Ping Labz

OSPF cost explained: the formula, the default reference bandwidth that breaks at 1 Gbps and above, manual overrides per interface, ECMP, and the misconfigurations to avoid.

How EtherChannel hides bundled links from STP, the bundling protocols (LACP, PAgP, on), the dangerous failure modes, and why LACP active on both sides is the only safe configuration.

RSTP (802.1w) explained: the new port roles, three-state model, proposal/agreement handshake, Rapid-PVST+ vs MST, and the real show spanning-tree output.