Taking Cisco SD-WAN to the Next Level : Multi-Region Fabric (MRF)

Taking Cisco SD-WAN to the Next Level 
Multi-Region Fabric

Cisco SD-WAN Multi-Region Fabric lets you take advantage of the best of both worlds: the ability to divide the Cisco SD-WAN overlay network into multiple, while having region to manage inter-regional traffic.

Plus, with the release of Cisco vManage Release 20.7.1 and minimum software version for Cisco IOS XE Cisco SD-WAN devices IOS XE Release 17.7.1a, you can take advantage of the hierarchical design in order to optimize cost and traffic performance. 

This way, you can employ multiple traffic transport service providers for each area and the central core-region, which creates a strong, adaptable topology that can help prevent routing failures in some network settings and simplifies traffic design in others.

Cisco SDWAN Multi-Region Fabric (MRF)
Fig 1.1-Cisco SDWAN Multi-Region Fabric (MRF)

Traffic Between Regions and Within Regions
Cisco SD-WAN vEdge/cEdge routers communicate with other Cisco SD-WAN vEdge/cEdge routers in the region directly during intra-regional traffic. Direct tunnels are used for the traffic to go between the source and destination devices.

Cisco SD-WAN vEdge/cEdge routers in various regions are not physically connected to one another. When there is inter-regional traffic, the edge routers connect to the core border routers, which then forward the traffic to the core border routers designated for the target region, who then forward the traffic to the edge routers located in the target area. Between the source device and the destination device, the traffic passes via three tunnels.

Benefits of Multi-Region Fabric

  • Policy-caused traffic routing failures are prevented, especially routing failures that can occur when a device responsible for one of the hops between the source and destination of a traffic flow is unavailable.
  • Flexibility in selecting the optimal mode of transportation for each location can result in improved traffic performance across geographical regions. In a typical use scenario, a company arranges for premium traffic transit in the core region, resulting in improved traffic performance throughout distant geographical regions.
  • Controlling how traffic is routed across domains, such as geographical areas, is helpful in some cases. The Multi-Region Fabric architecture makes this easier.
  • The Multi-Region Fabric architecture distinguishes between edge and border routers. This allows you to construct site-to-site traffic pathways between discontinuous providers, which are two providers that cannot be reached directly via IP routing. If each site is connected to a core-region border router, the core-region network can connect the two sites.

Restrictions while using Multi-Region Fabric (MRF)

  • Multi-tenancy and end-to-end SLA aware routing for edge routers/border routers not supported
  • There is no support for Overlay Management Protocol (OMP) route aggregation on border routers or IP multicast on overlays.
  • A border router always applies the SLA policy of its region to traffic to and from other regions, regardless of whether the SLA setups in the other regions are supported.
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