I have been having issues with the granular concepts of STP. In particular, loopguard. I think I would understand its full potential and functionality if I understood which ports send and receive BPDUs. According to my CCNP: Implementing Cisco IP Switched Networks book, which has soooo many errors that it has lost its integrity, ports in the listening state send and receive BPDUs. Forwarding ports do the same. Blocking ports only receive BPDUs?
When I verify this on my 3550s, it does appear to be true. I forgot exactly which ports where sending or receiving BPDUs, but it seems that a port is almost always sending OR receiving, never both.
Can someone please verify which ports send and/or receive BPDUs and if its port state matters? Thanks a million!
Blocking ports only receive BPDUs. I am not sure if the author meant literally send and receive at the same time?
before Root is selected, all switches will send and receive BPDUs; then, when Root is chosen,
Only Root Sw will send BPDUs and other Switches get it and forward it.
This goes thru Election of Root ports and Designated ports as well to last step in the process: Blocking ports.
So, Yes I would say the "send and receive" fiasco is about the process of STP and current stage.
Root BPDU comes in on Root port and leaves out of all of my DPs;
When there is TC on one of my ports, I will send TCN BPDU to Root out of my Root port.
DP ports are sending BPDUs; and Root ports are receiving BPDUs; Blocking ports only receive.
No, in RSTP, every switch communicate with directly connected neighbor sending/receiving BPDUs. They have to agree who is Root.
Upstream port (root port) is recieving BPDUs;
and same switch will send BPDUs out of its Downstream ports (DP or Forwarding)
attaching details of interfaces; look at number of BPDUs per ports.
Edit: adding attachment: Martin
Don't get confused with the forwarding of BPDU's and Data traffic.
Yes, this is from my personal study document for CCNA. Its almost 140 pages long
I've created this dcument from watching CCNA video's and also looking stuff up on the internet.
As per my knowledge Actually when stp is run at that time they run STA (Spaning tree algorithem) and they all manage regarding BPDU it's default time limit is 2 Sec.... for sent/rcv..