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

The correct BGP design is to attach the well-known No-Export community to the prefixes that should not be advertised beyond the service provider boundary. Cisco BGP communities are policy attributes that allow routes to carry instructions or classifications across BGP peers. The No-Export community tells a receiving BGP speaker not to advertise the route outside its confederation or autonomous system. That behavior is exactly what is needed when branch prefixes may be exchanged with the provider but must not be propagated to the public Internet. The No-Advertise community is stronger: it prevents the route from being advertised to any BGP peer, which may block reachability even where the provider still needs to know the route. NOPEER is used for route-server or peering policy control and is not the clean answer for excluding branch prefixes from Internet propagation. Setting a generic “Internet community” is not a standard solution by itself. The architect should also ensure that outbound prefix filters and provider-side community support are documented in the service agreement. Reference topics: BGP communities, No-Export, No-Advertise, provider edge filtering, Internet route policy.

Integrated Services is the QoS model that allows an application to signal its traffic requirements to the network and request specific service treatment. Cisco QoS guidance distinguishes IntServ from DiffServ by explaining that IntServ follows a signaled-QoS model, while DiffServ uses provisioned per-hop behavior based on markings. IntServ uses RSVP to reserve resources along the end-to-end path. That reservation process allows the network to admit or deny the flow based on available bandwidth and policy, which is why IntServ aligns with applications that require consistent and dedicated bandwidth. DiffServ is much more scalable and widely deployed in enterprise networks, but it does not provide per-flow resource reservation by itself. LLQ is a queuing mechanism commonly used inside a DiffServ design for delay-sensitive traffic such as voice. WRED is a congestion-avoidance technique, not an end-to-end reservation architecture. Because the question explicitly says that the application informs the network of its traffic profile and requests a service level, the correct QoS architecture is IntServ.

The required BGP address family is L2VPN EVPN. The design calls for VXLAN over a Layer 3 IPv4 fabric while preserving Layer 2 adjacency and allowing workload mobility between sites. EVPN is the BGP control plane used with VXLAN overlays to advertise MAC reachability, IP host information, and Ethernet segment information in a scalable way. It separates the Layer 2 and Layer 3 overlay control plane from the underlay IGP, which in this case is OSPF. VPNv4 is used for MPLS Layer 3 VPN routes, not VXLAN Layer 2 adjacency. IPv4 unicast advertises ordinary IP prefixes and does not carry MAC mobility or Ethernet VPN information. L2VPN VPLS or VPWS address families are associated with MPLS-based Layer 2 VPN services and do not provide the VXLAN EVPN control-plane model required here. EVPN is therefore the correct family for VXLAN fabrics that need host mobility and scalable Layer 2 extension. Reference topics: BGP EVPN, VXLAN, L2VPN EVPN address family, MAC reachability, workload mobility.