Re: MSTP IST( MSTI0) vs MIST confusion

Thanks a lot hemanth .Gud explanation.

 One more question What does M-Record contain and wat r the contents in IST
BPDU . What is the difference between the contents in M-Record and IST BPDUs
?

On Wed, Sep 7, 2011 at 6:54 PM, HEMANTH RAJ <hemanthrj_at_gmail.com> wrote:

> Hi kid,
>
> IST is nothing but ur MST Instance 0 which mainly serves the purpose of
> distributing STP topology information for MST Instances. IST has a root
> bridge, elected based on the lowest Bridge ID (Bridge Priority + MAC
> address). The situation changes with multiple MSTP regions in the network.
>
> By default, all VLANs are mapped to the IST .Other MSTP instances could be
> enabled and they are referred to as Multiple Spanning Tree Instances
> (MSTIs). Every MSTI assign its own priorities to the switches and use its
> own link costs to come up with a private logical topology which is
separate
> from IST
>
> Since MSTP does not send MSTIs information in separate BPDUs, this
> information is attached into the ISTs BPDUs using special M-Record
fields.
> I think these M-Records are one for every active MST Instances. They have
> extended TLVs to do that I guess if i remember correctly.
>
> I hope this helps u
>
>
>
>
>
> On Wed, Sep 7, 2011 at 2:33 PM, CCIE KID <eliteccie_at_gmail.com> wrote:
>
>> Hi fellas,
>>
>> I am reading MSTP and i came across two terminologies IST and MIST.
>> IST is used to send all the BPDU related information which is all the
>> information regarding which VLANS mapped to which instances and to
>> maintain
>> consistency check on all the switches.
>> Now there is a line which states " *MSTI information is attached to IST *"
>> What does MSTI carry and why does it use IST for that
>> Correct me if i am wrong in understanding the logic.
>>
>> I have a confusion regarding Internal Spanning tree (IST) aka MST Instance
>> 0 and Multiple Intances of Spanning tree(MIST). Can some point me what
>> is
>> the difference between IST and MST ?
>>
>> --
>> With Warmest Regards,
>>
>> CCIE KID
>> CCIE#29222 ( SECURITY)
>>
>>
>> Blogs and organic groups at http://www.ccie.net
>>
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>>
>>
>
>
> --
> Problems arise because we talk,problems are not solved because we don't
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>
> Yours Friendly,
> H P HEMANTH RAJ
> CCIE#28593 (R&S)
> Cisco Systems
>
>

--
With Warmest Regards,
CCIE KID
Blogs and organic groups at http://www.ccie.net