From: Sean C (tecmochamp@hotmail.com)
Date: Wed Aug 30 2006 - 16:36:49 ART
Sorry, I'm jumping back a thread here.
Scott - concerning your comment "Although the lab scenario may ask you to
specifically change one piece, don't automatically assume you have to
recalculate everything else! If you aren't asked to, don't do it."
Perhaps that is why you have four CCIE's and I'm beyond my fourth attempt at
my first CCIE. I'd be looking at the scenario in the regards of - assuming
that the vlan is on all the switches (possibly via VTP), even if no physical
interface is assigned the vlan in question, that the lab would be wanting
you to apply the statement to all switches that have that vlan in their vlan
database. But, I can certainly understand your reasoning - if only one of
the switches has a port applied to that vlan, then only change that switch.
Perhaps, the lab would be seeing if you know that you only need to apply the
command to one switch, it's not something that has to be applied everywhere.
Again, thanks for the re-think.
This is kind-of along the lines of that vaunted question in OSPF where the
task is to adjust the auto-cost bandwidth. For the cost to be computed the
same on every device, the config would need to be applied to every device.
But perhaps the task only is looking to see if you recognize that you need
to configure this on one device with that type of interface. <Hope that
made sense!>
Again, thanks,
Sean
----- Original Message -----
From: "Scott Morris" <swm@emanon.com>
To: "'Sean C'" <Upp_and_Upp@hotmail.com>; "'ROCHA Leandro ORANGE-FT'"
<leandro.rocha@orange-ft.com>; "'Aamir Aziz'" <aamiraz77@gmail.com>
Cc: "'GroupStudy'" <ccielab@groupstudy.com>
Sent: Wednesday, August 30, 2006 12:33 PM
Subject: RE: Forward-delay time
> While technically your thinking is correct and a good idea in REAL LIFE
> network design, in the CCIE lab you are often presented with scenarios
that
> logically would not play in real life.
>
> Don't over-think things! With a two-switch ethernet network, there really
> isn't any magical difference that setting the max-age timer is going to
> play! Watch your "show spanning-tree" information to see what the
switches
> do.
>
> Although the lab scenario may ask you to specifically change one piece,
> don't automatically assume you have to recalculate everything else! If
you
> aren't asked to, don't do it.
>
> If the scenario asked you to keep all of the 802.1D ratios, yet still make
> convergence time faster with those specifics, THEN perhaps you'll think
down
> this path!
>
> Believe me, this is a path that many people take because of real-world
> expectations that we have and knowledge of the actual
> application/implication of changing things like this. But in a lab
> environment, particularly with the limited pieces of equipment that we
have,
> you should ask yourself whether it will make a difference, or not work
> properly otherwise.
>
> HTH,
>
>
> Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, JNCIE
> #153, CISSP, et al.
> CCSI/JNCI-M/JNCI-J
> IPExpert VP - Curriculum Development
> IPExpert Sr. Technical Instructor
> smorris@ipexpert.com
> http://www.ipexpert.com
>
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Sean
> C
> Sent: Wednesday, August 30, 2006 11:49 AM
> To: ROCHA Leandro ORANGE-FT; Aamir Aziz
> Cc: GroupStudy
> Subject: Re: Forward-delay time
>
> Hi Leandro,
>
> If the task was asking to go from blocking to forwarding state in under 16
> secs, wouldn't that be when you would take into consideration the max-age
> timer?
>
> This task specifically states to alter the forward-delay time only,
nothing
> about altering the entire STP equation - "Configure the forward-delay time
> of a Vlan X under 16 seconds." Taking the task into consideration, I
would
> just alter the forward-time to a value of 7.
>
> I understand what you're trying to do, I'm just not sure that your answer
> would meet the requirements of this task.
>
> Also, Aamir - to answer the 2nd part of your original post - "do we need
to
> issue this command on both the switches or only on where the Vlan X
exists."
> - while, technically, you would only need to apply it to a switch where
the
> vlan exists - personally - as long as the vlan in question is able to be
on
> the 2nd switch (no vlan pruning, or the switch w/out the vlan is a VTP
> transparent switch, etc...), I would apply the timer to both switches.
> Or, if I was really questioning it, I would ask the proctor something
along
> the lines of "Should I take into consideration the chances of that vlan
> being used on the 2nd switch in the future?...."
>
> HTH,
> Sean
>
> ----- Original Message -----
> From: "ROCHA Leandro ORANGE-FT" <leandro.rocha@orange-ft.com>
> To: <ccielab@groupstudy.com>
> Sent: Wednesday, August 30, 2006 10:05 AM
> Subject: RE: Forward-delay time
>
>
> > I think we have to take in account the max-age timer too.
> >
> > To have less than 16 seconds in any case, we should put max-age to 6 and
> > fwd-delay to 4 (the minimum values).
> >
> > Then we have a total of 6+4+4=14.
> >
> > Leandro
> >
> >
> >
> >
> >
> > "Brian McGahan" <bmcgahan@internetworkexpert.com>
> > Sent by: nobody@groupstudy.com
> > 08/30/06 10:39 AM
> > Please respond to "Brian McGahan"
> >
> >
> > To: "Aamir Aziz" <aamiraz77@gmail.com>,
> <ccielab@groupstudy.com>
> > cc:
> > bcc:
> > Subject: RE: Forward-delay time
> >
> >
> >
> > The forward-delay command configures each of the listening and
> > learning phase timers. This means that if you have it configured as 15
> > that it will take 30 seconds to go through both phases. If you want to
> > move from blocking to forwarding in less than 16 seconds your forward
> > delay would have to be 8 or lower.
> >
> > Brian McGahan, CCIE #8593
> > bmcgahan@internetworkexpert.com
> >
> > Internetwork Expert, Inc.
> > http://www.InternetworkExpert.com
> > Toll Free: 877-224-8987 x 705
> > Outside US: 775-826-4344 x 705
> > 24/7 Support: http://forum.internetworkexpert.com
> > Live Chat: http://www.internetworkexpert.com/chat/
> >
> >
> > > -----Original Message-----
> > > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
> > Of
> > > Aamir Aziz
> > > Sent: Wednesday, August 30, 2006 6:48 AM
> > > To: ccielab@groupstudy.com
> > > Subject: Forward-delay time
> > >
> > > Hi there,
> > >
> > > If the task says Configure the forward-delay time of a Vlan X under 16
> > > second then what value do we use 15 or 16?
> > >
> > > #spanning-tree VLAN X forward-time 15 or 16
> > >
> > > since by default it is 15, and do we need to issue this command on
> > both
> > > the
> > > switches or only on where the Vlan X exists.
> > >
> > > Thanks
> > > Aamir
> > >
> > >
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