Data search apparatus and internetwork relay apparatus using data search apparatus

An internetwork relay apparatus for analyzing a form and a protocol of a received transmission frame from the contents of field data of the received frame to perform relay processing on the transmission frame according to the analyzed result, comprising:

• a first memory where field data representing a frame form and a protocol of each of all transmission frames to be subjected to relay processing is divided into a plurality of portion data each having a predetermined length, a plurality of search sequences different from one another are set on the basis of the portion data, and, for each sequence, associative data representing search control contents in the sequence is preliminarily stored so as to be associated with the portion data constituting the search sequence and a search identifier representing the search sequence;
• a second memory in which the transmission frame received is temporarily stored;
• first search means, each time when a transmission frame is stored in the second memory, for selectively reading one of the portion data from the field data to perform a search in the first memory on the basis of the portion data and the search identifier representing the search sequence;
• second search means for reading other portion data from the second memory according to an instruction of the associative data read from the first data read and the search identifier included in the associative data;
• and
• determination means for determining a search completion or a search continuation on the basis of the associative data read from the first memory by the first and second search means and for causing the second search means to perform search processing repeatedly in a case of the search continuation and outputting information representing the transmission frame form and the protocol of the transmission frame included in the associative data read in a case of the search termination;
• wherein the associative data comprises information for representing the search continuation or the search termination, information for specifying a reading-out position of the portion data to be searched next, and information for specifying the search identifier to be used for the next search.