07-09-2007 03:29 AM - edited 03-05-2019 05:11 PM
I have a network with four cisco switches
3560(12.2(25)SEC)---trunk---3560GS1(12.2(25)SEE3)---trunk---3560GS2(12.2(25)SEE3)(GEth0/26)---trunk---3550(12.2(37)SE)(GEth0/1)
Switches are has same MST region and has same MST instance.
3560(0014.A80B.3B80):
spanning-tree mode mst
spanning-tree extend system-id
!
spanning-tree mst configuration
name XXX
revision 10
instance 1 vlan 500
instance 2 vlan 508
instance 3 vlan 511
instance 4 vlan 725
instance 5 vlan 706
instance 6 vlan 504-506, 509-510, 512-513, 700-705, 707-724, 726-799
3560GS1(0018.19CF.CC00):
spanning-tree mst configuration
name XXX
revision 10
instance 1 vlan 500
instance 2 vlan 508
instance 3 vlan 511
instance 4 vlan 725
instance 5 vlan 706
instance 6 vlan 504-506, 509-510, 512-513, 700-705, 707-724, 726-799
!
spanning-tree mst 1-4 priority 28672
spanning-tree mst 5-6 priority 24576
3560GS2(0015.FA9A.DD80):
spanning-tree mode mst
spanning-tree extend system-id
!
spanning-tree mst configuration
name XXX
revision 10
instance 1 vlan 500
instance 2 vlan 508
instance 3 vlan 511
instance 4 vlan 725
instance 5 vlan 706
instance 6 vlan 504-506, 509-510, 512-513, 700-705, 707-724, 726-799
!
spanning-tree mst 5 priority 28672
3550(0012.80F6.6E00):
spanning-tree mode mst
spanning-tree extend system-id
!
spanning-tree mst configuration
name XXX
revision 10
instance 1 vlan 500
instance 2 vlan 508
instance 3 vlan 511
instance 4 vlan 725
instance 5 vlan 706
instance 6 vlan 504-506, 509-510, 512-513, 700-705, 707-724, 726-799
!
spanning-tree mst 0-6 priority 61440
Switch 3560 is root for CIST.
Problem:
MSTP is not stable, sometime 3550 send BPDU with TC, because his port GEth0/1 setting BOUNDARY and switching to PVST mode. What is cause maybe?
debug 3550 in attachment
07-09-2007 09:12 AM
Hi Sergey,
ge0/1 on the 3550 seems to be receiving two kinds of bpdus.
-Some MST bpdus from region, with better information (root port).
-Some RSTP bpdus, probably tagged (probably coming from a switch running Rapid-PVST).
What is exactly g0/1? What is it connected to? Is is a shared segment (or it is connected to an emulated LAN with different peers?). You usually expect a single peer from a point-to-point link.
Another possibility is that this port is connected to a third party bridge that floods PVST+ bpdus. In that case, the bpdus that are causing this flapping you see in the debug may be caused by some remote devices sending PVST+ bpdus (again, probably some Rapid-PVST devices) across the L2 network handled by the third party boxes.
Regards,
Francois
07-09-2007 09:45 PM
Thank you Francois. I have found the reason of the arisen problem. It's remote-span vlan 706 on 3560GS2 for monitoring some ports. This vlan was allowed between 3560GS2 and 3550. I blocked it, but I want monitoring ports traffic and my server wouldn't connect to 3560GS2. I shall search for the decision of this problem. Thanks once again Francois, good luck:)
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