Embedded Packet Capture: Wireshark Inside Your Router
You are troubleshooting a problem that only the packets can explain - a malformed handshake, an unexpected retransmission, a mystery drop.
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.
Latest
SNMPv3 in Production: Users, Groups, Views, Traps, and Informs
SNMPv1 and v2c send everything - including your community string, which is effectively a password - in cleartext across the network. Anyone
The IOS DHCP Server in Depth: Options, Classes, and Manual Bindings
Most people configure an IOS DHCP server once, with three lines - network, default-router, dns-server - and never touch it
VRF-Aware NAT on Cisco IOS XE
Two customers connect to your router. Both, entirely by coincidence, use 10.5.5.0/24 internally. Both have a
MPLS
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Expert Transport Troubleshooting: MPLS and DMVPN Ticket Scenarios
Transport technologies fail in layers, and the art of troubleshooting them is knowing which layer to suspect. An MPLS L3VPN
DMVPN
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DMVPN with IKEv1 vs IKEv2: Configuration and Migration
Every DMVPN carries IPsec, and every IPsec deployment sits on one of two key-exchange protocols: IKEv1, the original from
DMVPN
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Dual-Hub DMVPN: Redundancy Designs That Actually Fail Over
Everyone builds a second DMVPN hub for redundancy. Far fewer people test that the failover actually works - and the ones
MPLS
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BGP as the PE-CE Protocol: as-override, allowas-in, and SoO
BGP is the most powerful choice for the PE-CE protocol in an MPLS L3VPN - it scales, it carries policy,
MPLS
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MPLS VPNv6 and 6VPE: IPv6 L3VPN over an IPv4 Core
You have an IPv4 MPLS L3VPN running. Your customers each have their own VRF, their own routing table, their own
STP
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Expert Layer 2 Troubleshooting: Five Broken Scenarios, Ticket Style
Layer 2 problems have a special quality: the switches all say everything is fine, and yet nothing works. There is
VLAN
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Switch Administration: SDM Templates, Errdisable Recovery, and CAM Aging
The switching features that make headlines are the protocols - spanning tree, VLANs, EtherChannel. The features that actually keep a switch
VLAN
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Dynamic ARP Inspection and IP Source Guard: The L2 Security Stack
ARP is the most trusting protocol in the building. A host asks "who has 10.10.10.1?"