As per wikipedia – Fusion is the process of combining two or more things together into one.
So it is the same here – when you deploying SD-Access in the Brown or Green Field deployment – you need to integrate exiting Live Traditional network with the new SD-Access Fabric network. ( Since most of the shared Services always resides outside Fabric).
Cisco SD-Access Border connecting External Domain with existing Global Routing Table should use a “Fusion” router with MP-BGP & VRF import/export.
The function of aggregating VRFs (VNs) and/or leaking routes between them can be done on any device that supports the features required (VRF, BGP, etc.) – this mostly connected to exiting CORE Routers.
Example like below Fabric with Shared Services (where Shared Services will be located in Existing DC Environment).
Network Layer connection to exiting DC or CORE network.
• What traffic will be routing through this device?
• What protocol is used in the Global Routing Table?
• What type of leaking does the protocol support (route-map, etc.)?
• What Subnets/Routes need to be shared?
Finally, The Role of Fusion Router in the fabric VRF’s subnets that need access to these shared services will be leaked into GRT(Global Routing Table), and vice-versa. Route maps can be used to help contain routing tables to subnets specific to SDA Fabric.
What device can be use here for Fusion Router – Personally any device which support below features ( can be router / switch / Firewall)
– IP routing
– Support for dynamic routing protocols (ISIS, BGP, EIGRP, etc.)
– VRF support
– Route redistribution
here is the step by step configuration from cisco document :
configuring fusion router –
Happy Labbing !!!!!