> For the complete documentation index, see [llms.txt](https://davidjosearaujo.gitbook.io/online-courses/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://davidjosearaujo.gitbook.io/online-courses/ccna-200-301/rapid-spanning-tree-protocol/bpdu.md).
# BPDU
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In classic STP, only the root bridge originated BPDUs, and other switches just forwarded the BPDUs they received. In Rapid STP, **all switches** originate and send their own BPDUs from their designated ports.
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## Other differences
* All switches running Rapid STP send their own BPDUs every hello timer (2 seconds).
* Switches 'age' the BPDU information much more quickly. In classic STP, a switch waits for 10 hello intervals (20 seconds). In rapid STP, a switch considers a neighbor lost if it misses 3 BPDUs (6 seconds). It will then 'flush' all MAC addresses learned on that interface.
