As an aid to diagnosing basic network connectivity, many network protocols support an echo protocol. The protocol involves
sending a special datagram to the destination host, then waiting for a reply datagram from that host. Results from this echo
protocol can help in evaluating the path-to-host reliability, delays over the path, and whether the host can be reached or
is functioning.
Configuration for Checking Network Connectivity
The following configuration shows an extended ping command sourced from the Router A HundredGigEinterface and destined for the Router B HundredGigE interface. If this ping succeeds, it is an indication that there is no routing problem. Router A knows how to get to the
HundredGigEinterface of Router B, and Router B knows how to get to the HundredGigE interface of Router A. Also, both hosts have their default gateways set correctly.
If the extended ping command from Router A fails, it means that there is a routing problem. There could be a routing problem on any of the three
routers: Router A could be missing a route to the subnet of Router B's interface, or to the subnet between Router C and Router
B; Router B could be missing a route to the subnet of Router A's subnet, or to the subnet between Router C and Router A; and
Router C could be missing a route to the subnet of Router A's or Router B's Ethernet segments. You should correct any routing
problems, and then Host 1 should try to ping Host 2. If Host 1 still cannot ping Host 2, then both hosts' default gateways
should be checked. The connectivity between the HundredGigE interface of Router A and the HundredGigE interface of Router B is checked with the extended ping command.
With a normal ping from Router A to Router B's HundredGigE interface, the source address of the ping packet would be the address of the outgoing interface; that is the address of the
HundredGigE interface, (192.0.2.2). When Router B replies to the ping packet, it replies to the source address (that is, 192.0.2.1).
This way, only the connectivity between the HundredGigE interface of Router A (192.0.2.2) and the 10gige interface of Router B (192.0.2.1) is tested.
To test the connectivity between Router A's HundredGigE interface (192.0.2.2) and Router B's interface (192.0.2.1), we use the extended ping command. With extended ping, we get the option to specify the source address of the ping packet.
Configuration Example
In this use case, the extended ping command verifies the IP connectivity between the two IP addresses Router A (192.0.2.2) and Router B (192.0.2.1) .
Router# ping 192.0.2.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.0.2.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5)
Router#!!!!!
*/If you do not enter a hostname or an IP address on the same line as the ping command,
the system prompts you to specify the target IP address and several other command parameters.
After specifying the target IP address, you can specify alternate values for the
remaining parameters or accept the displayed default for each parameter /*
Router# ping
Tue Sep 24 02:41:45.739 UTC
Protocol [ipv4]: ipv4
Target IP address: 192.0.2.1
Repeat count [5]: 5
Datagram size [100]: 1
% A decimal number between 36 and 18024.
Datagram size [100]: 36
Timeout in seconds [2]: 1
Interval in milliseconds [10]: 1
Extended commands? [no]: y
Source address or interface: 12.12.1.1
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? [no]:
Type escape sequence to abort.
Sending 5, 36-byte ICMP Echos to 192.0.2.1, timeout is 1 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/3/7 ms
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