could any body help explain the following:
show spanning-tree vlan 4 commands show alot of information such as designated cost. what is designated cost?
thanks a lot !
It is the cost to reach root from this bridge. The root bridge transmits a BDPU with a cost of zero. It is only incremented when it is received and sent on by the next switch.
For instance, if the switch that receives the BPDU is connected directly to the root bridge, the designated cost will be zero:
Name Port ID Prio Cost Sts Cost Bridge ID Port ID
------- ------- ---- ---- --- ---- -------------- -------
Fa0/22 128.1 128 3010 FWD 0 000a.4191.7900 128.65
If you have a designated cost of 12, then perhaps there is another switch in between your switch and the root switch, that is connected to the root via a fastetherchannel.