Hi Laz,
Thanks for your answer. I don’t use SPAN but direct observation through GNS3.
I always think that I work on real devices !!! I’ll remember about those simulators limitations next time !!!
Thanks for pointing me that out .
Regards
1 Like
First of all really appreciate for such a wonderful explanation .
I wan to know If we are receiving BPDU on same switch from more than one port So in this case blocking will not take 20s to move to listening and learning ?
If switch only receive from one direction than in that case only It requires 20s from blocking to listening and learning .
Thanks
Hello Osama
It is possible to have the same BPDU arrive on more than one port of the same switch. First of all, this lesson and the related configurations are all using classic STP 802.1D. This means that all BPDUs are generated by the root bridge, and are propagated down the tree. If there is a physical Layer 2 loop, then one switch can receive BPDUs from multiple ports.
Of course, each BPDU will have a specific cost value in the header, and whichever BPDU has the lower cost, it will become the root port. Take a look at the following lesson for details about this process.
Remember that BPDUs may still be received on blocked ports, but if they are not superior, they are simply ignored.
I hope this has been helpful!
Laz
if the situation changed to that the link between SW1 & SW2 is the one that goes down and still we have connectivity between SW1 & SW3 , will it take still 30 seconds for STP to re-converge or 50 seconds ?
Hello Mohamed
Whenever there is a topology change (a link goes down) on a switch other than the local switch, (an indirect link failure) then in such a situation, STP will reconverge in 50 seconds. This is due to the addition of the blocking timer, which is 20 seconds. Take a look at this post which refers to the blocking timer:
For a more comprehensive view of the reconvergence of STP, take a look at the following lesson:
I hope this has been helpful!
Laz
1 Like