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Troubleshooting Guide

CloudEngine 16800, 12800, 12800E, 8800, 7800, 6800, and 5800 Series Switches

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Huawei uses machine translation combined with human proofreading to translate this document to different languages in order to help you better understand the content of this document. Note: Even the most advanced machine translation cannot match the quality of professional translators. Huawei shall not bear any responsibility for translation accuracy and it is recommended that you refer to the English document (a link for which has been provided).
Packets Are Discarded on an Inbound Interface

Packets Are Discarded on an Inbound Interface

Keywords

Traffic control, inbound direction, packet discarding, switch

Abstract

The remote device does not respond to the traffic control message sent by the local device and continues to send packets to the local device. As a result, packets are discarded in the inbound direction on the local device.

Problem Description

In Figure 16-14, after packets are congested on SwitchB, SwitchB sends a traffic control message to SwitchA. However, packet congestion is not alleviated on SwitchB, and packets are discarded in the inbound direction on SwitchB.

Figure 16-14 Networking diagram

Procedure

  1. Check statistics of 10GE1/0/1 on SwitchB. If Discard under Input has a value, packet loss occurs on the inbound interface. Generally, this occurs because SwitchA does not respond to the traffic control message sent by SwitchB.
    <HUAWEI> display interface 10ge 1/0/1
    10GE1/0/1 current state : UP (ifindex: 5)
    Line protocol current state : UP
    Description:
    Switch Port, PVID :    1, TPID : 8100(Hex), The Maximum Frame Length is 9216
    Internet protocol processing : disabled
    IP Sending Frames' Format is PKTFMT_ETHNT_2, Hardware address is 206b-88f3-3f11
    Port Mode:    COMMON COPPER,     Port Split:                         -
    Speed:                 1000,     Loopback:                        NONE
    Duplex:                FULL,     Negotiation:                   ENABLE
    Input Flow-control:  ENABLE,     Output Flow-control:           ENABLE
    Mdi:                   AUTO
    Last physical up time   : 2018-11-05 14:42:43
    Last physical down time : 2018-10-29 20:38:50
    Current system time: 2018-11-05 15:16:45
    Statistics last cleared:never
        Last 10 seconds input rate: 999739730 bits/sec, 822154 packets/sec
        Last 10 seconds output rate: 27157 bits/sec, 40 packets/sec
        Input peak rate 1000000000 bits/sec, Record time: 2018-11-05 14:59:20
        Output peak rate 27824 bits/sec, Record time: 2018-11-05 15:15:07
        Input :       131971080264 bytes,          868231263 packets
        Output:             651057 bytes,               6771 packets
        Input:
          Unicast:              868230190,   Multicast:                      53
          Broadcast:                 1020,   Jumbo:                           0
          Discard:               79259545,   Frames:                          0
          Pause:                        0
    
          Total Error:                  0
          CRC:                          0,   Giants:                          0
          Jabbers:                      0,   Fragments:                       0
          Runts:                        0,   DropEvents:                      0
          Alignments:                   0,   Symbols:                         0
          Ignoreds:                     0
    
        Output:
          Unicast:                      0,   Multicast:                    2111
          Broadcast:                  510,   Jumbo:                           0
          Discard:                      0,   Buffers Purged:                  0
          Pause:                     4150
    
        Input bandwidth utilization threshold : 90.00%
        Output bandwidth utilization threshold: 90.00%
        Last 10 seconds input utility rate:  99.97%
        Last 10 seconds output utility rate: 0.01%
  2. CE series switches can send the following types of traffic control messages to the remote device: flow control backpressure frame and PFC backpressure notification packet. Determine the type of flow control message sent by a CE switch using the following methods:
    • Flow control backpressure frame
      Check for flow-control in the configurations of 10GE1/0/1 on SwitchB. If flow-control is found and Pause under Output has a value, packet congestion occurs on SwitchB but SwitchA does not respond to the flow control backpressure frame sent by SwitchB and continues to send packets.
      <HUAWEI> display interface 10ge 1/0/1
      10GE1/0/1 current state : UP (ifindex: 5)
      Line protocol current state : UP
      Description:
      Switch Port, PVID :    1, TPID : 8100(Hex), The Maximum Frame Length is 9216
      Internet protocol processing : disabled
      IP Sending Frames' Format is PKTFMT_ETHNT_2, Hardware address is 206b-88f3-3f11
      Port Mode:    COMMON COPPER,     Port Split:                         -
      Speed:                 1000,     Loopback:                        NONE
      Duplex:                FULL,     Negotiation:                   ENABLE
      Input Flow-control:  ENABLE,     Output Flow-control:           ENABLE
      Mdi:                   AUTO
      Last physical up time   : 2018-11-05 14:42:43
      Last physical down time : 2018-10-29 20:38:50
      Current system time: 2018-11-05 15:16:45
      Statistics last cleared:never
          Last 10 seconds input rate: 999739730 bits/sec, 822154 packets/sec
          Last 10 seconds output rate: 27157 bits/sec, 40 packets/sec
          Input peak rate 1000000000 bits/sec, Record time: 2018-11-05 14:59:20
          Output peak rate 27824 bits/sec, Record time: 2018-11-05 15:15:07
          Input :       131971080264 bytes,          868231263 packets
          Output:             651057 bytes,               6771 packets
          Input:
            Unicast:              868230190,   Multicast:                      53
            Broadcast:                 1020,   Jumbo:                           0
            Discard:               79259545,   Frames:                          0
            Pause:                        0
      
            Total Error:                  0
            CRC:                          0,   Giants:                          0
            Jabbers:                      0,   Fragments:                       0
            Runts:                        0,   DropEvents:                      0
            Alignments:                   0,   Symbols:                         0
            Ignoreds:                     0
      
          Output:
            Unicast:                      0,   Multicast:                    2111
            Broadcast:                  510,   Jumbo:                           0
            Discard:                      0,   Buffers Purged:                  0
            Pause:                     4150
      
          Input bandwidth utilization threshold : 90.00%
          Output bandwidth utilization threshold: 90.00%
          Last 10 seconds input utility rate:  99.97%
          Last 10 seconds output utility rate: 0.01%
    • PFC backpressure notification packet
      Check for dcb pfc enable in the configurations of 10GE1/0/1 on SwitchB. If dcb pfc enable is found and the PFC frame field has a value in the display dcb pfc command output, packet congestion occurs on SwitchB but SwitchA does not respond to the PFC backpressure notification packet sent by SwitchB and continues to send packets.
      <HUAWEI> display dcb pfc interface 10ge 1/0/1
      -------------------------------------------------------------------------------
      Interface         Queue         Received(Frames)      Transmitted(Frames)
                                           DeadlockNum              RecoveryNum
      -------------------------------------------------------------------------------
      10GE1/0/1             3                        0                   685177
                                                     0                        0
      -------------------------------------------------------------------------------

Root Cause

When packets are congested on the local device, the local device sends a traffic control message to the remote device, requesting the remote device to stop packet sending. However, after receiving the traffic control message, the remote device does not respond to the message and continues to send packets to the local device. As a result, packets are discarded in the inbound direction on the local device.

Solution

Enable the traffic control function on the remote device so that it can properly respond to the traffic control message sent by the local device.

Suggestion

Properly plan the network traffic forwarding paths to prevent congestion on the network.

Translation
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Updated: 2020-01-07

Document ID: EDOC1000060766

Views: 611761

Downloads: 2956

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