Ok, so what's connected to

johnny_5 · ‎04-11-2014

Hi there,

Yesterday all of sudden some of our machines(dumb terminals) could no longer connect to their server. A quick test - I disconnected the Ethernet cable and plugged it into my laptop, pinging any server on my network was at 50% at the most sometimes 75% packet loss.

These machines are connected via wall jack which connects to a WS-C2950G-48 ver 12.1 which connects to another switch back in the server room. When I check the port in question I see a lot runt errors and input errors (identical numbers) see below:

sh int fa0/31
FastEthernet0/31 is up, line protocol is up (connected)
Hardware is Fast Ethernet, address is 0017.596c.269f (bia 0017.596c.269f)
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 100BaseTX
input flow-control is unsupported output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input never, output 00:00:00, 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 14000 bits/sec, 15 packets/sec
     24368282 packets input, 2163698437 bytes, 0 no buffer
     Received 1862 broadcasts (0 multicast)
     2910 runts, 0 giants, 0 throttles
     2910 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 12 multicast, 0 pause input
     0 input packets with dribble condition detected
     239158164 packets output, 63981736 bytes, 0 underruns
     0 output errors, 0 collisions, 4 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

Fa0/31
Switchport: Enabled
Administrative Mode: dynamic desirable
Operational Mode: static access
Administrative Trunking Encapsulation: dot1q
Operational Trunking Encapsulation: native
Negotiation of Trunking: On
Access Mode VLAN: 1 (default)
Trunking Native Mode VLAN: 1 (default)
Voice VLAN: 2 (voice)
Administrative private-vlan host-association: none
Administrative private-vlan mapping: none
Administrative private-vlan trunk native VLAN: none
Administrative private-vlan trunk encapsulation: dot1q
Administrative private-vlan trunk normal VLANs: none
Administrative private-vlan trunk private VLANs: none
Operational private-vlan: none
Trunking VLANs Enabled: ALL
Pruning VLANs Enabled: 2-1001
Capture Mode Disabled
Capture VLANs Allowed: ALL
Protected: false
Unknown unicast blocked: disabled
Unknown multicast blocked: disabled
Appliance trust: none

I have changed out the cable but I doubt this is the problem as we have 10 of these machines that are all down.

The only change recently was connecting an un-managed POE switch to the switch in question - again his was done about 2 months with no issues reported since.

Any thoughts?

Richard Burts · ‎04-12-2014

One thing that can produce runts is a mismatch of duplex settings. I see that your switch port is operating in full duplex mode. I suggest that you check with whatever is connected and see whether that device is operating in half duplex mode.

HTH

Rick

HTH

Rick

johnny_5 · ‎04-12-2014

I have read about the mismatch. First off how would that change? I mean there have been no issues for months and all of a sudden this?

The other thing is that the devices that connect to the switch are N-Computing dumb terminals that communicate back to a server running MS terminal services - there is no option on the dumb terminal to change speeds. In the setup it has an option of what location to boot from, password, login, screen size etc...

Do you think a reload of the switch might "free" up all the errors?

Leo Laohoo · ‎04-12-2014

Can't remember if 2950-series support this command but can you see if you can enter this command: sh controll e f0/31

Please post the output.

johnny_5 · ‎04-12-2014

Hi

Yes that command does work...

sh controllers ethernet-controller fa0/31

Transmit                                Receive
112041548 Bytes                       2165259485 Bytes
239610847 Frames                        24387149 Frames
50230393 Multicast frames                     0 FCS errors
141882647 Broadcast frames                    12 Multicast frames
         0 Pause frames                      1919 Broadcast frames
         0 Single defer frames                  0 Control frames
         0 Multiple defer frames                0 Pause frames
         0 1 collision frames                   0 Unknown opcode frames
         0 2-15 collisions                      0 Alignment errors
         0 Late collisions                      0 Length out of range
         0 Excessive collisions                 1 Symbol error frames
         0 Total collisions                   107 False carrier errors
         0 Control frames                    2910 Valid frames, too small
         0 VLAN discard frames                  0 Valid frames, too large
         0 Too old frames                       1 Invalid frames, too small
68317502 Tagged frames                        0 Invalid frames, too large
         0 Aborted Tx frames                    0 Discarded frames

Transmit and Receive
98034152 Minimum size frames
108731085 65 to 127 byte frames
16295229 128 to 255 byte frames
12954764 256 to 511 byte frames
6432371 512 to 1023 byte frames
21547484 1024 to 1518 byte frames
0 1519 to 1522 byte frames

Leo Laohoo · ‎04-13-2014

Ok, so what's connected to port 13? It's sending UNDERSIZED frames. Switch is passing this through but that's where the so-called "CRC" errors are coming from.

PS: Whoever rated my previous post with a "3" ...

johnny_5 · ‎04-13-2014

Connected to the switch on this port and many others are dumb terminals that communicate back to a server using MS terminal services -

If I unplug the Ethernet cable and plug it into my laptop(connects the dumb terminal to the wall jack that goes back to the switch ) and ping anything I only get 25% success rate 3 out of 4 pings fail.

Leo Laohoo · ‎04-13-2014

Can you please post the interface configuration?

johnny_5 · ‎04-13-2014

I posted the interface config???

Here it is again,

Thanks

Fa0/31
Switchport: Enabled
Administrative Mode: dynamic desirable
Operational Mode: static access
Administrative Trunking Encapsulation: dot1q
Operational Trunking Encapsulation: native
Negotiation of Trunking: On
Access Mode VLAN: 1 (default)
Trunking Native Mode VLAN: 1 (default)
Voice VLAN: 2 (voice)
Administrative private-vlan host-association: none
Administrative private-vlan mapping: none
Administrative private-vlan trunk native VLAN: none
Administrative private-vlan trunk encapsulation: dot1q
Administrative private-vlan trunk normal VLANs: none
Administrative private-vlan trunk private VLANs: none
Operational private-vlan: none
Trunking VLANs Enabled: ALL
Pruning VLANs Enabled: 2-1001
Capture Mode Disabled
Capture VLANs Allowed: ALL
Protected: false
Unknown unicast blocked: disabled
Unknown multicast blocked: disabled
Appliance trust: none

Leo Laohoo · ‎04-13-2014

That's not the configuration of an interface in question. The above output is from the command "sh interface <BLAH> switchport".

Post the output to the command "sh run interface <BLAH>".

Input errors and runts