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.
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.
Mobile-Computing%20notes.docx