Dynamic Multipoint VPN troubleshooting becomes manageable when the engineer stops treating DMVPN as one feature. A working tunnel depends on underlay IP reachability, GRE tunnel […]
Cisco Certifications
Cisco 300-410: VRF-Lite vs MPLS L3VPN for Route Separation
VRF-Lite and MPLS Layer 3 VPNs both create separate routing contexts, but they solve different scale and transport problems. VRF-Lite uses virtual routing and forwarding […]
Cisco 300-410: IPv6 First-Hop Security on Enterprise Networks
IPv6 first-hop security protects the access layer where hosts learn routers, addresses, prefixes, and neighbors. The risk is different from ordinary IPv4 access control: a […]
Cisco 300-420: Scaling OSPF and IS-IS Networks
OSPF and IS-IS both scale link-state routing by limiting how far topology information must be flooded and recalculated. OSPF uses areas; IS-IS uses Level 1 […]
Cisco 300-420: Designing Resilient Enterprise BGP
Resilient enterprise BGP design is about preserving policy and reachability when links, providers, route reflectors, or sites fail. BGP already has mechanisms for selecting alternate […]
Cisco 300-420: Campus High Availability Design
Campus high availability is a system design problem that spans physical redundancy, Layer 2 loop prevention, first-hop gateway resilience, routed convergence, power, software, and operational […]
Cisco 300-420: SD-Access Fabric Design
Cisco Software-Defined Access changes campus design by separating endpoint identity and segmentation from the physical underlay that transports packets. A fabric site combines edge nodes, […]
Cisco 300-420: Enterprise QoS and Multicast
Quality of Service and multicast are often taught as separate feature sets, but enterprise design frequently brings them together. Multicast determines how one source efficiently […]
Cisco 350-501: MPLS Segment Routing and Traffic Engineering
Segment routing changes how a service-provider core expresses paths without changing the fundamental job of MPLS forwarding. In the active 350-501 SPCOR scope, engineers are […]
Cisco 350-501: MPLS L2VPN vs L3VPN Services
MPLS L2VPN and L3VPN services both use a provider backbone to separate customer traffic, but they place very different responsibilities on the customer edge and […]
Cisco 350-501: BGP Route Policy on Cisco IOS XR
Cisco IOS XR uses Routing Policy Language (RPL) to express route filtering and attribute changes in a structured way that fits large service-provider environments. The […]
Cisco 350-501: Service Provider QoS Design
Service-provider QoS is a resource-allocation architecture, not a collection of interface commands. The 350-501 SPCOR scope includes provider QoS architecture and implementation because a carrier […]
Cisco 350-501: Protecting BGP in Service Provider Networks
BGP protection in a service-provider network has to defend both the routing protocol and the forwarding infrastructure that depends on it. The active 350-501 SPCOR […]
Cisco 350-601: VXLAN EVPN in Cisco Data Centers
VXLAN EVPN gives a data-center fabric a scalable way to carry Layer 2 segments and Layer 3 tenant reachability across an IP underlay. The active […]
Cisco 350-601: ACI Contracts, EPGs, and VRFs
Cisco ACI expresses application connectivity through an object model rather than traditional interface-by-interface firewall rules. The 350-601 DCCOR scope includes ACI and data-center security because […]