Questions about ML Arista with OpenStack

Hi guys,

I build a testbed OpenStack with an Arista router as TOR. I tried ML2 features but it’s not clear to me in some facets. Here are my concerns and I want to know more detail about them.

1. ML2 Hierarchical Port Binding
As I know this feature is used to offload encap/decap VXLAN packets at physical router TOR rather than using software (such as ovs) on compute node.
However in my testbed, I only use one Arista TOR router connect to compute node A. I have another compute node B without any TOR connected to it. Does ML2 HPB support creating VXLAN network to connect VM on compute node A and B like traffic is encapsulated VXLAN on TOR and decap-ed VXLAN by ovs on compute node B?

2. About configuration the ML2 HPB above
In OpenStack Deployment Guide, I’m not clear the value bridge_mappings.
If compute node A connect to TOR A, compute B connect to TOR B, what’s the value bridge_mappings on
– neutron server node
– compute node

3. Arista L3 Service
Using this feature, I configure service_plugins = arista_l3. If I create a router to connect some virtual networks, so on my Arista router, I see vlan interface is configured. Is this feature only support on vlan network? Because I see that with VXLAN networks, routing still happens on network node.

Thank you so much.