Multi-destination Packet Forwarding via Synchronized Election
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Solution Overview
Problem
Existing technologies face challenges in efficiently forwarding multi-destination packets in virtual networks, particularly during failover events, leading to packet duplication due to concurrent designation of forwarders by partner switches.
Innovation Solution
The solution involves a switch architecture with a network-virtualization module, update module, acknowledgment module, and election module that ensures synchronized route updates and designates a single forwarder for multi-destination traffic by using indicators in route update messages to prevent duplication, particularly through the use of a transitive Extended Community field in BGP route updates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple PE switches independently elect designated forwarders for multi-destination traffic during failover events, then high-availability operation is maintained, but packet duplication occurs due to concurrent designation
Solution Approach 1:
The patent implements a feedback mechanism where PE switches send route update messages to notify partner switches of forwarding segment changes. Partner switches respond with route update messages containing indicator values (e.g., ESI, VLAN ID, PE switch identifier) that provide feedback on their forwarding state. This feedback loop ensures that designated forwarder elections are coordinated, preventing concurrent designation and packet duplication while maintaining high-availability operation during failover events.
2Productivity
If switches increase size and capability to handle more traffic efficiently, then bandwidth capacity improves, but system complexity and cost increase
Solution Approach 1:
The patent segments the forwarding function by designating specific PE switches as designated forwarders for specific forwarding segments and VLANs. Instead of requiring all switches to handle all multi-destination traffic, the system divides the forwarding responsibility among multiple PE switches based on their role as designated forwarder for particular segments. This segmentation allows traffic handling capacity to scale across multiple switches without requiring each individual switch to be overly large and complex.
Data Source
AI summary
One embodiment of the present invention provides a switch. The switch includes a network-virtualization module, an update module, an acknowledgment module, and an election module. During operation, the network-virtualization module establishes a forwarding segment for an end device multi-homed with the switch and a second switch. The forwarding segment can be identified by a segment identifier persistent in the switch and the second switch. The update module constructs, for the second switch, a first route update message comprising an indicator value for the forwarding segment. The acknowledgment determines the indictor value in a second route update message from the second switch as an acknowledgment for the first route update message. If the switch receives the acknowledgment from a respective switch participating in the forwarding segment, the election module initiates a designated forwarder election for the forwarding segment. The designated forwarder is responsible for forwarding multi-destination traffic in the forwarding segment.