300-420 Exam Dumps : Designing Cisco Enterprise Networks (ENSLD) v1.1

Cisco SD-WAN components map to distinct control, management, orchestration, and forwarding roles. vManage is the centralized management plane used for configuration templates, monitoring, software management, and operational visibility. vSmart is the centralized control-plane component that distributes OMP routes, TLOC information, security parameters, and centralized policy to WAN Edge devices. vBond is the orchestration component used during onboarding; it authenticates devices, helps them discover controllers, and assists with NAT traversal. The WAN Edge router, whether physical or virtual, forms the data plane at the branch, campus, or data center and forwards user traffic through secure overlay tunnels. Correctly identifying these roles is essential because SD-WAN scale and resiliency depend on separating management, control, orchestration, and forwarding responsibilities. A design that confuses vManage with vSmart or vBond will misplace policy, onboarding, and forwarding functions. Reference topics: Cisco SD-WAN architecture, vManage, vSmart, vBond, WAN Edge, OMP, overlay control plane.

The most efficient campus design aligns the active first-hop gateway with the Layer 2 forwarding path. In a traditional access-distribution topology using STP and HSRP, traffic should not cross the distribution-to-distribution link simply because the HSRP active gateway is on the opposite distribution switch from the STP forwarding path. Cisco campus design guidance stresses aligning the STP root bridge with the active FHRP gateway so hosts forward northbound traffic directly to the distribution switch that owns the optimal Layer 2 path. Reconfiguring distribution switch A to become the HSRP active device fixes the asymmetric and inefficient traffic flow in the exhibit. Adding a link between access switches would extend the Layer 2 domain and increase loop-prevention complexity, not improve the northbound default-gateway path. Changing the distribution interconnect to a routed link may be valid in a routed-access redesign, but it is not the targeted correction for this Layer 2/FHRP misalignment. An EtherChannel between distribution switches only increases interswitch capacity; it does not remove the unnecessary hairpin path caused by the wrong active gateway.

L2VPN is the correct solution because the customer requires point-to-point connectivity while preserving existing VLAN infrastructure. Cisco describes Layer 2 VPN services as emulating Layer 2 connectivity across a provider IP or MPLS backbone, commonly through Ethernet pseudowires or VPWS. This allows sites such as dispersed data centers and a colocation facility to exchange Ethernet frames as if they were directly connected at Layer 2. The design is especially useful when data center synchronization, backup workflows, or application dependencies require VLAN continuity or minimal changes to existing addressing and routing. L3VPN would provide routed connectivity and VRF separation, but it would not preserve the VLAN-based service model. GRE would add an overlay tunnel but would not natively provide provider-managed Layer 2 service. DMVPN is designed for scalable Layer 3 IPsec/GRE overlays between branches, not for VLAN extension or point-to-point data center interconnect. Reference topics: L2VPN, VPWS, Ethernet pseudowire, VLAN extension, data center interconnect, WAN service design.