Ping Labz

CCNP-level networking tutorials — OSPF, STP, 802.1X, and BGP explained with real lab configs and topology diagrams.
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Recent posts
BGP public

Troubleshooting BGP Route Advertisement Problems

J
The BGP session is Established but routes are missing. A missing prefix can be stopped at any of several pipeline stages, from injection to best path to output filtering. A methodical troubleshooting guide to BGP route advertisement.
4 min read
BGP public

Troubleshooting BGP Neighbor Adjacency Issues

J
A BGP session that will not reach Established is the most common BGP issue. The FSM state tells you exactly where the problem is; the root cause inside each state can be one of many things. A systematic IOS XE methodology.
4 min read
STP public

Spanning Tree and First-Hop Redundancy: Aligning STP with HSRP/VRRP

J
The STP root bridge and the HSRP/VRRP active gateway should reside on the same switch. When they don't, traffic flows upstream to one switch and returns via another, wasting bandwidth and causing asymmetric path problems. This article covers alignment strategy and verification.
6 min read
STP public

STP in Multi-Layer Campus Designs: Access, Distribution, and Core

J
In a three-layer campus, STP topology must align with the physical hierarchy. This article shows how to place root bridges, design inter-layer redundancy, and troubleshoot anomalous topologies created by misconfiguration across access, distribution, and core layers.
7 min read
STP public

STP Design Best Practices for Enterprise Campus Networks

J
Enterprise STP designs require deliberate placement of the root bridge, careful use of guards and protection mechanisms, and proper L2 domain sizing. This article covers the configuration strategy and verification steps that distinguish reliable campus networks from problematic ones.
8 min read
STP public

STP and VLAN Trunking: How Spanning Tree Operates Across Trunk Links

J
On trunked links, STP doesn't operate as a single global instance—it runs independently for each VLAN. This article explains per-VLAN spanning tree behavior, native VLAN BPDU handling, PVST+ specifics, trunk pruning effects, and the common misconfigurations that break spanning tree topology.
8 min read
STP public

Troubleshooting STP Convergence Problems and Slow Failover

J
When a link fails, 802.1D STP takes 30–50 seconds to reconverge. Rapid PVST+ handles it in seconds. This article explains the timing mechanisms, diagnoses convergence delays, addresses unidirectional link failures, and shows how to migrate from legacy timers to modern rapid convergence.
9 min read
STP public

Troubleshooting Errdisable and STP Guard Features

J
STP guard features protect your network topology, but misconfigured guards cause legitimate ports to shut down. This article covers all three guards (BPDU Guard, Root Guard, Loop Guard), how to identify which one triggered, interpret syslog messages, and implement proper auto-recovery.
10 min read
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