MPLS
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PE-CE Routing Protocols in MPLS L3VPN: Static, OSPF, EIGRP, and BGP
Once the MPLS core is built and MP-BGP is carrying VPNv4 between your PEs, one question remains: how does
Labs
Hands-on Cisco IOS XE lab walkthroughs. Each lab ships with a real CML topology, configs you can paste, and verified show output. Articles tagged Labs cover the full CCNA 200-301 blueprint across Network Fundamentals, Network Access, IP Connectivity, IP Services, and Security Fundamentals.
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MPLS
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MPLS L3VPN Configuration Step by Step: VRF, RD, RT, and MP-BGP
MPLS L3VPN is the service that made MPLS a service-provider standard, and it is still what most enterprises are
DMVPN
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Troubleshooting DMVPN: NHRP, Tunnel State, and Spoke-to-Spoke Failures
DMVPN failures cluster hard. After the underlay itself, almost every broken cloud comes down to a spoke that cannot register,
DMVPN
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Securing DMVPN with IPsec Profiles (IKEv2)
Everything DMVPN sends is cleartext. GRE is an envelope with the contents printed on the outside, and a DMVPN cloud
DMVPN
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Routing Over DMVPN: EIGRP and OSPF Design Choices
NHRP builds the tunnels; the routing protocol decides what flows through them, and DMVPN is unusually opinionated about how you
DMVPN
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DMVPN Phase 3 Configuration on Cisco IOS XE
This is the complete, working DMVPN Phase 3 build: one hub, two spokes, a router simulating the internet underlay, EIGRP
DMVPN
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DMVPN Phase 1 vs Phase 2 vs Phase 3: What Actually Changes
Ask what separates DMVPN Phase 1 from Phase 2 from Phase 3 and you will usually get a memorized answer:
DMVPN
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NHRP Deep Dive: Registration, Resolution, and Redirects
Every interesting thing DMVPN does, it does with NHRP. Spokes appearing on the hub without configuration? NHRP registration. Spoke-to-
DMVPN
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DMVPN Explained: mGRE + NHRP + Routing in One Overlay
DMVPN has a reputation for being complicated, and it is entirely undeserved. The technology is three well-understood pieces (multipoint
Troubleshooting IP Multicast: Reading show ip mroute, RPF Failures, and Silent Receivers
Multicast fails silently, and nearly every ticket collapses into three signatures: a silent receiver, an RPF failure, or a missing RP. Captured on CML with IOS XE 17.18.2: healthy PIM sparse mode state before and after the source goes active, how to read every field of show ip mroute, and each...
Bidirectional PIM and MSDP: Scaling Multicast Across Domains
Standard PIM sparse mode scales beautifully for a handful of sources and thousands of receivers. Push it the other direction,
Source-Specific Multicast (SSM): PIM Without an RP
Everything hard about PIM sparse mode traces back to one assumption: receivers do not know who the sources are. Drop