How do you troubleshoot a spanning-tree loop?
Action Plan:
- Implement Spanning Tree PortFast and BPDUGuard on all edge ports.
- Verify that currently the proper switch is STP root for all VLANs.
- Enable loop guard on all distribution/access layer switches*
- Enable BPDU guard on all distribution/access layer switches*
- Enable UDLD on all fiber uplinks*
What are the issues of Spanning Tree Protocol?
Spanning Tree is not inherently bad or wrong, but it does have many limitations in its design and operation. The most serious shortcoming is that STP has a brittle failure mode that can bring down entire data center or campus networks when something goes wrong.
How do you verify a spanning tree protocol?
To view the configured Spanning Tree PortFast enabled ports, run the “show running-config” IOS command as shown below. We can see that PortFast is enabled on access ports fa0/1 to fa0/24. To display a detailed summary of interface information, run “show spanning-tree detail” command as shown below.
How does a switch prevent loops IEEE?
How does STP prevent loops? Because the “best ports” are put into forwarding state and the other ports are put into blocking state, there are no loops in the network. When a new switch is introduced to the network, the algorithm and port states are recalculated to prevent a new loop.
Why does STP fail?
One frequent reason for STP failures is a unidirectional link between the bridges. In such a condition, one bridge sends BPDUs, but the downstream bridge never receives them. STP processing can also be disrupted by an overloaded CPU (99 percent or more), because the switch is unable to process received BPDUs.
What causes STP?
The network topology can happen in a network due to different reasons like a link failure, a Switch (Bridge) failure, or a port transitioning to forwarding state. The Root Switch (Bridge) bridge broadcasts the topology change information into the whole network.
What happens when STP is disabled?
Disabling Spanning Tree Protocol (STP) can cause Broadcast Storms and Layer 2 Switching Loops, which can make your network down within a short span of time.
Should I enable STP?
Broadcast storms caused by loops can slow or stop traffic on your network, but STP can prevent loops by ensuring that only one path between each set of switches is active. You must enable or disable STP or RSTP for each network location in which you are using Insight Managed Switches.