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Networking

An S series switch is connected to an NE router.

Fault Symptom

No packet loss occurs when data is exchanged between the S series switch and the NE router. However, when the S series switch pings the peer device, 1% of packets are discarded.

Cause Analysis

This problem is caused by the ping delay. After the timeout interval for the ping operation is prolonged, the problem can be resolved.

Troubleshooting Procedure

1.         Log in to the S series switch, and run the display this interface command in the interface view to check packet statistics on the interface that is connected to the NE router. Run this command multiple times, and no statistics about packet loss is displayed.

<SwitchC> system-view                           
[SwitchC]interface GigabitEthernet  2/0/3           
[SwitchC-GigabitEthernet2/0/3] display this interface   
 GigabitEthernet2/0/3 current state : UP
Line protocol current state : UP
Description:ISPNETWORK_C;ABS-SW1-S9303-GE-2/0/3:ABS-PE1-NE40E-GE-2/1/1_CORE;ABS_GE_ABS_1000000000;
Switch Port, TPID : 8100(Hex), The Maximum Frame Length is 9216
IP Sending Frames' Format is PKTFMT_ETHNT_2, Hardware address is 0025-9efc-10ab
Last physical up time   : 2015-05-04 02:27 UTC+02:00
Last physical down time : 2015-05-04 02:27 UTC+02:00
Current system time: 2015-05-04 02:27+02:00
Port Mode: COMMON FIBER
Speed : 1000,   Loopback: NONE
Duplex: FULL,   Negotiation: DISABLE
Mdi   : NORMAL, Flow-control: DISABLE
Last 300 seconds input rate 52570032 bits/sec, 7538 packets/sec
Last 300 seconds output rate 25088640 bits/sec, 7968 packets/sec
Input peak rate 999814120 bits/sec, Record time: 2015-05-04 02:27
Output peak rate 996697912 bits/sec, Record time: 2015-05-04 02:27
 
Input:  373188197913 packets, 338287744879142 bytes
  Unicast:               360614673925,  Multicast:                   633806578
  Broadcast:                917168042,  Jumbo:                     11022549363
  Discard:                          0,  Pause:                               0
 
  Total Error:                     10
  CRC:                              4,  Giants:                              0
  Jabbers:                          1,  Fragments:                           0
  Runts:                            0,  DropEvents:                          0
  Alignments:                       0,  Symbols:                             5
  Ignoreds:                         0,  Frames:                              0
 
Output:  336892407889 packets, 109124037884050 bytes
  Unicast:               328253519036,  Multicast:                   363844421
  Broadcast:               7635139626,  Jumbo:                       639904806
  Discard:                          0,  Pause:                               0
                                          
  Total Error:                      0
  Collisions:                       0,  ExcessiveCollisions:                 0
  Late Collisions:                  0,  Deferreds:                           0
  Buffers Purged:                   0
 
    Input bandwidth utilization threshold : 90.00%
    Output bandwidth utilization threshold: 90.00%
    Input bandwidth utilization  : 5.26%
    Output bandwidth utilization : 2.51%

2.         Collect traffic statistics, and no packet loss occurs.

3.         Run the ping -v -c 100  10.15.5.1 command in any view. The command output shows that one of 100 ping packets is discarded. Locate the fault based on the implementation of the ping operation.

<HUAWEI> ping -v -c 100  10.15.5.1
    PING 10.15.5.1: 56  data bytes, press CTRL_C to break
    Reply from 10.15.5.1: bytes=56 Sequence=1 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=2 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=3 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=4 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=5 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=6 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=7 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=8 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=9 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=10 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=11 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=12 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=13 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=14 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=15 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=16 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=17 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=18 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=19 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=20 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=21 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=22 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=23 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=24 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=25 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=26 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=27 ttl=254 time=1 ms
    Request time out
Error: Sequence number = 28 is less than the correct = 29!
    Reply from 10.15.5.1: bytes=56 Sequence=29 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=30 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=31 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=32 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=33 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=34 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=35 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=36 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=37 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=38 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=39 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=40 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=41 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=42 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=43 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=44 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=45 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=46 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=47 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=48 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=49 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=50 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=51 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=52 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=53 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=54 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=55 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=56 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=57 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=58 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=59 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=60 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=61 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=62 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=63 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=64 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=65 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=66 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=67 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=68 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=69 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=70 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=71 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=72 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=73 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=74 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=75 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=76 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=77 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=78 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=79 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=80 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=81 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=82 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=83 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=84 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=85 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=86 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=87 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=88 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=89 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=90 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=91 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=92 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=93 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=94 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=95 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=96 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=97 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=98 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=99 ttl=254 time=1 ms
    Reply from 10.15.5.1: bytes=56 Sequence=100 ttl=254 time=1 ms
 
  --- 10.15.5.1 ping statistics ---
    100 packet(s) transmitted
    99 packet(s) received
    1.00% packet loss
    round-trip min/avg/max = 1/1/1 ms

4.         Attempt to prolong the timeout interval of the ping operation. The result shows that the ping operation is normal and no packet loss occurs.

<HUAWEI> ping -v -c 100 -t 4000  10.15.5.1

Conclusions and Suggestions

When the S series switch is connected to other devices, no packet loss occurs in data exchange. However, packet loss occurs when the ping operation is performed. Since the ping delay and the number of ping packets are different, you need to analyze differences of the implementation mode and the ping operation.