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[Troubleshooting Series] Case 48 Direct connection devices cannot ping successfully

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Physical Network Topology

As shown in the figure, two CE12800 directly connected devices, two different IP addresses are configured on device A, and the directly connected IP address is configured on device B.

Figure 1-1 Direct connection devices cannot ping successfully



Fault Description

The device A can ping device B as follows:

PING 56  data bytes, press CTRL_C to break
Reply from bytes=56 Sequence=1 ttl=254 time=2 ms
Reply from bytes=56 Sequence=2 ttl=254 time=2 ms 

When the source IP address is an interface IP address on the device A, the ping cannot be pinged. The details are as follows:

[~R4U13-CE12800]ping -a
PING 56  data bytes, press CTRL_C to break
Request time out
Request time out
Request time out
Request time out
Request time out
--- ping statistics ---
5 packet(s) transmitted
0 packet(s) received
100.00% packet loss

Configuration Files

dfs-group 1
 source ip 
ip vpn-instance huawei-1
ip vpn-instance huawei-2
ip vpn-instance huawei-3
bridge-domain 10
 vxlan vni 5010
interface Vlanif100
 ip binding vpn-instance huawei-1
 ip address
interface Vlanif200
 ip binding vpn-instance huawei-2
 ip address
interface Vlanif300
 ip binding vpn-instance huawei-3
 ip address
interface Vlanif1000
 ipv6 enable
 ip address
 ipv6 address 1000:1000::102/64
 ipv6 address auto link-local
 vrrp vrid 1 virtual-ip
 vrrp6 vrid 2 virtual-ip FE80::1 link-local
 vrrp6 vrid 2 virtual-ip 1000:1000::1000
interface Eth-Trunk1
 peer-link 1
 port vlan exclude 1000 
interface Eth-Trunk10
 port default vlan 1000
 dfs-group 1 m-lag 500
interface Eth-Trunk10.1 mode l2
 encapsulation dot1q vid 4000
 bridge-domain 10
interface 10GE2/0/1
 port link-type trunk
 port trunk allow-pass vlan 100 200 300
 device transceiver 10GBASE-FIBER
interface 10GE2/0/20
 eth-trunk 10
 device transceiver 10GBASE-FIBER
interface 10GE2/0/22
 eth-trunk 1
 device transceiver 10GBASE-FIBER
interface LoopBack1
 ip address
interface Nve1
 vni 5010 head-end peer-list
bgp 10088
 peer as-number 10086
 ipv4-family unicast
  preference 20 20 255
  import-route direct  
  peer enable
 ipv4-family vpn-instance huawei-1
  peer as-number 10086
 ipv4-family vpn-instance huawei-2
  peer as-number 10086
 ipv4-family vpn-instance huawei-3
  peer as-number 10086
ospf 100
 import-route direct
 import-route static

Troubleshooting Procedure

                              Step 1     View the routing table and ARP entries in this segment. The data is normal. The details are as follows:

[~R4U13-CE12800]dis ip routing-table
Proto: Protocol        Pre: Preference
Route Flags: R - relay, D - download to fib, T - to vpn-instance
Routing Table : _public_
Summary Count : 1
Destination/Mask    Proto   Pre  Cost        Flags NextHop         Interface  Direct  0    0             D     Vlanif300
[~R4U13-CE12800]dis arp | in
ARP Entry Types: D - Dynamic, S - Static, I - Interface
EXP: Expire-time
------------------------------------------------------------------------------     200b-c73c-9337   13   D/300     10GE1/0/1
Total:52         Dynamic:40       Static:0    Interface:12

                              Step 2     The packet can be sent out normally from the interface, but there is no return packet, as follows:

<R4U13-CE12800>dis int 10g 1/0/1
10GE1/0/1 current state : UP (ifindex: 64)
Line protocol current state : UP
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 200b-c73c-9301
Port Mode:     COMMON FIBER,     Port Split:                   DISABLE
Speed:                10000,     Loopback:                        NONE
Duplex:                FULL,     Negotiation:                  DISABLE
Input Flow-control: DISABLE,     Output Flow-control:          DISABLE
Mdi:                      -#goback
Last physical up time   : 2018-07-02 00:37+02:00
Last physical down time : 2018-07-02 00:37+02:00
Current system time: 2018-07-02 00:37+02:00
Statistics last cleared:2018-07-02 00:37+02:00
Last 300 seconds input rate: 148 bits/sec, 0 packets/sec
Last 300 seconds output rate: 367 bits/sec, 0 packets/sec
Input peak rate 148 bits/sec, Record time: 2018-07-02 00:37+02:00
Output peak rate 367 bits/sec, Record time: 2018-07-02 00:37+02:00
Input :                536 bytes,                  3 packets
Output:  Q             1383 bytes,                 10 packets
Unicast:                      2,   Multicast:                       1
Broadcast:                    0,   Jumbo:                           0
Discard:                      0,   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
Unicast:                      7,   Multicast:                       3
Broadcast:                    0,   Jumbo:                           0
Discard:                      0,   Buffers Purged:                  0
Pause:                        0
Input bandwidth utilization threshold : 90.00%
Output bandwidth utilization threshold: 90.00%
Last 300 seconds input utility rate:  0.01%
Last 300 seconds output utility rate: 0.01%

From the current port count, the message has been sent, but the message has not returned.

                              Step 3     Query the routing entries of the peer device, as follows:

[~R4U13-CE12800-SWITCH-A]dis ip routing-table vpn-instance huawei-3

The routing entry does not exist. Add the corresponding routing entry:


When the device is pinged with the source IP address, the source IP address and the peer device are not in the same network segment. As a result, packets are sent without a routing entry.

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  • convention:


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