Difference in responses

Posted by: Ubar

Difference in responses - 04/06/09 06:06 AM

I have setup ping plotter to trace an IP address 17 hops away from my router. on hope 5 I get constent errors but when I start a second instance of ping plotter and target the IP address at hop 5 shows no errors.

I have also tried tracing to hop 6 during the errors and it shows no errors at 6 but does at 5.
Posted by: Ubar

Re: Difference in responses - 04/06/09 06:14 AM

second trace.
Posted by: Pete Ness

Re: Difference in responses - 04/07/09 02:10 AM

We talk about this topic a bit here:

http://www.nessoft.com/kb/24
and here:
http://www.nessoft.com/kb/5

The most likely problem is that hop 5 is down-prioritizing the creation of ICMP TTL Expired packets, but it's returning packets for other routers just fine. That's not abnormal. When you directly ping that router, it's creating a different type of reply packet (ICMP Echo Reply), which probably has different routing rules.