Cisco

Cisco networking tutorials covering IOS and IOS-XE configuration, platform features, and hands-on guides for routing, switching, and security across Cisco hardware and software.

134 posts

HSRP vs VRRP vs GLBP: Choosing the Right FHRP

HSRP, VRRP, and GLBP all solve first-hop redundancy with different trade-offs. The side-by-side comparison, when each wins, failover times, and migration paths.

4 min read Apr 26, 2026

GLBP public

GLBP for Active/Active Load Balancing

GLBP (Gateway Load Balancing Protocol) is Cisco's load-balancing FHRP. AVG, AVFs, three load balancing methods, configuration, and when GLBP is actually the right answer.

4 min read Apr 26, 2026

VRRP public

VRRP Explained: The Vendor-Neutral FHRP

VRRP (Virtual Router Redundancy Protocol, RFC 5798) is the vendor-neutral FHRP. How it works, master election, IP address owner trap, vs HSRP, Cisco IOS XE configuration, and tracking.

5 min read Apr 26, 2026

MPLS public

Cisco MPLS Configuration on IOS XE

Cisco MPLS configuration on IOS XE: enabling MPLS forwarding, LDP, LDP-IGP sync, VRFs for L3VPN, and MP-BGP between PEs. With a complete PE config example.

5 min read Apr 26, 2026

MPLS public

MPLS L3VPN with MP-BGP and VPNv4

MPLS L3VPN architecture: VRFs, Route Distinguishers, Route Targets, MP-BGP for VPNv4, the two-label stack, PE-CE routing, and the Cisco IOS XE configuration.

7 min read Apr 26, 2026

MPLS public

LDP and MPLS Label Distribution

LDP (Label Distribution Protocol) distributes MPLS labels across the network. Discovery, session establishment, distribution and retention modes, LDP-IGP sync, and Cisco IOS XE configuration.

5 min read Apr 26, 2026

MPLS public

MPLS Labels Explained: Format, Stacking, and Penultimate Hop Popping

MPLS labels byte-by-byte: 20-bit label, EXP/TC, S bit, TTL. The label stack model, reserved labels, Penultimate Hop Popping, TTL handling, and what labels look like in Wireshark.

5 min read Apr 26, 2026

EIGRP public

EIGRP Stub Routing for Hub-and-Spoke

EIGRP stub routing makes hub-and-spoke topologies scale. The five stub options, query suppression, DMVPN integration, and the production patterns for branch deployments.

5 min read Apr 26, 2026

EIGRP public

EIGRP vs OSPF: When to Use Each

EIGRP vs OSPF in 2026. The technical differences, the convergence story, vendor reality (EIGRP is still Cisco-only in practice), and the design implications for new vs existing networks.

5 min read Apr 26, 2026

EIGRP public

EIGRP Configuration on Cisco IOS XE: Classic and Named Mode

EIGRP configuration on Cisco IOS XE: classic mode, named mode, network statements, passive-interface default, summarization, HMAC-SHA-256 authentication, and the production template.

6 min read Apr 26, 2026

EIGRP public

EIGRP Metric and K Values Explained

The EIGRP composite metric formula, the five K values and why never to change them, the 64-bit wide metric for modern interfaces, and how to verify metrics in show output.

5 min read Apr 26, 2026

EIGRP public

EIGRP DUAL Algorithm Deep Dive: Successors, Feasible Successors, FD, RD

DUAL gives EIGRP sub-second failover via pre-computed feasible successors. The four key concepts (successor, FS, FD, RD), the feasibility condition that prevents loops, active states, and queries.

6 min read Apr 26, 2026