Static and Dynamic Routers

Dynamic Routers
Dynamic routers are those routers which automatically find their own routes by communicating with each other.
These routers require minimal configuration.
This is because their routing tables are built and modified through these communications.
This approach is very flexible as it can quickly react to changes in the internetwork e.g. router failure or broken links.
Open Shortest Path First (OSPF)

Open Shortest Path First (OSPF) uses a 'link state' algorithm to calculate routes based on number of hops line speed traffic and cost.
TCP/IP supports OSPF.
Routers use an algorithm to send routing information to all nodes in an internetwork.
This algorithm is done by the shortest path to each node based on a topography of the Internet constructed by each node.
The routing table is also attached along with the routing information.
The advantage of this algorithm is that the updates are smaller and more frequent.
These algorithms end quickly thus preventing problems like routing loops and Count-to-Infinity thus making a stable network.
Count-to-Infinity is when routers continuously increment the jumps (hops) from one router to the next in a particular network.
The only disadvantage of this algorithm being that they require a lot of CPU time and power.
Netware Link State Protocol (NLSP)

Netware Link State Protocol (NLSP) is the equivalent of OSPF for the NetWare environment.
Routing Information Protocol (RIP)

Routing Information Protocol (RIP) uses distance vector algorithms to determine routes.
This protocol is defined by RFC 1058.
This protocol specifies how routers exchange routing table information.
Sometimes the entire table is also exchanged.
Since this is inefficient it is replaced by OSPF.