Re: a question on SPANTREE - '0' to quit election

From: Sandro Ciffali (sandyccie@xxxxxxxxx)
Date: Sat Mar 02 2002 - 01:07:24 GMT-3


   
I did get a chance to clarify this, I configured
router for a transparent bridge, Connected to a cat
switch, Made router a root bridge, set it's priority
to zero, It is still a root, So making zero is
definatly making it a root bridge.
Thus my vote is still to make priority to max. in
order to not make it a root bridge.

sandro

I think you are confusing this with the OSPF election.
 In OSPF, of course,
a zero priority does withdraw it from the election.
In STP, zero is the
best priority when selecting a root bridge.

-Joe

-----Original Message-----
From: Khurram Khani [mailto:kkhani@nortelnetworks.com]
Sent: Friday, March 01, 2002 4:16 PM
To: jezerski@broadcom.com; Khurram Khani
Cc: ccielab@groupstudy.com
Subject: Re: a question on SPANTREE - '0' to quit
election

Joe,

I agree with the lower the priority the higher the
chance thing , but I
remember "1" is the highest priority.
and if you put '0' the switch should withdraw from
Root election. Can any
plz correct me if I am wrong?

Or I think i may need to try connecting two switches
now

Thanks
Khurram.

----- Original Message -----
From: "Joseph Ezerski" <jezerski@broadcom.com>
To: "Khani, Khurram [INGO1:8851:EXCH]"
<kkhani@americasm06.nt.com>
Sent: Friday, March 01, 2002 4:02 PM
Subject: RE: a question on SPANTREE

> No, the lower the priority the higher the chance
that the Bridge-ID will
win
> the root war. Setting a Cisco switch spantree
priority to zero will
> definitely make it the root bridge, assuming you
left all other switches
at
> the default value. Now, I am talking of Cisco only.
 I have no
familiarity
> with other vendor switches.
>
> -Joe
>
> -----Original Message-----
> From: Khurram Khani
[mailto:kkhani@nortelnetworks.com]
> Sent: Friday, March 01, 2002 3:09 PM
> To: Joseph Ezerski; 'Przemyslaw Karwasiecki'
> Cc: 'alain faure'; 'Leigh Anne Chisholm'; 'Clark J';
> ccielab@groupstudy.com
> Subject: Re: a question on SPANTREE
>
>
> In order to ensure that Switch wont become Root
bridge, IEEE document says
> make the priority 0.
> I think this is the best way to ensure that you will
be compatible with
> multi-vendor also.
>
> Thanks
> Khurram.
> ----- Original Message -----
> From: "Joseph Ezerski" <jezerski@broadcom.com>
> To: "'Przemyslaw Karwasiecki'" <karwas@ifxcorp.com>
> Cc: "'alain faure'" <alainfaure@yahoo.fr>; "'Leigh
Anne Chisholm'"
> <lachisho@tnc.com>; "'Clark J'" <clark.j@163.com>;
<ccielab@groupstudy.com>
> Sent: Friday, March 01, 2002 1:32 PM
> Subject: RE: a question on SPANTREE
>
>
> > AH yes, I read the question wrong. He was
attempting to make it so a
> switch
> > could NOT become root. My bad. So, to clear up
confusion, what I wrote
> is
> > the explanation to make a switch the definitive
root bridge. So sorry
for
> > the misread on my part.
> >
> > -Joe
> >
> > -----Original Message-----
> > From: Przemyslaw Karwasiecki
[mailto:karwas@ifxcorp.com]
> > Sent: Friday, March 01, 2002 12:19 PM
> > To: Joseph Ezerski
> > Cc: 'alain faure'; 'Leigh Anne Chisholm'; 'Clark
J';
> > ccielab@groupstudy.com
> > Subject: RE: a question on SPANTREE
> >
> >
> > Joseph,
> >
> > This statement is taken vaebatim from CCO:
> >
> > "The switch with the highest bridge priority (the
lowest numerical
> > priority value) is elected as the root switch. If
all switches are
> > configured with the default priority (32768), the
switch with the
> > lowest MAC address in the Layer 2 network becomes
the root switch"
> >
> > Here:
> >
>
http://www.cisco.com/univercd/cc/td/doc/product/lan/cat5000/rel_6_3/config/s
> > pantree.htm#xtocid129753
> > (beware wrap)
> >
> > According to this priority 0 will garantee that
switch will
> > become root, because it is lowest numerical
priority value.
> >
> > I understand that I am missing something, as you
sound
> > very confident in your statement, which is
contradictory
> > to CCO. Can you please clarify a bit more?
> >
> > Thank you,
> >
> > Przemek
> >
> > On Fri, 2002-03-01 at 14:47, Joseph Ezerski wrote:
> > > Alain, I am assuming that you only have one
vlan? The command you
> entered
> > > here will set the spantree priority first to 0,
then back to 65535 but
> > only
> > > for VLAN 1.
> > >
> > > Try this instead:
> > >
> > > set spantree priority 0 <vlan #>
> > >
> > > Do that for every vlan you have but only on the
root bridge. Leave
> every
> > > other switch the default. Note that you stand a
good chance of seeing
a
> > > major recovergence if you are entering that
command on the switch that
> is
> > > not currently the root.
> > >
> > > That will work. I am 100% sure.
> > >
> > > Forget about root guard for now. Spantree
Priority 0 protects you
from
> > > about 99.999% of anything else becoming the
root.
> > >
> > > -Joe
> > >
> > > -----Original Message-----
> > > From: alain faure [mailto:alainfaure@yahoo.fr]
> > > Sent: Friday, March 01, 2002 11:30 AM
> > > To: jezerski@broadcom.com; 'Leigh Anne
Chisholm'; 'Clark J';
> > > ccielab@groupstudy.com
> > > Subject: RE: a question on SPANTREE
> > >
> > >
> > > hi,
> > >
> > > to solve the problem with another way i try :
> > > - set spantree priority 0
> > > - set spantree priority 65535
> > > - set spantree guard root 4/28 (one port of my
catalyst)
> > >
> > > Without success, any comments ?
> > >
> > > Best regards
> > >
> > > --- Joseph Ezerski <jezerski@broadcom.com> a
icrit : > If you want to
> get
> > > really advanced and you have bigger switches,
like the
> > > > Cat6509, look into the root guard feature.
> > > >
> > > > -Joe
> > > >
> > > > -----Original Message-----
> > > > From: nobody@groupstudy.com
[mailto:nobody@groupstudy.com]On Behalf
Of
> > > > Leigh Anne Chisholm
> > > > Sent: Friday, March 01, 2002 10:34 AM
> > > > To: alain faure; Clark J;
ccielab@groupstudy.com; clark.j@163.com
> > > > Subject: RE: a question on SPANTREE
> > > >
> > > >
> > > > That's a drastic response to what is actually
a simple problem. In
> > > > implementing that solution, you're creating
the potential for
problems
> > > well
> > > > beyond those that you want to resolve.
Spanning Tree has a simple
> > > priority
> > > > system that's easy to manipulate that doesn't
have the implications
of
> > > your
> > > > solution.
> > > >
> > > > Check the CCNA curriculum for information on
how to configure a
switch
> > so
> > > > that
> > > > it can't become the root switch in any given
VLAN.
> > > >
> > > >
> > > > -- Leigh Anne
> > > >
> > > > -----Original Message-----
> > > > From: nobody@groupstudy.com
[mailto:nobody@groupstudy.com]On Behalf
Of
> > > > alain faure
> > > > Sent: Friday, March 01, 2002 11:23 AM
> > > > To: Clark J; ccielab@groupstudy.com
> > > > Subject: Re: a question on SPANTREE
> > > >
> > > >
> > > > hi,
> > > >
> > > > that's interresting question, and we have a
long debate on this with
> > some
> > > of
> > > > my
> > > > friends about one of our customer site.
> > > >
> > > > for me, i think the better way (but they don't
agree with me) is to
> > > disable
> > > > spanning tree on the VLAN for the switch you
don't want they become
> root
> > ?
> > > > What
> > > > do you think about ?
> > > >
> > > > best regards
> > > >
> > > >
> > > > --- Clark J <clark.j@163.com> a icrit : >
Dear CCIEs and Near
CCIEs,
> > > > > How to configure a switch so that it can't
become the root
switch
> in
> > > > VLAN
> > > > A
> > > > > ?
> > > > > Best regards,
> > > > > Clarke J
> > > > >



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