Using these messages, every cluster-head maintains a table containing the IDs of nodes belonging to it and their most recent sequence numbers. Cluster-heads exchange these tables with each other through gateways; eventually, each node will have an entry in the affiliation table of each cluster-head. This entry shows the node’s ID & cluster-head of that node. Each cluster-head and each gateway maintains a routing table with an entry for every cluster-head that shows the next gateway on the shortest path to that cluster head. Disadvantages: The same disadvantage common to all hierarchal algorithms related to cluster formation and maintenance. Hierarchal State Routing (HSR) A hierarchal link routing protocol that solves the location management problem found in MMWN by using the logical subnets. A logical subnet is : a group of nodes that have common characteristics (e.g. the subnet of students, the subnet of profs , employees etc. ). Nodes of the same subnet do not have to be close to each other in the physicaldistance. HSR procedure: on the physical distance, nodes are grouped into clusters that are supervised by cluster-heads. There are more than one level of clustering. node has two addresses : a hierarchal-ID ,(HID), composed of the node’s MAC address prefixed by the IDs of its parent clusters. a logical address in the form <subnet,host>. Every logical subnet has a home agent, i.e. a node that keeps track of the HID of all members of that subnet. The HIDs of the home agents are known to all the cluster-heads, and the cluster-head can translate the subnet part of the node’s logical address to the HID of the corresponding home agent. when a node moves to a new cluster, the head of the cluster detects it and informs the node’s home agents about node’s new HID. When a home agent moves to a new cluster, the head of the cluster detects it and informs all other cluster-heads about the home agent’s new HID. To a session: The source node informs its cluster-head about the logical address of the destination node.
Jamming: In jamming, attacker initially keep monitoring wireless medium in order to determine frequency at which destination node is receiving signal from sender. It then transmit signal on that frequency so that error free receptor is hindered. Man- in- the- middle attack: An attacker sites between the sender and receiver and sniffs any information being sent between two nodes. In some cases, attacker may impersonate the sender to communicate with receiver or impersonate the receiver to reply to the sender. Gray-hole attack: This attack is also as routing misbehavior attack which leads to dropping of messages. Gray-hole attack has two phases. In the first phase the node advertise itself as having a valid route to destination while in second phase, nodes drops intercepted packets with a certain probability.
WDP offers source and destination port numbers used for multiplexing and demultiplexing of data respectively. The service primitive to send a datagram is TDUnitdata. req with the destination address (DA), destination port (DP), Source address (SA), source port (SP), and user data (UD) as mandatory parameters. Destination and source address are unique addresses for the receiver and sender of the user data. could be MSISDNs (i.e., a telephone number), IP addresses, or any other unique identifiers. The T-DUnitdata.ind service primitive indicates the reception of data. Here destination address and port are only optional parameters. If a higher layer requests a service the WDP cannot fulfil, this error is indicated with the T-DError.ind service primitive. An error code (EC) is returned indicating the reason for the error to the higher layer. WDP is not allowed to use this primitive to indicate problems with the bearer service. It is only allowed to use the primitive to indicate local problems, such as a user data size that is too large. If any errors happen when WDP datagrams are sent from one WDP entity to another, the wireless control message protocol (WCMP) provides error handling mechanisms for WDP and should therefore be implemented. WCMP contains control messages that resemble the internet control message protocol messages and can also be used for diagnostic and informational purposes. WCMP can be used by WDP nodes and gateways to report errors. Typical WCMP messages are destination unreachable (route, port, address unreachable), parameter problem (errors in the packet header), message too big, reassembly failure, or echo request/reply. An additional WDP management entity supports WDP and provides information about changes in the environment, which may influence the correct operation of WDP.