From: kevin gannon (kevin@gannons.net)
Date: Sat Nov 19 2005 - 06:14:01 GMT-3
John
There is other differences read the following for details in particular
the CAM flush alcelartion:
http://www.cisco.com/en/US/tech/tk389/tk621/technologies_tech_note09186a0080094641.shtml#uplink_fail
Worth labbing this up below is a little test with fwd-delay=4 (lowest
on the 3550):
SW2(config-if)#do sh log | i 222
*Mar 9 13:04:46.741: STP: VLAN0222 new root port Fa0/14, cost 19
*Mar 9 13:04:46.741: STP: VLAN0222 Fa0/14 -> listening
*Mar 9 13:04:48.741: STP: VLAN0222 sent Topology Change Notice on Fa0/14
*Mar 9 13:05:01.741: STP: VLAN0222 Fa0/14 -> learning
*Mar 9 13:05:16.741: STP: VLAN0222 sent Topology Change Notice on Fa0/14
*Mar 9 13:05:16.741: STP: VLAN0222 Fa0/14 -> forwarding
SW2(config-if)#do sh span vl 222
VLAN0222
Spanning tree enabled protocol ieee
Root ID Priority 32990
Address 000d.29e7.3580
Cost 19
Port 13 (FastEthernet0/13)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32990 (priority 32768 sys-id-ext 222)
Address 000d.29ed.9f00
Hello Time 2 sec Max Age 20 sec Forward Delay 4 sec
Aging Time 300
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/1 Desg FWD 19 128.1 P2p
Fa0/13 Root FWD 19 128.13 P2p
Fa0/14 Altn BLK 19 128.14 P2p
Now with uplink fast and no timers changed:
SW2(config-if)#shut
SW2(config-if)#
*Mar 9 13:11:28.665: STP: VLAN0001 new root port Fa0/14, cost 3019
*Mar 9 13:11:28.665: %SPANTREE_FAST-7-PORT_FWD_UPLINK: VLAN0001
FastEthernet0/14 moved to Forwarding (UplinkFast).
Its so quick I can not really show it based on a debug without
writting a script. But basically the ~1s after I shut the current root
port the Alt port takes over as the root.
But I would advised you not to trust me and test it yourself.
Regards
Kevin
On 11/18/05, T. N. Noble <tn.noble@inserviceindia.com> wrote:
> From documentation cd....
>
> Use the spanning-tree uplinkfast global configuration command to accelerate
> the choice of a new root port when a link or switch fails or when the
> spanning tree reconfigures itself.
>
> Use the spanning-tree mst forward-time global configuration command to set
> the forward-delay time for all multiple spanning-tree (MST) instances. The
> forwarding time determines how long each of the listening and learning
> states last before the interface begins forwarding.
>
> HTH,
>
> T. N. Noble
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of John
> Matus
> Sent: Saturday, November 19, 2005 1:03 AM
> To: ccielab@groupstudy.com
> Subject: spanning-tree equivalent command question
>
> does
>
> spanning-tree uplink fast
>
> do the same thing as
>
> spanning-tree forward- 3
>
>
>
> Regards,
>
> John D. Matus
> Technical Support / PAS
> Fujitsu Consulting
> 626-568-7716
> John.Matus@tokiom.com
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