12-15-2022 02:02 PM - last edited on 12-18-2022 09:39 PM by Translator
hi all,
I'm having trouble running MST on 4 switches.
The MST should be configured for the same region, 2 instances.
Instance 1 with Vlans 10, 20, 50
Instance 2 with Vlans 30, 40, 80
Core1 should be root bridge for instance 1 and core2 should be root bridge for instance 2.
On the two Access switches i get porttype "P2p Bound (RSTP)" which im not sure how to fix.
Also, on Access 2, it doesnt even seem to be running instance 1, even though it is configured. Below picture is an overview of the output of
show span mst
from all 4 switches. As you can see in lower right corner, Access2 only has Instance 2.
output of
sh run | sec mst
from all 4 switches:
I hope someone can explain to me why Access2 is not running instance 2, what port type P2p Bound (RSTP) means, why it's there and how to get it right. Thanks in advance
Solved! Go to Solution.
12-16-2022 05:36 AM - last edited on 12-18-2022 09:43 PM by Translator
12-15-2022 02:38 PM
since the MST can compatible with RSTP,
f one SW run MST and other run RSTP then the MST will mark the port that connect to SW run RSTP as p2p bound (RSTP).
check the spanning tree mode config in all SW
12-15-2022 03:17 PM - last edited on 12-18-2022 09:40 PM by Translator
Here is output of
show span summary
which shows all switches are running MST. What else can i do?
12-15-2022 03:19 PM
@MHM Cisco Worldas you can also see, it looks like something has gone wrong with the MST configuration, since i have 3 switches being root bridge for instance 2 and 2 switches being root bridge for instance 1. But i really have no idea what i did wrong.
12-15-2022 03:34 PM - edited 12-15-2022 03:52 PM
what you do wrong is
SW have two MST
SW have three MST
why you config it like this
the number of MST must be same in all SW, and the VLAN mapping to MST instance must be same in all SW.
12-16-2022 12:37 AM - last edited on 12-18-2022 09:42 PM by Translator
Hello again,
Of course, but it seems to me that i have made the exact same configuration on all of the switches. Please help me find my error, i will provide all necessary information. First output of
show current
in MST configuration mode and output of
sh run | sec mst
Here output of
show spanning-tree mst:
I found a command for restarting the protocol, the command
clear spanning-tree detected-protocol
which i ran on all 4 switches. It seems to have cleared something up:
1. In instance 1, there is now only one root bridge and 2 other are participating in the instance. Access2 is still missing.
2. In instance 2, there is also only one root bridge and all 3 other switches are participating in the instance.
3. Now there isn't any "P2p Bound" port types.
As you can clearly see in the first picture, Access2 is configured with both instances, but it wont show in the second picture. Any help would be highly appreciated.
12-16-2022 02:34 AM
Access2 the missing MST,
are you see vlan of this MST appear in MST 0??
I think you missing config instance in Acc2.
12-16-2022 05:02 AM
I just reconfigured, as seen in this picture:
and here is the result:
Do you have any other ideas?
12-16-2022 05:36 AM - last edited on 12-18-2022 09:43 PM by Translator
show vlan
do you see vlan for mst 1 ?
12-16-2022 06:02 AM
No. Thank you. You are a legend!
12-16-2022 06:16 AM
and you are so so welcome
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