9 Replies Latest reply on Mar 31, 2011 7:31 AM by elvinng

    Interface Errors & Discards

      Hi what are the causes for the interface to have high errors both on Receive and Transmit on a daily basis? Our client complaints they are having problems in retrieving and transmitting data. They are getting a lot of errors. We are monitoring wireless network.

       

      Thanks,

        • Re: Interface Errors & Discards
          Andy McBride

          Typically that is a malfunctionong transmitter on a wireless device or low signal strength. Troubleshooting steps may include connecting to the WAP and examining counters, rebooting a troubled WAP or replacing the WAP.

            • Re: Interface Errors & Discards

              Hi Andy,

              Thank you for your response. When you say examining counters, does it mean they have to check the performance of the WAP itself?

               

              thanks

                • Re: Interface Errors & Discards
                  Andy McBride

                  Yes - if the WAP controller has a console you might be able to see what the issue is using that console.

                    • Re: Interface Errors & Discards

                      I understand,  A follow up question Mr Mcbridea. if there are Receive and Transmit Errors but (0) zero Receive and Transmit Discards, does it mean that the error packets were “re-transmitted” successfully?  Are there not automatic “retry” for error packets?

                       

                      Again, thanks a lot for your continous reply to my question.

                        • Re: Interface Errors & Discards
                          Andy McBride

                          Discards happen because the device cannot do anything with a packet. This can be because the device does not have a route to sent the packet to the destination, the device has been configured to discrad certain traffic or the device lacks resources to do anything with the packet (such as full buffers). To some devices have discard countrs that will tell you why they discarded packets. Otherwise a packet capture at he devices inbound interfaces may help.

                            • Re: Interface Errors & Discards

                              Okay. In the case of the device that we are concern with, it shows the following data:

                                                                Receive                      Transmit
                              Errors This Hour         281 errors               73,488 errors
                              Errors Today              2,103 errors       1,063,655 errors

                              Discards This Hour    0 discards     0 discards
                              Discards Today         0 discards     0 discards

                              If it is showing 0 on discards, does it mean the data/packet was sent in successfully even though there are lots of errors showing up? We were advise that this device is not sending in data accurately. There are errors on the data (reports) they are getting.

                              Thanks.

                                • Re: Interface Errors & Discards
                                  Andy McBride

                                  Errors are failed packets. Problems like malformation, CRC failure, runts, giants and such. How does that device compare to others like it in your network? It seems like the xmit errors are high, but check with a similar device.

                                  If this on is way worse that other I recommend a ticket with the vendor. They will probably ask what you have done to troubleshoot it like check the BIOS level, firmware and reboot. Of course, only do these according to your procedures.

                      • Re: Interface Errors & Discards

                        You say you are monitoring wireless network.

                        Are these counters  for

                            the RADIO interface of an AP?

                            The EThernet port of AP?

                            The  ethernet port of a Cisco WLC or other centralized controller?

                        Are these counters reported from the SWITCH or the DEVICE plugged into a switch.

                         

                        A  radio with those number would scream interference and excessive  noise/overlap.

                         

                        If it is an ethernet port, have all the basics been covered?  Device & Switch both agree on autonegotiation settings.  Where possible, have GBICs, SPFs have been replaced?  Cables replaced?  Any questionable cable lengths?  What is the model/age of the switch involved(assuming switch).  4006 Sup2 perform poorly in large spanning tree environment (high CPU, transmits errs).  Older (crappy 3750xl for instance) smaller switches will show a lot of errors in a busy environment.  Missed buffer reports will be high on solarwinds too. 

                         

                        Many times I've come in on a pre-existing problem, sometimes years long, only to find that the thorough basics had never been fully investigated.