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New Member

2960 Flapping Ports

I have just installed a new C2960-24PC-L switch and i have noticed a few of the ports keep changing their states.


*Mar 2 03:49:13.727: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/17, changed state to down

*Mar 2 03:49:14.733: %LINK-3-UPDOWN: Interface FastEthernet0/17, changed state to do

*Mar 2 03:49:16.822: %LINK-3-UPDOWN: Interface FastEthernet0/17, changed state to up

*Mar 2 03:49:17.829: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/17, changed state to up

Most of the ports that seem to have the problem have Canon printers and a Canon photocopier connected to them. On this particular port I have changed the cable and set the duplex and speed settings manually. I have also set the Ethernet driver settings on the Canon photocopier to 100 Base-TX (Full Duplex).

interface FastEthernet0/17

switchport mode access

switchport nonegotiate

speed 100

duplex full

spanning-tree portfast

I can also see alot of late collisions on this interface.

FastEthernet0/17 is up, line protocol is up (connected)

  Hardware is Fast Ethernet, address is 04da.d248.1d11 (bia 04da.d248.1d11)

  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, media type is 10/100BaseTX

  input flow-control is off, output flow-control is unsupported

  ARP type: ARPA, ARP Timeout 04:00:00

  Last input never, output 00:00:01, output hang never

  Last clearing of "show interface" counters never

  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 4000 bits/sec, 4 packets/sec

     234028 packets input, 237228056 bytes, 0 no buffer

     Received 2887 broadcasts (265 multicasts)

     0 runts, 0 giants, 0 throttles

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

     0 watchdog, 265 multicast, 0 pause input

     0 input packets with dribble condition detected

     704084 packets output, 124099205 bytes, 0 underruns

     0 output errors, 228 collisions, 1 interface resets

     0 babbles, 2101 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 done a TDR test on the interface.

TDR test last run on: March 02 04:08:45

Interface Speed Local pair Pair length        Remote pair Pair status
--------- ----- ---------- ------------------ ----------- --------------------
Fa0/17    100M  Pair A     4    +/- 15 meters Pair B      Normal
                Pair B     4    +/- 15 meters Pair A      Normal
                Pair C     N/A                Pair D      Not Supported
                Pair D     N/A                Pair C      Not Supported

One other port that has a Snom 320 IP phone connected keeps changing it state as well.

*Mar  2 04:04:54.878: %ILPOWER-7-DETECT: Interface Fa0/6: Power Device detected: IEEE PD

*Mar  2 04:04:55.910: %ILPOWER-5-IEEE_DISCONNECT: Interface Fa0/6: PD removed

*Mar  2 04:04:56.942: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/6, changed state to down

*Mar  2 04:04:58.947: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/6, changed state to up

Any other tips on how to fix the problems?

Hall of Fame Super Gold

2960 Flapping Ports

Collissions are aggravated because you have hard-coded the speed and duplex settings.

When the link is flapping, is the remote end device (RED) rebooting? 

New Member

Re: 2960 Flapping Ports

No, none of the devices are rebooting. Why does manually setting the speed and duplex settings at both ends cause late collisions? The IP phone is saying Ethernet disconnected when the port changes state, though.