definition
In layered network structure, for example in the open systems interconnection (OSI) model, the transmission system of each layer will have built protocol data unit (units = pdus). Units = pdus contains the information from the top, and the current layer entities additional information. Then, the units = pdus being transferred to the next lower layers. In an actual physical Ed frame bits of these units = pdus transmission flow form by protocol stack, but higher build these units = pdus. The receiving system bottom-up transmitted through these subgroups and protocol stack in protocol stack of each layer of isolated units = pdus pertinent information. The important thing is that each layer attached to the information on the units = pdus is assigned to another system of the same layer. This is equivalent to a layer of communication session coordination. Through detachment from the transport layer segment header, and performance of this agreement data detection to determine as part of the transport layer protocol data segment of data, and performing section symbol verification and dissection, thus processing data segment. Also provide used for processing the data segment of the technology, which receives protocol data unit's header section. Using receives header parts to determine will be stored in application of bytes in space. Moreover, using receives header parts to finalize the next protocol data unit next header section. Then, issued a command to obtain peeping header section. Additionally provided for using the stored part cyclic redundancy check summary and residual data to carry out cyclic redundancy check technology.
classification
The SNMP stipulated the five kinds of protocol data unit units = pdus (i.e. SNMP message), used in management process and agent between the exchange. Get - that operation: from acting extraction process in one or more of the parameter value get - next - that operation: from acting in extraction process parameter value of follow closely the current under a parameter value set - that operation: setting agent process of one or more parameter value get - 5 operation: return to one or more of the parameter values. The operation is issued by the agent process, it is the front three operating response operation. Tissues operation: active agent process issued message, inform management processes have some things to happen.
In front of the three kinds of operation is by management processes to agency issued, behind the process of 2 operation is acting process to management processes, in order to simplify the reasons, front three operating in the future, get - called the get next and set operation. Figure 4 describes the SNMP these 5 kinds of message operation. Please note that in the process is known as agent with 161 to receive the get port or set, while in a message with the administration process is known as port 162 to receive message tissues.
No comments:
Post a Comment