EVPN E-Tree BUM Handling Through Post-Convergence Unicast
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Solution Overview
Problem
Existing network devices struggle to handle broadcast, unknown unicast, and multicast (BUM) traffic effectively in EVPN E-Tree configurations, as they lack the ability to enforce proper segmentation rules due to the absence of classification information in the traffic, leading to improper forwarding of BUM traffic.
Innovation Solution
Network devices are configured to initially drop potentially problematic BUM traffic and subsequently handle a known unicast version of this traffic after network convergence, leveraging unicast traffic handling to enforce EVPN E-Tree segmentation rules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If network devices forward BUM traffic in EVPN E-Tree configurations, then traffic delivery coverage is improved, but segmentation rule compliance deteriorates due to lack of classification information
Solution Approach 1:
The network device performs preliminary actions by dropping BUM traffic before network convergence is complete, and only forwards it after convergence when proper classification information is available. This ensures segmentation rules are enforced at the right time while still delivering traffic when conditions permit.
Solution Approach 2:
The forwarding behavior of BUM traffic is made dynamic based on network convergence state. The device transitions from dropping traffic to forwarding traffic as network conditions change, allowing flexible adaptation to maintain both delivery coverage and segmentation compliance.
2Reliability
If network devices drop BUM traffic to enforce segmentation rules, then segmentation compliance is improved, but traffic delivery completeness deteriorates
Solution Approach 1:
The device drops BUM traffic preliminarily during the network convergence period when classification information is unavailable, then resumes forwarding after convergence when proper segmentation can be enforced, balancing compliance with delivery completeness.
Solution Approach 2:
The traffic handling follows a periodic pattern: drop during pre-convergence phase, forward during post-convergence phase. This time-based differentiation allows the system to maintain segmentation compliance while ensuring traffic delivery when conditions allow.
3Quantity of substance
If network devices forward all BUM traffic without classification, then traffic delivery is improved, but network congestion increases due to improper forwarding
Solution Approach 1:
The device performs preliminary filtering by dropping unclassified BUM traffic before network convergence, preventing improper forwarding that would cause congestion. After convergence, when classification is available, it forwards traffic appropriately, balancing delivery with congestion prevention.
Solution Approach 2:
The device extracts and removes problematic BUM traffic lacking classification information from the forwarding path during pre-convergence, preventing it from causing network congestion while preserving delivery of properly classified traffic post-convergence.
Data Source
AI summary
An EVPN device may convey broadcast, unknown unicast, or multicast (BUM) traffic to one or more peer EVPN devices. Leaf-sourced BUM traffic may be dropped. After the network configuration for (known) unicast traffic has resolved, unicast versions of the BUM traffic may be appropriately forwarded to provide EVPN E-Tree service.