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New Member

MST on CatOS

Hi,

I started experiencing strange behavior between MST enabled IOS-based WS-C6503 and CATOS WS-C6509.

IOS configuration:

spanning-tree mst configuration

name domain.com

revision 27809

instance 1 vlan 2-200

instance 2 vlan 702, 712, 722

instance 3 vlan 703, 713, 723

instance 4 vlan 704, 714, 724

instance 5 vlan 705, 715, 725

instance 6 vlan 706, 716, 726

When TCN happens in instance 0, IOS-based switch behaves properly. Only proper instance MACs are flushed from mac address table.

sw-bbone0#sh spanning-tree vlan 1 detail

MST0 is executing the mstp compatible Spanning Tree protocol

Bridge Identifier has priority 24576, sysid 0, address 000b.45b1.26c0

Configured hello time 2, max age 20, forward delay 15, tranmsit hold-count 6

Current root has priority 8192, address 000b.45b1.2680

Root port is 2 (GigabitEthernet1/2), cost of root path is 0

Topology change flag not set, detected flag not set

Number of topology changes 378 last change occurred 00:03:02 ago

from GigabitEthernet1/2

sw-bbone#sh spanning-tree vlan 722 detail

MST2 is executing the mstp compatible Spanning Tree protocol

Bridge Identifier has priority 32768, sysid 2, address 000b.45b1.26c0

Configured hello time 2, max age 20, forward delay 15, tranmsit hold-count 6

Current root has priority 32770, address 000b.45b1.2640

Root port is 135 (GigabitEthernet2/7), cost of root path is 20000

Topology change flag not set, detected flag not set

Number of topology changes 108 last change occurred 06:24:12 ago

from GigabitEthernet1/2

Times: hold 1, topology change 35, notification 2

hello 2, max age 20, forward delay 15

Timers: hello 0, topology change 0, notification 0

CatOS configuration

set spantree macreduction enable

set spantree defaultcostmode long

set spantree mode mst

#spantree

set spantree mst config rollback force

set spantree mst config name domain.com revision 27809

set spantree mst 0 vlan 1,201-701,707-711,717-721,727-4094

set spantree mst 1 vlan 2-200

set spantree mst 2 vlan 702,712,722

set spantree mst 3 vlan 703,713,723

set spantree mst 4 vlan 704,714,724

set spantree mst 5 vlan 705,715,725

set spantree mst 6 vlan 706,716,726

set spantree mst config commit

When CatOS switch receives TCN for instance 0 from the trunk between these switches, it flushes CAM for all instances.

Could you please advise why it happens? I can't disable macreduction in Catos as the switch's running extended VLANs.

Maybe it's somehow related.

2 REPLIES
New Member

Re: MST on CatOS

what i think...

from the documenation...

"Instance 0, the Internal Spanning-Tree (IST), is reserved for interacting with other Spanning-Tree Protocols (STPs) and other MST regions."

So, make sure all NON-operational vlans are prunned from your trunks!

in your case...

clear trunk 1/1 1,201-701,707-711,717-721,727-1005, 1025-4094

so only the vlans mapped to mst instances 1-6 are passed over trunks...

Re: MST on CatOS

Does the CatOS switch see the trunk on which it receives the TC as a boundary port? If so, it has to flush all the instances (btw, it should flush for all port except the one on which it received the TC). From your config, the port should not be boundary, but if it is for some reason, do a clear spantree detected-protocols on the it.

Regards,

Francois

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