Wednesday , October 23 2019
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why does subinterface fail to forward packets

Let’s imagine that we have a simple topology like below:

arp-topology

Configure subinterfaces on both AR routers for VLAN tag termination:

[R1]interface GigabitEthernet 0/0/0.100
[R1-GigabitEthernet0/0/0.100]ip address 10.0.0.1 24
[R1-GigabitEthernet0/0/0.100]dot1q termination vid 100

[R2]int GigabitEthernet 0/0/0.100
[R2-GigabitEthernet0/0/0.100]ip address 10.0.0.2 24
[R2-GigabitEthernet0/0/0.100]dot1q termination vid 100

Try to ping IP address of neighboring router:

[R1]ping 10.0.0.2
  PING 10.0.0.2: 56  data bytes, press CTRL_C to break
    Request time out
    Request time out
    Request time out
    Request time out
    Request time out

  --- 10.0.0.2 ping statistics ---
    5 packet(s) transmitted
    0 packet(s) received
    100.00% packet loss

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