Re: mac-address ageing per vlan

Abraham, Johnny, and team,

I hope all is well.

Abraham - the 'accelerated aging' is the same as the default forward time
per the docs. It is 'accelerated' from 5 minutes to 15.

My theory (will try and test it later tonight after the family goes to bed)
is that 15 seconds will be the aging time for STP, but I believe that rapid
and mstp would age it out immediately since they would begin forwarding
immediately. Just a theory ... unless someone else has already tested
this.

My thoughts on testing:

2 switches and two routers. The two routers will ping each other.
Successful pings and show mac-address.

On each switch I will modify the root and initial port cost. I hope to
cause a reconfigure that will stop ping and also show the mac-address
learned on the wrong link.

We shall see ... only once I begin to test this will I see if my testing /
theory is accurate. Have a great night team,

Andrew Lee Lissitz

On Sat, Nov 14, 2009 at 11:56 AM, Johnny B CCIE <jbccie_at_gmail.com> wrote:

> This might help.
>
>
>
http://books.google.com/books?id=eskSfkT3QMkC&pg=PA41&lpg=PA41&dq=accelerated
+aging+forward-time&source=bl&ots=QZgqUkVCQc&sig=tNQOBdhMfuJKJwql_DCoKlLJBgs&
hl=en&ei=jOD-Sun0AYe0tgez5Y2SDg&sa=X&oi=book_result&ct=result&resnum=1&ved=0C
AgQ6AEwAA#v=onepage&q=accelerated%20aging%20forward-time&f=false
>
>
>
> On Sat, Nov 14, 2009 at 11:50 AM, Abraham, Tharak
> <tharakabraham_at_gmail.com> wrote:
> > Thanks Johny !
> > That answered my question directly but i had a confusion with accelerated
> > aging/forward delay config.and thats why this thread popped up.
> >
> > Andrew,
> > Is it 15 secs that the "short aging" time the Doc refers to in the case
> of
> > pvst+ ?
> > Better to test it though, i can do it tomorrow.
> >
> > Thanks again guys !
> >
> > Tharak Abraham.
> >
> >
> > On Sat, Nov 14, 2009 at 6:57 PM, ALL From_NJ <all.from.nj_at_gmail.com>
> wrote:
> >>
> >> I have always found this to be an interesting topic ... mainly, because
> it
> >> occurs automatically and we do not think much of it (except for CCIE
> >> studies!)
> >>
> >> Here is the link I assume you are referring to?
> >>
> >>
>
http://www.cisco.com/en/US/docs/switches/lan/catalyst3560/software/release/12
.2_25_se/configuration/guide/swstp.html#wp1169222
> >>
> >>
> >> Johnny mentioned the command to set the aging time manually. I think he
> >> answers your question.
> >>
> >> - Team - keep me honest here ...
> >>
> >> A couple of thoughts around this and to try and keep things clear (at
> >> least
> >> in my head).
> >>
> >> W/ rapid spt the mac address is immediately deleted when a TCN is
> learned,
> >> no need to rely on the aging timers per mac address. MSTP is built on
> >> rapid
> >> stp, so it also performs the same.
> >>
> >> When spt needs to converge different paths may exist throughout. What
> >> would
> >> happen if all the mac addresses are learned over an interface that is no
> >> longer the forwarding one? Some confusion within the switch perhaps;
> >> especially when it starts to learn mac addresses over different
> >> interfaces.
> >>
> >>
> >> So the switch should age these mac addresses per the forwarding time,
> and
> >> as
> >> the documentation mentions. This makes sense for STP.
> >>
> >> Does the forwarding time have affect with rapid and or mstp for
> alternate
> >> links? Humm ... not really. What does this mean for the aging times?
> My
> >> understanding is that these are aged out immediately for the vlans that
> >> were
> >> affected.
> >>
> >> Anyone see this in the docs or a lab test? I would lab test it but I
> have
> >> no time today till maybe late tonight.
> >>
> >> Can you believe I am still working on leaves and honey-do lists? Ok,
> >> honey-do lists of course ... these never end, but still raking leaves?
> >> Sadly true ...
> >>
> >> I feel like Fred Sanford from 'Sanford and son' crying about my back and
> >> heart ... no one seems to care. ;-) ... crickets and tumbleweeds are
> all
> >> I
> >> hear and see when I say these things ... oh humm ... it is hard to be
> me.
> >> lol
> >>
> >> Andrew Lee Lissitz
> >>
> >>
> >>
> >>
> >> On Sat, Nov 14, 2009 at 1:11 AM, Johnny B CCIE <jbccie_at_gmail.com>
> wrote:
> >>
> >> > conf t
> >> > mac address-table aging-time x vlan xx
> >> >
> >> > The default value x is 300 seconds = 5minutes.
> >> > If you use x = 0, then you have disabled aging for the vlan in
> question.
> >> >
> >> >
> >> >
> >> > On Sat, Nov 14, 2009 at 12:42 AM, Abraham, Tharak
> >> > <tharakabraham_at_gmail.com> wrote:
> >> > > Gents,
> >> > >
> >> > > Could you explain how to enable mac-add ageing for a particular vlan
> ?
> >> > >
> >> > > Just read that accelerated-ageing for a particular vlan can be
> linked
> >> > with
> >> > > STP for that vlan with the forward time.
> >> > > i.e spanning-tree vlan x forward-time y
> >> > >
> >> > > Could someone add more thoughts on this ?
> >> > >
> >> > > Tharak
> >> > >
> >> > >
> >> > > Blogs and organic groups at http://www.ccie.net
> >> > >
> >> > >
> >> > >
> _______________________________________________________________________
> >> > > Subscription information may be found at:
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> >> >
> >> >
> >> > Blogs and organic groups at http://www.ccie.net
> >> >
> >> >
> _______________________________________________________________________
> >> > Subscription information may be found at:
> >> > http://www.groupstudy.com/list/CCIELab.html
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >>
> >>
> >> --
> >> Andrew Lee Lissitz
> >> all.from.nj_at_gmail.com
> >>
> >>
> >> 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
>
> _______________________________________________________________________
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>
>
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--
Andrew Lee Lissitz
all.from.nj_at_gmail.com
Blogs and organic groups at http://www.ccie.net