Re: STP Timer values on the secondary bridge

Hello Anantha ,

 these timers are not really used with RSTP Switch doesnt wait for the timers.
the only time we might need them is when we connect switch runing RSTP with
another bridge runing STP.

..as per cisco
RSTP (IEEE 802.1w) natively includes most of the Cisco proprietary
enhancements to the 802.1D spanning tree, such as BackboneFast, UplinkFast,
and PortFast. RSTP can achieve much faster convergence in a properly
configured network, sometimes in the order of a few hundred milliseconds.
Classic 802.1D timers, such as forward delay and max_age, are only used as a
backup and should not be necessary if point-to-point links and edge ports are
properly identified and set by the administrator. Also, the timers should not
be necessary if there is no interaction with legacy bridges.

http://www.cisco.com/en/US/tech/tk389/tk621/technologies_white_paper09186a008
0094cfa.shtml

  ----- Original Message -----
  From: Anantha Subramanian Natarajan
  To: Mohamed El Henawy ; Cisco certification
  Sent: Saturday, September 05, 2009 6:13 PM
  Subject: Re: STP Timer values on the secondary bridge

  Hi Mohammed,

    Atleast I am not sure whether it is right or wrong ...But with my
understanding,it make logical that all the switches in the Rapid Spanning-Tree
protocol participate in providing topology informations to others via
BPDUs,which is different from 802.1d,where Root switch alone sends periodic
BPDUs down the tree and so assuming that is the characteristics,it sounds
right for me that in case of Rapid SPT all the bridges/switches in that doamin
needs to be configured with the timer values for consistency.

  Obviously would like to hear expert comment on his question and also
correcting my understanding is wrong

  Thanks for the help

  Regards
  Anantha Subramanian Natarajan

  On Sat, Sep 5, 2009 at 6:52 AM, Mohamed El Henawy <m.henawy_at_link.net>
wrote:

    I think if this is Rapid SPT we need to modify it on all Switches....Right
or Wrong ??

    ----- Original Message ----- From: "Anantha Subramanian Natarajan"
<anantha.natarajan_at_gravitant.com>
    To: "Cisco certification" <ccielab_at_groupstudy.com>
    Sent: Saturday, September 05, 2009 4:07 AM

    Subject: STP Timer values on the secondary bridge

      Hi All,

       I was going through spanning tree protocol and here by referencing the
      below paragraph read

      "You can only modify the timer values from the root bridge.Modifying
the
      values on other bridges has no effect.However,don't forget to update
any
      "backup" root bridges "

      My question is ,if for example in the real lab they give a task to
configure
      SW1 has primary root for vlan x and SW2 has secondary root for Vlan x
and
      then in another task,if they ask to change the forward-delay timer value
to
      y seconds for Vlan x,do we have to configure this on both root primary
and
      secondary switch.I heard many times that we don't neeed to worry about
      redundancy unless specifically asked in the lab.But just want to make
      sure,if they ask the above task,can we just configure the timer value on
the
      root primary and not on the secondary.

      Kindly clarify the same.Thanks for the help

      Regards
      Anantha Subramanian Natarajan

      Blogs and organic groups at http://www.ccie.net

      _______________________________________________________________________
      Subscription information may be found at:
      http://www.groupstudy.com/list/CCIELab.html

    -------------------------------------------------------------------------
-------

    No virus found in this incoming message.
    Checked by AVG - www.avg.com
    Version: 8.5.409 / Virus Database: 270.13.76/2345 - Release Date: 09/04/09
05:51:00

-----------------------------------------------------------------------------
-

  No virus found in this incoming message.
  Checked by AVG - www.avg.com
  Version: 8.5.409 / Virus Database: 270.13.76/2345 - Release Date: 09/04/09
05:51:00

Blogs and organic groups at http://www.ccie.net
Received on Sat Sep 05 2009 - 17:41:42 ART