Cisco 2960 port flapping

[DevinMarks3331]

Yes we know this is a very old switch but this behavior is quite odd.  We are running the latest release of IOS 12 on these switches, and this has happened now on two different switches.

This is the only switch with VLAN 10, and this VLAN is used for the internet access to out ATT circuit.  The only devices on this VLAN are the circuit, the primary and secondary ASAs, and another Cisco router.  There is no other switch on this VLAN.  At random times, the port that is plugged into the circuit will constantly change its port state until we do a shut, no shut on the interface.  We have tried a few things we saw that may cause high CPU utilization like taking logging off every interface, but it happened again last night.  Anyone have any ideas?

May  6 16:56:09.880 EDT: %SPANTREE-6-PORT_STATE: Port Fa0/3 instance 10 moving from disabled to blocking
May  6 16:56:09.880 EDT: %SPANTREE-6-PORT_STATE: Port Fa0/3 instance 10 moving from blocking to forwarding
May  6 17:17:30.941 EDT: %SPANTREE-6-PORT_STATE: Port Fa0/3 instance 10 moving from forwarding to disabled
May  6 17:17:30.941 EDT: %SPANTREE-7-PORTDEL_SUCCESS: FastEthernet0/3 deleted from Vlan 10
May  6 17:17:30.983 EDT: %SPANTREE-6-PORT_STATE: Port Fa0/3 instance 10 moving from disabled to blocking
May  6 17:17:30.983 EDT: %SPANTREE-6-PORT_STATE: Port Fa0/3 instance 10 moving from blocking to forwarding
May  6 17:19:57.726 EDT: %SPANTREE-6-PORT_STATE: Port Fa0/3 instance 10 moving from forwarding to disabled
May  6 17:19:57.726 EDT: %SPANTREE-7-PORTDEL_SUCCESS: FastEthernet0/3 deleted from Vlan 10

[balaji.bandi]

what is the device connected to

Fa0/3 

can yoiu post below information

show spanning brief

show run inter fas 0/3

show ver

[DevinMarks3331]

This is connected to our primary internet circuit.  The logging events were put back on there last night for testing.

interface FastEthernet0/3
 description ****
 switchport access vlan 10
 switchport mode access
 logging event spanning-tree
 logging event status
 speed 100
 duplex full
 spanning-tree portfast

show spanning-tree for vlan 10:

VLAN0010
  Spanning tree enabled protocol ieee
  Root ID    Priority    32778
             Address     0021.56d6.f800
             This bridge is the root
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    32778  (priority 32768 sys-id-ext 10)
             Address     0021.56d6.f800
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  300 sec

Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Fa0/1               Desg FWD 19        128.1    P2p Edge
Fa0/2               Desg FWD 19        128.2    P2p Edge
Fa0/3               Desg FWD 19        128.3    P2p Edge

Show ver:

Cisco IOS Software, C2960 Software (C2960-LANBASEK9-M), Version 12.2(55)SE12, RELEASE SOFTWARE (fc2)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2017 by Cisco Systems, Inc.
Compiled Thu 28-Sep-17 02:53 by prod_rel_team
Image text-base: 0x00003000, data-base: 0x01900000

ROM: Bootstrap program is C2960 boot loader
BOOTLDR: C2960 Boot Loader (C2960-HBOOT-M) Version 12.2(44)SE5, RELEASE SOFTWARE (fc1)

MCO-inet uptime is 3 days, 18 hours, 19 minutes
System returned to ROM by power-on
System restarted at 15:16:05 EDT Fri May 8 2020
System image file is "flash:c2960-lanbasek9-mz.122-55.SE12.bin"


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cisco WS-C2960-48TT-L (PowerPC405) processor (revision E0) with 65536K bytes of memory.
Processor board ID FOC1218Z21U
Last reset from power-on
1 Virtual Ethernet interface
48 FastEthernet interfaces
2 Gigabit Ethernet interfaces
The password-recovery mechanism is enabled.

64K bytes of flash-simulated non-volatile configuration memory.
Base ethernet MAC Address       : 00:21:56:D6:F8:00
Motherboard assembly number     : 73-10391-05
Power supply part number        : 341-0097-02
Motherboard serial number       : FOC121725Y4
Power supply serial number      : DCA121586LX
Model revision number           : E0
Motherboard revision number     : A0
Model number                    : WS-C2960-48TT-L
System serial number            : FOC1218Z21U
Top Assembly Part Number        : 800-27222-04
Top Assembly Revision Number    : A0
Version ID                      : V04
CLEI Code Number                : COM3H00BRC
Hardware Board Revision Number  : 0x02


Switch Ports Model              SW Version            SW Image
------ ----- -----              ----------            ----------
*    1 50    WS-C2960-48TT-L    12.2(55)SE12          C2960-LANBASEK9-M


Configuration register is 0xF

[balaji.bandi]

High level based on the information, it configired access port.

Other side i look to look for Physical any Loose connection (between your Port and NTU of Service provider)