the intermediate nodes may generate messages that are responsible of refining the tree structure.

In this project, we propose a link stability based multicast routing scheme that establishes a route from source to multicast destinations in MANET. A multicast mesh is created with stable links when a source node needs to send data to receiver nodes. The scheme consists of following phases.

A multicast channel in HBH is identified by , where is the unicast address of the source and is a class-D IP address allocated by the source. This definition solves the address allocation problem while being compatible with SSM’s channel definition. Therefore, HBH can support IP Multicast clouds as leaves of the distribution tree.

The tree structure of HBH has the advantage of an enhanced stability of the table entries when compared with REUNITE. The tree management scheme of HBH minimizes the impact of member departures in the tree structure.

There is no route changes for other members when a member leaves the group because the unicast routes are symmetric.
Advantage of Project
• a multicast routing protocol that implements multicast distribution through recursive unicast trees.
• The main goals of HBH are: to support unicast clouds, allowing incremental deployment; to have a stable tree structure, by minimizing the impact of receiver departures; and to construct low-cost trees.
• To reduce administrative costs.
• To lower error rates.
To increase productivity.



1. Dynamically Node Addition

In this module, all the nodes that are attached to the particular node will be displayed in the list and the left and the right node to which the message has to be sent are selected from the list. When we want to send a message the data will be sent to those nodes which are selected from the list.

• A mesh is created between the members of the group by a Mesh Creation technique, which involves broadcasting a Control Packet to identify the members of the Group. This is an “ Expanded Ring Search” algorithm.

• Each of the mesh created consists of a Logical Core node, which is responsible for maintaining the tree and its members. The core is selected by using a “Core Resolution” algorithm.

• Once a Mesh is created a User Multicast Tree is built from it. This tree is formed in such a way that the nodes of the tree are the members of the group.

• The next step is to maintain the Tree created. This is done by periodically sending a message to all the members of the group. The core node is responsible for sending this packet. It maintains a TREE_CREATE_TIMER.

• To improve the efficiency of the AMRoute protocol a Core Migration technique is used in our algorithm. A new core is being elected periodically so that the core migrates and thereby the tree is maintained effectively.

A description of each of the above steps is given in detail in the following pages.

2. Remove a node dynamically

REUNITE [13] implements multicast distribution based on the unicast routing infrastructure. The basic motivation of REUNITE is that, in typical multicast trees, the majority of routers simply forward packets from one incoming interface to only one outgoing interface, because only a few routers are branching nodes [18]. REUNITE identifies a conversation by a pair, where is the unicast address of the source and is a port number. Class-D IP addresses are not used. As receivers join the group REUNITE populates its tables to construct the distribution tree, using two control messages: and . messages travel upstream from the receivers to the source, whereas messages are periodically multicast by the source to refresh the soft-state of the tree. Only the branching nodes for the group keep entries in their MFTs. The control table, MCT, is exclusively used for tree construction, not for packet forwarding. Nonbranching routers in the tree have MCT entries for but no MFT entry.

3.Path Discovery
The shortest path from the source node i.e.n the root to the left and the right is found out and the request is sent from the left and right nodes to the root node by which the shortest path is found and the message is sent along the shortest path found through the found shortest path.

1) Mesh creation through the route request (RR) packets and route reply (RP) packets,
2) finding stable routes between source to destination by selecting SFNs using link
stability metric,

3) mesh maintenance and handling link failures. The link stability is computed using power received at a node, distance between nodes and the packet losses.

Our contributions in this paper are as follows.
1) Defining route request and route reply packets to create a mesh by using
transmission power and antenna gains.

2) Creation and maintenance of routing information for hop by hop routing
for a multicast connection by using route request and route reply packets based on link stability.

3) Selecting stable forwarding node for multicast paths based on link stability computed using the parameters such as received power, distance between the nodes and link quality.

4) Attempts to select different stable forwarding node in a mesh during link
failures rather than immediately going in for route discovery.

5) Comparing the performance of the proposed scheme with

4.Hop By Hop Transmission

 The HBH multicast protocol has a tree construction algorithm which finds the end-host
in the specified subnet by checking node by node.
 This is achieved by checking the every node IP address against destination IP

5.Prediction of link failure(a node with a weaker link)the prediction module.

• Source S broadcasts RR packet to discover the route for two multicast receivers R1 and R2.
• Nodes x, y and z receive RR packet from S. These nodes update the paths to S in its MRIC by using next hop as S. Also updates the link stability database and stability factor of next hop in MRIC.
• Node x broadcasts RR packet to R1 and y. Node z broadcasts to y and R2. Node y broadcasts to x, R2, R1 and z.
• Node y finds that these packets are duplicates of the same RR packet already received. Thus they will be discarded by node y, which is indicated by cross mark in the figure. Similarly nodes x and z discard duplicate RR packets received from y.
• R2 and R1 discards duplicates from nodes z and x,
• R2 and R1 updates MRIC and link stability database.
• Now, R2 and R1 have path to the source S, R1-x-S,
R1-y-S, R2-z-S, and R2-y-S.

6.Alternate tree construction when a node fails.

1) link failure between SFN nodes and 2) link failure between a multicast source/receiver and a SFN. In the case of link failure between two SFN’s, the failure detecting node will try to find the next stable link in the mesh and route the packet through such a link. In case, if all the forwarding nodes links fail, RE packet
is sent to the source to rediscover the routes. The route through the failed link in MRIC will be removed and the FW flag for the chosen next hop will be updated accordingly. When links fail between a SFN node and a multicast node, the multicast node detecting failure deletes the multicast node routing information from its MRIC corresponding to failed SFN. Multicast node updates next hop SFN based on high stability factor. In case, all the forwarding nodes’ links connected to multicast node fail, then the node rediscovers the mesh and stable route using RR and RP packets.

7.Forward Error Correction.

This section presents the functioning of proposed link stability based multicast routing scheme in MANET (LSMRM). Here, we discuss the process of creating a mesh of multicast routes with the help of RR and RP packets, routing information maintained in multicast routing information cache (MRIC) and link stability database. MRIC is maintained at every node. After creating a multicast mesh,
a stable route between source destination pair is established by using SFNs (which are a part of multicast mesh) that have stable link connectivity. Link stability database is maintained at every node, which stores the updated information that is
used for finding stable multicast routes in a mesh.

Hardware Requirements:

• System : Pentium IV 2.4 GHz.
• Hard Disk : 40 GB.
• Floppy Drive : 1.44 Mb.
• Monitor : 15 VGA Colour.
• Mouse : Logitech.
• Ram : 512 Mb.

Software Requirements:-

Language: Java, J2ME

OS: Windows XP

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