OpenFlow Controller Interlayer Address Resolution
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Solution Overview
Problem
In OpenFlow networks, efficient interlayer address resolution and aggregation of flow entries are challenging, especially when dealing with overlapping IP address spaces and the need to multiplex network services without relying on VLAN identification information.
Innovation Solution
A communication control system comprising a control server and forwarding nodes that perform interlayer address resolution using logical network identifiers and aggregate flow entries by storing network information and managing address resolution requests, allowing efficient packet processing and multiplexing of network services.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If ARP request packets are broadcast to the entire OpenFlow network for address resolution, then any communication device can be reached regardless of L2 domain, but the number of broadcast packets increases and network traffic is wasted
Solution Approach 1:
The OpenFlow network is segmented into multiple logical networks (L2 broadcast domains) using VLAN tags. ARP request packets are broadcast only within the specific logical network where the target device resides, rather than flooding the entire physical network. This segmentation reduces unnecessary network traffic while maintaining the ability to resolve addresses across different logical networks through the controller's routing functionality.
2Measurement precision
If separate flow entries are created for each communication device to handle ARP requests, then precise packet processing is achieved, but the number of flow entries increases significantly
Solution Approach 1:
Multiple flow entries that handle similar ARP processing logic are merged into a single flow entry at the OpenFlow controller. The controller uses a single flow entry to receive ARP request packets from any logical network, performs the address resolution processing centrally, and then distributes the appropriate ARP reply packets to the target devices. This merging reduces the total number of flow entries while maintaining precise packet processing through centralized control.
3Adaptability or versatility
If VLAN tags are used to identify logical networks for multiplexing, then network services can be multiplexed on the same physical infrastructure, but the system requires special VLAN identification information and cannot handle overlapping IP address spaces
Solution Approach 1:
The OpenFlow controller acts as an intermediary that manages logical network identification and routing. Instead of requiring end devices to understand and process VLAN tags and logical network identifiers, the controller intercepts packets, adds or modifies VLAN tags based on the destination logical network, and forwards packets through the appropriate paths. This intermediary approach enables network service multiplexing and handles overlapping IP address spaces without increasing complexity at the edge devices.
Data Source
AI summary
A communication control system includes a control server for controlling a process rule held in a forwarding node. The control server includes a network information storage unit for storing a logical network identifier which is an identifier of a logical network defined by setting of the forwarding node, and a correspondence relation between a device connected to the forwarding node and the logical network; and an address resolution unit for, upon receiving from the forwarding node an address resolution request for a destination communication device which is a destination of the packet or a communication device for forwarding the packet received from a source communication device which is a source of the packet to another device, performing interlayer address resolution for the destination communication device or the communication device, and setting the logical network identifier of the logical network to which the source communication device belongs.