Options
cost to reach the root switch
Satcom
Member Posts: 110
in CCNA & CCENT
Im studying STP ICND2 ch2 and i am about to catch some z's. I was trying to understand how the Cost is calculated. I know that in routing protocols things such as hop count or metrics? ...go into affect to calculate the best path. I guess I am trying to compare hop counts and cost on a layer 2 protocol or how it comes about. I only read half so im guessing the answer to my question is in the other half of the chapter regarding STP timers....
ZZZZZzzzz
ZZZZZzzzz
Comments
-
Optionsphoeneous Member Posts: 2,333 ■■■■■■■□□□Cost is based on the receiving ports speed. Take the example below. If switch C is the root and if all ports on all switches are 100Mb then the cost from B to C is 19. The cost from A to C is also 19. Always remember, cost is calculated on the receiving port, not the sending port!
These are the common port costs:
10Mb = 100
100Mb = 19
1000Mb = 4
10000Mb = 2
-
OptionsSatcom Member Posts: 110Cost is based on the receiving ports speed. Take the example below. If switch C is the root and if all ports on all switches are 100Mb then the cost from B to C is 19. The cost from A to C is also 19. Always remember, cost is calculated on the receiving port, not the sending port!
These are the common port costs:
10Mb = 100
100Mb = 19
1000Mb = 4
10000Mb = 2