Ethernet Virtual Private Network MAC Learning via Data Plane
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Solution Overview
Problem
In large Ethernet virtual private networks, the existing mechanism for MAC learning using BGP signaling leads to explosive signaling overheads, reducing the scalability of the control plane and failing to implement flow-based load sharing in multihoming scenarios.
Innovation Solution
A method where a local PE device learns a remote MAC address based on an Ethernet segment (ES) and forwards packets using ES route information, reducing the need for control plane signaling and enabling flow-based load sharing by establishing a correspondence between ES and MAC addresses through a data plane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If BGP signaling is used to advertise each customer MAC on a same E-VPN, then MAC reachability information can be obtained, but signaling overheads increase explosively when network size is very large
Solution Approach 1:
The patent segments the MAC address information into two parts: the customer VLAN ID (CVLAN ID) and the customer MAC address (C-MAC). Instead of advertising complete C-MAC routes for each MAC, the system advertises only CVLAN ID routes on the control plane. The complete MAC reachability information is then obtained through data plane packet forwarding, where the encapsulated CVLAN ID and C-MAC are used to identify remote MAC addresses. This segmentation dramatically reduces control plane signaling overhead while maintaining complete MAC reachability information.
Solution Approach 2:
The patent introduces an intermediary mechanism using Ethernet Segment (ES) identification and CVLAN ID encapsulation. The ES identifier acts as an intermediary that groups multiple MAC addresses under a single route advertisement. When packets are forwarded, the CVLAN ID embedded in the data plane packets serves as an intermediary key that allows PE devices to learn remote MAC addresses without requiring direct C-MAC route advertisements. This intermediary approach reduces signaling overhead while preserving MAC reachability.
2Loss of information
If C-MAC routes are flooded to all PE devices on the same E-VPN, then complete MAC reachability is achieved, but control plane scalability is reduced
Solution Approach 1:
The patent segments MAC address advertising into control plane and data plane functions. The control plane only handles CVLAN ID route advertisements, which are significantly fewer in number compared to individual C-MAC routes. The data plane handles the propagation of complete MAC reachability information through encapsulated packets. This segmentation reduces control plane device complexity and improves scalability while maintaining complete MAC reachability information across all PE devices.
Solution Approach 2:
The patent moves MAC address propagation from the control plane to the data plane, effectively changing the dimension in which MAC reachability information is distributed. Instead of using control plane signaling (BGP) to advertise each MAC address, the system uses data plane packet forwarding with CVLAN ID encapsulation. This dimensional shift reduces control plane complexity and allows the network to scale more efficiently while still achieving complete MAC reachability information distribution.
3Productivity
If data plane MAC learning is used for local sites, then learning efficiency is improved, but remote site MAC learning still requires control plane signaling
Solution Approach 1:
The patent makes the data plane multi-functional by enabling it to perform both local and remote MAC learning functions. Through CVLAN ID encapsulation in data plane packets, the same data plane mechanism that provides efficient local MAC learning also enables remote MAC learning without requiring separate control plane signaling. This universal approach allows a single learning mechanism to handle both local and remote scenarios, improving overall productivity while reducing control plane complexity.
Data Source
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AI summary
Embodiments of the present invention provide a method and a device used for an Ethernet virtual private network, where the method includes: receiving, by a first provider edge PE device, a second data packet sent by a second PE device, where the second data packet carries a second label and a second source Media Access Control MAC address; and determining, by the first PE device according to the second label, that the second data packet is received by the second PE device from an Ethernet segment ES of the second PE device, and establishing a correspondence between the ES of the second PE device and the second source MAC address. Based on an ES and by using a data plane, a local PE learns a MAC address of a remote site, and there is no need to exchange C-MAC information by using a control plane, thereby reducing signaling overheads between PE devices on the control plane, and improving scalability of the control plane.