Re: RSTP problem

Counting to infinity might be a problem with classic RSTP in certain
topologies, e.g. those having multiple loops. More accurately,
counting to infinity behavior might be observed in a situation where
network failure isolates a part of the network from the root bridge,
and the isolated part has loop. In this situation, stale information
would circulate for a long as MaxAge is not exceeded. This is typical
to any distance-vector protocol.

For the second question, it is normally not possible to connected a
full-duplex link to a shared topology. However, this could be done
when using L2 protocol tunneling and interconnecting multiple links
into a stretched L2 domain. In this situation, RSTP behavior is not
very well predictable and may exhibit certain race condition behavior.

In most cases, the above configurations could and should be avoided.
This being said, there has been theoretical work to make RSTP
resistant to counting to infinity problem by adding root bridge
information version tracking, similar to AODV protocol. For more
information, I would suggest looking up papers on AODV and RSTP, e.g.
http://research.yahoo.com/files/ToN.pdf

Regards,

-- 
Petr Lapukhov, petr_at_INE.com
CCIE #16379 (R&S/Security/SP/Voice)
CCDE #20100007
Internetwork Expert, Inc.
http://www.INE.com
Toll Free: 877-224-8987
Outside US: 775-826-4344
2011/12/16 Routing Freak <routingfreak_at_gmail.com>:
> In RSTP, it will work fine only for Poin to Point ethernet link. In a
> shared sthernet space ( ie a Hub is present in between the domain , then
> one of the bridge will be designated and the synchronisation ripple follows
> .
>
> Full duplex link can be connected to a Hub . But Hub doesnt support full
> duplex transmission of data.
>
>
> On Fri, Dec 16, 2011 at 5:41 PM, CCIE KID <eliteccie_at_gmail.com> wrote:
>
>> Hi all,
>>
>> I am going through the doc cd of RSTP and saw a point whihc i cant
>> understand. Can anyone shed some light on it
>> The doc cd states that
>> Counting to Infinity problem is a factor in RSTP .
>> Could a full-duplex link connect to a shared topology in RSTP?
>>
>>
>> --
>> With Warmest Regards,
>>
>> CCIE KID
>> CCIE#29992 (Security)
>>
>>
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