Self ping to serial takes more time than ping to other side interface

[shrikant4u]

Networkers

pinging to own serial interface takes more time than pinging to other side ip of serial link.

Ex:-

Router-A#sho ip int brie

......

Serial5/0/5 172.22.1.138 YES NVRAM up up

.......

Router-A#ping 172.22.1.138

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 172.22.1.138, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 32/32/36 ms

Router-A#ping 172.22.1.137

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 172.22.1.137, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 16/17/20 ms

Router-A#

I tried with diff router ...got same result...Can some one help me to understand this??

TIA

Shri

[Kevin Dorrell · Accepted solution]

The reason is simple. When you ping the other guy, you send a ping, and he sends you a "pong" response.

When you ping yourself (on a point-to-point) you send a ping out on the line and the other end sends it back to you. You then generate a "pong" response and send it out on the line, and the other guy sends it back to you.

Kevin Dorrell

Luxembourg

[Edison Ortiz]

I echo Kevin's response and one suggestion for the future, when you don't understand something, try turning debug. You will be amazed of the things you can see under the hood with debug.

Of course, I can only recommend this for 'lab' environment.