Advanced Traffic Management Guide K/KA/KB.15.15

NOTE: The show spanning-tree commands described in this section allow you to troubleshoot
RPVST+ activity in your network by focusing on increasingly specific levels of operation. For
example, you can display debug information for:
• All VLANs
• All ports of one VLAN
• A specific port or several ports used in one VLAN
Viewing the change history of root bridges
Syntax:
show spanning-tree root-history vlan vlan-id
Displays he last 10 root bridge changes on a specified VLAN configured with
RPVST+. Included are the timestamp and Root Bridge ID recorded at each root
bridge change.
Use the show spanning-tree root-history command to view the number and dates of
changes in the assignment of a root bridge. Possible intrusion into your VLAN network may occur
if an unauthorized external device gains access to a spanning tree by posing as the root device
in a topology. To prevent a port connected to the device from being selected as the root port in a
topology, use the spanning-tree root-guard command.
Example 121 Viewing the change history of root bridges
HP Switch#: show spanning-tree root-history vlan 20
Status and Counters - RPVST Root Changes History
VLAN ID : 20
Root Changes Counter : 53
Current Root Bridge ID : 32768:0024a8-d13a40
Root Bridge ID Date Time
------------------- ---------- --------
32768:0024a8-d13a40 05/04/2012 21:54:11
0:001185-c6e500 05/04/2012 21:54:07
32768:0024a8-d13a40 05/04/2012 16:41:11
0:001185-c6e500 05/04/2012 16:41:11
Enabling traps and Viewing trap configuration
Syntax:
[no] spanning-tree trap
[[errant-bpdu | loop-guard | new-root ] | [topology-change [vlan<vid-list
| instance [instance-ID] {cstt}|root-guard]]
Enables or disables SNMP traps for errant-BPDU, loop guard, new root, and root
guard event notifications.
errant-bpdu Enables SNMP notification when an errant BPDU is received.
Designed for use with BPDU filtering.
loop-guard Enables SNMP notification when a loop guard inconsistency is
detected. Designed for use with the Loop Guard option.
new-root Enables SNMP notification when a new root is elected on any
VLAN configured for RPVST+ on the switch.
156 Rapid per-VLAN spanning tree (RPVST+) operation