Flexible NetFlow tells you who is making the link busy, talking to what, on which port. Build the record, monitor, and exporter on Cisco IOS XE, export flows to a real Linux collector, and decode them so you see the data arrive.
An L3VPN route can quietly disappear at six points between customer VRF and remote CE, none of them logging an error. This article gives you a repeatable path to walk the route, with captures from a live five-router IOS XE lab with induced failures.
MPLS forwarding runs on labels, not on IP reachability, so a dead LDP session leaves every green light green while the customer blackholes. Captured on CML with IOS XE 17.18.2: the unusable: no label CEF entry, the full LDP LIB, a hop-by-hop walk to find where the binding stops, and No Label...
Route distinguishers make prefixes unique; route targets control which VRFs import them. They look identical and do unrelated jobs, and this article proves it with one BGP table holding the same prefix twice.
Static, OSPF, EIGRP, or eBGP: the PE-CE protocol decides what the customer sees and how fast the L3VPN reconverges. This article runs three of them back to back on the same MPLS lab and shows exactly what changes.
Configure MPLS L3VPN step by step: VRF, RD, RT, LDP, and MP-iBGP carrying VPNv4 between PE routers. Every command and every line of output comes from a five-router Cisco IOS XE lab running OSPF as the core IGP.
We broke a healthy Phase 3 DMVPN lab three ways on purpose: a spoke that cannot register, an up/up tunnel eating packets, and shortcuts that never form. Real IOS XE 17.18 output shows each failure, including when the hub logs nothing.
DMVPN sends everything cleartext until you add tunnel protection. This post builds the IKEv2 and IPsec profile stack on two Catalyst 8000v routers running IOS XE 17.18, with every show command captured live.
A DMVPN hub relaying routes between spokes trips over split horizon, next-hop handling, and OSPF network types. Run EIGRP named mode and OSPF point-to-multipoint over the same live Phase 3 lab and compare what lands in the RIB.
A complete DMVPN Phase 3 build: one hub, two spokes, a simulated internet underlay, and EIGRP over the top. Every command and every verification step captured from live IOS XE 17.18 devices.
One DMVPN lab reconfigured live from Phase 1 to Phase 2 to Phase 3 on IOS XE 17.18, with the routing table, NHRP cache, and traceroutes captured at each stop. What actually changes in configuration, routing requirements, and the RIB.
NHRP registration, resolution, and redirects are everything interesting DMVPN does. Walk all three message flows with real debugs and cache states from an IOS XE 17.18 lab with one hub and two spokes.