From: Scott M Vermillion (scott_ccie_list@it-ag.com)
Date: Thu Dec 04 2008 - 16:29:43 ARST
Sent to the list yesterday but I don't know if it ever made it...
(yes, "BKN" ports, regardless of what Cisco may be calling it in some
documentation, is a port in a "blocking" state -- BUT, it is as a result of
some consistency-checking/root-placement-enforcement feature such as
RootGuard vs. the result of normal Spanning Tree convergence)
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Scott M Vermillion
Sent: Wednesday, December 03, 2008 5:19 PM
To: 'Ronnie Angello'; 'Derek Maffei'
Cc: 'haider aly'; 'L Pham'; 'Amr'; 'ccielab'
Subject: RE: Spanning Tree on Doc CD
Funny that "BKN" is described in some Cisco documentation as "broken
inconsistent," but when a port goes into that state, the error logged refers
to "blocking."
SW1(config-if)#span guard root
%SPANTREE-2-ROOTGUARD_CONFIG_CHANGE: Root guard enabled on port
FastEthernet0/7.
%SPANTREE-2-ROOTGUARD_BLOCK: Root guard blocking port FastEthernet0/7 on
VLAN0001.
SW1#sh span vl 1
VLAN0001
Spanning tree enabled protocol ieee
Root ID Priority 24577
Address 001c.f6b9.6780
Cost 19
Port 9 (FastEthernet0/8)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32769 (priority 32768 sys-id-ext 1)
Address 001c.f6ad.7d80
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 15
Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- --------
--------------------------------
Gi0/1 Desg FWD 19 128.1 P2p
Fa0/1 Desg FWD 19 128.2 P2p
Fa0/2 Desg FWD 19 128.3 P2p
Fa0/3 Desg FWD 19 128.4 P2p
Fa0/4 Desg FWD 19 128.5 P2p
Fa0/5 Desg FWD 19 128.6 P2p
Fa0/6 Desg FWD 19 128.7 P2p
Fa0/7 Desg BKN*19 128.8 P2p *ROOT_Inc
Fa0/8 Root FWD 19 128.9 P2p
Here is one such document (you have to scroll down a ways or just do a
search on the page for "BKN")...
http://www.cisco.com/en/US/docs/ios/bridging/command/reference/br_r1.html#wp
1014500
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Ronnie Angello
Sent: Wednesday, December 03, 2008 1:35 PM
To: Derek Maffei
Cc: haider aly; L Pham; Amr; ccielab
Subject: Re: Spanning Tree on Doc CD
FYI if you want to lab this up - I just ran into this in the real
world. All you need is a simple 3 switch lab with the switches
connected in series. Switch C probably isn't really needed but is
what I was dealing with in this case.
A---B---C
Switch A is Cisco and runs MST. Switch B is Cisco and runs rapid
PVST+, and is configured to be the root for all VLANs. Switch C is HP
ProCurve and runs RSTP.
Observe the behavior on the MST boundary switch - switch A. There is
a really good explanation of the problem here.
http://blog.internetworkexpert.com/2008/09/24/mstp-tutorial-part-ii-outside-
a-region/
The section of particular interest is "Interoperating with PVST."
On Wed, Dec 3, 2008 at 3:23 PM, Ronnie Angello <ronnie.angello@gmail.com>
wrote:
> I meant BroKeN but you get the point...
>
> On Wed, Dec 3, 2008 at 3:22 PM, Ronnie Angello <ronnie.angello@gmail.com>
wrote:
>> Actually that means BRoKen - root inconsistent. Blocking would be
>> BLK. Remember what a designated port is - why would it be blocking?
>>
>> On Wed, Dec 3, 2008 at 2:24 PM, Derek Maffei <dmaffei@midwave.com> wrote:
>>> BKN actually means blocking
>>>
>>> VLAN0123
>>> Spanning tree enabled protocol rstp
>>> Root ID Priority 32891
>>> Address 0050.3e05.9c00
>>> This bridge is the root
>>> Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
>>> Bridge ID Priority 32891 (priority 32768 sys-id-ext 123)
>>> Address 0050.3e05.9c00
>>> Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
>>> Aging Time 300
>>> Interface Role Sts Cost Prio.Nbr Type
>>> ---------------- ---- --- --------- --------
>>> --------------------------------
>>> Fa8/1 Desg BKN*19 240.897 P2p *ROOT_Inc
>>> Fa8/45 Desg FWD 19 128.941 P2p
>>> Gi9/14 Desg FWD 4 128.1038 P2p
>>> Gi9/15 Desg FWD 4 128.1039 Edge P2p
>>>
>>> ! "Desg" means designated port role; BKN means status blocking;
>>> ! FWD means forwarding. Notice the "ROOT Inc" status for port Fa8/1.
>>>
>>> -----Original Message-----
>>> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
>>> Ronnie Angello
>>> Sent: Wednesday, December 03, 2008 1:17 PM
>>> To: haider aly
>>> Cc: L Pham; Amr; ccielab
>>> Subject: Re: Spanning Tree on Doc CD
>>>
>>> Broken! The port is in a broken state for an inconsistency - root
>>> inconsistent, loopguard inconsistent, etc.
>>>
>>> On Wed, Dec 3, 2008 at 11:06 AM, haider aly <ccie.aly.110@gmail.com>
>>> wrote:
>>>> Hi Friends,
>>>> i just want to know.....what is this BKN state in STP...?
>>>>
>>>>
>>>> thanks & regards
>>>>
>>>> Haider Ali
>>>>
>>>>
>>>> On 12/3/08, L Pham <ccie17030@gmail.com> wrote:
>>>>>
>>>>> Amr, most ccie-wanabe should (at least ) know how to get here ...
>>>>>
>>>>> but, here it is:
>>>>> The Cisco Documentation pages have the same information that
>>>>> currently resides on UniversCD, please refer to the links on the CCIE
>>>>> web pages to view these pages and become familiar with the new
>>> format.
>>>>>
>>>>> Cisco Documentation: http://www.cisco.com/web/psa/products/index.html
>>>>>
>>>>> ->goto SWitching->your favorite-ios->pick a release -> look for your
>>>>> answers!!!
>>>>>
>>>>> HTH,
>>>>> Loc
>>>>>
>>>>> On Wed, Dec 3, 2008 at 7:15 AM, Amr <amr.ccie@gmail.com> wrote:
>>>>> > Dear All
>>>>> > Where to find Spanning tree (PVST , MST , RSTP) on the
>>> DOC CD
>>>>> ?
>>>>> >
>>>>> > Thanks In Advance
>>>>> >
>>>>> > Regards
>>>>> >
>>>>> >
>>>>> > Blogs and organic groups at http://www.ccie.net
>>>>> >
>>>>> >
>>> _______________________________________________________________________
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>>>>
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>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>>
>>> --
>>> Ronald Angello
>>> CCIE #17846
>>>
>>>
>>> Blogs and organic groups at http://www.ccie.net
>>>
>>> _______________________________________________________________________
>>> Subscription information may be found at:
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>>>
>>>
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>>>
>>>
>>>
>>>
>>
>>
>>
>> --
>> Ronald Angello
>> CCIE #17846
>>
>
>
>
> --
> Ronald Angello
> CCIE #17846
>
-- Ronald Angello CCIE #17846Blogs and organic groups at http://www.ccie.net
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