Layer 2
When troubleshooting Layer 2 issues, verify:
-
That the MAC addresses are learned, in the correct Virtual
LAN (VLAN), and are not blackhole entries.
-
To display FDB entries, use the show
fdb command.
-
Your VLAN configuration, including the VLAN tag, ports
in the VLAN, and whether or not the ports are tagged.
-
To display detailed information for each VLAN
configured on the switch, use the show vlan detail command.
For additional VLAN troubleshooting tips, see
VLANs.
-
Your Spanning Tree Protocol (STP) configuration, including
the STP domain (STPD) number, VLAN assignment, and port state.
-
To display STP information, use the following
commands:
show stpd detail—Displays the STP
settings on the switch
show vlan stpd—Displays the
STP configuration of the ports assigned to a specific VLAN
For additional STP troubleshooting tips, see STP.