Closed loop formation preventing system and closed loop formation preventing method

摘要

In an open flow network system in which there are a plurality of networks, in each of which one OFC (OpenFlow Controller) manages a plurality of OFSs (OpenFlow Switches), and a large network is formed by a combination of them, registration of a flow entry which forms a closed loop is prevented without a component and a procedure for cooperation of the plurality of OFCs. Specifically, after route calculation, the OFC temporarily registers an flow entry of a calculation result on a flow table of the OFS as the flow entry for a test. After that, the OFS flows the test packet according to the temporarily registered flow entry. When the test packet is routed without forming the closed loop, the OFS detects it and normally registers the flow entry for a first time. Detecting that the test packet forms a closed loop, the OFS deletes a temporarily registering flow entry and returns an error to the OFC.

主权项

1. A closed loop formation preventing system comprising:
a switch configured to receive a packet and transfer the packet based on a flow entry registered on a flow table; and a controller configured to register the flow entry on the flow table in response to an inquiry from said switch, wherein said switch comprises: means for confirming whether or not the received packet is a test packet; means for confirming whether or not there is the flow entry matching the received packet in existing flow entries of the flow table, when the received packet is not the test packet; means for inquiring to said controller when there is no flow entry matching to the received packet; generating means for generating the test packet based on the flow entry temporarily registered from said controller; means for retaining the received packet, transferring the test packet based on the temporarily registered flow entry and starting a test for detecting formation of a closed loop; and means for discarding the temporarily registered flow entry when detecting the formation of the closed loop as a result of the test.