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

BGP outbound route filtering is the correct solution because the enterprise wants control over which routes it receives without waiting for a provider change cycle each time the prefix set changes. Cisco BGP prefix-based ORF allows a receiving BGP speaker to send an inbound prefix-list filter to the remote peer, which then applies that list as an outbound filter. This reduces unwanted routing updates before they cross the session and lets the enterprise update the desired prefixes locally when business requirements change. Requesting only fixed prefixes from the ISP would work initially but fails the flexibility requirement because the provider has a two-week change process. Requesting a full table and filtering inbound would provide flexibility but wastes memory and CPU on the customer router because all routes are still received before filtering. A maximum-prefix limit does not select the correct routes. ORF is therefore the scalable operational design for receiving a default route and selected prefixes with minimal provider involvement. Reference topics: BGP ORF, prefix-based filtering, inbound route control, ISP peering design, routing table scale.

IntServ with RSVP is the correct model when an application must request a specific service level and receive guaranteed bandwidth or delay treatment. Cisco describes the Integrated Services model as a flow-based QoS architecture in which applications signal their resource requirements to the network. RSVP is the signaling protocol used to reserve resources along the path. This differs from DiffServ, which marks packets and applies per-hop behavior without creating per-flow reservations. The question states that the application can request a particular type of service to support its delay requirements and that bandwidth must be guaranteed. Those are classic IntServ and RSVP characteristics. DiffServ with DSCP is scalable and widely used in enterprise networks, but it cannot guarantee resources end to end unless every hop is engineered and provisioned accordingly. IntServ with DSCP is not the standard model because RSVP is the reservation mechanism. Reference topics: Integrated Services, RSVP, resource reservation, guaranteed service, QoS architecture, delay-sensitive applications.

The SD-Access overlay should reduce subnet sprawl and avoid overlapping IP subnets unless there is a specific operational requirement. Cisco SD-Access creates overlay virtual networks over an IP underlay and uses anycast gateway, VXLAN encapsulation, LISP control-plane mapping, and policy constructs to simplify endpoint mobility and segmentation. Reducing the number of subnets simplifies DHCP scope management, default-gateway placement, and operational troubleshooting. Avoiding overlapping address space across overlay networks is also a practical design recommendation because overlapping subnets complicate shared services, fusion routing, security logging, and policy troubleshooting. LAN automation and a dedicated IGP process are underlay deployment considerations, not overlay design choices. Layer 3 to the access design is also associated with routed underlay and campus fabric transport, not the overlay segmentation model. A clean overlay design should define virtual networks, scalable groups, IP pools, shared-services reachability, and external connectivity before deployment. Reference topics: Cisco SD-Access overlay design, anycast gateway, virtual networks, DHCP simplification, overlapping subnet avoidance.