SNMP | Simple Network Management Protocol | Application Layer

What is Simple Network Management Protocol? 

Simple Network Management Protocol refers to Simple Network Management Protocol. The protocol that allows us to read,write,various pieces of state information on different network nodes is called Simple Network Management Protocol. 

Simple Network Management Protocol: 

Simple Network Management Protocol is a request/reply protocol that supports two kinds of request messages. GET & SET. GET is used to retrieve a piece of state from some node. SET is used to store a new piece of state in some New node. A system administrator interacts with a client program that displays information about the network.This client program usually has a graphical interface.This interface plays same role as web browser. Whenever the administrator selects a certain piece of information,the client program uses Simple Network Management Protocol to request that information from the node. An Simple Network Management Protocol server running on node receives the request,locates the appropriate piece of information and returns it to the client program,which then displays it to the user. 

Simple Network Management Protocol depends on a companion specification called Management Information Base [M I B]. Management Information Base organizes variables into 10 different groups. 

SYSTEM : General parameters of the system including where the node is located where the node is located,and system name. 

INTERFACES : Information about all the network interfaces attached to this node,such as the physical address of each interface and how many packets have been sent. 

ADDRESS TRANSLATION : Information about address resolution protocol,contents of address translation table. 

IP : Variables related to IP including its routing table,how many data gram forwarded successfully, statistics about data gram reassembly. 

TCP : Information about TCP connections,such as the number of passive and active opens,the number of resets,The number of timeouts,default timeeout settings . 

UDP : Information about UDP traffic,including total number of UDP data gram that have been sent and received. 

There are also group for Internet control Message protocol [ICMP],Exterior Gateway protocol[EGP],and SNMP itself.The tenth group is used by different multimedia. 

Working of SNMP: 

The SNMP client puts the ASN.1 identifier for the MIB Variable it wants to get into the request message and send this message to server. The server then maps this identifier into a local variables,retrieves the current value held in this variable and uses ASN.1/BER to encode the value it sends back to the client. M/B variables are either tables or structures.Such variables explains the reason for GET-NEXT operation. This operation,when applied to a particular variable 10,returns the value of that variable plus 10 of the next variable.