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.
Archive
Latest posts — page 40
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.
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.
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.
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.
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.
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.
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.
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.
EIGRP DUAL Algorithm Deep Dive: Feasible Successors and the Real FD/RD Math
Everyone memorises RD < FD; nobody shows the arithmetic on a real router. Here it is on captured show ip eigrp topology output: one prefix with a feasible successor (409600 < 640000), one without (537600 > 512000), and a live failover where the route never left Passive.
QoS in Modern Networks: SD-WAN, Cloud, and Application-Aware Steering
QoS in 2026 is application-aware steering at the SD-WAN edge plus local queueing per tunnel. Why DSCP stops being honored at administrative boundaries, and how SD-WAN path conditioning compensates.
Voice and Video QoS on Cisco IOS XE
Voice and video are the use cases QoS exists for. Latency and jitter budgets, DSCP markings, IP phone trust, LLQ configuration, codec bandwidth math, and wireless voice via WMM.