Re: Spanning tree .. Killing me .. :-(

PortFast can indeed be enabled on a trunk port, but this is rare. It
is up to you to ensure there can be no loops created with this
configuration. One case in which it might be used is to speed
convergence for a "router on a stick" configuration. Router on a stick
means that we are connecting to a router via a trunk port so that the
external route processor can handle inter-vlan routing for the L2-only
switch device.

The only command required on the 3560 to enable PortFast on a trunk
port is spanning-tree portfast trunk.

Warmest Regards,

Anthony J. Sequeira, CCIE #15626
http://www.INE.com

Test your Core Knowledge today!
Q: In classic STP, which switch is responsible for notifying all
switches of a topology change?
A: the root bridge
More Info: http://www.cisco.com/en/US/tech/tk389/tk621/technologies_white_paper09186a0080094cfa.shtml#newtop

On Dec 11, 2009, at 3:50 AM, MDevarajan_at_inautix.co.in wrote:

> Anthony,
>
> Small doubt. :-) , Mainly port fast is used for end host system
> rite ? are
> we using portfast for between switches tooo ?? How this will imapact
> in
> between switches. in this case do we need to disable bpdu guard
> tooo ???
>
>
>
>
>
>
>
>
> Anthony Sequeira <asequeira_at_ine.com>
> Sent by: nobody_at_groupstudy.com
> 12/10/2009 10:47 AM
> Please respond to
> Anthony Sequeira <asequeira_at_ine.com>
>
>
> To
> Mohan Kumar Devarajan/Chennai/iNautix_at_iNautix
> cc
> Radioactive Frog <pbhatkoti_at_gmail.com>, Cisco certification
> <ccielab_at_groupstudy.com>, nobody_at_groupstudy.com
> Subject
> Re: Spanning tree .. Killing me .. :-(
>
>
>
>
>
>
> Hi Mohan!
>
> The line <spanning tree enabled protocol ieee> on a 3560 indicated you
> are running Per VLAN STP (802.1D or classic STP). What deceives
> students is the fact that the interface output will still show
> properties of RSTP, even though the switch is not implementing that
> technology. This is kind of like how the show interface trunk output
> will show the Native VLAN for an ISL trunk when we know there is no
> such thing. :-)
>
> In order to run RSTP on the device, you have two options. You can go
> with Per VLAN RSTP, or you can go with MSTP, which will give you RSTP
> automatically.
>
> In order to engage in the fast convergence, all inter-switch links
> must be full-duplex, point-to-point connections. For ports that
> connect to hosts, we have Edge Ports. The PortFast command is still
> recommended and used for the configuration of these ports.
>
> Warmest Regards,
>
> Anthony J. Sequeira, CCIE #15626
> Senior CCIE Instructor
> http://www.INE.com
>
> Test your Core Knowledge today!
> Q: What does Cisco use to optimize the Forwarding Information Base?
> A: Cisco Express Forwarding
> More Info:
> http://www.cisco.com/en/US/products/hw/routers/ps167/products_tech_note09186a00801e1dc2.shtml
>
>
> On Dec 10, 2009, at 8:56 AM, MDevarajan_at_inautix.co.in wrote:
>
>> Can someone please help me to understand the below concept..
>>
>>
>> As per the below output .. I am thinking its running RSTP protocol
>> rite
>> ????
>>
>> Question 1 : if link type EDGE means .. its connected to enf HOST ..
>> Am I
>> rite ??
>> Question 2: if link type is P2P means.. Its connected to other
>> switch...
>> Am I rite ???
>>
>>
>> VLAN0005
>> Spanning tree enabled protocol ieee
>> Root ID Priority 8192
>> Address 00d0.0152.1805
>> Cost 3
>> Port 1665 (Port-channel1)
>> Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
>>
>> Bridge ID Priority 32768
>> Address 00d0.015c.9c05
>> Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
>> Aging Time 300
>>
>> Interface Role Sts Cost Prio.Nbr Type
>> ---------------- ---- --- --------- --------
>> --------------------------------
>> Fa2/44 Desg FWD 19 128.172 Edge P2p
>> Po1 Root FWD 3 128.1665 P2p
>> Po2 Desg FWD 3 128.1666 P2p
>>
>>
>> See the running config
>>
>> Hxxxxxxxx#sh run | inc span
>> spanning-tree mode pvst
>>
>>
>>
>> Please advise me .. if router is running PVST .. Why the hell its
>> showing
>> as " Spanning tree enabled protocol ieee "
>>
>>
>> Thanks,
>> Mohan
>>
>>
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>>
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Received on Fri Dec 11 2009 - 11:02:05 ART