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WS-C2960S-48LPS-L MAC flapping between ports

Taggart2004
Beginner
Beginner

Hi

New issue since upgrading the WS-C2960S-48LPS-L to c2960s-universalk9-mz.150-2.SE8.bin, MAC flapping between local access ports and the uplink.

 

These are all users PCs connected, anyone else seen this before for single NIC devices?

 

Jul 17 11:52:47.743: %SW_MATM-4-MACFLAP_NOTIF: Host 54be.xxxx.xxxx in vlan 108 is flapping between port Gi3/0/1 and port Po1
Jul 17 11:52:58.507: %SW_MATM-4-MACFLAP_NOTIF: Host 54be.xxxx.xxxx in vlan 108 is flapping between port Gi3/0/1 and port Po1
Jul 17 11:53:13.109: %SW_MATM-4-MACFLAP_NOTIF: Host 54be.xxxx.xxxx in vlan 108 is flapping between port Gi3/0/1 and port Po1
Jul 17 11:53:28.985: %SW_MATM-4-MACFLAP_NOTIF: Host 54be.xxxx.xxxx in vlan 108 is flapping between port Po1 and port Gi3/0/1
Jul 17 11:53:44.059: %SW_MATM-4-MACFLAP_NOTIF: Host 54be.xxxx.xxxx in vlan 108 is flapping between port Gi3/0/1 and port Po1
Jul 17 11:53:58.504: %SW_MATM-4-MACFLAP_NOTIF: Host 54be.xxxx.xxxx in vlan 108 is flapping between port Gi3/0/1 and port Po1
Jul 17 11:56:23.430: %SW_MATM-4-MACFLAP_NOTIF: Host 28d2.xxxx.xxxx in vlan 108 is flapping between port Po1 and port Gi1/0/29
Jul 17 13:00:09.956: %SW_MATM-4-MACFLAP_NOTIF: Host 28d2.xxxx.xxxx in vlan 108 is flapping between port Po1 and port Gi1/0/29
Jul 17 13:00:16.782: %SW_MATM-4-MACFLAP_NOTIF: Host 28d2.xxxx.xxxx in vlan 108 is flapping between port Po1 and port Gi1/0/29
Jul 17 13:03:53.266: %SW_MATM-4-MACFLAP_NOTIF: Host 28d2.xxxx.xxxx in vlan 108 is flapping between port Po1 and port Gi1/0/29
Jul 17 13:08:22.443: %SW_MATM-4-MACFLAP_NOTIF: Host 000e.xxxx.xxxx in vlan 108 is flapping between port Po1 and port Gi3/0/39

 

3x WS-C2960S-48LPS-L stacked running c2960s-universalk9-mz.150-2.SE8.bin for 1 week, 2 days.

 

#sh etherchannel sum
Flags:  D - down        P - bundled in port-channel
        I - stand-alone s - suspended
        H - Hot-standby (LACP only)
        R - Layer3      S - Layer2
        U - in use      f - failed to allocate aggregator

        M - not in use, minimum links not met
        u - unsuitable for bundling
        w - waiting to be aggregated
        d - default port


Number of channel-groups in use: 1
Number of aggregators:           1

Group  Port-channel  Protocol    Ports
------+-------------+-----------+-----------------------------------------------
1      Po1(SU)         LACP      Gi1/0/47(P) Gi1/0/48(P) Gi2/0/47(P)
                                 Gi2/0/48(P) Gi3/0/47(P) Gi3/0/48(P)

#sh run int Gi1/0/47
Building configuration...

Current configuration : 231 bytes
!
interface GigabitEthernet1/0/47
 description ### Uplink to Core-3750-switch-Gi1/0/1 ###
 switchport trunk allowed vlan 1,10,100-103,105,106,108,112,116,120,301
 switchport mode trunk
 mls qos trust dscp
 channel-group 1 mode active
end

#sh run int Gi1/0/48
Building configuration...

Current configuration : 231 bytes
!
interface GigabitEthernet1/0/48
 description ### Uplink to Core-3750-switch-Gi2/0/1 ###
 switchport trunk allowed vlan 1,10,100-103,105,106,108,112,116,120,301
 switchport mode trunk
 mls qos trust dscp
 channel-group 1 mode active
end

#sh run int Gi2/0/47
Building configuration...

Current configuration : 292 bytes
!
interface GigabitEthernet2/0/47
 description ### Uplink to Core-3750-switch-Gi1/0/2 ###
 switchport trunk allowed vlan 1,10,100-103,105,106,108,112,116,120,301
 switchport mode trunk
 power inline auto max 15400
 mls qos trust dscp
 spanning-tree bpduguard enable
 channel-group 1 mode active
end

#sh run int Gi2/0/48
Building configuration...

Current configuration : 260 bytes
!
interface GigabitEthernet2/0/48
 description ### Uplink to Core-3750-switch-Gi2/0/2 ###
 switchport trunk allowed vlan 1,10,100-103,105,106,108,112,116,120,301
 switchport mode trunk
 power inline auto max 15400
 mls qos trust dscp
 channel-group 1 mode active
end

#sh run int Gi3/0/47
Building configuration...

Current configuration : 260 bytes
!
interface GigabitEthernet3/0/47
 description ### Uplink to Core-3750-switch-Gi1/0/3 ###
 switchport trunk allowed vlan 1,10,100-103,105,106,108,112,116,120,301
 switchport mode trunk
 power inline auto max 15400
 mls qos trust dscp
 channel-group 1 mode active
end

#sh run int Gi3/0/48
Building configuration...

Current configuration : 260 bytes
!
interface GigabitEthernet3/0/48
 description ### Uplink to Core-3750-switch-Gi2/0/3 ###
 switchport trunk allowed vlan 1,10,100-103,105,106,108,112,116,120,301
 switchport mode trunk
 power inline auto max 15400
 mls qos trust dscp
 channel-group 1 mode active
end

#

 

#sh spanning-tree sum
Switch is in pvst mode
Root bridge for: VLAN0099, VLAN0107, VLAN0118, VLAN0121-VLAN0122, VLAN0555
  VLAN0999
EtherChannel misconfig guard is enabled
Extended system ID           is enabled
Portfast Default             is disabled
PortFast BPDU Guard Default  is disabled
Portfast BPDU Filter Default is disabled
Loopguard Default            is disabled
UplinkFast                   is disabled
BackboneFast                 is disabled
Configured Pathcost method used is short

Name                   Blocking Listening Learning Forwarding STP Active
---------------------- -------- --------- -------- ---------- ----------
VLAN0001                     0         0        0          6          6
VLAN0010                     0         0        0         77         77
VLAN0099                     0         0        0          2          2
VLAN0100                     0         0        0          3          3
VLAN0101                     0         0        0          7          7
VLAN0102                     0         0        0          3          3
VLAN0103                     0         0        0          6          6
VLAN0105                     0         0        0          3          3
VLAN0106                     0         0        0          3          3
VLAN0107                     0         0        0          2          2
VLAN0108                     0         0        0         72         72
VLAN0112                     0         0        0          6          6
VLAN0116                     0         0        0          3          3
VLAN0118                     0         0        0          2          2
VLAN0120                     0         0        0          4          4
VLAN0121                     0         0        0          2          2
VLAN0122                     0         0        0          2          2
VLAN0301                     0         0        0          6          6
VLAN0555                     0         0        0          2          2
VLAN0999                     0         0        0          2          2
---------------------- -------- --------- -------- ---------- ----------
20 vlans                     0         0        0        213        213
UKHPASW1#

 

Thanks

 

Iain

 

 

 

12 Replies 12

Sudeb Das
Beginner
Beginner

For troubleshooting U can - 

check Gi3/0/1 interface for any kind of errors with sh int Gi3/0/1

Check arp table frequently changes or not ?

Check for interface speed on both side

 

 

Thanks for your reply;

This is one that flapped recently (Gi3/0/1) has not flapped since.

Jul 17 15:36:58.362: %SW_MATM-4-MACFLAP_NOTIF: Host 8434.xxxx.xxxx in vlan 108 is flapping between port Po1 and port Gi2/0/11



#sh int  Gi2/0/11
GigabitEthernet2/0/11 is up, line protocol is up (connected)
  Hardware is Gigabit Ethernet, address is e840.405c.470b (bia e840.405c.470b)
  MTU 1500 bytes, BW 100000 Kbit/sec, DLY 100 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Full-duplex, 100Mb/s, media type is 10/100/1000BaseTX
  input flow-control is off, output flow-control is unsupported
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:00:53, output 00:00:44, output hang never
  Last clearing of "show interface" counters 00:33:04
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 21000 bits/sec, 22 packets/sec
     998 packets input, 160991 bytes, 0 no buffer
     Received 202 broadcasts (107 multicasts)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 107 multicast, 0 pause input
     0 input packets with dribble condition detected
     32836 packets output, 4551141 bytes, 0 underruns
     0 output errors, 0 collisions, 0 interface resets
     0 unknown protocol drops
     0 babbles, 0 late collision, 0 deferred
     0 lost carrier, 0 no carrier, 0 pause output
     0 output buffer failures, 0 output buffers swapped out
#

I have also changed the aging

 

#sh mac address-table aging-tim
Global Aging Time:   10
Vlan    Aging Time
----    ----------
#

 

 

This could indicate a possible loop some where in the network. I might guess that an end user may have been introducing this (may be a hub or something plugged in). Please check spanning tree for vlan 108 and try to identify what links are blocking.  Also have a check on every switch which has vlan 108.  Check sh log to see if any abnormality.

 

** Please rate useful posts**

Just checked spanning tree again and nothing is blocked.

We have a 3750 core stack with port channels to 2960 stacks, All of the stacks are only connected to the core 3750 stack.

All of the MAC addresses are linked to users PCs, laptops etc, they do move around the office - different meeting rooms, connect between wire and wireless but we also have the same issues with static thin clients.

Checking the core 3750 logs; most, if not all of the flaps include switch 4 (po14)

 

Example
Jul 21 15:18:10 UTC: %SW_MATM-4-MACFLAP_NOTIF: Host 28d2.xxxx.xxxx in vlan 108 is flapping between port Po14 and port Po13
CSW1#

Po13 -> Stack 3

SW3#sh mac address-table | i 28d2.xxxx.xxxx
 108    28d2.xxxx.xxxx    DYNAMIC     Fa2/0/9
SW3#

Po14 -> Stack 4

SW4#sh mac address-table | i 28d2.xxxx.xxxx
 108    28d2.xxxx.xxxx    DYNAMIC     Po1
SW4#

CS spanning tree

SW1#sh spanning-tree vlan 108

VLAN0108
  Spanning tree enabled protocol rstp
  Root ID    Priority    4204
             Address     f025.xxxx.xxxx
             This bridge is the root
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    4204   (priority 4096 sys-id-ext 108)
             Address     f025.xxxx.xxxx
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  300 sec

Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Po1                 Desg FWD 3         128.488  P2p
Po2                 Desg FWD 3         128.496  P2p
Po11                Desg FWD 3         128.568  P2p Peer(STP)
Po12                Desg FWD 3         128.576  P2p Peer(STP)
Po13                Desg FWD 3         128.584  P2p Peer(STP)
Po14                Desg FWD 3         128.592  P2p Peer(STP)
Po41                Desg FWD 3         128.808  P2p

SW3 spanning tree

SW3#sh spanning-tree vlan 108

VLAN0108
  Spanning tree enabled protocol ieee
  Root ID    Priority    4204
             Address     f025.xxxx.xxxx
             Cost        3
             Port        584 (Port-channel13)
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    32876  (priority 32768 sys-id-ext 108)
             Address     0027.xxxx.xxxx
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  300 sec

Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Fa1/0/1             Desg FWD 19        128.3    P2p Edge
Fa1/0/9             Desg FWD 100       128.11   P2p Edge
Fa1/0/10            Desg FWD 19        128.12   P2p Edge
Fa1/0/11            Desg FWD 19        128.13   P2p Edge
Fa1/0/14            Desg FWD 100       128.16   Shr Edge
Fa1/0/16            Desg FWD 19        128.18   P2p Edge
Fa1/0/18            Desg FWD 19        128.20   P2p Edge
Fa1/0/19            Desg FWD 19        128.21   P2p Edge
Fa1/0/21            Desg FWD 19        128.23   P2p Edge
Fa1/0/22            Desg FWD 19        128.24   P2p Edge
Fa1/0/23            Desg FWD 19        128.25   P2p Edge
Fa1/0/25            Desg FWD 19        128.29   P2p Edge
Fa1/0/26            Desg FWD 19        128.30   P2p Edge
Fa1/0/27            Desg FWD 19        128.31   P2p Edge
Fa1/0/28            Desg FWD 19        128.32   P2p Edge
Fa1/0/29            Desg FWD 19        128.33   P2p Edge
Fa1/0/30            Desg FWD 19        128.34   P2p Edge
Fa1/0/32            Desg FWD 19        128.36   P2p Edge
Fa1/0/33            Desg FWD 19        128.37   P2p Edge
Fa1/0/35            Desg FWD 19        128.39   P2p Edge
Fa1/0/36            Desg FWD 19        128.40   P2p Edge
Fa1/0/37            Desg FWD 19        128.41   P2p Edge
Fa1/0/38            Desg FWD 19        128.42   P2p Edge
Fa1/0/39            Desg FWD 19        128.43   P2p Edge
Fa1/0/40            Desg FWD 19        128.44   P2p Edge
Fa1/0/41            Desg FWD 19        128.45   P2p Edge
Fa1/0/42            Desg FWD 19        128.46   P2p Edge
Fa1/0/43            Desg FWD 19        128.47   P2p Edge
Fa1/0/45            Desg FWD 19        128.49   P2p Edge
Fa1/0/47            Desg FWD 19        128.51   P2p Edge
Fa1/0/48            Desg FWD 19        128.52   P2p Edge
Po13                Root FWD 3         128.584  P2p
Fa2/0/1             Desg FWD 19        128.57   P2p Edge
Fa2/0/4             Desg FWD 19        128.60   P2p Edge
Fa2/0/6             Desg FWD 19        128.62   P2p Edge
Fa2/0/7             Desg FWD 19        128.63   P2p Edge
Fa2/0/8             Desg FWD 100       128.64   P2p Edge
Fa2/0/9             Desg FWD 19        128.65   P2p Edge
Fa2/0/11            Desg FWD 19        128.67   P2p Edge
Fa2/0/12            Desg FWD 19        128.68   P2p Edge
Fa2/0/13            Desg FWD 19        128.69   P2p Edge
Fa2/0/14            Desg FWD 19        128.70   P2p Edge
Fa2/0/15            Desg FWD 19        128.71   P2p Edge
Fa2/0/18            Desg FWD 19        128.74   P2p Edge
Fa2/0/22            Desg FWD 19        128.78   P2p Edge
Fa2/0/24            Desg FWD 19        128.80   P2p Edge
Fa2/0/25            Desg FWD 19        128.83   P2p Edge
Fa2/0/26            Desg FWD 19        128.84   P2p Edge
Fa2/0/27            Desg FWD 19        128.85   P2p Edge
Fa2/0/29            Desg FWD 19        128.87   P2p Edge
Fa2/0/30            Desg FWD 19        128.88   P2p Edge
Fa2/0/31            Desg FWD 19        128.89   P2p Edge
Fa2/0/32            Desg FWD 19        128.90   P2p Edge
Fa2/0/39            Desg FWD 19        128.97   P2p Edge
Fa2/0/40            Desg FWD 19        128.98   P2p Edge
Fa2/0/47            Desg FWD 19        128.105  P2p Edge

 

SW4 spanning tree

SW4#sh spanning-tree vlan 108              

VLAN0108
  Spanning tree enabled protocol ieee
  Root ID    Priority    4204
             Address     f025.xxxx.xxxx
             Cost        3
             Port        232 (Port-channel1)
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    32876  (priority 32768 sys-id-ext 108)
             Address     34db.xxxx.xxxx
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  10  sec

Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi1/0/2             Desg FWD 4         128.2    P2p Edge
Gi1/0/3             Desg FWD 19        128.3    P2p Edge
Gi1/0/7             Desg FWD 4         128.7    P2p Edge
Gi1/0/8             Desg FWD 4         128.8    P2p Edge
Gi1/0/13            Desg FWD 19        128.13   P2p Edge
Gi1/0/17            Desg FWD 4         128.17   P2p Edge
Gi1/0/20            Desg FWD 4         128.20   P2p Edge
Gi1/0/21            Desg FWD 4         128.21   P2p Edge
Gi1/0/25            Desg FWD 4         128.25   P2p Edge
Gi1/0/26            Desg FWD 19        128.26   P2p Edge
Gi1/0/29            Desg FWD 19        128.29   P2p Edge
Gi1/0/30            Desg FWD 19        128.30   P2p Edge
Gi1/0/31            Desg FWD 19        128.31   P2p Edge
Gi1/0/33            Desg FWD 100       128.33   P2p Edge
Gi1/0/34            Desg FWD 4         128.34   P2p Edge
Gi1/0/36            Desg FWD 19        128.36   P2p Edge
Gi1/0/37            Desg FWD 4         128.37   P2p Edge
Gi1/0/38            Desg FWD 4         128.38   P2p Edge
Gi1/0/43            Desg FWD 4         128.43   P2p
Gi1/0/44            Desg FWD 4         128.44   P2p
Gi1/0/45            Desg FWD 4         128.45   P2p
Gi1/0/46            Desg FWD 4         128.46   P2p
Po1                 Root FWD 3         128.232  P2p
Gi2/0/9             Desg FWD 4         128.65   P2p Edge
Gi2/0/11            Desg FWD 4         128.67   P2p Edge
Gi2/0/12            Desg FWD 19        128.68   P2p Edge
Gi2/0/15            Desg FWD 19        128.71   P2p Edge
Gi2/0/16            Desg FWD 19        128.72   P2p Edge
Gi2/0/17            Desg FWD 19        128.73   P2p Edge
Gi2/0/18            Desg FWD 4         128.74   P2p Edge
Gi2/0/19            Desg FWD 19        128.75   P2p Edge
Gi2/0/21            Desg FWD 19        128.77   P2p Edge
Gi2/0/22            Desg FWD 19        128.78   P2p Edge
Gi2/0/23            Desg FWD 19        128.79   P2p Edge
Gi2/0/24            Desg FWD 19        128.80   P2p Edge
Gi2/0/25            Desg FWD 4         128.81   P2p Edge
Gi2/0/27            Desg FWD 19        128.83   P2p Edge
Gi2/0/28            Desg FWD 19        128.84   P2p Edge
Gi2/0/32            Desg FWD 19        128.88   P2p Edge
Gi2/0/33            Desg FWD 19        128.89   P2p Edge
Gi2/0/35            Desg FWD 19        128.91   P2p Edge
Gi2/0/36            Desg FWD 19        128.92   P2p Edge
Gi2/0/37            Desg FWD 19        128.93   P2p Edge
Gi2/0/39            Desg FWD 19        128.95   P2p Edge
Gi2/0/40            Desg FWD 19        128.96   P2p Edge
Gi2/0/43            Desg FWD 4         128.99   P2p
Gi2/0/44            Desg FWD 4         128.100  P2p
Gi2/0/45            Desg FWD 4         128.101  P2p
Gi2/0/46            Desg FWD 4         128.102  P2p

 

 

 

 

 

 

 

 

 

 

 

If the users move around office on wireless it is expected. Can you identify couple of static think client and check there is no cabling loops or anything. And how frequent is the flapping for static machines? Do these machines complain? Also any service issue due to this logs?

You may see this flaps for wireless clients as they move around. If you don' want to see these messages, configure "no mac address-table notification mac move"

 

Thanks,

Madhu

I am not so sure if it is users moving around the office now, as it happened overnight

 

CSW1#sh log | i flap
Jul 21 16:37:34 UTC: %SW_MATM-4-MACFLAP_NOTIF: Host 000e.xxxx.xxx1 in vlan 108 is flapping between port Po14 and port Po13
Jul 21 16:37:41 UTC: %SW_MATM-4-MACFLAP_NOTIF: Host 000e.xxxx.xxx1 in vlan 108 is flapping between port Po14 and port Po13
Jul 21 17:41:39 UTC: %SW_MATM-4-MACFLAP_NOTIF: Host 3c97.xxxx.xxx2 in vlan 108 is flapping between port Po14 and port Po12
Jul 21 19:29:24 UTC: %SW_MATM-4-MACFLAP_NOTIF: Host 68f7.xxxx.xxx3 in vlan 108 is flapping between port Po14 and port Po11
Jul 21 20:54:18 UTC: %SW_MATM-4-MACFLAP_NOTIF: Host 685b.xxxx.xxx4 in vlan 108 is flapping between port Po14 and port Po12
Jul 21 21:01:35 UTC: %SW_MATM-4-MACFLAP_NOTIF: Host 68f7.xxxx.xxx3 in vlan 108 is flapping between port Po14 and port Po11
Jul 21 21:14:41 UTC: %SW_MATM-4-MACFLAP_NOTIF: Host 28d2.xxxx.xxx5 in vlan 108 is flapping between port Po14 and port Po12
Jul 22 02:16:39 UTC: %SW_MATM-4-MACFLAP_NOTIF: Host 8434.xxxx.xxx6 in vlan 108 is flapping between port Po14 and port Po12
Jul 22 02:17:10 UTC: %SW_MATM-4-MACFLAP_NOTIF: Host 28d2.xxxx.xxx7 in vlan 108 is flapping between port Po14 and port Po13
Jul 22 02:17:16 UTC: %SW_MATM-4-MACFLAP_NOTIF: Host 68f7.xxxx.xxx8 in vlan 108 is flapping between port Po11 and port Po14
Jul 22 02:23:34 UTC: %SW_MATM-4-MACFLAP_NOTIF: Host 8434.xxxx.xxx6 in vlan 108 is flapping between port Po14 and port Po12
Jul 22 02:30:01 UTC: %SW_MATM-4-MACFLAP_NOTIF: Host 18a9.xxxx.xxx9 in vlan 108 is flapping between port Po14 and port Po12
Jul 22 02:32:49 UTC: %SW_MATM-4-MACFLAP_NOTIF: Host 18a9.xxxx.xxx9 in vlan 108 is flapping between port Po14 and port Po12
Jul 22 04:47:08 UTC: %SW_MATM-4-MACFLAP_NOTIF: Host 8434.xxxx.xxx6 in vlan 108 is flapping between port Po14 and port Po12
Jul 22 06:17:22 UTC: %SW_MATM-4-MACFLAP_NOTIF: Host 68f7.xxxx.xx10 in vlan 108 is flapping between port Po14 and port Po12
Jul 22 06:30:09 UTC: %SW_MATM-4-MACFLAP_NOTIF: Host 88ae.xxxx.xx11 in vlan 108 is flapping between port Po14 and port Po11
Jul 22 06:30:15 UTC: %SW_MATM-4-MACFLAP_NOTIF: Host 3c97.xxxx.xxx2 in vlan 108 is flapping between port Po14 and port Po12
CSW1#

Port channel 14 is in most of the logs, This is only connected to the core switch via the port channel.

Cabling has not changed for a while and this is a recent issue. The only recent change was the IOS upgrade to c2960s-universalk9-mz.150-2.SE8.bin.

 

 

Taggart,

I have the same issue, and I am also using a 2960-48 port switch with the same IOS version c2960-lanbasek9-mz.150-2.SE8.bin

I am suspecting it's an IOS flaw after reading your post.  My loop activates when configuring "switchport trunk native vlan 99" on my trunks.  But when I switch it back to Vlan 1, the loop ceases.  In addition, I can stop the loop by shutting down all unused interfaces. 

Have you found a resolution yet? 

Hi Swillet

 

Yesterday I checked the logs and it has not appeared recently. Checked again today and it is back

 

Not sure if it is relivent but I am also using vlan 99 however it is not native. It is used for the uplink to the private network.

 

Thanks

 

 

Taggart,

I don't think its VLan 99 exclusively since I changed to a random vlan and had the issue still.

Have you considered installing a different version of your IOS? 

Hi Taggart2004,

Please chk this:

https://tools.cisco.com/bugsearch/bug/CSCuu69332/?reffering_site=dumpcr

I was also facing the same issue. After applying the work-around it stopped.

Please let me know if this helps.

Regards,

Tripati

Hi Taggart2004,

Hope you are doing well.

Im sure by now this has been resolved. May I please know how?

Thank you.

Alen

 

Hi pro .I am currently encountering errors like you. have you fixed this error, please help me
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