Home > Spanning Tree Protocol STP Tutorial – Premium Tutorial

Spanning Tree Protocol STP Tutorial – Premium Tutorial

June 1st, 2011 Go to comments

To provide for fault tolerance, many networks implement redundant paths between devices using multiple switches. However, providing redundant paths between segments causes packets to be passed between the redundant paths endlessly. This condition is known as a bridging loop.

(Note: the terms bridge, switch are used interchangeably when discussing STP)

To prevent bridging loops, the IEEE 802.1d committee defined a standard called the spanning tree algorithm (STA), or spanning tree protocol (STP). Spanning-Tree Protocol is a link management protocol that provides path redundancy while preventing undesirable loops in the network. For an Ethernet network to function properly, only one active path can exist between two stations.

Let’s see a situation when there is no loop-avoidance process in operation. Suppose you have two switches connected with redundant links. One switch connected to PC A and the other switch connected to PC B.

Now PC A wants to talk to PC B. It then sends a broadcast, say an Address Resolution Protocol (ARP) to find out where the location of PC B, the green arrow shows a broadcast frame sent by PC A.

When the switch A receives a broadcast frame, it forwards that frame to all ports except the port where it receives the request -> SwA forwards that ARP frame out of fa0/0 and fa0/1 ports.

STP_broadcast_storm.jpg

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Comments (105) Comments
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  1. sanbt
    July 15th, 2012

    9tut please help i will give ccnp Routing exame in next 15 days
    where i can study ccnp simulator please provide the link.

  2. sanbt
    July 15th, 2012

    i will waiting for you replay

  3. This is It!! :-)
    July 20th, 2012

    @Jamwal – The answer is A.

    A) root and alternate – RSTP introuduce alternate route. Thanks

    please refer to 9tut explanation on RSTP

  4. This is It!! :-)
    July 20th, 2012

    @Jamwal – The answer is C

    C) alternate and backup – RSTP introuduce alternate and backup route. Thanks

    please refer to 9tut explanation on RSTP

  5. This is It!! :-)
    July 20th, 2012

    @Jamwal – The answer is B

    B) root and desiginated

    In RSTP, root and designated ports are the only ones forwarding and therefore the only ones included in the active topology. All ports on the root bridge are designated ports. Each non-root bridge has a root port. Every segment has only one designated port. All other ports are not forwarding.

  6. Anonymous
    July 30th, 2012

    Hi All, I did not understand the process of changing Bridge Priority. Can anyone please explain how we change Bridge Priority as stated like (4096+vlan no). From where did we get the VLAN No. ? Please assist me in this regards. Also how do we take multiple of 4096?

  7. Abinaya
    July 31st, 2012

    understood the basic concept. thank u for the simplification:)

  8. learner
    August 7th, 2012

    @9tut – good explanation regarding broadcast storm

  9. learner
    August 7th, 2012

    @9tut – Nice tutorial , understood it well… Xallax and 9tut , plz let me know your email id . atleast , i want to communicate with you guys

  10. Jien
    August 10th, 2012

    Hi 9tut, do you have tutorial for MSTP? Most of the switch currently is running on MSTP. I can learn from google, but I prefer your way :-) thanks.

  11. amila
    August 12th, 2012

    pls help me. if anyone have Spanning Tree Protocol STP Tutorial of this site. pleas email me.
    asankatm@gmail.com

  12. Muditha
    August 18th, 2012

    shit…what you did for poor guys like us 9tut… :(

  13. Anonymous
    September 3rd, 2012

    Need STP tutorial
    Please send me at rehan-500@hotmail.com

  14. Anonymous
    September 11th, 2012

    How to register to 9tut

  15. 9tut
    September 11th, 2012

    @Anonymous: You can find out more here: http://www.9tut.com/we-want-to-write-more

  16. Anonymous
    October 18th, 2012

    I need STP tutorial from 9tut.com
    Can anyone send me at haigoo77@live.com

  17. Ben
    October 24th, 2012

    Great learning experience 9Tut :) Many thanks, price for premium is such a low price for what we get in return.

  18. Anonymous
    November 14th, 2012

    anyone got the tutorial send me at burn_notice33@yahoo.com pleaseeeeee , ThanQ

  19. Dave
    December 2nd, 2012

    in a ring of four switches how are the ports decided on the last link – the one containing the blocking/designated ports between 3 and 4 (1 being the route and all costs being the same)

    2d r3
    r ?

    d ?
    1d r4

  20. Dave
    December 2nd, 2012

    in a ring of four switches how are the ports decided on the last link – the one containing the blocking/designated ports between 3 and 4 (1 being the route and all costs being the same)

    2d r3
    r ?

    d ?
    1d r4

  21. DERK
    December 18th, 2012

    Dear 9tut and all

    I was confusing of these two commands between the “spanning tree@ global config” and “spanning tree @ interface config.I don’t know what command to be use for spanning tree in several vlan

    Can anyone help me ;)

  22. 9tut
    December 18th, 2012

    @DERK: The “spanning tree” in global config is used to enable STP for all ports in all VLANs while the “spanning tree” in interface/vlan config is used to enable STP on an individual Port/vlan.

    Note: By default, spanning tree runs on all ports of a Cisco switch.

  23. DERK
    December 19th, 2012

    @ 9TUT

    I’m so greatly to have a prompt response from you 9tut
    Now, I have knowledge for these differences functionality between the two commands..
    Thank a lot to you 9tut..

  24. Anonymous
    December 29th, 2012

    please email STP tut9 tutorial to anita.krajput@gmail.com

  25. Trish
    February 11th, 2013

    Would anyone be so kind to share the full tutorial? I do not have credit card, but I really want to pass my exam this coming March. Would be needing your help and support in here. Praying for somebody to share success with. Thanks, you guys! :)

  26. Jose
    February 22nd, 2013

    Need STP tutorial
    Please send me at josetelematica@gmail.com

  27. BuNh0nG
    March 3rd, 2013

    Please, kindly help me to send STP tutorial.
    Thank
    bunhongkruy168@gmail.com

  28. sAM
    March 12th, 2013
  29. inshad
    July 5th, 2013

    can any one send me STP tutorial of 9tut. plz plz
    agminshad@gmail.com

  30. era
    July 30th, 2013

    Need STP tutorial
    Please send me at erangadpm@gmail.com

  31. Matt Snihur
    August 19th, 2013

    The Cisco Link is a dead one.

  32. Adam
    September 21st, 2013

    Explained very nicely.

  33. GDR!
    September 29th, 2013
  34. shakeel
    November 13th, 2013

    can any one send me stp tutorial of 9tut plz plz at…..
    ranashakeel.iet@gmail.com

  35. alfaris
    December 31st, 2013

    hi guys
    many thanks for your help and Mr SAM your web site http://www.routerrellay.com it is more usefull , and i have a question what is last version of pass4sure because i need to join cisco exam or if anyone have it he can send me in my email : alfaris200@yahoo.com

  36. Guman
    January 10th, 2014

    Hello Guys.!!
    Can somebody send me CCNA dumps at gchauhan@unomaha.edu ?

  37. Zamil Mesteliyev
    January 25th, 2014

    is that all tutorial for stp ?

  38. ali
    February 19th, 2014

    how to access 9tut on free basis

  39. rayback
    March 27th, 2014

    is that all??

  40. avik
    April 10th, 2014

    How gross! How come this is theory about STP?? This is not STP theory

  41. jj123
    June 30th, 2014

    @avik, wanting everything for free or everything for minimal charge is gross, maybe

  42. K Bonsu
    July 19th, 2014

    @tut This is by far the best explanation I have ever come across.

  43. behnam
    July 28th, 2014

    Hello Guys.!!
    Can somebody send me CCNA dumps at behnam.zanjani@gmail.com ?

  44. Prabhakaran
    August 19th, 2014

    Hi dudes..
    Can somebody send me CCNA dumps 200-100 or link at spprabhakarancse@gmail.com

  45. Muhammad Siddique
    November 10th, 2014
  46. Dhina
    November 11th, 2014

    Hi all, Actually I planned to do CCNA(200-120) certification on r before 20th Nov this year. I just wanna know whether watson 314, examtut 278 and Acme 261 dumps are all enough or not for to do the certification… Moreover I have practiced all simulations from 9 tut… Anything else more than this… pls guide

  47. Hugo
    November 17th, 2014

    Also need STP tutorial…
    can any one send me stp tutorial of 9tut please
    heavncong@gmail.com

  48. Anonymous
    March 7th, 2015

    Hi

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