Hi everyone Can someone please explain to me so that I understand the following output better:
switch# show spanning-tree interface Po1 detail Port 1665 (Port-channel1) of VLAN0001 is designated forwarding Port path cost 3, Port priority 128, Port Identifier 128.1665. Designated root has priority 24577, address 0009.12e9.aec0 Designated bridge has priority 32769, address 0014.f113.fc00 Designated port id is 128.1665, designated path cost 10 Timers: message age 0, forward delay 0, hold 0 Number of transitions to forwarding state: 16 Link type is point-to-point by default BPDU: sent 9090982, received 2782 Please find the breakdown of my questions below: "Port 1665 (Port-channel1) of VLAN0001 is designated forwarding" *** Where does the switch get the value of "Port 1665" from? Is this an STP internal identifier of the port? "Port path cost 3, Port priority 128, Port Identifier 128.1665." *** The port path cost and port priority shown here are LOCAL values, am I correct in this assumption? There are no cumulative values represented here. "Designated port id is 128.1665, designated path cost 10" *** The designated port ID is the REMOTE value sent from the neighboring switch, but *what* is the "designated path cost" and how is it calculated? *** Is the designated path cost the same as the "root path cost"? "Number of transitions to forwarding state: 16" *** What exactly does this mean? I used to think that this number represented the classic STP states, but a value of 16 has me confused. What states are they referring to here? "Link type is point-to-point by default" *** In Cisco's CCIE official study guide, it is recommended that a port channel is configured with the "spanning-tree link-type point-to-point" command, in order to facilitate a quick connection, but is it really necessary to hard-code this command on the interface, as it is obviously the default link-type on etherchannel? A bit confusing Thanks! Atle
_______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com
