OFS In-Band Communication via LLDP Controller List
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Solution Overview
Problem
The existing out-of-band connection mode between OpenFlow switches (OFS) and controllers (OFC) requires maintaining two independent physical networks and network management systems, leading to high costs.
Innovation Solution
An OFS in-band communication method that uses a controller list to store OpenFlow controller information, allowing the OFS to create or update entries based on received LLDP data packets, and establish TCP connections using flow tables to forward packets to the OFC, thereby integrating control plane signaling and forwarding plane data within a single network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If out-of-band connection mode is used between OFS and OFC, then reliable control plane communication is achieved, but networking costs increase due to requiring two independent physical networks and two network management systems
Solution Approach 1:
The patent merges the control plane and forwarding plane into a single physical network. The OFS uses its existing data plane resources to carry both data packets and control messages (LLDP packets) to the OFC, eliminating the need for separate out-of-band management networks. This is achieved by treating control plane communication as a special case of data plane forwarding.
Solution Approach 2:
The OFS's data plane is made universal by enabling it to handle multiple types of traffic: user data packets, LLDP control messages, and TCP connection establishment packets. The same physical network infrastructure and management system serve both forwarding and control functions, reducing overall system complexity.
2Ease of operation
If out-of-band connection mode is used, then control plane signaling is isolated from data plane, but network management costs increase due to maintaining two separate management systems
Solution Approach 1:
The patent combines control plane signaling and data plane operations into a single managed network. The OFC manages both data forwarding and control communication through one network management system, eliminating the need for separate management infrastructure while maintaining functional isolation through protocol-based separation.
Solution Approach 2:
The patent uses LLDP packets as intermediaries to carry control information through the data plane network. These LLDP packets serve as mediators that enable control plane communication over the data plane infrastructure, allowing the single management system to handle both control and data functions.
3Device complexity
If in-band communication method is implemented, then networking costs are reduced by using a single network management system, but controller discovery and connection establishment complexity increases
Solution Approach 1:
The OFS performs self-service by autonomously discovering the OFC through LLDP packet reception and processing. The OFS automatically creates controller list entries, monitors for LLDP packets, and establishes TCP connections without requiring manual configuration or complex discovery protocols. The system serves itself by using existing data plane resources for control plane functions.
Data Source
AI summary
An OFS in-band communication method and an OFS are disclosed. The method includes: receiving an LLDP data packet; creating a controller list entry or updating a controller list entry when it is determined, by using a role sub-field, that a sender type of the received LLDP data packet is OFC; acquiring a first-time TCP handshake packet used for establishing a TCP connection, and checking, according to a destination MAC and a destination IP that are carried in the TCP handshake packet, whether a corresponding controller list entry exists in a controller list; and if yes, updating a flow entry according to the MAC, the IP, and the in_port in the corresponding controller list entry in the controller list, so that an OFS can forward, by using a flow table, a packet to be sent to an OFC to the OFC.