EVPN Designated Forwarder Election Using Link Bandwidth Feedback
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Solution Overview
Problem
Current designated forwarder (DF) election methods in Ethernet virtual private networks (EVPN) lead to heavy load or overload on links due to inadequate consideration of link bandwidth usage during the election process.
Innovation Solution
A method for electing a designated forwarder based on bandwidth information, including available and used bandwidth rates, to balance the load across links, ensuring that the designated forwarder with higher available or lower used bandwidth is selected for a larger number of VLANs or EVPN instances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If DF election is based on source IP address sequence or VLAN ID formula, then the election process is simple and deterministic, but it causes heavy load or overload on links because it does not consider actual bandwidth usage
Solution Approach 1:
The patent changes the election parameter from static IP address sequence or VLAN ID to dynamic bandwidth information. The DF election now considers actual link bandwidth usage, available bandwidth, and bandwidth rates, transforming the election from a purely deterministic process to one that adapts to real-time network conditions, thereby preventing link overload while maintaining election simplicity through standardized information exchange mechanisms
Solution Approach 2:
The patent introduces feedback mechanisms where PEs exchange bandwidth notification messages containing information about link bandwidth usage, available bandwidth, and bandwidth rates. This feedback loop allows the DF election to continuously adapt to changing network conditions, ensuring that traffic is always forwarded through the PE with the most available bandwidth capacity, thus preventing link overload
2Device complexity
If a single DF handles all VLANs or EVPN instances, then the election process is simplified, but it creates traffic concentration and potential bottlenecks on that PE's links
Solution Approach 1:
The patent applies local quality by allowing different PEs to be elected as DF for different VLANs or EVPN instances based on their respective bandwidth capacities. Instead of a uniform single-DF approach, each VLAN/EVPN instance can have a DF selected according to the specific bandwidth conditions, optimizing traffic distribution across multiple PEs and preventing any single link from becoming a bottleneck
3Loss of time
If DF election does not consider bandwidth information, then the election is faster and requires less information exchange, but it leads to suboptimal traffic routing and link congestion
Solution Approach 1:
The patent implements preliminary action by having PEs proactively send bandwidth notification messages to each other before DF election is needed. This pre-exchange of bandwidth information (including link bandwidth, used bandwidth, and available bandwidth) allows the DF election to proceed quickly using already-available data, while still achieving optimal traffic routing decisions based on current network conditions
Data Source
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AI summary
Embodiments of this application relate to the field of data communications technologies, and provide a designated forwarder election method and device, to avoid a problem of heavy load or even overload of traffic on a link. The method includes: A first PE receives a bandwidth notification message sent by another PE, where the first PE and the another PE are connected to a first CE, and the bandwidth notification message includes bandwidth information of a link between the another PE and the first CE; and the first PE elects a DF from the first PE and the another PE based on the bandwidth information of the another PE and bandwidth information of a link between the first PE and the first CE. Based on this solution, the DF may be elected, based on the bandwidth information of the links to the first CE, from the first PE and the another PE connected to the first CE, so that the DF election process considers the bandwidth information of the links and load on different links in a DF election result. This can avoid heavy load or even overload on the links.