Community,
I am labbing up MST in prep for the CCNP SWITCH exam and cannot for the life of me make the CST RB outside the MST region. Whenever I do this I get the following message:
%SPANTREE-2-PVSTSIM_FAIL: Blocking root port Fa1/0/21: Inconsistent inferior PVST BPDU received on VLAN 10, claiming root 10:0018.1828.3480
When I do a show span mst 0 on the IST master it does show the following:
##### MST0 vlans mapped: 1-9,11-19,21-29,31-39,41-4094
Bridge address 001f.2792.aa00 priority 32768 (32768 sysid 0)
Root address 0018.1828.3480 priority 1 (0 sysid 1)
port Fa1/0/21 path cost 200019
Regional Root this switch
Operational hello time 2 , forward delay 15, max age 20, txholdcount 6
Configured hello time 2 , forward delay 15, max age 20, max hops 20
FastEthernet1/0/21 of MST0 is broken (PVST Sim. Inconsistent)
Port info port id 128.23 priority 128 cost 200000
Designated root address 0018.1828.3480 priority 1 cost 19
Design. regional root address 0019.e76c.8680 priority 32769 cost 0
Designated bridge address 0019.e76c.8680 priority 32769 port id 128.26
Timers: message expires in 5 sec, forward delay 0, forward transitions 0
pvst inconsistency timer expires in 19 sec
Bpdus sent 41, received 4032
##### MST0 vlans mapped: 1-9,11-19,21-29,31-39,41-4094
Bridge address 001f.2792.aa00 priority 32768 (32768 sysid 0)
Root address 0018.1828.3480 priority 1 (0 sysid 1)
port Fa1/0/21 path cost 200019
Regional Root this switch
Operational hello time 2 , forward delay 15, max age 20, txholdcount 6
Configured hello time 2 , forward delay 15, max age 20, max hops 20
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa1/0/21 Root BKN*200000 128.23 P2p Bound(PVST) *PVST_Inc
Fa1/0/23 Desg FWD 200000 128.25 P2p
Fa1/0/24 Desg FWD 200000 128.26 P2p
This particular switch was elected the IST master because it had the lowest path cost to the RB which lies outside the MST region (its running RPVST) but as soon as that happens I get the message and the port goes into an inconsistent state. It almost like its behaving in a rootguard fashion except I do not have rootguard enabled on this port..or any ports for that matter.
Any ideas? Thanks.
