OpenFlow Trunk Port Designation for Broadcast Packet Forwarding
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Solution Overview
Problem
Existing packet forwarding systems, such as those using OpenFlow, face challenges in appropriately forwarding broadcast and multicast packets when network topology changes occur, leading to redundant transmissions and unintended paths due to the lack of control over external relay apparatuses that form trunks with OpenFlow switches.
Innovation Solution
A control apparatus configures a trunk as a virtual logical link using physical links among relay apparatuses, including an external relay apparatus, and designates specific ports to control the forwarding of control target packets like broadcast and multicast, preventing redundant transmissions and loops by setting appropriate flow entries in the forwarding tables of relay apparatuses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flow entries are set in each OpenFlow switch to forward broadcast packets, then broadcast packets can be forwarded along predetermined paths, but the same packet is transmitted to certain destinations multiple times when external relay apparatuses are involved
Solution Approach 1:
The patent introduces a control apparatus as an intermediary between OpenFlow switches and external relay apparatuses. This control apparatus manages the trunk configuration and coordinates packet forwarding decisions, preventing duplicate transmissions by centrally controlling which switches forward broadcast packets to which destinations through the trunk.
Solution Approach 2:
The patent changes the state parameter of ports from ordinary to designated ports when forming trunks. This parameter change triggers different forwarding behavior - only switches with designated ports forward broadcast packets, while others drop them. This prevents redundant transmissions while maintaining reliable forwarding along predetermined paths.
2Device complexity
If no flow entry is set for broadcast packets, then the system operates with simpler configuration, but broadcast packets are forwarded along unintended paths
Solution Approach 1:
The patent performs preliminary action by pre-configuring designated ports and trunk relationships before broadcast packet transmission occurs. The control apparatus预先 designates specific ports on each switch as designated ports and establishes trunk configurations, so that when broadcast packets arrive, the forwarding paths are already predetermined and controlled, preventing unintended path forwarding.
3Adaptability or versatility
If trunk is configured by multiple physical links, then link redundancy and load balancing are achieved, but control over packet forwarding becomes difficult when external relay apparatuses are involved
Solution Approach 1:
The patent segments the trunk into multiple physical links while introducing a control apparatus that manages each link's forwarding behavior. By designating specific ports as designated ports and configuring specific flow entries, the system maintains link redundancy and load balancing capabilities while the control apparatus ensures proper packet forwarding control across all segments.
Data Source
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AI summary
A packet forwarding system comprises: first relay apparatuses that are connected to each other; second relay apparatus that comprises ports and that is connected to first relay apparatuses; and control apparatus that configures trunk serving as virtual logical link by using physical links among first and second relay apparatuses. The control apparatus determines designated port from ports of first relay apparatuses included in the trunk. When relay apparatus included in first relay apparatuses receives predetermined control target packet, control apparatus controls first relay apparatuses to transmit received control target packet via relay apparatus having the designated port. The packet forwarding system causes relay apparatuses, which form a trunk with an external relay apparatus that is not under control of a control 1 apparatus, to appropriately forward predetermined control target packets such as broadcast packets or multicast packets.