Re: PVST - MSTP interop : Error

Hi,

As far as I remember only option in cisco's pvst-mst interoperability
implementation is having root bridge for all vlans/instances at mst region.

regards,

On Sat, Mar 26, 2011 at 8:45 AM, GAURAV MADAN <gauravmadan1177_at_gmail.com>wrote:

> Hi All
>
> As far as I know (from readings etc) :
>
> 1) In case of MSTP - PVSTP inter-op scenarios ; we should either have
> [A] root for all vlans (all instances) in MST region
> [B] root for all vlans on PVST switch
>
> 2) Having root for half vlans in MST region and half on PVST switch is not
> a
> valid scenario and we will see PVST_Inc error in this .
>
> 3) Best practice suggest having root in MSTP region
>
> 4) However there is no stopping having root on PVST switch as well .
>
> Now My problem is following (My intent is to get SW2 PVST switch as root):
>
> SW-1 (MSTP) g1/1---------------------g1/1- SW-2(PVST)
> g1/2---------------------g1/2
>
> SW1 config
> ===========
> spanning-tree mode mst
> spanning-tree extend system-id
> !
> spanning-tree mst configuration
> name aa
> revision 10
> instance 1 vlan 1-5
> instance 2 vlan 6-10
> !
> spanning-tree mst 1 priority 8192
> spanning-tree mst 2 config 32768
>
> SW2 config
> ========
> !
> spanning-tree mode pvst
> spanning-tree extend system-id
> spanning-tree vlan 1-4094 priority 4096
> !
>
> At SW1 ; I am getting following error :
> C4924(config)#
> *Mar 26 06:39:35.735: %SPANTREE-2-PVSTSIM_FAIL: Blocking root port Gi1/1:
> Inconsitent inferior PVST BPDU received on VLAN 2, claiming root
> 2:0024.1430.2f00
>
> C4924#sh span mst 1
>
> ##### MST1 vlans mapped: 1-5
> Bridge address 001d.450d.0700 priority 8193 (8192 sysid 1)
> Root this switch for MST1
>
> Interface Role Sts Cost Prio.Nbr Type
> ---------------- ---- --- --------- --------
> --------------------------------
> Gi1/1 Mstr BKN*20000 144.1 P2p Bound(PVST) *PVST_Inc
> Gi1/2 Altn BLK 20000 128.2 P2p Bound(PVST)
>
> C4924#sh span mst 2
>
> ##### MST2 vlans mapped: 6-10
> Bridge address 001d.450d.0700 priority 32770 (32768 sysid 2)
> Root this switch for MST2
>
> Interface Role Sts Cost Prio.Nbr Type
> ---------------- ---- --- --------- --------
> --------------------------------
> Gi1/1 Mstr BKN*20000 128.1 P2p Bound(PVST) *PVST_Inc
> Gi1/2 Altn BLK 20000 128.2 P2p Bound(PVST)
>
> Please let me know where am i wrong ?
>
> Thanks
> Gaurav Madan
>
>
> Blogs and organic groups at http://www.ccie.net
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
>
>
>
>
>
>
>
>

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