07-28-2009 12:16 AM - edited 03-06-2019 06:58 AM
Hi all
I am running rstp on my switch, however it says the below
Spanning tree enabled protocol rstp
Root ID Priority 32836
Address 0026.5182.6980
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
I thought the max age should be 6 secs and the forward day under a sec ?
cheers
07-28-2009 12:20 AM
Hello Carl,
max age is 20 seconds but it is used only on ports where a legacy PVST neighbor is detected or on an half duplex port.
on point-to-point links where a RSTP neighbor is present a device waits up to 3 times the hello timer (6 seconds)
Hope to help
Giuseppe
07-28-2009 01:49 AM
Guiseppe,
I've just tested it: the max_age of 20 seconds is not used on half duplex - or better said, shared links for RSTP neighbors. For them, the normal 6 second timeout applies.
I did a quick test: I have interconnected two switches by a crossover cable, forced the ports to half duplex, run the RSTP on both switches and made one to be the root bridge by lowering the priority to 0. On the second switch, I have turned on STP debugging and back on the root bridge, I have activated the BPDU Filter on its port towards the second switch. After 6 seconds, the second switch reported a loss of previous root and elected itself as a new root bridge.
So the max_age parameter seems to apply only to legacy 802.1D STP neighbors.
Best regards,
Peter
Discover and save your favorite ideas. Come back to expert answers, step-by-step guides, recent topics, and more.
New here? Get started with these tips. How to use Community New member guide