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Using diagnostic tools
Ping
Use ping to determine if a specific address is reachable.
Ping operates as follows:
1. The source device sends ICMP echo requests (ECHO-REQUEST) to the destination device.
2. The destination device responds by sending ICMP echo replies (ECHO-REPLY) to the source device
after receiving the ICMP echo requests.
3. The source device displays related statistics after receiving the replies.
Output of the ping command might include the following:
• You can ping the IP address or the host name of a destination device. A prompt appears if the target
host name cannot be resolved.
• If the source device does not receive an ICMP echo reply within the timeout time, it displays:
{ A prompt.
{ Ping statistics.
• If the source device receives ICMP echo replies within the timeout time, it displays:
{ Number of bytes for each echo reply.
{ Message sequence number.
{ Time to Live (TTL).
{ Response time.
{ Ping statistics.
Ping statistics include:
• Number of echo requests sent.
• Number of echo replies received.
• Percentage of echo replies not received.
• Minimum, average, and maximum response time.
Traceroute
Traceroute retrieves the IP addresses of Layer 3 devices in the path to a specific destination. You can use
traceroute to test network connectivity and identify failed nodes.
You can trace route the IP address or the host name of a destination device. If the target host name cannot
be resolved, a prompt appears.
Traceroute operates as follows:
1. The source device sends a packet with a TTL value of 1 to the destination device.
2. The first hop (the device that first receives the packet) responds with a TTL-expired ICMP message
to the source. In this way, the source device gets the address of the first device.
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