Re: Spanning-tree root port selection

Thank you divin for clarifying point no.4 ............

Regards
Anantha Subramanian Natarajan

On Tue, Sep 15, 2009 at 2:18 PM, Divin Mathew John <divinjohn_at_gmail.com>wrote:

> hey!
> its
> 1) Lowest Cost to root
> 2) Lowest BID of upstream device
> 3) Lowest upstream portid.priority
> 4) If all the 3 are the same then lowest interface ID on local switch
>
> @Joe. BID comes into play when u have 2 paths of the same cost to root
> bridge! it serves as a tie breaker!
>
>
> On Wed, Sep 16, 2009 at 12:43 AM, Joe Astorino <jastorino_at_ipexpert.com>wrote:
>
>> 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
>>
>>
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Received on Tue Sep 15 2009 - 14:21:29 ART