Guest

Cisco 12000 Series Routers

Potential Self-Ping or Self-Traceroute Failures on Routers Running 12.0(25)S


May 21, 2003



Products Affected

Product

Comments

gsr-p-mz.120-25.S.bin

Cisco IOS® Software Release 12.0(25)S

c7200-p-mz.120-25.S.bin

?

rsp-pv-mz.120-25.S.bin

?

Problem Description

The following two problems associated with ping were identified in Cisco caveat CSCuk42211 and may occur on Cisco 7200, 7500, or 12000 Routers running Cisco IOS Software Release 12.0(25)S:

  1. On a point-to-point interface (serial, Packet-over-Sonet, PPP), an interface may not be able to properly trace its own IP address. Tracing its own serial (or other point-to-point address) IP address will not display the peer address any more.

  2. On an interface in loopback, self-ping may fail. If it succeeds, the Rx LED may not flash to indicate successful packet receipt.

Background

The self-ping and traceroute failures indicated by this field notice do not affect all Cisco 7200, 7500, or 12000 line cards, and will not affect any line card's ability to pass traffic.

Traceroute symptoms are limited to an interface being able to properly trace its own IP address for test purposes.

With the topology UUT-(x.x.x.x)----serial----(x.x.x.y)-peer, where UUT sends a trace to x.x.x.x (itself), the expected behavior is shown below.

UUT#traceroute x.x.x.x 
Type escape sequence to abort.
Tracing the route to x.x.x.x
1 x.x.x.y 16 msec 16 msec 16 msec
2 x.x.x.x 40 msec 32 msec *

This is incorrect behavior, and indicates the failure described in this field notice.

UUT#traceroute x.x.x.x
Type escape sequence to abort.
Tracing the route to x.x.x.x
1 x.x.x.x 16 msec 16 msec *  

Problem Symptoms

  • Self-ping on an interface in loopback can demonstrate the following problems:

    1. The ping succeeds, but the Rx LED does not flash to indicate successful packet receipt.

    2. The ping fails, as reported by on the console.

  • On a very limited number of line cards, only the local router and not next-hop routers will be listed after the traceroute command has been issued.

Workaround/Solution

This is a cosmetic problem that does not effect live traffic nor are these problems any indication of hardware failures.

The following mechanisms can be used as a workaround to verify a working interface and good hardware:

  1. The interface of a line card or port adapter is fine when the interface is in service, is connected to another interface, and you can ping the other interface.

  2. If the interface of a line card or port adapter is not in service, loop the interface either physically (with a fiber cable) or enter the loopback interface configuration command; when the state of the interface is "up," the hardware is fine.

DDTS

To follow the bug ID link below and see detailed bug information, you must be a registered user and you must be logged in.

DDTS

Description

CSCuk42211 (registered customers only)

Trace doesnt show peer address anymore.

CSCea00253 (registered customers only)

Unable to ping from out->in when outside static NAT is used

CSCea66677 (registered customers only)

Self ping not working

For More Information

If you require further assistance, or if you have any further questions regarding this field notice, please contact the Cisco Systems Technical Assistance Center (TAC) by one of the following methods: