Re: IERS Lab4 Task1.3 - Loopguard and UDLD

Hello,

UDLD and loopguard are essentially two ways to solve the same problem
using different methods. Like Nadeem said, UDLD physically detects
the uni-directional links, whereas loopguard is more geared towards
STP specifically. Typically you will deploy one or the other. You
may want to check out the following link which does a nice comparison
: )

http://www.cisco.com/en/US/tech/tk389/tk621/technologies_tech_note09186a0080094640.shtml#loop_guard_vs_uld

On Sun, Jan 24, 2010 at 7:05 AM, Michael McFarlin
<router.genie_at_gmail.com> wrote:
> Experts,
>
> I have a question about UDLD and Loopguard in one of the IERS labs. I don't
> think that loopguard is needed at all here. Why would you have to worry
> about SW1 making the Fa0/15 a designated port if UDLD has already taken the
> port down? By default UDLD acts faster than Loopguard by default right?
>
>
> Task
>
> Administrators of your network are concerned about SW1 and SW2 not
> being able to detect a link failure on port Fa0/15.
>
> Configure SW1 and SW2 so that port Fa0/15 is brought down in the case
> that either switch can send traffic, but not receive, or vice versa.
>
> As an additional precaution, configure SW1 so that interface Fa0/15 is not
> mistakenly elected as a designated port in the above case.
>
> Answer
>
> SW1:
> interface FastEthernet0/15
> udld port aggressive
> spanning-tree guard loop
> SW2:
> interface FastEthernet0/15
> udld port aggressive
>
>
> -Mike
>
>
> Blogs and organic groups at http://www.ccie.net
>
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>

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