Counter value of "0" in Loopback Interface

[Suzukikoki]

Any information would be appreciated.

I just performed a ping on interface Loopback0, which is the interface where the IP address is assigned,
I noticed that the Packet counter value did not go up.
※When I ping myself, the result is the same.

#show run int Loopback0
ip address X.X.X.X X.X.X.X

#show int Loopback0
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec

#Ping X.X.X.X
Sending 5, 100-byte ICMP Echos to X.X.X.X, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/1 ms

#show int Loopback0
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec

The counter value of "0" is undesirable for monitoring purposes,
I would appreciate any advice on possible causes as to why the counter value is not increasing.

Models are Cisco C800 and ISR series.

[balaji.bandi]

Depending on the device where you testing, 

Try the below command you should see PKTS IN increasing.

#show interfaces loopback 0 accounting

[Suzukikoki]

Hi @balaji.bandi 
Thank you for your reply.

When we tried it, there was no change in the counter value and the following display was obtained.

------------------

#show interfaces loopback 0 accounting
Loopback0
Protocol Pkts In Chars In Pkts Out Chars Out
No traffic sent or received on this interface.

------------------

There is no change when pinging is performed on its own equipment.

I would appreciate any advice you can give me on what you can tell me.

[Richard Burts]

If you ping to or through a physical interface then packets are transmitted and the input and output will be greater than zero. But loopback is a virtual interface and no packets are transmitted through virtual interfaces. So zero in and out is the expected result.

[Suzukikoki]

Hi @Richard Burts 
Thank you very much for your valuable feedback.

As you say, the counter value for the physical Interface counts up without any problem.
Also, as you advised here, the counter value does not go up even when the source is specified, indicating that the Loopback Interface is not involved in the sending or receiving of packets.

#ping X.X.X.X source loopback 0

 was implemented, the results did not change.

#show interface loop 0 accounting
Loopback0
Protocol Pkts In Chars In Pkts Out Chars Out
No traffic sent or received on this interface.

However, the counter value is increased when pinging is performed with LoopBack specified as the source on other devices as well.

The equipment is also ISR, but what is the difference?
The only difference is that they handle voice configurations.

#sh int lo 0 accounting
Loopback0
Protocol Pkts In Chars In Pkts Out Chars Out
IP 6856926 386855678 6856926 386855678

[balaji.bandi]

Loopback works in a different way than other interfaces like SVI and Physical Interfaces.

Generally, no traffic transit using Loopback in most cases.

Just test one of the test devices:

Are you trying from the same device where the Loopback is configured? ( you should see the counter either case)

[Suzukikoki]

Hi @balaji.bandi 
Thank you very much for your valuable feedback.

I am pinging the same device that has loopback configured with

#ping X.X.X.X source loopback 0

but the status remains the same and the counter value does not increase.

#show interface loop 0 accounting
Loopback0
Protocol Pkts In Chars In Pkts Out Chars Out
No traffic sent or received on this interface.

However, the counter value is increased when pinging is performed with LoopBack specified as the source on other devices as well.

The equipment is also ISR, but what is the difference?
The only difference is that they handle voice configurations.

[MHM Cisco World · Accepted solution]

I check the LO account is increase with each ping (echo + echo reply)
so I think it some kind of  cosmetic bug 

[Suzukikoki]

Thank you for your confirmation.
I understand that it is a bug.