Category Archives: Cisco

VPN design becomes much easier to reason about when the tunnel is treated as one part of an access system rather than as the security system itself. The current 350-701 SCOR v2.0 blueprint still includes standards-based IPsec, SSL VPN, virtual tunnel interfaces, DMVPN, FlexVPN, GETVPN, site-to-site deployment, remote-access VPN, and tunnel-establishment troubleshooting. The difficult work […]

A next-generation firewall policy can be syntactically valid and still fail its security objective. A rule may be too broad, traffic may bypass the enforcement point, encrypted sessions may hide the application, identity can be missing, inspection can be disabled, or logging can be insufficient to prove what happened. The current 350-701 SCOR v2.0 explicitly […]

Secure network access is not simply authenticating a username before allowing a device onto the LAN. A modern access decision can include user identity, device identity, authentication method, endpoint type, security posture, location, network context, and the resource being requested. Cisco’s current 350-701 SCOR v2.0 explicitly emphasizes identity, device context, policy-driven access, and ISE-based wired […]

High availability is not achieved by adding a second device. It is achieved when the system can lose a component, detect the loss, move traffic to a valid alternative, preserve enough state, and recover without creating a larger failure. Redundancy is one ingredient. Convergence behavior, shared dependencies, failure domains, and operational testing determine whether the […]

Network device security is often discussed as a hardening checklist: disable old services, use SSH, configure AAA, protect SNMP, add ACLs, and enable control-plane policing. Those controls matter, but secure infrastructure is not created by counting them. It is created by understanding what each plane of the device is protecting, which identities can reach it, […]

Python becomes valuable in network operations when it removes repeated judgment from tasks that are already well understood. It becomes dangerous when a script hides assumptions, changes too much at once, or treats every device as if it were in the same state. The language is rarely the hard part. The hard part is designing […]

NETCONF, RESTCONF, and YANG are often taught as three terms in a programmability list. That makes them harder than they need to be. The useful architecture is simpler: YANG describes the shape and meaning of data, while NETCONF and RESTCONF provide standardized ways to read or change data represented by those models. One is a […]

Catalyst Center automation becomes useful when teams stop thinking of it as a device configuration shortcut. The real value is that it can connect network hierarchy, inventory, profiles, templates, provisioning, policy, assurance, and APIs into a repeatable operating model. That also means a bad design can repeat mistakes at scale. Automation does not remove operational […]

NetFlow is easy to describe and surprisingly easy to misuse. At a high level, a device observes traffic, groups packets into flows, records selected fields, and exports records to a collector. That description is correct, but it can tempt operators to treat flow data as if it were a packet capture with less storage. It […]

Network assurance fails when teams collect more data than they can interpret. A modern enterprise can produce interface counters, SNMP polls, syslog messages, streaming telemetry, NetFlow records, packet captures, synthetic probes, controller health scores, and application metrics at the same time. The operational problem is not lack of signals. It is deciding which signal can […]

Enterprise wireless design becomes expensive when every problem is treated as a reason to add more access points, more transmit power, more channels, or more roaming features. A network can look stronger on a floor plan while becoming noisier, harder to troubleshoot, and less predictable for clients. The better starting point is the outcome: which […]

SD-Access failures are often blamed on configuration because configuration is the part engineers can see most easily. A fabric edge is provisioned, a virtual network exists, endpoints receive addresses, and the dashboards look normal. Yet a user cannot reach an application, a device appears in the wrong policy context, or a border node forwards traffic […]

Cisco SD-WAN becomes easier to troubleshoot when the engineer stops treating it as “routers plus a controller” and instead separates the underlay, control plane, management plane, and data plane. Policy acts on relationships created by those planes. If control connections or route information are unhealthy, changing policy is often the wrong first move. That systems […]

Multicast is useful when one source needs to send the same stream to many receivers and duplicating that stream at the source would waste bandwidth. The architecture changes where replication occurs: the network builds distribution state so traffic is copied only at branching points. Before PIM modes, rendezvous points, or advanced tuning make sense, an […]

Quality of Service becomes necessary when different traffic classes compete for a resource that cannot serve them all immediately. In a converged enterprise, voice, interactive video, transactional applications, backups, software distribution, and ordinary web traffic may cross the same links. QoS does not create bandwidth. It decides how scarcity is handled. That is why the […]