cost to reach the root switch

SatcomSatcom Member Posts: 110
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....
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Comments

  • ncsugrad2002ncsugrad2002 Member Posts: 131
    what are you asking? lol

    i think you need sleep ;)
  • phoeneousphoeneous 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

    65b.gif
  • SatcomSatcom Member Posts: 110
    phoeneous wrote: »
    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

    65b.gif
    Thanks this is what I was looking for icon_thumright.gif
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