From: Przemyslaw Karwasiecki (karwas@xxxxxxxxxxx)
Date: Sat Mar 02 2002 - 01:05:01 GMT-3
Khurram,
I have browsed through Radia Perlman Interconnction...
chapter about spanning tree, and I haven't noticed
any reference to special meaning of "priority 0".
I belive that we need to re-think original question:
"How to ensure that switch will NOT become root on given VLAN?"
All of us are trying to use single CatOS knob
-- "spantree priority", but maybe solution is somewhere else?
Maybe we need to set some filters, change port priorities or cost
or something else.....
I don't know.....
But I am definitelly not convinced that "spantree priority 0 <vlan_id>"
will prevent switch from beeing elected as a root.
At least I dont see any definitive reference to any standart
defining such behaviour of bridge with priority set to 0.
Przemek
On Fri, 2002-03-01 at 19:16, Khurram Khani wrote:
> 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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