Traceroute does not display intermediate hops between X-series chassis and a destination host

Products

• XOS

Issue/Introduction

The article presents a known issue of traceroute in XOS 9.7.2 and howto resolve it.Customer starts traceroute through X-series chassis, intermediate hops between X-series chassis and the target host are not displayed in command output until the destination hop replies back.

# tracert <SOME_IP>

 

Tracing route to <SOME_IP> over a maximum of 30 hops: 

 

1 <1 ms <1 ms <1 ms <HOP1_IP> 

2 <1 ms <1 ms <1 ms <HOP2_IP> 

3 1 ms 320 ms <1 ms  <X-SERIES_HOP>  

4 * * * Request timed out. 

5 * * * Request timed out. 

6 * * * Request timed out. 

7 * * * Request timed out. 

8 * * * Request timed out. 

9 3 ms 6 ms *  <SOME_IP>

 

Trace complete.

The symptom is present on series-6 NPMs and XOS 9.7.2.

Please, also run traceroute from the 1st hop behind X-series to the target host to verify you're indeed affected by this bug and that the "TTL expired" messages are not accidentally blocked by some other device on the return path.

 

Cause

The behavior is caused by "ICMP Error message handling issue" with series-6 NPMs in XOS 9.7.2.
Series-9 NPMs are not affected.

Resolution

Upgrade to XOS 9.7.3 or higher (when available) or contact Blue Coat technical support for a patch.

Workaround

N/A