Spanning tree in Blocking but there are input and output packets
Good day to you.
When I issued show spanning-tree of an interface, the state is in blocking mode. However, when I issued show interfaces of the same interface, I can notice there is input and output packets traversing the interface. WHy is it so? I thought spanning will not allow any packet to pass through if it is in blocking mode. I am afraid this will cause a potential loop.
Re: Spanning tree in Blocking but there are input and output pac
When a port is blocking, it blocks at the point that the interface joins the bridge, not at transmitter/receiver of the interface.
What does this mean in practice?
It means that the interface can still receive packets, and will still count them. Don't forget that the other end of this link will still be forwarding - mainly broadcasts and flooded unicasts. The bridge port will discard everything except the link-local stuff - CDP, BPDUs, etc.
In terms of transmission, the interface will not be getting any traffic from the bridge. But it will still be sending link-local protocols such as BPDUs, CDP, etc. Expect some transmitted traffic, but not as much as is being received.
It is precisely because the BPDUs are still being transmitted and received that the bridge knows to keep the (bridge-)port blocked, and so avoids the forwarding loop.
This is actually a pretty cool feature, i didn't even know it existed until I was looking for a solution to advertise a subnet (prefix in BGP talk), only if a certain condition existed. This is exactly what conditional advertisements does
j ai une question j ai achete un routeur cisco 887VA-k9 , je le configuré avec la configuration ci- dessous
si je le lier avec mon pc portable sur l un de ses ports directement ça marche toute est bien ( la connexion internet + m...
Attached policy provides CLI access to the Cisco 4G router over text messaging. Two files are in the attached .tar file:
2. PDF with instructions on how to load and use the .tcl file.