Root Guard stops a port from ever becoming a root port: a superior BPDU puts it in root-inconsistent state until the offender goes quiet. Configure it on SW1's uplinks and learn the canonical placement and how it differs from BPDU Guard.
PortFast skips STP's 15-plus seconds of waiting on end-host ports; BPDU Guard protects against someone plugging a switch into one. This lab configures both, per port and globally, and reads the results.
Route between VLANs with one physical router interface: a trunk to the switch and a dot1Q subinterface per VLAN, each with its own IP. Configure the classic router-on-a-stick design on R1 and SW1 and verify it end to end.
Enable CDP and LLDP on the base topology, read the neighbors and detail output of each, and compare what they advertise. Covers Cisco-only vs the open standard and the security trade-off of leaking device information.
One access port, two VLANs: this lab configures a data VLAN plus a tagged voice VLAN for a Cisco IP phone, shows how CDP signals the setup to the phone, and verifies it with show interfaces switchport.
Hands-on Rapid-PVST on a three-switch triangle: root bridge election, how priority plus sys-id-ext form the Bridge ID, and the port states and roles that decide which link blocks.
PAgP vs LACP side by side: the mode keywords for each, how to read show etherchannel summary to tell which protocol negotiated the bundle, why you cannot mix them across a link, and where PAgP still shows up in production.
Read the LACP EtherChannel between SW1 and SW2: the logical Port-channel plus member interfaces, how LACP negotiates the bundle, the flags in show etherchannel summary, and the LACP modes.
Map the OSI and TCP/IP models to the show commands you type every day: show interfaces for Layers 1 and 2, show ip interface for Layer 3. The layers become a diagnostic checklist instead of exam trivia.
See what DTP is doing under the hood with show dtp interface, learn the four modes, and then disable it with switchport nonegotiate. Covers why modern practice hardcodes trunk mode instead of letting switches negotiate.
Create three VLANs on a Cisco IOSvL2 switch, name them, assign access ports, and verify with show vlan brief. Covers what a VLAN is as a broadcast domain and how an access port differs from a trunk.
Open the MAC address table on a Cisco IOSvL2 switch and watch it populate. Three switches in a triangle show how the CAM table learns source MACs per port and why it is the heart of Layer 2 forwarding.