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Home / Glossary / BPDU
Glossary · Networking

BPDU

Bridge Protocol Data Unit

In plain language

Small messages that switches pass to each other to avoid creating a loop in the network.

The metaphor

Like traffic marshals radioing each other so two roads never feed into a circle that cars follow forever.

Going deeper

How it works

  • Switches elect one as the root.
  • They share messages to find the shortest path.
  • They block extra paths that would form a loop.
  • A loop can flood the network and take it down.

What can go wrong (example scenario)

Someone in a small office plugged a cable between two wall ports. The loop slowed the whole network to a crawl until the cable was removed.

How WILDCARD handles it

Network covers the managed switches and their settings.

In practice
  • A switch blocks a port when it sees a loop.
  • A rogue switch is detected on a user port.
  • The network recovers after a cable is unplugged.

A question owners ask

Can I cause a loop by mistake?

Yes, by connecting two sockets of the same network together. Managed switches guard against it.

Where WILDCARD handles this
Network
  • Firewall managed and monitored
  • Switches kept current
  • On-prem Active Directory auth
Start with Network
Related terms
ACLAccess Control ListAHAuthentication HeaderAPAccess PointARPAddress Resolution ProtocolCCMPCounter Mode/CBC-MAC ProtocolCCTVClosed-circuit TelevisionCHAPChallenge Handshake Authentication ProtocolCSUChannel Service Unit

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