We are moving towards Internet of Things (IoT). Ubiquitous and pervasive computing is a nucleus of IoT. The number of sensors deployed across the globe is very huge in number and their rate of growth is very high. These sensors are acting like the digital skin of the earth. Sensors collect the raw data continuously and interpret this raw data for generating the knowledge out of it. The routing of data from source to sink is a fundamental component of any large scale network. In IoT the communication devices works with dissimilar networking standards, may experience irregular connectivity with each other and many of them can be resource constrained. These characteristics raise several routing challenges which were not present in the traditional routing protocols. So it is essential to understand the context while routing the data on the future networks. This survey addresses routing mechanism and related challenges in IoT.