GroupStudy.com GroupStudy.com - A virtual community of network engineers
 Home  BookStore  StudyNotes  Links  Archives  StudyRooms  HelpWanted  Discounts  Login
Re: Always in the back of my head: STP posted 01/09/2006
[Chronological Index] [Thread Index] [Top] [Date Prev][Date Next] [Thread Prev][Thread Next]


STP is always recommended for L2 links to avoid unecessary loops.

If there only one link, there is loop, so STP can be technically turned off
but not recommended in real world.

If there is 2 links and there is a physical loop for a specific vlan, then
STP is needed.   If one vlan is going on 1 link and another vlan is going on
another link, it is not needed technically.

You have everything right except the case with 2link etherchannel on access
mode, it is not required technically.

HTH
Balaji



On 1/8/06, lim es <tiga72@xxxxxxxxx> wrote:
>
> Hi Group,
>
> I am still pretty shaky on STP concepts. I know in
> short, it is needed to provide a loop-free path in
> multiaccess networks, have it thought over, i've laid
> out some scenario, i am not too sure if i got it
> correct, would sure appreciate some advice
> on this.
>
> Suppose we have
>
>
> [sw1]-------[sw2]
>
>
>
> sw1 & sw2   etherchannel(L2)    mode            Need STP?
>
> 1 link          NA              Access          Required
>
> 2 links         no              Access          Required
>
> 2 links         Yes             Access          Required
>
> 1 link          NA              Trunk           Not required
>
> 2 links         no              Trunk           Required
>
> 2 links         Yes             Trunk           Not required*
>
>
> L2: Layer 2 aggregation
>
> * switch will look at it as a single link, hence STP
> not required.
>
> All Layer 3 inplementation of etherchannel will not
> need to run STP
>
>
>
> Please correct me if i am wrong
>
> Thanks
>
>
>
>
> __________________________________________
> Yahoo! DSL  Something to write home about.
> Just $16.99/mo. or less.
> dsl.yahoo.com
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html