Per-CE Label Packet Forwarding with VRF Load Balancing
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Solution Overview
Problem
Communications networks face challenges in reliably forwarding packets when network topology changes, such as when a primary path becomes unavailable, as existing techniques often rely on single backup paths that do not efficiently distribute packet load across resources.
Innovation Solution
Implementing a packet switching device that uses per-customer edge (per-CE) labels to perform lookups in forwarding and Virtual Routing and Forwarding (VRF) data structures, allowing for the identification of output interfaces and load balancing across multiple egress line cards when primary links are unavailable, thereby distributing packet load across resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single backup path is used for packet forwarding when the primary path becomes unavailable, then network reliability is maintained, but resource utilization efficiency deteriorates due to concentrated packet load on limited backup resources
Solution Approach 1:
The patent segments the backup forwarding resources by creating multiple egress Virtual Routing and Forwarding (VRF) instances, each associated with specific egress line cards. Instead of relying on a single backup path, the backup forwarding capability is divided across multiple segmented paths through different egress VRFs, allowing packet load to be distributed to multiple egress line cards simultaneously, thereby improving resource utilization efficiency while maintaining network reliability
Solution Approach 2:
The patent introduces a new dimension of forwarding by implementing per-Customer Edge (CE) label-based lookup that maps to multiple egress VRFs. This dimensional expansion allows the system to move from a single-dimension backup path to a multi-dimensional forwarding structure where packets can be routed through multiple egress line cards based on the per-CE label, effectively distributing the packet load across additional forwarding dimensions
2Productivity
If per-CE label-based forwarding with multiple egress VRFs is implemented, then resource utilization efficiency is improved through load distribution, but device complexity increases due to additional data structures and lookup operations
Solution Approach 1:
The patent merges the per-CE label forwarding function with the existing egress VRF data structure. By integrating the per-CE label lookup with the egress VRF association, the system reuses existing data structures (FIB, egress VRF tables) rather than creating entirely new complex structures. This merging approach allows multiple egress VRFs to be associated with a single per-CE label entry, distributing packet load across multiple egress line cards while minimizing the increase in device complexity through structural integration
3Measurement precision
If per-CE label lookup in forwarding data structure is performed, then forwarding precision is improved for identifying specific output interfaces, but lookup operation time increases due to additional processing steps
Solution Approach 1:
The patent performs preliminary action by pre-establishing the association between per-CE labels and multiple egress VRFs in the forwarding data structure before packet arrival. The FIB is pre-configured with per-CE label entries that directly reference associated egress VRFs, so when a packet arrives with a per-CE label, the lookup operation can immediately retrieve the pre-computed egress VRF associations without performing complex real-time calculations, thereby reducing lookup operation time while maintaining high forwarding precision
Data Source
AI summary
In one embodiment, a packet switching device is configured to perform a lookup operation, based on a particular per-CE label (per-Customer Edge label) included in a particular packet, in a forwarding data structure for identifying forwarding information for the particular packet. When a corresponding outbound path is unavailable, a per-VRF (per-Virtual Routing and Forwarding) lookup operation in a VRF data structure, identified based on the particular per-CE label, based on a destination address of a packet encapsulated within the received packet. A corresponding packet is forwarded based on the results of the VRF lookup operation. In one embodiment, a set of more than one egress line card is identified based on this lookup operation, and packets of different routes are load balanced among egress line cards in this identified set of egress line cards.