Explanation/Reference:
Section: Enterprise Network Design Explanation
Explanation
The Multiprotocol Label Switching (MPLS) WAN deployment model for branch connectivity supports both single-router and dual-router configurations. Cisco defines three general deployment models for branch connectivity:
MPLS WAN

Hybrid WAN

Internet WAN

The MPLS WAN deployment model can use a single-router configuration with connections to multiple MPLS service providers or a dual-router configuration where each router has a connection to one or more MPLS service providers. Service provider diversity ensures that an outage at the service provider level will not cause an interruption of service at the branch. The MPLS WAN deployment model can provide service- level agreement (SLA) guarantees for Quality of Service (QoS) and network availability through service- provider provisioning and routing protocol optimization. Although using multiple MPLS services provides increased network resilience and bandwidth, it also increases the complexity and cost of the deployment when compared to other deployment models.
The Hybrid WAN deployment model can use a single or dual-router configuration and relies on an MPLS service provider for its primary WAN connection and on an Internet-based virtual private network (VPN) connection as a backup circuit. Unlike the MPLS WAN deployment model, the Hybrid WAN deployment model cannot ensure QoS capabilities for traffic that does not pass to the MPLS service provider. In the Hybrid WAN deployment model, low-priority traffic is often routed through the lower cost Internet VPN circuit, which can reduce the bandwidth requirements for the MPLS circuit, further lowering the overall cost without sacrificing network resilience.
The Internet WAN deployment model can use a single or dual-router configuration and relies on an Internet-based VPN solution for primary and backup circuits. Internet service provider (ISP) diversity ensures that carrier level outages do not affect connectivity between the branch and the central site.
Because the Internet WAN deployment model uses the public Internet, its QoS capabilities are limited.
However, the Internet WAN deployment model is the most cost effective of the three models defined by Cisco.
Reference:
CCDA 200-310 Official Cert Guide, Chapter 7, Branch Connectivity, p. 271