Re: STP Loop Guard doubt

Let me introduce an analogy I find simple:

STP function is to define who (which switch) is in charge of each
segment in a L2 domain, so there is only 1 switch in charge of every
segment (Designated ports).

The way it works is like you have strings linking the switches; you
choose one as root and pull it high, so "attached" switches hang below,
like a children mobile set. You keep all your topology "hanging" from
the root switch.

All links that are tight have a top switch and a bottom one: the top
most is the root. The port on top of each string is the designated port.
The bottom port is the root port of the bottom switch for the "tight"
links, and in the case of having a link with slack, that would be an
alternate port.

If you get the idea, now rootguard and loopguard are easy: rootguard
means "the string from this port must go down", or "the root switch
can not be this way".
Loopguard means "the string from this portmust go up" or "the root
switch should be this way".

-Carlos

want2bccie . @ 7/6/2011 14:38 -0300 dixit:
> Hi GS,
>
> My understanding on Loop Guard feature - *If BPDUs are not received on a
> non-designated port with loop guard enable, port moves to loop-inconsistent
> blocking state*.
>
> Need to understand if loop guard is enabled on designated/root ports and
> unidirectional link failure occurs, whether port will still moves to
> loop-inconsistent
> blocking state? or is it only designed for blocking port?
>
>
> Blogs and organic groups at http://www.ccie.net
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
>
>
>
>
>
>
>

-- 
Carlos G Mendioroz  <tron_at_huapi.ba.ar>  LW7 EQI  Argentina
Blogs and organic groups at http://www.ccie.net