Nt1330 Unit 1 Paper

Now we suppose that network 192.168.3.0 fails. C stops routing packets to it and marks it as “unreachable” with

Flow deviation from predefined paths is not allowed. Vehicle flows can’t deviate from the preplanned paths while passing by detectors, otherwise it is necessary to define an alternative for each path.

| Given a network topology of three or more routers with bandwidth designations, compare the metrics used during the route selection process and the resulting routing tables generated by the DUAL and SPF algorithms.

routing. In this chapter, we introduce some popular routing protocols in each of the three

The basic approach is when a node needs to send a message to a particular destination, it broadcasts the RREQ message in the network that shown in figure 3.7.1 (a). When RREQ message

The request asks that a router send all or part of its routing table. The response can be a spontaneous regular routing update or a reply to a request. Responses contain routing table entries.

By dividing the study area into different zones which is called Network Modeling, students could establish the relationship between traffic demand and road network, from these, a further relationship between zones are created and the travel demands are calculated on VISUM. The size of zones varies and determined by the traffic analysis.

This type of protocol combines the advantages of proactive and reactive routing. The routing is initially established with some proactively prospected routes and then serves the demand from additionally activated nodes through reactive flooding. The choice of one or the other method requires predetermination for typical cases. The main disadvantages of such algorithms are:

A Mobile Agent starts from every node and moves to an adjacent node at every time. A node visited next is selected at the equivalent probability. The MA brings its own history of movement and updates the routing table of the node it is visiting [1].

Several energy-aware routing protocols have been proposed in literature for heterogeneous WSNs. In \cite{Georgios2004}, the authors proposed SEP, a Stable Election Protocol, that improves homogenous LEACH protocol \cite{Heinzelman2000} by considering two levels of heterogeneity: normal nodes and advanced nodes, where the later are equipped with an extra amount of energy. The cluster head is selected based on a weighted probability according to the node initial energy in such a way that the nodes having a higher initial energy become cluster heads more times than the other nodes. The election probabilities for the normal and advanced nodes are given as follows:

The UPR makes routing decisions locally based on the destination address in the packet header and availability of outgoing channels. If

However, there are many limitations with DTN’s. For example, asynchronous connectivity among the devices makes it necessary for the sensors to forward messages via relays or alternate paths to ensure delivery, or they need to store and forward the packets opportunistically until they reach the destination. This very often results in huge transmission delay, high overhead or low delivery rate. Taking into consideration the constraints on remote sensing devices, such as battery power, storage capacity, processing power, and communication bandwidth can affect the network performance and successful message delivery rate. Hence there is a need for routing protocols of DTNs be enabled to adapt according to network variations and effectively use the existing resources. Recent studies show that the most of existing protocols for DTNs look very similar in concepts; however, their performance significantly differs from each other. Epidemic [5] is a robust algorithm as it floods packets to all devices in the network. Spray and Wait [6], a modified version of Epidemic, controls flooding of messages forwarded. It simply limits the amount of messages that can be forwarded International Journal of Wireless & Mobile Networks (IJWMN) Vol. 7, No. 3, June 2015 56. The

1. For each node calculate the distance between the node N and the S of origin i.e. DNS and the distance between node N and the destination D i.e. DND.

\noindent Several existing studies employ simulations to explore the impact of node selfishness on data delivery performance. The authors in \cite{EffNonCoo-15} explore the impact of the nodes' non-forwarding and partially-forwarding actions on the performance of Epidemic, SnW, and Prophet protocols in terms of the data delivery ratio and delay. The experimental results demonstrate that DTNs tolerate a high percentage of non-cooperative nodes (20-40\% or even 60\%) without too much harm, even though they still utilize the other nodes' resources to deliver their own messages. Meanwhile, synthetic random mobility models are most vulnerable to less cooperation that implies that DTNs are robust against the nodes' non-cooperative behavior.

when there is a need to transmit data from source to destination a route discovery process is initiated by the source. In this process, the network is flooded with route request packets to create a suitable route from source to destination. The Routing table is also created on demand. Flooding is a reliable method of passing information to all the nodes present in the network; however it uses bandwidth and cause delays in packet transmission but decreases the control traffic overhead. After getting the best route, route establishment phase ceases with initiation of route maintenance phase which keeps up valid routes and remove all the invalid routes thus reducing