At what point does a ping fail on my LAN? How far do the packets get?

Unanswered Question
May 2nd, 2002
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When pinging from a telnet session on my 2620's serial interface, I cannot get responses back from a host on the ethernet LAN until I set the 2620's ethernet interface as the gateway on the host.


So my question/assumption is this - will the packet that is generated on the serial interface (172.16.32.2) get out onto the ethernet LAN (192.168.2.0) with the header only showing the 172 address?


I guess I have been under the assumption that the 2620's ethernet interface would add it's address, giving the target host a local interface to answer back to - then the ethernet port would place it on the directly connected serial interface.


Now, I am thinking that the packet gets onto the LAN with only 172 addressing, makes it to the host and the host can't answer back because it doesn't know how to get to the 172 network.


Am I right or wrong?

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When you performed your ping, did you perform an extended ping and specify a source address (assuming that you have multiple interfaces with IP addresses on them)?


My suggestion, if you really want to go deep into this, is to get some free sniffer software like Ethereal and sniff the LAN adapter of the host on the lan segment. Then, you will see for yourself what is happening with the incoming icmp request and the icmp reply.


Chuck


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