本檔案介紹旨在提高第2層網路穩定性的環路防護STP功能。 本檔案也說明橋接通訊協定資料單元 (BPDU)歪斜偵測。 BPDU偏差檢測是一種診斷功能，可在未及時收到BPDU時生成系統日誌消息。 Cisco IOS. STP環路防護功能在適用於Catalyst 4500交換器的Cisco IOS®軟體版本12.1 (12c)EW和適用於Catalyst 6500的Cisco IOS軟體版本12.1 (11b)EX中匯入。 在內部，STP根據配置、拓撲、埠在拓撲中的相對位置以及其他考慮因素，為每個網橋（或交換機）埠分配一個角 …

All spanning-tree protocols use a special type of frame called bridge protocol data units (BPDUs) to communicate with each other. The Spanning Tree Protocol (STP) family is designed to break possible loops in a Layer 2 bridged network. Loop prevention avoids damaging broadcast storms that can potentially render the network useless.

2024年10月10日 · Loop Guard:Loop Guard STP 功能通过防止桥接环路来提高第2层网络的稳定性。 UDLD: UDLD检测并禁用单向l链路。 当配置为STP PortFast的接口收到BPDU时，BPDU Guard会将其为置于err-disable状态。 BPDU Guard禁用接口作为预防步骤，以避免潜在的危险桥接环。 BPDU保护功能用于保护生成树域免受外部影响。 BPDU Guard默认情况下处于禁用状态，但建议已启用portfast功能的所有端口使用BPDU Guard。 这样可以防止将错误信息注入禁 …

本文档介绍了旨在提高第 2 层网络的稳定性的环路防护 STP 功能。 本文档还介绍了网桥协议数据单元 (BPDU) 迟滞检测。 BPDU 迟滞检测是一种诊断功能，用于在未及时收到 BPDU 的情况下生成 syslog 消息。 Cisco IOS. STP环路防护功能在适用于Catalyst 4500交换机的Cisco IOS®软件版本12.1 (12c)EW和适用于Catalyst 6500的Cisco IOS软件版本12.1 (11b)EX中引入。 在内部，STP 分配给每个网桥（或交换机）端口一个角色，该角色基于拓扑中的该端口的配置、拓扑、相对 …

2024年4月19日 · At the heart of such management lies the Spanning Tree Protocol (STP), a fundamental technology in network design that ensures a loop-free network topology. This blogpost explores the pivotal role of Bridge Protocol Data Units (BPDUs) within STP, detailing how they help preserve network integrity and efficiency.

BPDU Guard is the mechanims that protect a port towards any Bridge Protocol Data Unit. In other words, this mechanims avoid receiving BPDU packets. By doing this, BPDU Guard provide the stability of STP Topology. BPDU Guard avoid receiving BPDU with an Error-Disabled Mode.

2023年12月18日 · This document describes the loop guard STP feature that is intended to improve the stability of the Layer 2 networks. This document also describes Bridge Protocol Data Unit (BPDU) skew detection. BPDU skew detection is a diagnostic feature that generates syslog messages when BPDUs are not received in time. Feature Availability. Cisco IOS

交换机的一个端口发出的bpdu报文，又从该口收到，此时端口状态为loopback，置为discarding状态。 注意loopback状态和loop状态的区别。 loop状态为端口启用了stp loop-protection导致。

Loop protection performs a specified action when BPDUs are not received on a nondesignated port interface. You can choose to block the interface or issue an alarm when bridge protocol data units (BPDUs) are not received on the port.

Bridge Protocol Data Units (BPDUs) are the messages used in a switching domain which allow switches to gather information about other switches and participate in Spanning Tree Protocol (STP). They are the key messages used in an STP topology.