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INTRODUCTION
The purpose of network mobility is to guarantee the continuity of the sessions of fixed or mobile nodes within mobile networks, such as car, bus, subway train, airplane and submarine. IETF NEMO working group has been performing the standardization of network mobility support. Given the NEMO Basic Support protocol, all data packets to and from Mobile Network Nodes must go through the Home Agent, even though a shorter path may exist between the Mobile Network Node and its Correspondent Node. In addition, with the nesting of Mobile Routers, these data packets must go through multiple Home Agents and several levels of encapsulation, which may be avoided. Nested Mobile Networks is a cluster of multiple mobile networks forming a larger mobile network. These Nested Mobile Network cause problems such as suboptimal routing and overhead caused by multiple encapsulation. To overcome these problems some protocols are proposed such as Reverse Routing Header, Recursive Binding Update, and Prefix Delegation for Route Optimization. But these methods have some disadvantages.
1.1) Purpose:
This document is a Software Requirement Specification for Optimizing the Routing Technique in Nested Mobile IPv6 it provides optimal path without additional packet overhead and it decreases packet delay, signalling overhead in nested mobile networks. It provides a sufficient optimization and is applicable for various configurations of nested mobile networks.
1.2) Scope:
Optimization the Routing Technique in Nested Mobile IPv6 provides the following features,
• Provide a solution for Sub optimal routing in nested mobile networks
• Provide Optimal path in nested mobile networks
• Reduce additional packet overhead
• Decreases packet delay
• Decreases signalling overhead in nested mobile networks
• Apply for various configurations of nested mobile networks.
1.3) Intended Audience:
This system is useful to passengers who using handheld PC, laptop, mobile networks.
1.4) Abbreviations:
Mobile Node (MN): A host with capabilities to move between different access networks, while keeping movement transparency to its upper layers and protocols.
• Home Agent (HA): A router which assists the movement of a MN.
• Correspondent Node (CN): A node communicating with a MN.
• Home Address: An unchanging address allocated to MN.
• Care of Address: An address of which MN configures on the visiting link.
• Mobile Router (MR): A router connecting the mobile network to internet.
• Mobile Network (NEMO): A set of hosts and routers which moves as an entity, between different attachment point on the internet.
• Egress Interface: The interface of a MR which is attached to a link outside the mobile network.
• Ingress Interface: The interface of a MR which is attached to a link inside the mobile network.
• Mobile Network Prefix (MNP): The prefix advertised inside a mobile network by a MR.
• Mobile Network Node (MNN): A node attached behind a MR. If the node is a MN; it is referred to as a Visiting Mobile Node (VMN). If the node is a fixed host, it is referred to as a Local Fixed Node (LFN).
1.5) Tools & Technologies Used:
• TCL script language with object oriented extensions.
• NS2- Network Simulator.
• NAM- Network Animator.
Product Functions:
The main function of the system is described as follows,
• Detection of the nested mobile network
• Exchange of routes within the nest
• Detection of the suboptimal flow
• Discovery of the Correspondent Router
• Notification of the Nest Entrance Point to the Correspondent
• Exchange of binding information
• Provide an optimized route
2.3) User Characteristics:
The passengers in bus, car, train, airplane can access and communicate through internet with very minimum packet delay and packet loss.
2.4) Constraints:
• Operating system should be Linux to run NS2.
• User should know TCL & C++ languages.
• Since mobile node, router is wireless there is no acknowledgment for UDP packets.
• The protocol uses the UDP CBR packets to achieve real life scenario.
2.5) Assumptions and Dependencies
• In case of NEMO all the networks under consideration are wireless networks.
• The user must be aware of the other problems that occur in the wireless networks.
• The user while implementing the proposed architecture must consider the parameters which affects the Quality of services.
• The packet flow takes place only in IPV6 Networks
• The mobility solutions are anachronistic, the nodes as well as network must not be aware of mobility and act as they are static.
Overall Use Case model Survey for
Optimizing routing technique in Nested mobile Network
2.8) User Documentation:
• Packet forwarding:
Description: Correspondent router forwards a packet to mobile node.
Primary Actor: Mobile User
Secondary Actor: Correspondent Node, Home Agent
Main flow: To send packet from CN to Mobile Node it first intercepts the packet to corresponding MN’s HA then it forwards to MN.
Pre-Condition: CN know MN’s HA from its routing table.
Post-Condition: HA forward packet to MN.
• Generating Care of Address:
Description: To bind MN with its HA, it generate a Care of Address to HA’s fixed Address.
Primary Actor: Mobile User
Secondary Actor: Home Agent
Main Flow: MN generates a care of address to communicate with CN and maintain continuity on move.
Pre-Condition: HA send packet to MN.
Post-Condition: MN Bind with HA
• Binding Update:
Description: MN sends a binding update to HA to bind.
Primary Actor: Mobile User
Secondary Actor: Home agent
Main Flow: MN send binding request to HA, then HA send Binding reply to MN.
Pre-Condition: MN sends Binding request to HA.
Post-Condition: HA reply with a Binding reply message to MN.
• Correspondent node Discovery:
Description: In case of nested network, MR sends request to discover the CR to make tunnel with it.
Primary Actor: Mobile user
Secondary Actor: Correspondent node
Main flow: To make tunnel with CR, MR send request to CR to discover it.
Pre-Condition: MR sends correspondent node discovery request to CR.
Post-Condition: CR replies by a Correspondent node discovery reply.
• Tunnelling to CN:
Description: MN makes a tunnel with its CN by using Care of address through reflexive binding update.
Primary Actor: Mobile User
Secondary Actor: Correspondent node
Pre-Condition: MN request for reflexive binding update to its CR.
Post-Condition: CR tunnel with MN by using its care of address.
SCOPE AND OBJECTIVE
3.1) User Interfaces:
NAM- Network Animator is used to visualise the implemented system functions.
3.2) Hardware Interfaces:
3.3) Software Interfaces:
• Linux Operating System.
• NS2, NAM tools.
3.4) Communication Interfaces:
• UDP network protocol
• Router queue management mechanism such as Drop tail, RED & CBQ.
3.5) Objective
The objective of the project is to solve the suboptimal routing problem and to reduce the multiple encapsulation overheads.
3.6) Scope
In Nested mobile IPv6 network, packets forwards many MR’s HA and it causes Sub optimal routing and multiple encapsulations overhead. There are many concepts are proposed such as ‘Reverse Routing Header’, ‘Recursive binding update’, ‘Prefix Delegation for route optimization’ but the degree of optimization in these method are still sub optimal in some cases. So a good solution is to be proposed to solve sub optimal routing and multiple encapsulations overhead in nested mobile network.
3.7) Existing System
To overcome Sub Optimal routing and multiple encapsulation overhead systems such as Reverse Routing Header(RRH), Recursive binding update, Prefix Delegation for route optimization are developed but these systems still cause suboptimal path and it does not support various nested network configuration.
3.8) Proposed System
The nest optimization protocol (NEO) is designed to use only a single encapsulation. The proposed architecture solves the problem by using following functions,
• Detection of the nested mobile network
• Exchange of routes within the nest
• Detection of the suboptimal flow
• Discovery of the Correspondent Router (CR)
• Notification of the Nest Entrance Point to the Correspondent
• Exchange of binding information
• Provide a optimized route
3.10) Modules
1. Detection of Sub Optimal flow
2. Discovery of Correspondent Router
3. Notification of Nest Entrance Point
4. Establishment of Bindings
5. Establishment of Optimized Route
3.11) Module Description
Detection of Sub Optimal flow:
The route optimization is first initialized by a mobile router when receiving a tunnelled packet from its home agent. A packet which is tunnelled from a home agent indicates that the flow has not been optimized. When the mobile router detects such packet, initialization for the route optimization can be started for the corresponding communication flow.
Discovery of Correspondent Router:
If the MR decides that route optimization is needed for a specific flow, it performs a Correspondent Router Discovery to discover the anchor router to become the tunnel end point. The Correspondent Router Discovery consists of a request and reply message. The request message is sent to the network with the prefix used in the source address of the suboptimal packet. When the MR2 detects a flow to optimize, it sends a Correspondent Router Discovery Request message to the correspondent network. The message is used to discover the correspondent router of the MR which can offer optimal path for the correspondent node.
Establishment of Bindings:
After receiving a valid Correspondent Router Discovery Reply message, the sub-MR notifies the correspondent of its own attachment point for route optimization. In providing such optimized route, a new mechanism called, “Reflective Binding Update” is introduced which is sent by the sub-MR to inform the correspondent of the Nest Entrance Point of the nested mobile network. The Reflective Binding Update is indicated with a corresponding flag in the binding update message, together with the care-of address of the root-MR in the sub-option.
Notification of Nest Entrance Point:
The key idea of the NEO is the use of the Nest Entrance Point as the tunnel end point of a nested mobile network. All packets meant for a nested mobile network are always routed to the care-of address of the root-MR. Once the root- MR Decapsulates the packet, packets are routed down the nest to the destination based on the routing table of the sub- MRs. In order to notify the care-of address of the root-MR to the sub-MRs, the Router Advertisement message is extended to carry the care-of address. When the root-MR moves and changes its point of attachment to the Internet, the information in the Router Advertisement message is changed to the new care of address. By updating the changes to the Router Advertisement message, the sub-MRs can resend its correspondents and notify them of the new Nest Entrance Point.
Establishment of Optimized Route:
After a successful creation of the bindings between the CR and the root-MR, packets meant for the mobile network under the sub-MRs are directly tunnelled to the root-MR at the correspondent router. Likewise, packets meant for the correspondent network are directly tunnelled to the CR from the root-MR.
Detection of Sub Optimal flow:
The route optimization is first initialized by a mobile router when receiving a tunnelled packet from its home agent. A packet which is tunnelled from a home agent indicates that the flow has not been optimized. When the mobile router detects such packet, initialization for the route optimization can be started for the corresponding communication flow.
Discovery of Correspondent Router:
If the MR decides that route optimization is needed for a specific flow, it performs a Correspondent Router Discovery to discover the anchor router to become the tunnel end point. The Correspondent Router Discovery consists of a request and reply message. The request message is sent to the network with the prefix used in the source address of the suboptimal packet. When the MR2 detects a flow to optimize, it sends a Correspondent Router Discovery Request message to the correspondent network. The message is used to discover the correspondent router of the MR which can offer optimal path for the correspondent node. The destination address of the Correspondent Router Discovery Request message is an anycast address derived from the prefix of the correspondent node. When the CR receives the message, it replies back with a Correspondent Router Discovery Reply message. The message informs the prefix owned by the CR along with the tunnel end point to the MR.
Establishment of Bindings:
After receiving a valid Correspondent Router Discovery Reply message, the sub-MR notifies the correspondent of its own attachment point for route optimization. In providing such optimized route, a new mechanism called, “Reflective Binding Update” is introduced which is sent by the sub-MR to inform the correspondent of the Nest Entrance Point of the nested mobile network. The Reflective Binding Update is indicated with a corresponding flag in the binding update message, together with the care-of address of the root-MR in the sub-option.
Establishment of Optimized Route:
After a successful creation of the bindings between the CR and the root-MR, packets meant for the mobile network under the sub-MRs are directly tunnelled to the root-MR at the correspondent router. Likewise, packets meant for the correspondent network are directly tunnelled to the CR from the root-MR.
Notification of Nest Entrance Point:
The key idea of the NEO is the use of the Nest Entrance Point as the tunnel end point of a nested mobile network. All packets meant for a nested mobile network are always routed to the care-of address of the root-MR. Once the root- MR Decapsulates the packet, packets are routed down the nest to the destination based on the routing table of the sub-MRs. In order to notify the care-of address of the root-MR to the sub-MRs, the Router Advertisement message is extended to carry the care-of address. When the root-MR moves and changes its point of attachment to the Internet, the information in the Router Advertisement message is changed to the new care of address. By updating the changes to the Router Advertisement message, the sub-MRs can resend its correspondents and notify them of the new Nest Entrance Point. When the nest level of a mobile network is larger than 2, the sub-MRs must relay the care-of address down the nest.