ing information by the update process. The update process generates local link-state information, based on the adjacency database built by the subnetwork- dependent functions, which the router advertises to all its neighbors in link-state packets. A routing entity also receive similar link-state information from every adjacent neigh- bor, keeps copies of GLSPs received, and readvertises them to other neighbors. Routing entities in an area maintain identical link-state databases, which are synchronized using SNPs. This means that routing entities in an area will have identical views of the area topology, which is necessary for routing consistency within the area. The decision process creates the forwarding database by running the Dijkstra algorithm on the link-state data- base SO selecting for each GLSP and for the forward of each control packet the shortest path in terms of whatever weight is associated to each network link in the topology database. The IS-IS forwarding database, which is made up of only best IS-IS routes, is fed into the routing information base. 8.3.2.3 Brief Comparison between OSPF-TE and IS-IS IS-IS and OSPF-TE are link-state protocols, that is routing protocols that perform routing on the ground of information on the state of the links of the network that is derived from a map of the network topology that each routing network element stores and updates using the protocol flooding functionality. Moreover, OSPF-TE and IS-IS have several other com- mon characteristics: They use the Dijkstra algorithm for computing the best path through the network. They allow any link tag as weight for the Dijkstra calculation. They exchange via protocol packets records composed by sets of TVL fields that describe the characteristics of the link they are advertising. They use the concept of subnetwork and virtual node to leverage on hierarchical routing to simplify routing tables and routing computation. Telecommunication Networks They can use multicast to discover neighboring routing equipment using hello pack