VPLS Backup Forwarding Entry Generation for Fast Rerouting
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Solution Overview
Problem
In VPLS networks, when a designated forwarder or its pseudo wire fails, existing methods often result in unnecessary data packet broadcasting to all remote PEs, wasting bandwidth and processing resources, as they require relearning MAC addresses and path switching, which can cause service interruptions.
Innovation Solution
A method and device that generate a backup forwarding entry based on MAC address information learned from data packets, allowing seamless switching to non-designated forwarders without broadcasting, by synchronizing MAC forwarding table information between PEs and using backup entries to forward packets unicastly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing VPLS processing mechanism is used where PE learns MAC addresses according to received data packets and broadcasts when primary path fails, then service reliability is maintained through broadcast fallback, but bandwidth is wasted and processing resources are consumed unnecessarily
Solution Approach 1:
The patent applies preliminary action by pre-establishing backup forwarding entries that associate MAC addresses with multiple pseudo-wires before failure occurs. When the primary pseudo-wire fails, the remote PE can immediately switch to the backup entry and forward packets through the standby forwarder without broadcasting, thus maintaining service reliability while avoiding bandwidth waste.
Solution Approach 2:
The patent uses copying by creating backup forwarding entries that are copies of the primary forwarding entries. These backup entries contain the same MAC address information but are associated with alternative pseudo-wires, allowing fast failover without relearning MAC addresses or broadcasting packets.
2Reliability
If broadcast is used to forward packets when primary forwarder fails, then service continuity is ensured, but processing resources of PE are wasted
Solution Approach 1:
The patent prepares backup forwarding entries in advance that map MAC addresses to alternative pseudo-wires. When failure occurs, the remote PE performs a simple table lookup in the backup forwarding table and forwards packets unicastly through the standby forwarder, avoiding the need to broadcast to all PEs and thus conserving processing resources while ensuring service continuity.
3Reliability
If MAC address relearning and path switching is performed when forwarder fails, then correct forwarding path is restored, but service interruption occurs
Solution Approach 1:
The patent pre-configures backup forwarding entries that associate MAC addresses with multiple pseudo-wires before failure occurs. When the primary pseudo-wire or forwarder fails, the remote PE can immediately consult the backup forwarding table and switch to the associated standby forwarder without needing to relearn MAC addresses or wait for broadcast-based path discovery, thus eliminating service interruption while maintaining forwarding path correctness.
Solution Approach 2:
The patent creates backup forwarding entries as copies of primary forwarding entries, with each backup entry containing the same MAC address information but associated with alternative pseudo-wires. This copying mechanism allows instant failover by simple table lookup, avoiding the time-consuming process of MAC address relearning and path switching.
4Loss of energy
If unicast forwarding is used with backup entries, then bandwidth is saved, but device complexity increases due to backup entry generation and management
Solution Approach 1:
The patent merges the backup forwarding functionality with the existing forwarding table structure by creating backup forwarding entries that follow the same format and organization as primary entries. The backup entries are generated automatically from the same MAC address learning process, and the switching between primary and backup entries is managed through a unified control mechanism, thus reducing the perceived complexity while enabling bandwidth-efficient unicast forwarding.
Data Source
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AI summary
Embodiments of the present invention provide a virtual private local area network service VPLS fast rerouting method and device. The method includes: generating, by a remote provider edge device PE, a backup forwarding entry; and when a designated forwarder or a designated forwarder pseudo wire in a mltihoming protection group fails, or the designated forwarder is switched in the multihoming protection group, forwarding by the remote PE, a data packet according to the backup forwarding entry, thereby avoiding broadcasting the data packet to all remote PEs that belong to the same VPLS instance, and further reducing a waste of bandwidth resources in a backbone network and processing resources of the PE.