Adjust and diagnose Spanning Tree Protocol notes (BCMSN)

Adjust and diagnose Spanning tree Protocol Note (BCMSN) Bpdu guark: Spanning-tree portfast bpduguard diagnoses ports in portfast status. portfast ports generally do not accept bpdu packets, after configuration, when it receives the bpdu data packet, it is switched to the shutdown state. If not configured, it is blocked. Show spanning-tree summary total view guard status Portfast port filtering: Config # spanning-tree portfast bpdufilter default activates the filter status of the portfast port. When this port receives a bpdu packet, it changes to the normal port status, which can send and receive bpdu data packets Show spanning-tree summary totals www.2cto.com Bpdu offset: that is, the time difference between the time when the bpdu arrives at the destination port and the real time.
There are several possible causes for the offset: 1. timer failure 2. the network topology has changed. 3. bpdu not received 4. when the switch detects an offset, logs are generated, resulting in a decline in the switch performance. Network convergence is affected. Root protection: Config-if: spanning-tree guard root must be configured on the specified port to ensure that the status of the specified port does not change, thus protecting the status of the root switch. Show spanning-tree inunsistentports view the port Unidirecrtional link detection (unidirectional link detection) blocked by the root guard function of the switch: the switch at both ends of the link for redundant links. One link can communicate, and the other link cannot. This will cause a packet black hole, resulting in a broadcast storm. One-Way link must be shut down.
Config # udld enable activates one-way link detection of the optical interface, and cannot activate the link status of rj45. Shutdown automatically when a black hole occurs. Config-if # udld enable one-way detection of Ethernet interface activation Config-if # no udld enable disable one-way detection of Ethernet Config-if # udld disable one-way detection of optical interface Config # udld reset to reset the interface, reset the closed one-way detection and reset how udld intreface to view the information of the one-way detection port www.2cto.com Loop guard :( Loop protection ): loop protection prevents the unspecified ports on the vswitch from failing to receive the bpdu data packet within the max_age time. The unspecified ports on the vswitch are automatically converted into a forward loop. If the loopguard function is activated, the unspecified port is changed to the loopinconsistent State in the case of the preceding situation. This status can be configured on all unspecified ports, rp, and standby ap. After this status is activated, the root protection status becomes invalid.
Config # spantree guard loop 3/13 activates the loop protection function loop protection and One-Way link detection comparison: both are configured for a port, loop protection works for VLAN, one-way detection is used for all the valns of the entire port. Loop Protection provides automatic recovery and one-way links. Loop protection prevents tree generation failures caused by unidirectional links, prevents loops, and prevents unidirectional link detection. However, it requires activation on all links, the loop requires activation on all root ports and slave ports. When a tree fault occurs due to a software problem of a switch or bridge, the loop can prevent the fault and the one-way detection cannot be performed. Loop protection does not work due to wiring errors, but one-way detection is acceptable.
Failure of Spanning Tree Protocol: 1. the duplex mode at both ends of the link does not match. 2. One-Way link failure. 3. damaged root switch. 4. The cpu of the switch is busy. 5. The Portfast configuration is invalid. 6. The clock parameters of the spanning tree are incorrectly configured. Queuing failure steps: 1. combined with the network topology 2. locate the location where the loop exists. 3. restore network connectivity 4. check the port www.2cto.com 5. check that the vswitch CPU is insufficient and disable unnecessary features. 6. where can I test the root Switch Failure? The command is as follows: Debug spaning-tree allDebug spanning-tree elentDebug spanning-tree backbonefastDebug spanning-tree uplinkfast by Checker