A Proposal for Capacity-Aware Load Balancing in EVPN Multi-Homing
A Practical Proposal for Adding Capacity Awareness to EVPN Type 4 Routes — and Why Equal Load Balancing Was Never Truly Equal
Equal Load Balancing is Fiction
The picture has Provider Edge routers sharing a multi-homed customer site. PE1 has four uplinks bonded into a LAG. PE2 has two. Both advertise an EVPN Ethernet Segment route for the same ESI, and your network dutifully splits traffic 50/50 between them.
On paper, that’s perfectly balanced. In reality, every link on PE2 is carrying twice the load of every link on PE1. You have not balanced traffic — you have quietly overloaded half your fabric while the other half coasts.
EVPN knows which PEs share a segment, but it has no idea how much capacity each one actually brings to the table.
This is not a configuration mistake or an operator oversight. It is a structural gap in the protocol. RFC 7432...
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