Displaying STP Information
Displaying STP information allows you to
verify which switch ports are actively participating in the spanning tree topology,
identify
potential issues with redundant connections, and troubleshooting network connectivity
problems
that might arise from incorrect STP configurations.
You can display STP information in various modes using the various show
commands from privileged EXEC mode.
The following example displays the STP protection configuration for all the ports on the device.
device# show stp-protect-ports Port ID BPDU Drop Count 1/1/3 478 1/1/5 213 1/1/6 0 1/1/12 31
The following example displays the STP protection configuration for a specific port.
device# show stp-protect-ports ethernet 1/1/3 STP-protect is enabled on port 1/1/3. BPDU drop count is 478
The following example displays the STP protection configuration for a LAG port.
device# show stp-protect-ports lag 45 STP-protect is enabled on port lg45. BPDU drop count is 5
The following example displays the STP information for an entire device.
device# show span
VLAN 1 BPDU cam_index is 3 and the Master DMA Are(HEX)
STP instance owned by VLAN 1
Global STP (IEEE 802.1D) Parameters:
VLAN Root Root Root Prio Max He- Ho- Fwd Last Chg Bridge
ID ID Cost Port rity Age llo ld dly Chang cnt Address
Hex sec sec sec sec sec
1 8000d4c19e146905 0 Root 8000 20 2 1 15 251741390 d4c19e146905
Port STP Parameters:
Port Prio Path State Fwd Design Designated Designated
Num rity Cost Trans Cost Root Bridge
Hex
1/1/1 80 19 FORWARDING 1 0 800000e0804d4a00 800000e0804d4a00
1/1/2 80 0 DISABLED 0 0 0000000000000000 0000000000000000
1/1/3 80 0 DISABLED 0 0 0000000000000000 0000000000000000
1/1/4 80 0 DISABLED 0 0 0000000000000000 0000000000000000
1/1/5 80 19 FORWARDING 1 0 800000e0804d4a00 800000e0804d4a00
1/1/6 80 19 BLOCKING 0 0 800000e0804d4a00 800000e0804d4a00
1/1/7 80 0 DISABLED 0 0 0000000000000000 0000000000000000
<lines for remaining ports excluded for brevity>The following example shows the detailed STP information for a specific VLAN.
device# show span vlan 100
STP instance owned by VLAN 100
Global STP (IEEE 802.1D) Parameters:
VLAN Root Root Root Prio Max He- Ho- Fwd Last Chg Bridge
ID ID Cost Port rity Age llo ld dly Chang cnt Address
Hex sec sec sec sec sec
100 80008c7a153f13a0 16 1/1/2 ffff 20 2 1 15 1 55 8c7a153f13a0
Port STP Parameters:
Port Prio Path State Fwd Design Designated Designated
Num rity Cost Trans Cost Root Bridge
Hex
1/1/2 80 4 FORWARDING 2 12 80008c7a153f13a0 8000c0c52080b580
1/1/9 80 4 FORWARDING 1 16 80008c7a153f13a0 ffff8c7a153f13a0
1/1/13 80 0 DISABLED 0 0 0000000000000000 0000000000000000 The following example displays the STP information for each interface.
device# show span detail ====================================================================== VLAN 1 - SPANNING TREE (IEEE 802.1D) ACTIVE ====================================================================== Bridge identifier - 0x800000a0c9c002a0 Active global timers - Hello: 0 Topology change not set, Topology change detected not set, Topology change time 35 Number of topology changes: 113 Last topology change occured 46 second(s) ago on lg40 Port 1/1/1 is FORWARDING Port - Path cost: 4, Priority: 128, Port Identifier:128.0, Root: 0x800000a0c9c002a0 Root Bridge Priority:32768 Designated - Bridge: 0x800000a0c9c002a0, Priority:32768, Interface: 0, Identifier:128.0, Path cost: 0 Active Timers - Hold: 0 BPDUs - Sent: 5968, Received: 0 Port 1/1/2 is DISABLED Port 1/1/3 is DISABLED Port 1/1/4 is FORWARDING Port - Path cost: 4, Priority: 128, Port Identifier:128.3101, Root: 0x800000a0c9c002a0 Root Bridge Priority:32768 Designated - Bridge: 0x800000a0c9c002a0, Priority:32768, Interface: 3101, Identifier:128.3101, Path cost: 0 Active Timers - Hold: 0 BPDUs - Sent: 5978, Received: 52
The following example displays the STP information for a single port in a specific VLAN.
device# show span detail vlan 1 ethernet 1/1/1 ====================================================================== VLAN 1 - SPANNING TREE (IEEE 802.1D) ACTIVE ====================================================================== Bridge identifier - 0x800000a0c9c002a0 Active global timers - Hello: 0 Topology change not set, Topology change detected not set, Topology change time 35 Number of topology changes: 113 Last topology change occured 6 minute(s) 57 second(s) ago on lg40 Port 1/1/1 is FORWARDING Port - Path cost: 4, Priority: 128, Port Identifier:128.0, Root: 0x800000a0c9c002a0 Root Bridge Priority:32768 Designated - Bridge: 0x800000a0c9c002a0, Priority:32768, Interface: 0, Identifier:128.0, Path cost: 0 Active Timers - None BPDUs - Sent: 6152, Received: 0
The following example shows the STP information for a LAG port in a specific VLAN.
device# show span detail vlan 1 lag 40 ====================================================================== VLAN 1 - SPANNING TREE (IEEE 802.1D) ACTIVE ====================================================================== Bridge identifier - 0x800000a0c9c002a0 Active global timers - Hello: 0 Topology change not set, Topology change detected not set, Topology change time 35 Number of topology changes: 113 Last topology change occured 9 minute(s) 10 second(s) ago on lg40 Port lg40 is FORWARDING Port - Path cost: 4, Priority: 128, Port Identifier:128.3111, Root: 0x800000a0c9c002a0 Root Bridge Priority:32768 Designated - Bridge: 0x800000a0c9c002a0, Priority:32768, Interface: 3111, Identifier:128.3111, Path cost: 0 Active Timers - Hold: 0 BPDUs - Sent: 1842, Received: 4464
The following example shows the STP information for Ethernet interface 1/1/3.
device# show interfaces ethernet 1/1/3 FastEthernet 1/1/3 is up, line protocol is up Port up for 1 hour 50 minutes 30 seconds Hardware is FastEthernet, address is 0000.00a9.bb49 (bia 0000.00a9.bb49) Configured speed auto, actual 100Mbit, configured duplex fdx, actual fdx Member of L2 VLAN ID 1, port is untagged, port state is FORWARDING STP configured to ON, priority is level0, flow control enabled mirror disabled, monitor disabled Not member of any active trunks Not member of any configured trunks No port name MTU 1518 bytes, encapsulation ethernet 5 minute input rate: 352 bits/sec, 0 packets/sec, 0.00% utilization 5 minute output rate: 0 bits/sec, 0 packets/sec, 0.00% utilization 1238 packets input, 79232 bytes, 0 no buffer Received 686 broadcasts, 0 runts, 0 giants 0 input errors, 0 CRC, 0 frame, 0 ignored 529 multicast 918 packets output, 63766 bytes, 0 underruns 0 output errors, 0 collisions
The following example shows the STP information for a LAG interface in global configuration mode.
device(config)# show interfaces lag 45 Lag lg45 is down, line protocol is down Configured speed Auto, actual None, configured duplex fdx, actual none Untagged member of L2 VLAN 1, port state is None BPDU guard is Disabled, ROOT protect is Disabled, Designated protect is Disabled STP configured to ON, priority is level0, mac-learning is enabled Openflow is Disabled, Openflow Hybrid mode is Disabled Mirror disabled, Monitor disabled Mac-notification is disabled VLAN-Mapping is disabled Member of active trunk ports 1/1/3,1/1/4,lg45, Lag Interface is lg45 Member of configured trunk ports 1/1/3,1/1/4,lg45, Lag Interface is lg45 No port name 300 second input rate: 0 bits/sec, 0 packets/sec, 0.00% utilization 300 second output rate: 0 bits/sec, 0 packets/sec, 0.00% utilization 0 packets input, 0 bytes, 0 no buffer Received 0 broadcasts, 0 multicasts, 0 unicasts 0 input errors, 0 CRC, 0 frame, 0 ignored 0 runts, 0 giants 0 packets output, 0 bytes, 0 underruns Transmitted 0 broadcasts, 0 multicasts, 0 unicasts 0 output errors, 0 collisions Relay Agent Information option: Disabled
The following example displays a summary of management interface information for ports for which the interface link status is Up.
device# show interfaces brief | include up Port Link State Dupl Speed Trunk Tag Pvid Pri MAC Name 1/1/16 Up Forward Full 1G 1 Yes 1 0 cc4e.246c.ea1f 1/1/17 Up Forward Full 1G 1 Yes 1 0 cc4e.246c.ea1f 1/1/21 Up Blocked Full 1G 2 Yes 1 0 cc4e.246c.ea24 1/1/22 Up Blocked Full 1G 2 Yes 1 0 cc4e.246c.ea24 1/2/1 Up Forward Full 10G None Yes 1 0 cc4e.246c.ea41 lg1 Up Forward Full 2G 1 Yes 1 0 cc4e.246c.ea1f lg2 Up Blocked Full 2G 2 Yes 1 0 cc4e.246c.ea24