SDN Forwarding Table Resynchronization Using Pre-Post Synchronization Indicators
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Solution Overview
Problem
Existing methods for resynchronizing forwarding states in software-defined networks (SDNs) after connectivity disruptions between the control plane and data plane are inefficient, often disrupting packet processing and requiring significant bandwidth or implementing extra states in the network controller.
Innovation Solution
The method involves updating a subset of forwarding table entries with a post-synchronization indicator and deleting entries with a pre-synchronization indicator, allowing for selective updates and efficient resynchronization without disrupting packet processing, using OpenFlow commands to manage flow and group table entries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional resynchronization methods are used to restore forwarding states after connectivity disruption, then the control plane and data plane can be resynchronized, but packet processing is disrupted and significant bandwidth is consumed
Solution Approach 1:
The patent applies preliminary action by pre-tagging forwarding table entries with synchronization indicators (pre-synchronization and post-synchronization tags) before connectivity disruption occurs. When disruption happens, the network element can immediately identify and update only the affected entries using these pre-established tags, avoiding the need to re-synchronize the entire forwarding table and thus maintaining packet processing continuity while ensuring reliable resynchronization of only necessary entries.
2Reliability
If complete forwarding table resynchronization is performed after connectivity disruption, then all forwarding states are updated, but bandwidth requirements increase significantly
Solution Approach 1:
The patent extracts and identifies only the specific forwarding table entries that require resynchronization by using synchronization indicators (pre-synchronization and post-synchronization tags) attached to individual entries. Instead of transmitting and processing complete forwarding tables, the system extracts and updates only the necessary subset of entries, significantly reducing bandwidth consumption while maintaining forwarding state consistency.
3Productivity
If selective updating of forwarding table entries is implemented, then bandwidth is reduced and packet processing continues, but the complexity of tracking and managing synchronization states increases
Solution Approach 1:
The patent applies local quality by assigning different synchronization indicators (pre-synchronization tag, post-synchronization tag) to different forwarding table entries based on their individual synchronization status. This localized tagging approach allows the network element to efficiently identify and update only specific entries that need resynchronization, reducing overall system complexity compared to global resynchronization methods while maintaining high network efficiency.
Data Source
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AI summary
A method, in a network controller of a control plane in a software defined network (SDN) coupled to a network element (NE) of a data plane in the SDN, of re synchronizing forwarding table entries of the NE according to forwarding table entries of the network controller is disclosed. The method includes causing the NE to update a first subset of forwarding table entries from a set of one or more of forwarding table entries to include a post-synchronization indicator. The method continues with causing the NE to delete, following the update of the first subset of forwarding table entries, a second subset of zero or more forwarding table entries from the set of forwarding table entries, where each forwarding table entry from the second subset includes a pre -synchronization indicator.