Chapter 26
| IP Interface Commands
IPv4 Interface
– 651 –
Command Usage
◆ Use the traceroute command to determine the path taken to reach a specified
destination.
◆ A trace terminates when the destination responds, when the maximum time
out (TTL) is exceeded, or the maximum number of hops is exceeded.
◆ The traceroute command first sends probe datagrams with the TTL value set at
one. This causes the first router to discard the datagram and return an error
message. The trace function then sends several probe messages at each
subsequent TTL level and displays the round-trip time for each message. Not all
devices respond correctly to probes by returning an “ICMP port unreachable”
message. If the timer goes off before a response is returned, the trace function
prints a series of asterisks and the “Request Timed Out” message. A long
sequence of these messages, terminating only when the maximum time out
has been reached, may indicate this problem with the target device.
◆ If the target device does not respond or other errors are detected, the switch
will indicate this by one of the following messages:
■
* - No Response
■
H - Host Unreachable
■
N - Network Unreachable
■
P - Protocol Unreachable
■
O -Other
Example
Console#traceroute 192.168.0.1
Press "ESC" to abort.
Traceroute to 192.168.0.1, 30 hops max, timeout is 3 seconds
Hop Packet 1 Packet 2 Packet 3 IP Address
--- -------- -------- -------- ---------------
1 20 ms <10 ms <10 ms 192.168.0.1
Trace completed.
Console#
ping This command sends (IPv4) ICMP echo request packets to another node on the
network.
Syntax
ping host [count count] [size size]
host - IP address or alias of the host.
count - Number of packets to send. (Range: 1-16)
size - Number of bytes in a packet. (Range: 0-1452)
The actual packet size will be eight bytes larger than the size specified
because the router adds header information.
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