Cisco Systems Cisco IOS XR manual Using the traceroute Command

Chapter 7 Troubleshooting the Cisco IOS XR Software

Basic Troubleshooting Commands

Each exclamation point (!) indicates receipt of a reply. A period (.) indicates the network server timed out while waiting for a reply. Other characters may appear in the ping output display, depending on the protocol type.

Examples

In the following example, a successful ping attempt is shown:

RP/0/RP0/CPU0:router# ping 10.233.233.233

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 10.233.233.233, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/7 ms

In the next example, an unsuccessful ping attempt is shown:

RP/0/RP0/CPU0:router# ping 10.1.1.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 10.1.1.1, timeout is 2 seconds:

.....

Success rate is 0 percent (0/5)

The following example shows the output of ping through the fabric:

RP/0/RP1/CPU0:router(admin)# ping fabric location 0/6/5

Src node:	529	:	0/RP1/CPU0
Dest node:	109	:	0/6/5
Local node:	529	:	0/RP1/CPU0
Packet cnt:	1	Packet size:		128	Payload ptn type: default (0)
Hold-off (ms):	300	Time-out(s):		2	Max retries: 5
Running Fabric node ping.
Please wait...
Src: 529:, Dest: 109,		Sent: 1, Rec'd: 1, Mismatched: 0
Min/Avg/Max RTT: 20000/20000/20000
Fabric node ping	succeeded for node: 109

Using the traceroute Command

Use the traceroute command in EXEC mode to discover the routes that packets take when traveling to their destination. Enter a hostname or an IP address as an argument to this command.

This command works by taking advantage of the error messages generated by routers when a datagram exceeds its time-to-live (TTL) value.

The traceroute command starts by sending probe datagrams with a TTL value of 1, causing the first router to discard the probe datagram and send back an error message. The traceroute command sends several probes at each TTL level and displays the round-trip time for each.

The traceroute command sends one probe at a time. Each outgoing packet may result in one or two error messages. A time exceeded error message indicates that an intermediate router has seen and discarded the probe. A destination unreachable error message indicates that the destination node has received the probe and discarded it because it could not deliver the packet. If the timer times out before a response comes in, the traceroute command prints an asterisk (*).

The traceroute command terminates when the destination responds, the maximum TTL is exceeded, or the user interrupts the trace with the escape sequence.

Cisco IOS XR Getting Started Guide

7-4 OL-10957-02