FAT Implementation Example
In a data center leaf-spine fabric, multiple equal-cost paths exist between leaf switches (PEs) across the spine (core). Without FAT labels, EVPN traffic uses a single entropy-less service label, limiting load distribution. With FAT labels:
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Each flow receives a unique entropy label. |
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Core P-routers hash on the FAT label, distributing traffic across all spine links. |
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This achieves near-equal bandwidth utilization and avoids congestion. |
EVPN Service Inactive
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Verify FAT label configuration consistency across PEs. |
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Ensure control-word settings match between peers. |
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Confirm FAT label is present at BOS in MPLS stack using packet captures. |
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Check core router hashing algorithms to ensure they use MPLS labels for entropy. |
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Interoperability Issues |
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If the peer does not support FAT labels, disable static FAT configuration to maintain connectivity. |