From: Paul Cosgrove (paul.cosgrove@heanet.ie)
Date: Sat Aug 09 2008 - 15:51:11 ART
Hi Igor,
I don't have this lab, but from your description is would be worth
checking if the etherchannel configuration on SW4 matches that of SW2.
If all three ports are not channeling SW4 may send packets received from
SW2 back to SW2.
Paul.
Igor Manassypov wrote:
> Study,
> The stp tunnelling is for S1-S3 across S4, its got nothing to do with S2 being shut down... l2p tunnel stp is granted to make s1-s3 share one common tree. I cant reason why SW2, having three trunks in parallel run to SW4 is being shut down. Those three are the only paths up from SW2, so honestly I am lost here completely.
>
> cciestudy <cciestudy@mid-world.net> wrote: v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} st1\:*{behavior:url(#default#ieooui) } From what I understand (I am not even close to an expert), is that the keepalive is the loop detection mechanism on the switch. Turn it off and the loop doesnt go away, it just doesnt detect. The STP addition was the fix to detect and block the loop.
>
> Scott. Correct me if I am wrong on this.
>
>
> ---------------------------------
>
> From: Igor Manassypov [mailto:imanassypov@rogers.com]
> Sent: Friday, August 08, 2008 2:08 PM
> To: Igor Manassypov; cciestudy; 'GS CCIE-Lab'
> Subject: RE: IE Lab 20
>
>
> Besides, how does interface keepalive relate to spantree loops?
>
> Igor Manassypov <imanassypov@rogers.com> wrote:
> Hmm, whats the mechanism behind the interface keepalives that triggers the interface to shutdown? Besides, I really doubt that just by disabling the interface keepalive you avoid the loop, its just might stop going into errdisable but the loop will still occur if there is one (?)
>
> cciestudy <cciestudy@mid-world.net> wrote:
> I finished that lab a few weeks ago. All I can say is it was a bugger to
> solve. The IE message board has some good insight into why it was
> occurring. I believe turning off interface keep-alives resolved the looping
> problem. I believe it was SW4, F0/13, F0/15, F0/19, F0/21. Also, I tried
> doing L2protocol-tunnel on STP also...
>
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Igor
> Manassypov
> Sent: Friday, August 08, 2008 9:58 AM
> To: GS CCIE-Lab
> Subject: IE Lab 20
>
> Hi Gang,
>
> Has anyone done internetwork expert's lab 20 recently? I am having a hard
> time on the first section with STP where it keeps flipping interfaces to
> err-disabled mode due to 'loopback error'. I am wondering if anyone was able
> to solve it.
>
> Thanks!
>
>
> Igor M., M.Eng, P.Eng
> Network Architect
>
>
> Blogs and organic groups at http://www.ccie.net
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
>
>
>
>
>
>
>
>
>
>
>
> Igor M., M.Eng, P.Eng
> Network Architect
>
>
>
> Igor M., M.Eng, P.Eng
> Network Architect
>
>
>
>
> Igor M., M.Eng, P.Eng
> Network Architect
>
>
> Blogs and organic groups at http://www.ccie.net
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
Blogs and organic groups at http://www.ccie.net
This archive was generated by hypermail 2.1.4 : Mon Sep 01 2008 - 08:15:29 ART