From: Prashanth (prashanthcm@xxxxxxxxx)
Date: Sat Dec 08 2001 - 15:26:13 GMT-3
Portfast cannot be enabled on the trunk ports
else its a bug, I will check with a 1900 tomorrow
prashanth
--- "Erick B." <erickbe@yahoo.com> wrote:
> Hi,
>
> Some more details on portfast.
>
> If a port is configured for portfast it will go to
> forwarding state right away then spanning tree runs
> as
> normal. So if a BPDU comes in on this port then
> spanning tree reconverges as usual and this port is
> no
> longer in portfast mode.
>
> So, in your disucussion about having a port
> connected
> to another switch and one side had portfast on and
> other switch didn't. When the port on the other
> switch
> comes up spanning tree runs as usual and sends BPDUs
> and the port w/portfast on see's them and reverts
> back
> to normal spanning tree operation.
>
> I haven't seen portfast ran between switches, it is
> usually used and recommened for ports connecting to
> workstations and servers. Theres also uplinkfast and
> backbonefast which may be more suitable for
> switch-to-switch links. I don't have much experience
> with those options however.
>
> --- Michael Popovich <m.popovich@home.com> wrote:
> > It is my understanding of the portfast command
> that
> > if both ports on
> > both sides are configured for portfast it will
> > indeed immediately start
> > passing packets even if there is a loop in the
> > network. However, that is
> > only temporary. I understand that the spanning
> tree
> > algorithm is still
> > running and after the 50 seconds it takes to run
> > that loops will be
> > detected and spanning tree will run as normal.
> > Portfast doesn't disable
> > spanning tree.
> >
> > MP
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com
> > [mailto:nobody@groupstudy.com] On Behalf Of
> > Phil
> > Sent: Saturday, December 08, 2001 8:16 AM
> > To: Taz Kazam; Rivron Francois; thegroup
> > Subject: RE: Spantree Timer
> >
> >
> > If you have a port with portfast enabled when you
> > connect it to another
> > switch port it will be automatically placed in
> > disable, unless that
> > other port os also configured with portfast
> enabled
> > (and in this case
> > they will not block and a loop will occur). Phil.
> >
> > Taz Kazam <taz_kazam@yahoo.co.uk> escreveu:
> Thanks
> > Francois
> >
> > I managed to find out. I think that the Cat1900
> has
> > the ports status set to PORTFAST by default
> > (command: start-forwarding),
> > hence, it removes the foward delay time (15+15) =
> 30
> > sec, only using
> > MaxAge = 20 sec.
> > If you configure the port with no start-forwarding
> > i.e. disable the PORTFAST, it then takes the 50
> > seconds to change over.
> >
> > Thanks you you reply.
> >
> > Taz.
> >
> >
> > --- Rivron Francois
> > wrote: > Hello,
> > > my think is as the switch is able to detect a
> > fault
> > > at a physical level, the
> > > port state of the redondant link is move
> directly
> > to listening state.
> > > So the redondant path should be on in 30s.
> > >
> > > Francois
> > >
> > > > -----Message d'origine-----
> > > > De: Taz Kazam [SMTP:taz_kazam@yahoo.co.uk]
> > > > Date: vendredi 7 dicembre 2001 10:38
> > > > @: thegroup
> > > > Objet: Spantree Timer
> > > >
> > > > Can anyone help.
> > > >
> > > > I've step up four 1900 Catalyst switch in a
> > loop,
> > > to
> > > > test spanning tree. One port changes its state
> > to
> > > > blocking, as I expected, however, when I take
> > the
> > > > cable out of the non-redundant path, which
> cause
> > > the
> > > > redundant path to change from blocking to
> > > fowarding -
> > > > it does, but it only take 20 seconds. From my
> > > reading
> > > > this should take 50 seconds (15sec fwd delay -
> > > 20sec
> > > > MaxAge) Blocking -----15-----Listen---
> > > > 15-----Learning----20------Fowarding. Im using
> > the default factory
> > > > settings!
> > > >
> > > > Anyone can help?
> > > >
> > > > Taz.
>
>
>
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