Because HLE relies on the vRGW, it is carried in conjunction with vRGW home authentication and supports both implicit and explicit vRGW home authentication. Enabling the HLE service for a specific home (ESM subscriber) is triggered by a RADIUS server that returns an Alc-Bridge-Id message during home authentication.
The Alc-Bridge-Id attribute must be returned in both home and session authentication. The returned value must be equal on both authentication levels.
The Alc-Bridge-Id is the ID of the per-subscriber BD on the ISA. It is different from the Alc-BRG-ID, which is the ID of the BRG.
In addition to the Alc-Bridge-Id, the following optional attributes can be returned during BRG authentication:
HLE BGP EVPN route target: Alc-RT
HLE BGP EVPN route distinguisher: Alc-RD
HLE BGP EVPN VXLAN VNI: Alc-Vxlan-VNI