Networking - Networking Basics - Discussion

Discussion :: Networking Basics - Networking Basics (Q.No.16)


How often are BPDUs sent from a layer 2 device?

[A]. Never
[B]. Every 2 seconds
[C]. Every 10 minutes
[D]. Every 30 seconds

Answer: Option B


Every 2 seconds, BPDUs are sent out from all active bridge ports by default.

Mariya Francis said: (Jun 13, 2012)  
Please give me define the BPDU.

Tashu said: (Jun 29, 2012)  
It stands for Bridge Protocol Data Unit. BPDUs are data messages that are exchanged across the switches within an extended LAN that uses a spanning tree protocol topology. BPDU packets contain information on ports, addresses, priorities and costs and ensure that the data ends up where it was intended to go. BPDU messages are exchanged across bridges to detect loops in a network topology. The loops are then removed by shutting down selected bridge interfaces and placing redundant switch ports in a backup, or blocked, state.

Akki said: (Aug 14, 2012)  
Bridge Protocol Data Units (BPDUs) is used by bridges in a network to exchange information regarding their status. The Spanning-Tree Protocol uses the BPDU information to elect the root switch and root port for the switched network, as well as the root port and designated port for each switched segment.

Simran said: (Dec 28, 2016)  
What is a layer 2 device mentioned in the question?

Avijit said: (Jan 2, 2017)  
Because BPDU is sent from switches which operate at Layer 2 i.e. the Data Link Layer.

Nateu said: (Sep 30, 2018)  
Thanks all.

Shatrudhan said: (Nov 12, 2018)  
Thanks for the explanation.

Azharudhin said: (Jan 14, 2020)  
Thanks for explaining this.

Koushik N said: (Jul 9, 2020)  
Thanks all.

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