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Switch Interface changing state from down to up

cocc (IS/IT--Management) (OP)
14 Oct 03 15:57
I have a Catalyst 3548 with syslog messages:

%LINK-3UPDOWN: Interface FastEthernet0/16, changed state to down

The Interface and a number of others change their state from down to up and back down sometimes 9 times a minute for a period of time.  Is this an indication of a problem ?

Thanks for your time

Gary
IPKONFIG (Instructor)
15 Oct 03 12:38
These messages usually indicate that the host on that particular switch port is losing connectivity.  Usually this will be an end-user rebooting his/her PC.  Check with the user and see if they are doing this.  If it's a device like a printer or such, then check to see if there are excessive errors on the switch ports.  If not, then I'd look at cabling issues and possibly NIC card replacement.  Just my opinion though.

"I can picture a world without war.  A world without hate.  A world without fear.  And I can picture us attacking that world, because they'd never expect it."
- Jack Handey, Deep Thoughts

JabbaTheFart (MIS)
16 Oct 03 13:22
i had this same problem with a router set to auto detect.  I manually set the port on the catalyst to 100 full and had no more problems.
Jonoman1 (IS/IT--Management)
16 Oct 03 22:38
Definitely set the port speed or auto-detect.  (config t Router# Int f0/16>>> speed auto.  Then go to cabling.  Swap PCs w/ Cables.  I would always expect cabling first, unless this port is connected to something else, like a router.
4work (MIS)
29 Oct 03 9:42
Here is information from Cisco's web site.  This has been seen with 3Com NIC's as well as some others.

Under certain circumstances, interoperability issues between Cisco switches and various NICs may result in continuous or intermittent link up/down situations. These link up/down situations are usually a result of power management features or jitter tolerance issues associated with the NIC
silks101 (TechnicalUser)
30 Oct 03 12:56
We had the very same thing on one of our switch ports that was connected into a net to net which then went via a BT circuit to another net to net - we ended up swapping out the Net to Net at the remote office - cured the whole thing.  In other word it may well be the equipment at the other end.
Denda (MIS)
15 Dec 04 11:38
I know this post is way over a year old, but hoping that someone could shed some light on the following.  Our switches were config'd by a person that is no longer with the company.  In troubleshooting some 'so called connectivity issues (turned out not to be)'  I found the following on the Gigabit port:

GigabitEthernet0/2 is up, line protocol is up
  Hardware is Gigabit Ethernet, address is 0030.8506.ad5a (bia 0030.8506.ad5a)
  MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive not set
  Auto-duplex (Half), 1000Mb/s, media type is CX_GIGASTACK
  output flow-control is off, input flow-control is off
  ARP type: ARPA, ARP Timeout 04:00:00
  GigaStack module(0.2) in GBIC slot. Link1 is down, Link2 is up
  Last input 00:00:01, output 00:00:25, output hang never
  Last clearing of "show interface" counters never
  Queueing strategy: fifo
  Output queue 0/40, 0 drops; input queue 0/75, 0 drops
  5 minute input rate 109000 bits/sec, 140 packets/sec
  5 minute output rate 1577000 bits/sec, 193 packets/sec
     74191681 packets input, 871575046 bytes, 0 no buffer
     Received 789635 broadcasts, 0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 606578 multicast, 0 pause input
     68261244 packets output, 1033537667 bytes, 0 underruns
     0 output errors, 14506 collisions, 1 interface resets
     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

Would there be any reason what so ever to have -> Auto-duplex (Half), 1000Mb/s, media type is CX_GIGASTACK on a giga port?  Thanks in advance.
MTandSAV (MIS)
16 Dec 04 2:39
if the other side has hard coded half duplex, you get this as well when you use auto. I always hard coded these port full duplex. you can also see a bunch of collision,which are a result of the half duplex.

CCNA, CCNP..partly ;)

Denda (MIS)
16 Dec 04 10:06
Thanks a ton!  I started researching this more this morning & forgot I posted this yesterday.  I couldn't understand why it would have been at half, but also read the info about the auto.  Thanks again for your help.
Denda (MIS)
16 Dec 04 10:25
OK - one more question before I go...  Would the half duplex collisions be the instigator of the GigabitEthernet port state going from up to down several times a day?  Because that is what started me looking at this config.  Several times a day this specific port reports the following:
Dec 16 08:30:23: %LINK-CLUSTER_MEMBER_4-3-UPDOWN: Interface GigabitEthernet0/2, changed state to up
Dec 16 08:30:24: %LINEPROTO-CLUSTER_MEMBER_4-5-UPDOWN: Line protocol on Interface GigabitEthernet0/2, ch
anged state to up
Dec 16 08:40:54: %LINK-CLUSTER_MEMBER_4-3-UPDOWN: Interface GigabitEthernet0/2, changed state to down
Dec 16 08:40:55: %LINEPROTO-CLUSTER_MEMBER_4-5-UPDOWN: Line protocol on Interface GigabitEthernet0/2, ch
anged state to down
Dec 16 08:41:28: %LINK-CLUSTER_MEMBER_4-3-UPDOWN: Interface GigabitEthernet0/2, changed state to up
Dec 16 13:41:29: %LINEPROTO-CLUSTER_MEMBER_4-5-UPDOWN: Line protocol on Interface GigabitEthernet0/2, ch
anged state to up

Thanks for your help & letting me pick your brain
MarineBoy (TechnicalUser)
20 Dec 04 14:35
I can't believe that any manufacturer would make a GiG Eth i/f card and make it only half duplex. Make sure both are set to full duplex. Don't forget to look at the interface stats and not just the console messages! You should get a better idea what is happening at the both the physical and link layers.

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