Add BGP VPN Interconnection Service

The service aims at supporting inter-connection between L3VPNs
and Neutron resources, i.e. Networks, Routers and Ports.
The framework is generic to also support E-VPN [RFC7432],
which inherits the same protocol architecture as BGP/MPLS IP VPNs.

Related-Prod: PROD-17612
Change-Id: I236016669160f5bc6b52d5563b6471be820ec271
diff --git a/metadata/service/control/single.yml b/metadata/service/control/single.yml
index d0ee1c5..939856c 100644
--- a/metadata/service/control/single.yml
+++ b/metadata/service/control/single.yml
@@ -17,6 +17,9 @@
       security_groups_enabled: true
       qos: false
       vlan_aware_vms: false
+      bgp_vpn:
+        enabled: false
+        driver: bagpipe
       version: ${_param:neutron_version}
       controller_vip: ${_param:single_address}
       bind: