| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a method or the like of monitoring an UPDATE message based upon BGP through a normal sequence, to specify in real time a failed link which actually occurs. <P>SOLUTION: An observer node device determines, for each of links between node devices on a normal-state path, a prefix advertised from an upstream-side node device of the link as a monitored prefix. Then the observer node device measures only an UPDATE message including the monitored prefix. Further, the observer node device counts unmatched prefixes such that a reception path of the received UPDATE message is unmatched with the normal-state path. The observer node device extracts a link in which the unmatched prefix count of the link reaches the number of all monitored prefixes that the upstream-side node device of the link should advertise. The observer node device determines a link closest to the observer node device on the normal-state path among extracted links as a failure. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
