Loopback-Free Adaptive Routing via Ingress-Excluded AR Groups
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Solution Overview
Problem
Existing adaptive routing techniques in communication networks, such as those in Dragonfly-topology networks, face challenges in preventing loopback paths while maintaining performance, which can lead to packet reordering and degradation.
Innovation Solution
The method involves specifying Adaptive Routing (AR) groups for each destination address, where packets are routed through different egress ports than the ingress port, using multiple AR groups or a primary and secondary egress port approach to avoid loopback while minimizing reordering and memory usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If adaptive routing is used to select multiple paths for packet forwarding, then routing flexibility and load balancing are improved, but loopback paths may be created causing packet reordering and performance degradation
Solution Approach 1:
The patent segments the routing decision into two independent parts: (1) path selection based on destination address and ingress port, and (2) egress port selection from a restricted set that excludes the ingress port. This segmentation allows adaptive routing to operate while inherently preventing loopback paths, as the egress port is chosen from a subset that cannot include the ingress port.
Solution Approach 2:
The patent performs preliminary action by pre-defining the set of candidate egress ports for each destination address and ingress port combination, explicitly excluding the ingress port from this set before packet arrival. This preliminary restriction ensures that loopback-free routing is guaranteed without requiring complex real-time checks during packet forwarding.
2Productivity
If multiple egress ports are considered for adaptive routing, then load balancing and path diversity are improved, but memory requirements for routing tables increase
Solution Approach 1:
The patent applies local quality by creating different AR group configurations for different destination addresses and ingress ports. Each destination address has its own tailored AR groups that specify which egress ports are candidates, allowing the system to maintain multiple routing options where needed while using fewer options elsewhere, thus optimizing memory usage locally for each routing scenario.
Solution Approach 2:
The patent uses partial action by maintaining AR groups only for destination addresses that require adaptive routing, rather than for all possible destinations. For destinations that don't need adaptive routing, standard routing tables are used, reducing overall memory requirements while still providing load balancing where it is beneficial.
3Adaptability or versatility
If AR groups are specified for each destination address with multiple egress ports, then routing adaptability is improved, but device complexity increases
Solution Approach 1:
The patent achieves universality by designing AR groups that can serve multiple functions: they define candidate egress ports for adaptive routing, inherently prevent loopback by excluding ingress ports, and can be selectively applied to different destination addresses. This multi-functionality reduces the need for separate mechanisms for each function, thereby managing complexity while maintaining high adaptability.
Solution Approach 2:
The patent introduces dynamics by allowing the set of candidate egress ports in AR groups to be flexibly configured and adjusted based on network conditions, destination addresses, and ingress ports. This dynamic configuration enables the routing system to adapt to changing network topologies and traffic patterns without requiring complete reconfiguration, managing complexity through flexibility.
Data Source
AI summary
A method for communication includes, in a network node that includes a plurality of ports, specifying for a given destination address at least one Adaptive Routing (AR) group. The at least one AR group includes two or more ports over which packets destined to the given destination address are to be adaptively routed. A packet destined to the given destination address is received at the network node, via one of the ports serving as an ingress port. An egress port is adaptively selected for the packet, from the ports in the at least one AR group but excluding the ingress port over which the packet was received. The packet is routed to the selected egress port.