Dynamic Multipath Forwarding via Virtual MAC Addresses
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Solution Overview
Problem
Current software-defined networking (SDN) architectures face inefficiencies in multipath forwarding due to limited storage capacity in switches, particularly in Ternary Content Addressable Memory (TCAM), which restricts the implementation of fine-grained forwarding rules, leading to coarse-grained rule aggregation and reduced flexibility in managing network traffic.
Innovation Solution
The implementation of dynamic multipath forwarding in SDN networks involves assigning virtual destination MAC addresses to multiple forwarding paths, installing virtual destination-based forwarding rules, and configuring ingress switches to dynamically select paths based on a multipath policy, allowing for efficient per-flow multipathing without requiring new hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If fine-grained forwarding rules are implemented in switches, then network traffic management flexibility is improved, but TCAM storage capacity is exceeded
Solution Approach 1:
The patent introduces a new dimension by assigning virtual destination MAC addresses to different forwarding paths. Instead of storing all fine-grained forwarding rules in TCAM, the system uses virtual MAC addresses as an additional dimension for path identification, allowing switches to forward packets along specific paths without requiring exhaustive rule storage in limited TCAM memory.
Solution Approach 2:
Virtual destination MAC addresses serve as intermediaries between the control plane and data plane. The SDN controller assigns virtual MAC addresses to represent different forwarding paths, and switches use these virtual addresses for forwarding decisions. This intermediary mechanism enables fine-grained path control without requiring switches to store complex forwarding rules, thus resolving the TCAM capacity constraint.
2Productivity
If multiple forwarding paths are supported, then link utilization and bandwidth are improved, but path selection complexity increases
Solution Approach 1:
The patent implements dynamic path selection where the SDN controller can dynamically assign virtual MAC addresses to different forwarding paths based on real-time network conditions. The controller monitors link utilization and dynamically adjusts path assignments, enabling adaptive load balancing and optimized resource utilization without requiring complex static configuration at switches.
Solution Approach 2:
The system changes the parameter of destination MAC address from a fixed real address to a dynamic virtual address that encodes path information. By modifying the destination MAC address parameter, the system can direct packets along different paths without changing the underlying network topology or requiring complex path selection logic at each switch. The virtual MAC address acts as a parameter that carries path selection information.
3Adaptability or versatility
If virtual destination addresses are assigned to multiple paths, then path selection flexibility is improved, but address management complexity increases
Solution Approach 1:
The SDN controller implements self-service by automatically generating and managing virtual destination MAC addresses for multiple forwarding paths. When a new path is created or network conditions change, the controller autonomously assigns appropriate virtual MAC addresses and updates switch forwarding tables without requiring manual configuration. This self-service approach manages address complexity centrally while maintaining flexibility at the network edge.
Solution Approach 2:
Virtual destination MAC addresses serve multiple functions simultaneously: they identify destination endpoints, encode forwarding path information, and enable load balancing across multiple paths. This multi-functionality reduces the need for separate mechanisms for path identification and selection, simplifying address management while maintaining flexibility. A single virtual MAC address carries multiple pieces of information that would otherwise require separate management.
Data Source
AI summary
A mechanism is provided in a logically centralized controller for dynamic multipath forwarding in a software defined network. The mechanism identifies a set of multiple forwarding paths for a flow. The mechanism assigns a virtual destination address for each multiple forwarding path in the set of multiple forwarding paths. The mechanism installs virtual destination address based forwarding rules in switches for each multiple forwarding path and installs rewriting rules in an egress switch for all paths in the set of multiple forwarding paths. Each rewriting rule rewrites one of the virtual destination address to the real destination address. The mechanism configures an ingress switch to dynamically select a path from the set of multiple forwarding paths based on a multipath policy and rewrite the destination address from the real destination address to a virtual destination address corresponding to the selected path.