I am stuck at a very strange result after running the command ping -R in a unix environment. To be more specific, I am trying to follow the path to a server and back but there is quite a mismach between the results from running this command and the traceroute to the same server. Why is that? I am already familiar with the concept of ping -R command and have actually read the manual page very thoroughly, however, I had no luck in expldaining to myself why that could happen. Any suggestions would be much appreciated as I am really confused. Thanks
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user726730
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1Is this consistently appearing discrepancy? Remember that the actual route may change between or even in the middle of your trace. – Adam Zalcman Dec 23 '11 at 00:00
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Asymmetric routing? – joeqwerty Dec 23 '11 at 00:03
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@AdamZalcman: yes it is very consistent and the number of hops is small (8) so everything should work as supposed (I think!) – user726730 Dec 23 '11 at 00:06
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@joeqwerty: Well it could be routed asymmetrically, however the forward route should look the same either by using ping -R or traceroute (or am I wrong?) – user726730 Dec 23 '11 at 00:07
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Ping -r displays outgoing IP addresses, i.e. addresses when leaving the routers, while traceroute displays addresses when entering the routers. If the 9-address limit of ping -r is sufficient to display all the addresses encountered in a round trip, you can see first the addresses opposite to you, then the addresses towards you. With traceroute you only see the addresses towards you.
Alessandro Lazzari
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