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ICMP not working on all IP addresses to the same subnet

aaron-saz
Level 1
Level 1

I'm having some ping "Connection" issues. With 2 of 4 FTP Servers...

I've narrowed it down to this issue happening on the physical machine verses the Virtual Machine. From the Lab Router I can ping all IP's successfully, but if I source the ping from the other interface (192.168.1.10) on the router I can only ping the VM's inside the Physcial machines. All other functions work.

 

I have a co-worker, that in his backup script, tests the ping connection before starting his ftp session and this is causing some tension. He controls both the FTP Servers and the source's he's backing up from.

 

I put a network tap between the 10.10.1.9 physical machine and the unmanaged switch, using Wireshark I can see the ping echo request received to the target machine both 10.10.1.9 and 10.10.1.17.  Only 10.10.1.17 responds with a echo-reply, no echo-reply from the 10.10.1.9. Same thing happens to the 10.10.1.8 and 10.10.1.18 setup.

 

Please see below for a brief layout of my Physical / VM machines.

 

Does anybody have any thoughts on how this can be happening?


10.10.1.9 physcial machine
       10.10.1.17 - VM inside 10.10.1.9

10.10.1.8 physcial machine
       10.10.1.18 - VM inside 10.10.1.8


Ping commands successful from Lab router:
     ping 10.10.1.8
     ping 10.10.1.9
     ping 10.10.1.17
     ping 10.10.1.18
     ping 10.10.1.17 source 192.168.1.10
     ping 10.10.1.18 source 192.168.1.10

 

Ping commands unsuccessful from Lab Router:
     ping 10.10.1.9 source 192.168.1.10
     ping 10.10.1.8 source 192.168.1.10

1 Accepted Solution

Accepted Solutions

Just to end this....  After installing a firewall -> having some minor issues (Post) -> being lectured by someone with "20 IT / Network admin experience" that everything was working just fine before we did the upgrade, and now it's not...

 

I was reminded to be skeptical on everything and when all else fails check for yourself...

 

Turns out the VM host (Physical machine) had it's firewall turned on and seemed to be blocking the ICMP....  Once turned off, everything worked as expected...  

View solution in original post

3 Replies 3

Hello @aaron-saz

 

 Does hosts 10.10.1.8 and 10.10.1.9 know how to replay to 192.168.1.10 ?

Which default gateway they are using? 

 

 

 

-If I helped you somehow, please, rate it as useful.-

 

Just to end this....  After installing a firewall -> having some minor issues (Post) -> being lectured by someone with "20 IT / Network admin experience" that everything was working just fine before we did the upgrade, and now it's not...

 

I was reminded to be skeptical on everything and when all else fails check for yourself...

 

Turns out the VM host (Physical machine) had it's firewall turned on and seemed to be blocking the ICMP....  Once turned off, everything worked as expected...  

@flavio, yes it could reach everywhere in the network it needed to including the web..

thank you
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