Network management device, method for managing network, and network system

A method for managing a network including a plurality of edge routers and a plurality of intermediate routers connected between the plurality of edge routers, the method comprising:

• calculating respective communication routes of traffic to be forwarded from each of the plurality of edge routers to an attack target device that receives an attack from an outside of the network;
• setting the communication route of traffic to a second router such that the communication routes merge at a first router;
• instructing the first router to suppress forwarding of traffic of the attack;
• and
• selecting the first router and the second router so as to satisfy a condition regarding a load of forward processing of traffic in the network and not to allow the traffic to loop from among the plurality of edge routers and the plurality of intermediate routers on the basis of a connection relationship between the plurality of edge routers and the plurality of intermediate routers.

A network system, comprising:

• a plurality of edge routers;
• a plurality of intermediate routers;
• and
• a management device configured to:
• calculate respective communication routes of traffic to be forwarded from each of the plurality of edge routers to an attack target device that receives an attack from an outside of the network,
• set a communication route of traffic to a second router such that the communication routes merge at a first router, and
• instruct the first router to suppress forwarding of traffic of the attack, wherein, the processor selects the first router and the second router so as to satisfy a condition regarding a load of forward processing of traffic in the network and not to allow the traffic to loop from among the plurality of edge routers and the plurality of intermediate routers on the basis of a connection relationship between the plurality of edge routers and the plurality of intermediate routers.