Extended Ping – why use it?
Typically, when you ping a host, the device will use the closest interface to the destination eg SERIAL 0/1. The problem, however, you need to test an IPSEC tunnel that’s linked to another interface on that device. Let’s assume my LAN interface on my Cisco router is 172.16.1.1. I need to test whether my IPSEC POINT-to-POINT tunnel will generate and pass traffic. Without access to a PC at that location is where extended ping comes in. With extended ping, it’s possible to initiate interesting traffic from a particular interface to cause an event remotely. It’s simple at an enabled prompt example below:
- Assumptions:
gateway-rtr#
gateway-rtr#ping
Protocol [ip]:
Target IP address: 10.45.4.101
Repeat count [5]:
Datagram size [100]:
Timeout in seconds [2]:
Extended commands [n]: y
Source address or interface: 172.16.1.1
Type of service [0]:
Set DF bit in IP header? [no]:
Validate reply data? [no]:
Data pattern [0xABCD]:
Loose, Strict, Record, Timestamp, Verbose[none]:
Sweep range of sizes [n]:
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.45.4.101, timeout is 2 seconds:
Packet sent with a source address of 172.16.1.1
.!!!!
Success rate is 80 percent (4/5), round-trip min/avg/max = 32/33/36 ms
gateway-rtr#
Notice the first ping failed. This is due to the time it took to bring up the IPSEC tunnel. As confirmation, you’ll notice where the ping packet was sent from.