Re: Spanning-tree root port selection

Let me clarify -- I don't see how the BID ties into the root-port selection
process BEFORE the lowest cost path to the root bridge. The way I
understand the algorithm is that the first thing checked is the lowest cost
path to the root bridge, not the lowest BID. Now, if things are tied, yes I
agree we look at lowest sender BID.

On Tue, Sep 15, 2009 at 3:12 PM, Joe Astorino <jastorino_at_ipexpert.com>wrote:

> I don't see how the lowest BID ties into electing a root-port on a non-root
> bridge. The election so far as I know is based on what you originally
> said. If I am incorrect, please reference some documentation.
>
> On Tue, Sep 15, 2009 at 2:54 PM, Anantha Subramanian Natarajan <
> anantha.natarajan_at_gravitant.com> wrote:
>
>> Hi Guarav,
>>
>> Thanks for the response.Actually the below mentioned is true for all,but
>> when all those tied,which may be in the case where the topology in which
>> hub
>> is in between and the non-root bridge is having 2 connections to it.In
>> that
>> scenario,I am understanding that the local port id would be choosed as tie
>> breaker.If that is wrong,kindly correct me again.
>>
>> Thanks for the help
>>
>> Regards
>> Anantha Subramanian Natarajan
>>
>>
>>
>> On Tue, Sep 15, 2009 at 1:36 PM, GAURAV MADAN <gauravmadan1177_at_gmail.com
>> >wrote:
>>
>> > Small error ...
>> >
>> > Correct one is
>> >
>> > Lowest BID
>> > Lowest root path cost
>> > Lowest sender Bridge Id
>> > Lowest sender Port Id
>> >
>> > HTH
>> > Gaurav Madan
>> > CCIE
>> >
>> > On Tue, Sep 15, 2009 at 11:58 PM, Anantha Subramanian Natarajan
>> > <anantha.natarajan_at_gravitant.com> wrote:
>> > > Hi All,
>> > >
>> > > When I went through LAN Switching Book,I understood the below(Please
>> > > correct me,If I am wrong)
>> > >
>> > > In the below scenario(Same Hub)
>> > >
>> > > SW1(Root Bridge) ---------Hub --------- SW2
>> > > Hub ----------SW2
>> > >
>> > > When SW2 tries to calculate its root port to the root bridge,by
>> default
>> > all
>> > > the parameters(Path cost,sender bridge-id,port ID information SW1) all
>> > > ties,the SW2 uses it *local port ID* for the tie breaker. Is my
>> > > understanding right ? If so,when a question comes to describe a root
>> port
>> > > selection ,should I need to mention this also like as below
>> > >
>> > > 1)Highest Root path cost
>> > > 2)Lowest sender bridge-id
>> > > 3) Lowest sender Bridge port ID
>> > > 4)* Lowest local port ID ,if all the above Tie*
>> > > **
>> > > Kindly correct me if I am wrong.
>> > >
>> > > Thank you very much
>> > >
>> > > Regards
>> > > Anantha Subramanian Natarajan
>> > >
>> > >
>> > > Blogs and organic groups at http://www.ccie.net
>> > >
>> > >
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>
>
> --
> Regards,
>
> Joe Astorino - CCIE #24347 R&S
> Technical Instructor - IPexpert, Inc.
> Cell: +1.586.212.6107
> Fax: +1.810.454.0130
> Mailto: jastorino_at_ipexpert.com
>

-- 
Regards,
Joe Astorino - CCIE #24347 R&S
Technical Instructor - IPexpert, Inc.
Cell: +1.586.212.6107
Fax: +1.810.454.0130
Mailto:  jastorino_at_ipexpert.com
Blogs and organic groups at http://www.ccie.net