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## Friday, August 16, 2013

### What is meant by flow based routing?

- The routing algorithm that considers the flow in the network is known as flow based routing.
- It takes into consideration the amount of traffic flowing in the network before making a decision regarding the outgoing link over which the packet has to be sent.
- The ability to characterize the traffic flow’s nature with respect to time is the key to the successful implementation of the flow based routing.
- For any given line, if we know what is its average flow or capacity we can very well compute the mean packet delay of the line using the queuing theory. - This is the basic idea behind the implementation of this algorithm.
- This idea reduces the size of the problem i.e., only the minimum average delay has to be calculated for the sub net and nothing else.
- Thus, the flow based routing considers the load and topology of the network while other routing algorithms do not.
- In few networks, the mean data flow existing between two nodes might be predictable as well as relatively stable.
- There occur such conditions under which the average traffic between the two points is known.
- In such conditions the mathematical analyzation of the flow is possible.
- This calculation can be used in the optimization of the routing protocol.
- The flow weighted average can be straightforward calculated which in turn can be used for the calculation of the mean packet delay of the entire sub-net.

The flow based routing algorithm requires the following things in advance:
Ø  Topology of the subnet
Ø  Traffic matrix
Ø  Capacity matrix
Ø  A routing algorithm
- Information flow based routing algorithms are commonly used in the wireless sensor networks.
- These days, the measure of information is being used a criterion for the analyzation of the performance of the flow based routing algorithms.
- One research has put forward an argument stating that since the sensor network is driven by the objective of the estimation of a 2D random field, the information flow must be maximized over the entire field and the sensor’s lifetime.
In response to this algorithm two types of flow based routing algorithm have been designed namely:
1. Maximum information routing (MIR) and
2. Conditional maximum information routing (CMIR)
- Both of these algorithms have proved to be quite significant when compared to the exiting algorithm – maximum residual energy path or MREP.

- This proves to be quite effective in conservation of the energy.
- The battery energy which is limited is taken as the most important resource. - For the maximization of the lifetime, the energy consumption has to be balanced throughout the nodes.
- This should be done in proportion to the resource reserves.
- This is better than routing for the minimization of the absolute consumed power.

- The ideology behind the MIR algorithm is that there is inequality between the nodes.
- For example, two very close nodes might not provide twice as much information provided by a lonely node.
- Therefore, the nodes that provide more information are only given preference.
- An additional penalty according to the node’s contribution is added to the node for achieving the above mentioned preference.
- Dijkstra’s algorithm is used for the computation of the shortest path.
- This helps in sending the data to the sensor as per both the information of the origin and the power consumed.