port Flapped(status)

[Dinesh Kumar Mariappan]

                   i am connected my PC on my switch directly which was datacenter. there is no possiblity for disturbing the cable.. but my lan is diconnecting and connecting again.. what is reason behind.. How can i check the switch in port status(flapped or not). This is problem occuring for one server too.. Please give me solution how to fix this..

[paul driver]

Hello

Check the interface this server is attached to, look for any errors. protocol status, mtu, utilization issues.

please post the results of the below commands:

sh interface  x/x

sh interfaces x/x status

sh ip interface  fa0/0 ( for l3 interface only)

res

Paul

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Thanks.

[Eduardo Cesaro]

Hi Dinesh,

Your port probably has some security setting, like  as port security or something of the genre...as said pddriver, please send the configuration of ports for better analisys!!!

Tks

Eduardo

[Dinesh Kumar Mariappan]

Coreswitch#sh interfaces gigabitEthernet 1/33
GigabitEthernet1/33 is up, line protocol is up (connected)
  Hardware is Gigabit Ethernet Port, address is 649e.f327.d6e0 (bia 649e.f327.d6e0)
  MTU 1500 bytes, BW 100000 Kbit, 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, link type is auto, media type is 10/100/1000-TX
  input flow-control is on, output flow-control is on
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 5w3d, output never, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 3000 bits/sec, 3 packets/sec
  5 minute output rate 21000 bits/sec, 17 packets/sec
     13011341 packets input, 1875727280 bytes, 0 no buffer
     Received 1176151 broadcasts (684045 multicasts)
     2164 runts, 0 giants, 0 throttles
     2171 input errors, 7 CRC, 0 frame, 0 overrun, 0 ignored
     0 input packets with dribble condition detected
     149125664 packets output, 29826367777 bytes, 0 underruns
     0 output errors, 1054 collisions, 0 interface resets
     0 babbles, 0 late collision, 0 deferred
     0 lost carrier, 0 no carrier
     0 output buffer failures, 0 output buffers swapped out

Coreswitch#sh interfaces gigabitEthernet 1/33 status

Port      Name               Status       Vlan       Duplex  Speed Type
Gi1/33                       connected    100        a-full  a-100 10/100/1000-T            X

Coreswitch#sh ip interface gigabitEthernet 1/33
GigabitEthernet1/33 is up, line protocol is up
  Inbound  access list is not set
  Outgoing access list is not set

[Eduardo Cesaro]

@Dinesh, please send the following command:

Cores# sh run interfaces gigabitEthernet 1/33

Cores# sh interfaces gigabitEthernet 1/33 switchport

Tks

Eduardo

[Dinesh Kumar Mariappan]

Coreswitch#sh run interface gigabitEthernet 1/33

Building configuration...

Current Configuration : 89 bytes

!

Switchport access vlan 100

Switchport mode access

end

How this command help ful for you to the port flap status...

other command not working for me..

[paul driver]

Hello

2164 runts, 0 giants, 0 throttles

    2171 input errors, 7 CRC, 0 frame, 0 overrun, 0 ignored

     0 input packets with dribble condition detected

     149125664 packets output, 29826367777 bytes, 0 underruns

     0 output errors, 1054 collisions, 0 interface resets

Can you reset the interface counters , and after this if you see the above errores I would suggest change the cabling.

clear counters x/x

res

Paul

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Thanks.

[Dinesh Kumar Mariappan]

CRC crrors errors increased will due to cable we will get packet drops... But my issue only 2 seconds suddenly network cable disconnecting and again connecting there is no issue for some days.. again it was happening this is happening for multiple system. Can we enable port fast to avoid this?

This is primary some time it was happendng for server. Team saying that we are getting drops(continuos 8 packets) but when we checking there 100% sucess rate with minimum latency

then same complaint raised many times.. but then keep observing continusly we found that only 2 to 3 seconds its going down and fine for somedays there is no issue in it.

This type of issue are basic and simple but dont know what is exactly.

Changing the cable, unshut and shut the port, clear counters are not permanent solution for this.. Someother issue is persisting related to that?

[Eduardo Cesaro]

The problem is some fiber or UTP cable, it is fact!! you need to check if there is any problem between switches that connect to the server (if I understand correctly, you have a switch to the server ..)

[paul driver]

Hello

Stp portfast is recommended on access ports anyway, infact spanning -tree as a whole is recommended for loop prevention.

Unless the access- ports are trunking ( i.e. esx hosts).- disabling spanning tree or not having the access ports bypass stp negotiation(portfast) is isn't wise, because these access ports will go through this negotiation if a switch tcn occurs.

The above errors do signify bad layer1 -2 connectivity -  Can you confirm when you say these servers are directly connected, are they? or are they via cable management? - of so I would recommend changing all cabling between server and switch and harcoding the ports speed/duplex settings if applicable.

res

Paul

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Thanks.

[Leo Laohoo]

What is this switch? Is it a 6500?  If so, please post the complete output to the command "sh counters interface Gi 1/33".