49. Network properties: m ulti hop communication Let’s suppose that n ode A wants to communicate with node M . It should do the following: 1. find a route (using a routing protocol) 2. send packets using the path found by the routing protocol. In the source routing protocols sender specifies the full path to the destination. In the presented example, path from node M to node A includes nodes L-H-E
59. Definitions: activity Activity describes how often node is available for routing purposes. Nodes joining the network or nodes spending a lot of time in sleep mode will have lower activity levels. Power consumption in different modes
61. How to cope with selfishness? This approach enforces cooperation because selfish nodes will not be able to use the network for their own purposes (because of their bad reputation or low activity ) The scheme: 1. Each node is collecting reputation data concerning the behavior of network participants 2. Using reputation data , trust and activity of other known node s can be calculated 3. When it receives a packet that should be forwarded, first it checks the trust and activity level s to the source of the packet (original sender) 4. If such a packet comes from a non-trusted or not active node than it is very likely that it is going to be d iscarded . Solution: enforce cooperation based on trust and activity