From: Gregory Gombas (ggombas@gmail.com)
Date: Wed Sep 19 2007 - 12:14:03 ART
Thanks Scott,
I'm a little confused, are you saying if a link fails it will not wait
max age for expire?
What if its a non-directly connected link?
On 9/19/07, Scott Morris <smorris@ipexpert.com> wrote:
> Convergence time does not include the blocking timer (20 sec) so it's just 2
> x forward-time. (listen + learn)
>
> Therefore, set your spanning-tree forward-time to 6 and you'll get 12 second
> convergence and 32 second initial delay when first connecting to the switch.
>
> HTH,
>
>
> Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, JNCIE-M
> #153, CISSP, et al.
> CCSI/JNCI-M/JNCI-ER
> VP - Technical Training - IPexpert, Inc.
> IPexpert Sr. Technical Instructor
>
> A Cisco Learning Partner - We Accept Learning Credits!
>
> smorris@ipexpert.com
>
> Telephone: +1.810.326.1444
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>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Gregory Gombas
> Sent: Wednesday, September 19, 2007 9:40 AM
> To: Guyler, Rik
> Cc: alexey; davidytk; ccielab@groupstudy.com
> Subject: Re: STP and Routing questions
>
> Hi Rik,
>
> Can you share the configuration commands needed to achieve a 12 second
> convergence time?
>
> Thanks
>
> On 9/19/07, Guyler, Rik <rguyler@shp-dayton.org> wrote:
> > Well, 50s is the default *maximum* time it will take to transition
> > into the forwarding state, not the time it will take.
> >
> > Taken from your link:
> >
> > max_age
> > = End-to-end_BPDU_propa_delay + Message_age_overestimate = 14 + 6 = 20
> > sec
> >
> > 2 x forward_delay
> > = end-to-end_BPDU_propagation_delay + Message_age_overestimate +
> > Maximum_frame_lifetime + Maximum_transmission_halt_delay = 14 + 6 +
> > 7.5 + 1 = 28.5
> >
> > forward_delay
> > = 28.5 /2
> > = 15 (rounded)
> >
> >
> > So the maximum time it would take to transition into the forwarding
> > state by default is:
> >
> > max_age + 2 x forward_delay = 50sec (rounded)
> >
> > To answer Gary's question, if all you adjusted was max_age and
> > forward_delay then you're right, 14 seconds would be the minimum you
> > could achieve. To get below that number you will have to adjust
> > either the the hello interval or diameter. Here's the formula:
> >
> > End-to-end_BPDU_propa_delay
> > = ((lost_msg + 1) x hello) + ((BPDU_Delay x (dia - 1)) = ((3 + 1) x
> > hello) + ((1 x (dia - 1)) = 4 x hello + dia - 1 = 4 x 2 + 6 = 14 sec
> >
> > Message_age_overestimate
> > = (dia - 1) x overestimate_per_bridge
> > = dia - 1
> > = 6
> >
> > Maximum_frame_lifetime
> > = dia x transit_delay + med_access_delay = dia + 0.5 = 7.5 = 8
> > (rounded)
> >
> > Maximum_transmission_halt_delay
> > = 1
> >
> > Rik
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
> > Of alexey
> > Sent: Wednesday, September 19, 2007 7:56 AM
> > To: davidytk
> > Cc: ccielab@groupstudy.com
> > Subject: Re: STP and Routing questions
> >
> > 2007/9/19, davidytk <davidytk@netvigator.com>:
> > >
> > > Default the STP port from blocking to fowarding is 50s.
> >
> >
> > Don't agree!
> > http://cisco.com/en/US/tech/tk389/tk621/technologies_tech_note09186a00
> > 800949
> > 54.shtml
> >
> > "...The movement of a port into the listening state indicates that
> > there is a change in the active STP topology and that a port will go
> > from blocking to forwarding."
> >
> > For a definition of these changes is Max Age. But two timer Forward
> > Delay responsible for the transition from BLK to FWD!
> >
> >
> > This timer is
> > > related to forward delay and max age
> > >
> > > 50s = 2*forward delay + max age.
> > >
> > > Default forward delay = 15s
> > > Default max age = 20s
> > >
> > > I think the question is related to this item. But there is some
> > > other ways to minimum the timer.
> > >
> > > -----Original Message-----
> > > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
> > > Of alexey
> > > Sent: Wednesday, September 19, 2007 5:53 PM
> > > To: ccielab@groupstudy.com
> > > Subject: Fwd: STP and Routing questions
> > >
> > > > 1. What about max age time? The minimum max age is 6 seconds.
> > > > Minimum forward delay is 4 seconds.
> > > >
> > > > So 6+(4*2) = 14 seconds is the minimum, isn't it?
> > > >
> > > > Someone please verify these numbers...
> > >
> > >
> > > This is not true. Because the question specifically about port
> > > startup (BLK
> > > -> FWD), rather than on the time of convergence network (Max Age +
> > > -> Forward
> > > Delay + Forward Delay).
> > >
> > >
> > > > On 9/17/07, hadek.el-ayachi@nsn.com <hadek.el-ayachi@nsn.com> wrote:
> > > > > Hi Experts,
> > > > > I have the following questions:
> > > > > 1- In a non root switch, make the startup time of ports in vlan
> > > > > 15 equal to 12 seconds?
> > >
> > >
> > > All changes timers should be done only at the root switch. Changes
> > > timers at non-root switches will not lead to any results. Am I right?
> > >
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