EVPN-MPLS E-LAN flow-aware transport (FAT) label load balancing

You can configure provider edge (PE) devices to use FAT labels in an Ethernet VPN-MPLS (EVPN-MPLS) routing instance, according to Request for Comments (RFC) 6391. PE devices use these labels to load-balance EVPN-MPLS unicast packets across equal-cost multipaths (ECMPs) without performing deep packet inspection of the MPLS payload. This feature supports emulated LAN (ELAN) with single-homing and multi-homing active/standby and active/ active topologies and supports the VLAN-based, VLAN-bundle, and VLAN-aware bundle EVPNMPLS variants.

NOTE: This feature does not support MX Series devices with Advanced Forwarding Toolkit (AFT) cards. NOTE: On MX Series devices, a configuration where the local PE has a static-flow-label and the remote PE does not have a static-flow-label, the remote PE can process packets without dropping any traffic. Enabling Load Balancing Using Fat Labels for EVPN Routing Instances:

WARNING: Configuring a flow label or deleting a flow label with the following CLI commands causes a catastrophic event for the routing instance. As a best practice, perform these CLI commands during a maintenance period to avoid network disruptions.

• Configure the flow-label-static statement at the [edit routing-instances routing-instance-name protocols evpn] hierarchy level on PE devices to insert FAT flow labels into pseudowire packets sent to remote PE devices.
• Configure the flow-label statement at the [edit routing-instances routing-instance-name protocols evpn] hierarchy level on PE devices to signal flow-label capability in the EVPN Layer 2 Attributes Extended Community by setting the flow-label (F) bit in the EVPN Type 3 route.