10-09-2011 09:13 AM - edited 03-07-2019 02:41 AM
What is the command to see the culmlative cost to a root bridge?
I thought the info would be
Switch#sh span int fa0/11 det
Port 11 (FastEthernet0/11) of VLAN0001 is designated forwarding
Port path cost 19, Port priority 128, Port Identifier 128.11.
Designated root has priority 32769, address 0007.8432.dd00
Designated bridge has priority 32769, address 000b.fd67.6500
Designated port id is 128.11, designated path cost 19
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 1
Link type is point-to-point by default
BPDU: sent 68, received 1
Switch#
But it is not. My root bridge is a path cost of 38 away, not 19.
Thank you
Solved! Go to Solution.
10-09-2011 01:20 PM
Can you post the output of "sh spanning-tree vlan 1" from DSL2 ?
The path to root is the cost from the root port which i would have thought would be fa0/7 or fa0/8 from DSL2 to ALS2.
Yes BPDU's are sent on an access link port by default because there is nothing to stop you connecting up 2 switches using ports in only one vlan rather than a trunk link.
Jon
10-09-2011 09:22 AM
10-09-2011 09:30 AM
And I had the question recently of
Are BPDUs propagated w/out trunk link?
I would say yes, if you have a flat network, and everything is on VLAN 1. Is this wrong?
10-09-2011 01:20 PM
Can you post the output of "sh spanning-tree vlan 1" from DSL2 ?
The path to root is the cost from the root port which i would have thought would be fa0/7 or fa0/8 from DSL2 to ALS2.
Yes BPDU's are sent on an access link port by default because there is nothing to stop you connecting up 2 switches using ports in only one vlan rather than a trunk link.
Jon
10-09-2011 09:44 PM
Thank you, will do. Will log into lab tomorrow and post then.
10-10-2011 08:19 PM
Turns out I was not using the correct command,
Its below. Note this was just a lab, so the numbers might not jive with my previous post.
ALS2#sh spa vla 1 de
VLAN0001 is executing the ieee compatible Spanning Tree protocol
Bridge Identifier has priority 32768, sysid 1, address 0009.b79f.7d80
Configured hello time 2, max age 20, forward delay 15
Current root has priority 24577, address 000f.2303.2d80
Root port is 11 (FastEthernet0/11), cost of root path is 38
Topology change flag set, detected flag not set
Number of topology changes 15 last change occurred 00:00:54 ago
from FastEthernet0/8
Times: hold 1, topology change 35, notification 2
hello 2, max age 20, forward delay 15
Timers: hello 0, topology change 0, notification 0, aging 15
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