Virtual Links in Routed Ethernet Mesh Networks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Link state protocol controlled Ethernet networks face congestion issues due to the lack of bandwidth reservation, leading to traffic drop and application degradation, and require techniques to divert traffic from overloaded links to underutilized ones for capacity management and maintenance purposes without disrupting the network topology.
Innovation Solution
The implementation of virtual links with the same cost metric as the shortest path allows for traffic diversion by establishing a secondary path within the network, using a routing system to advertise and instantiate forwarding state, enabling nodes to preferentially select the virtual link over the shortest path through an Equal Cost Multi Path (ECMP) process, thereby manipulating traffic distribution without affecting other patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If link state protocol controlled Ethernet network uses shortest path forwarding, then network traffic follows optimal paths, but network congestion occurs on overloaded links
Solution Approach 1:
The patent introduces virtual links as intermediary logical paths that mediate between source and destination nodes. These virtual links allow traffic to be diverted from physically overloaded links while maintaining the appearance of shortest path forwarding. The virtual link acts as a mediator that redirects traffic through alternative physical paths without requiring changes to the underlying link state protocol or shortest path calculations.
Solution Approach 2:
The patent changes the forwarding behavior by introducing a new parameter: virtual link preference. Nodes are configured to prefer virtual links over traditional shortest path links when both are available. This parameter change allows traffic to be steered away from congested links while maintaining compatibility with the existing link state protocol and shortest path forwarding mechanism.
2Reliability
If additional capacity is installed on overloaded links, then network congestion is reduced, but network topology disruption occurs during maintenance
Solution Approach 1:
The patent implements preliminary action by pre-establishing virtual links that replicate the functionality of physical links before maintenance is performed. The virtual links are configured in advance to carry traffic that would otherwise use the physical link scheduled for maintenance. This allows the physical link to be taken down for maintenance without disrupting network topology or causing traffic loss, as the virtual link is already in place to handle the traffic.
Solution Approach 2:
The patent creates a copy of the physical link functionality through virtual links. The virtual link replicates the routing and forwarding characteristics of the physical link it protects, allowing traffic to be diverted to the virtual copy when the original physical link needs maintenance. This copying mechanism maintains network topology stability while enabling capacity management and maintenance activities.
3Reliability
If spanning tree protocol is used to prevent loops, then network loop-free operation is achieved, but link utilization is suboptimal
Solution Approach 1:
The patent segments the network forwarding paths by introducing virtual links as separate logical forwarding entities. Instead of using a single spanning tree structure that blocks certain physical links, the virtual links create additional segmented paths that can be actively used for forwarding. This segmentation allows multiple paths to be simultaneously active and usable, improving link utilization while maintaining loop-free operation through the virtual link abstraction.
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
Virtual links may be used to divert traffic within an Ethernet network without affecting overall traffic patterns on the Ethernet network. In one embodiment, the virtual link may be established on the network via a routing system in use on the network. Nodes on a defined path for the virtual link will install forwarding state for the virtual link so that traffic may follow the defined path through the network. The logical view of the virtual link, from a routing perspective however, has the same cost as the shortest path between the endpoints of the virtual link and, accordingly, does not affect other traffic patterns on the network. Once established, the end nodes on the virtual path will have two equal cost paths through the network - one following the shortest path tree and one along the path for the virtual link. The end nodes may use a tie breaking process in an Equal Cost Multi Path (ECMP) selection process to preferentially select the virtual link over the shortest path.