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Ping reply but no sent Ping and also destination unreachable

Hi all,


Got 2 Fortigate 100E's at 2 branches, these run BGP and connect in a hub and spoke setup to our head office with a site to site VPN. We have 2 sub-interfaces on each of the branch Fortigates (v7) for our VOIP phones. The setup is this, siteA have main LAN of and sub interface for VOIP of and there is a phone server on there on IP of siteB has main LAN of and sub interface for voip of and has a phone server on there on 

I can ping successfully from the Fortigates from to and also from to and from to and so the sub interfaces can see the devices on the sub-interfaces both ways however if i do a source ping from the phone servers on and to each other then i get no response.

I've ran a packet sniffer on both sides and weirdly enough the one when pinging from siteA and pinging from to i get an Echo Ping Reply frim (source) to (dest) but then a destination unreachable from (source) to (dest). If i then run it from siteB i ONLY get an Echo Ping Reply form (source) to (dest) but no Echo request ?

I've tried putting in a firewall rule on both sides to allow ICMP through from VOIP to the VPN HUB but it doesn't make any difference.

Anyone see what i'm doing wrong here or missing ?

Thanks (and i'm hoping i've written that down correctly :) )


I added a firewall rule to test for the siteA sip as the source to siteB sip as the dest and allowed ICMP and was getting a ping reply from siteB to site A but the request again is showing as Destination Unreachable (Protocol Unreachable)...just tried it again and there's nothing on either side....not sure if there's just a network issue that keeps going up and down





I have the same problem on some sites. Do you have a solution or found something ?


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