These packets are sent by networks cooperating using packet switching, through intermediate hubs and nodes, or different types of network equipment, such as routers, gateways, Firewalls, and more.
The routing process is recorded and dictated by a routing table, and determines the destination for the corresponding packets. The routing tables work alongside the routing algorithms to select the appropriate protocol for transmission. The routing tables provide a record in the switch’s memory, and are crucial for accurate routing procedures.
The routing algorithm may vary depending on the needs of the network, the routing table being used, and the packets being transmitted. (docswiki.cisco.com)
Commonly used routing algorithms are: Distance Vector, Link State, and Path to Vector routing. Each of these types of routing algorithms are used in different scenarios depending on the needs of the network. The router uses the routing algorithm to compute the optimal path for the transmissions. Distance Vector uses costs to determine which packets to send where.
By minimizing the cost of transmission, the Distance Vector routing algorithm’s goal is to be as cost effective as possible. (cs.ccsu.edu)
But this is not always possible, as other algorithms take other factors into consideration when determining how to send the packets. Link State, for example, will factor in the distance between the path, and the router will end up using the method which costs the least amount of computing power.
Lastly, Path to Vector routing algorithms use a dynamic path calculation to update computational requirements in real-time, and then determines the optimal path of delivery.
References
http://ecomputernotes.com/computernetworkingnotes/routing/routing-algorithms
http://www.cs.ccsu.edu/~stan/classes/cs490/slides/networks4-ch4-4.pdf
http://www.informit.com/articles/article.aspx?p=27267&seqNum=3
http://docwiki.cisco.com/wiki/Routing_Basics
