CCIE

The switching features that make headlines are the protocols - spanning tree, VLANs, EtherChannel. The features that actually keep a switch

ARP is the most trusting protocol in the building. A host asks "who has 10.10.10.1?"

Every Layer 2 security feature worth having is built on one foundation: a table that says "this IP address,

A single misbehaving host can take down an entire VLAN. It does not take a spanning tree loop - a NIC

Spanning tree has one blind spot, and it is a dangerous one. STP decides whether to block a port based

Two switching standards, both trying to prevent loops, neither aware the other exists. That is what an MST-to-PVST+