When creating a vlan, I get a loop after 1 hour in network. How can I check it?


hello Guys , I have added new switch type Summit X450-24x DC in my network , when i creating any Vlan after 1 hours loop happen in network , why that happened , Is there commanded or method to shows me where the defect was?

19 replies

Userlevel 1
I believe that you should do test without the cables of networks.
If not working.
The loop can be into your network.
You should do update in switch.
If you have problem, please write me.
I appreciate your feedback, but how I can doing test without Cable?
Assuming you are running stp,

show stpd s0 ports blocked-ports

show stpd s0 ports non-forwarding-reason

show stpd s0 ports detail

These commands might help you solve your problem.
Userlevel 1
Hello,

You should segment the network.
Taking the cables on to one.
You will see if there is one problem in your network.
you have create one instance Spanning tree.

create stpd [i] EX: stpd_S0
config [i] add vlan ports [u] dot1d
config [i] tag
config [i] mode dot1w
enable stpd [i]
enable stpd
Userlevel 6
How are you confirming there is a loop in the network? Loops usually present themselves instantly so it is odd it takes an hour.

If you could give us a brief topology that would be helpful as well.
yes you are right, i think got on broadcast in network
Userlevel 4
MUNIR ENG wrote:

yes you are right, i think got on broadcast in network

Hi Munir,

Yes, considering the time delay of the issue, this is more likely to be a broadcast storm. If you connect a PC to one of the switches and assign it to the same VLAN experiencing the issue, a Wireshark packet capture should help in tracking down the source of the broadcast traffic.
Userlevel 3
You can try to nail down the problematic port with..

.. Extreme Loop Recovery Protocol (ELRP)


configure elrp-client one-shot "VLANe-Name" ports all print[/code]
https://gtacknowledge.extremenetworks.com/articles/Q_A/Which-commands-can-be-used-to-detect-a-loop

or

.. check the pkts/sec counter for high counters

show ports utilization[/code]
SchmuFoo wrote:

You can try to nail down the problematic port with..

.. Extreme Loop Recovery Protocol (ELRP)


configure elrp-client one-shot "VLANe-Name" ports all print[/code]
https://gtacknowledge.extremenetworks.com/articles/Q_A/Which-commands-can-be-used-to-detect-a-loop

or

.. check the pkts/sec counter for high counters

show ports utilization[/code]

in which switch i would do configure elrp. the switch that has the problem?
Userlevel 6
SchmuFoo wrote:

You can try to nail down the problematic port with..

.. Extreme Loop Recovery Protocol (ELRP)


configure elrp-client one-shot "VLANe-Name" ports all print[/code]
https://gtacknowledge.extremenetworks.com/articles/Q_A/Which-commands-can-be-used-to-detect-a-loop

or

.. check the pkts/sec counter for high counters

show ports utilization[/code]

All of them. This will give you the best chance of finding the loop if there is one in the future.
SchmuFoo wrote:

You can try to nail down the problematic port with..

.. Extreme Loop Recovery Protocol (ELRP)


configure elrp-client one-shot "VLANe-Name" ports all print[/code]
https://gtacknowledge.extremenetworks.com/articles/Q_A/Which-commands-can-be-used-to-detect-a-loop

or

.. check the pkts/sec counter for high counters

show ports utilization[/code]

thank you
Userlevel 1
How is your topology?
If it is a ring, you will need a loop prevention protocol such as EAPS or ERPS Extreme.
The ERPS protocol there is the CFM, that work with switches that are not have ERPS.
Is very nice.
Thiago da Silva wrote:

How is your topology?
If it is a ring, you will need a loop prevention protocol such as EAPS or ERPS Extreme.
The ERPS protocol there is the CFM, that work with switches that are not have ERPS.
Is very nice.

Userlevel 1
What problem friend!
There seems to be a loop topology, can be a loop on the door or a machine with a virus.
Once I shared the problem in such a network.
I had a machine that had a virus.
This virus was flooding the network with broadcast.
I took a one of the machines on the network and saw what was the machine that was causing the issue. It was a machine with full access.
you will have to do the same.
if you want to put EAPS which only works on network ring tell me I mands commands.
the problem fixed, with new plan in our network i removed one switch and i re-arrange the vlan for each port , But my concerns when adding a new switch i will getting same problem. thank you fro your support
*Apr 14 02:05:53.689: %ETHCNTR-3-LOOP_BACK_DETECTED: Loop-back detected on Gigab itEthernet0/3.

*Apr 14 02:05:53.689: %PM-4-ERR_DISABLE: loopback error detected on Gi0/3, putti

ng Gi0/3 in err-disable state

*Apr 14 02:05:54.713: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEth

ernet0/3, changed state to down





*Apr 14 02:29:05.485: %ETHCNTR-3-LOOP_BACK_DETECTED: Loop-back detected on Gigab

itEthernet0/3.

*Apr 14 02:29:05.485: %PM-4-ERR_DISABLE: loopback error detected on Gi0/3, putti

ng Gi0/3 in err-disable state

*Apr 14 02:29:06.500: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEth

ernet0/3, changed state to down
MUNIR ENG wrote:

*Apr 14 02:05:53.689: %ETHCNTR-3-LOOP_BACK_DETECTED: Loop-back detected on Gigab itEthernet0/3.

*Apr 14 02:05:53.689: %PM-4-ERR_DISABLE: loopback error detected on Gi0/3, putti

ng Gi0/3 in err-disable state

*Apr 14 02:05:54.713: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEth

ernet0/3, changed state to down





*Apr 14 02:29:05.485: %ETHCNTR-3-LOOP_BACK_DETECTED: Loop-back detected on Gigab

itEthernet0/3.

*Apr 14 02:29:05.485: %PM-4-ERR_DISABLE: loopback error detected on Gi0/3, putti

ng Gi0/3 in err-disable state

*Apr 14 02:29:06.500: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEth

ernet0/3, changed state to down

i got on this massage , what mean and how i can fixing? this massage from Cisco switch ,its linking directly with extreme switch

MUNIR ENG wrote:

*Apr 14 02:05:53.689: %ETHCNTR-3-LOOP_BACK_DETECTED: Loop-back detected on Gigab itEthernet0/3.

*Apr 14 02:05:53.689: %PM-4-ERR_DISABLE: loopback error detected on Gi0/3, putti

ng Gi0/3 in err-disable state

*Apr 14 02:05:54.713: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEth

ernet0/3, changed state to down





*Apr 14 02:29:05.485: %ETHCNTR-3-LOOP_BACK_DETECTED: Loop-back detected on Gigab

itEthernet0/3.

*Apr 14 02:29:05.485: %PM-4-ERR_DISABLE: loopback error detected on Gi0/3, putti

ng Gi0/3 in err-disable state

*Apr 14 02:29:06.500: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEth

ernet0/3, changed state to down

https://supportforums.cisco.com/document/20111/error-ethcntr-3-loopbackdetected-catalyst-switch-runs-cisco-iosr-softwarE
MUNIR ENG wrote:

*Apr 14 02:05:53.689: %ETHCNTR-3-LOOP_BACK_DETECTED: Loop-back detected on Gigab itEthernet0/3.

*Apr 14 02:05:53.689: %PM-4-ERR_DISABLE: loopback error detected on Gi0/3, putti

ng Gi0/3 in err-disable state

*Apr 14 02:05:54.713: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEth

ernet0/3, changed state to down





*Apr 14 02:29:05.485: %ETHCNTR-3-LOOP_BACK_DETECTED: Loop-back detected on Gigab

itEthernet0/3.

*Apr 14 02:29:05.485: %PM-4-ERR_DISABLE: loopback error detected on Gi0/3, putti

ng Gi0/3 in err-disable state

*Apr 14 02:29:06.500: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEth

ernet0/3, changed state to down

thank you

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