MPLS Local Bias Forwarding for Multihomed EVPN Segments
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Solution Overview
Problem
In Ethernet virtual private networking (EVPN) networks, multihomed devices face inefficiencies due to redundant packet forwarding when the designated forwarder is not utilized, leading to slower transmission speeds and resource wastage.
Innovation Solution
Ingress provider edge (IPE) devices label packets with an IPE identifier and forward them directly on the Ethernet segment if they are multihomed, while egress provider edge (EPE) devices refrain from forwarding if the IPE is also multihomed on the same segment, thus avoiding duplicative forwarding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If packets are forwarded by all multihomed provider edge devices on the Ethernet segment, then packet delivery reliability is improved, but transmission speed deteriorates due to redundant forwarding
Solution Approach 1:
The patent applies local quality by enabling different forwarding behaviors for different packet types at different devices. Specifically, IPE devices forward local packets directly on the Ethernet segment without MPLS encapsulation, while EPE devices suppress forwarding of packets where the IPE is also multihomed on the same segment. This creates localized optimization at each device based on its role and the packet characteristics.
Solution Approach 2:
The patent extracts the redundant forwarding function from the EPE devices by introducing a suppression mechanism. EPE devices that would normally forward packets are instead instructed to suppress forwarding when the IPE is multihomed on the same Ethernet segment, removing the redundant path while maintaining reliability through the IPE's direct forwarding capability.
2Reliability
If packets are forwarded through the designated forwarder, then network protocol compliance is maintained, but transmission speed deteriorates due to additional forwarding steps
Solution Approach 1:
The patent segments the packet forwarding process into two distinct paths: (1) the traditional path through the designated forwarder for general packets, and (2) an optimized direct path for local packets at IPE devices. This segmentation allows each path to be optimized independently, with the direct path bypassing the designated forwarder for local traffic while maintaining protocol compliance for other traffic types.
Solution Approach 2:
The patent introduces an intermediary mechanism in the form of packet classification and handling logic at IPE devices. This intermediary determines whether a packet should be forwarded directly or through the designated forwarder based on packet characteristics and device role, enabling selective optimization without breaking protocol compliance.
3Adaptability or versatility
If all provider edge devices perform packet forwarding, then network coverage is maximized, but device complexity increases due to redundant forwarding logic
Solution Approach 1:
The patent applies dynamics by making the forwarding behavior adaptive based on device role and packet characteristics. IPE devices dynamically switch between direct forwarding and traditional forwarding based on whether the packet is local and whether the IPE is multihomed on the same segment. EPE devices dynamically suppress forwarding based on similar conditions. This dynamic behavior reduces complexity by enabling devices to act simply based on pre-configured rules rather than complex decision logic.
Data Source
AI summary
An ingress provider edge (IPE) device of a provider network receives a packet from outside of the provider network. The IPE device determines the packet is to be transmitted to a device on an Ethernet segment on which the IPE device is multihomed. The IPE device transmits the packet on the Ethernet segment even though the designated forwarder for the Ethernet segment is from IPE device. Furthermore, the IPE device labels the packet with an IPE identifier that identifies the IPE device for the packet, and forwards the labeled packet to other devices on the provider network. An egress provider edge (EPE) device that is (a) multihomed on the same Ethernet segment as the IPE device and (b) is the designated forwarder for the Ethernet segment receives the packet. The EPE device refrains from transmitting the packet on the Ethernet segment.