## Dijkstra’s & Bellman Ford algorithm

One interesting comparison can be made between these two algorithms. Consider first the Bellman-Ford algorithm where the calculation for node n involves knowledge of the link cost to all neighboring nodes to node n ( djn) plus the total path cost to each of those neighboring nodes from a particular source node s. Each node can maintain a set of costs and associated paths for every other node in the network and can exchange this information with its direct neighbors from time to time. Each node therefore deals with only one information from its neighbors and knowledge of its link costs,to update its costs and paths. On the other hand in Dijkstra’s algorithm each node must have complete topological information about the network. That is each node must know the link costs of all links in the network. Thus for this algorithm, information must be exchanged with all other nodes.

A final point : Both algorithms are known to converge under static conditions of topology and link costs and will converge to the same solution. If the link cost change over time, the algorithm will attempt to catch up with these changes. However , if the link cost depends on traffic ,which in turn depends on the routes chosen, then a feedback condition exists, and instabilities may result.

**What is ASN.1? Write down the utilities for using ASN.1.**

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**Ans**. ASN.1 is the acronym of Abstract Syntax Notation One. The development of ASN.1 is the most significant development in computer communications. It has become an important universal language for defining application-level protocols. ASN.1 is a language that can be used to define data structures. A structure definition is in the form of a named module.The named module can then be used to reference the structure.

The Abstract Syntax is used for the exchange consists of application-level PDUs,which contain protocol control information and user data.within a system, the information represented using an Abstract Syntax must be mapped into some form for presentation to the human user.Thus the Abstract Syntax Notation is employed by a user to define network management information; the application must then convert this definition to a form suitable for local storage.