[ovs-discuss] GRE tunnel - no ping reply

[krishna kumar]

Thanks for your reply!
Not sure if I understood what you said correctly... please correct me if I'm wrong.
The two subnets are each behind a router which has a public IP. 
Then the 10.x.x.x has a GRE tunnel interface with remote ip of 108.x.x.x and vice versa.
I have also setup a DNAT in the firewall to forward any packet to 108.x.x.x with protocol 47 to 192.168.x.x (VM).
And I also added a flow that says any traffic from 10.x.x.x to 192.168.x.x should goto GRE tunnel interface.
It seems it is working fine. The ICMP request from 10.x.x.x to 192.168.x.x is getting encapsulated and the GRE packets are received on the 192.168.x.x network. But the ICMP reply is not generated on the 192.168.x.x side.

Not sure where we would need another router between these two subnets.


________________________________
 From: Jesse Gross <jesse at nicira.com>
To: krishna kumar <ipower2 at yahoo.com> 
Cc: "discuss at openvswitch.org" <discuss at openvswitch.org> 
Sent: Thursday, February 28, 2013 9:14 PM
Subject: Re: [ovs-discuss] GRE tunnel - no ping reply
 
On Thu, Feb 28, 2013 at 8:53 PM, krishna kumar <ipower2 at yahoo.com> wrote:
> Hi.. I'm relatively new to OVS and GRE tunnel and not sure if my setup is
> working.
> My setup is this:
>
> 10.x.x.x ----  50.x.x.x
> ------------GRE------------------108.x.x.x----192.168.x.x
>
> I'm ping 192.168.x.x from 10.x.x.x.
> Wireshark shows that the ICMP request with GRE encapsulation arrived from
> 10.x.x.x to 192.168.x.x.
> I can also see the decapsulated ICMP request in Wireshark. But no ICMP reply
> is generated, instead a bunch of ARP requests are generated for the 10.x.x.x
> network which I see in Wireshark on 192.168.x.x host.
>
> Is ping supposed to work in this setup above? Is there any other easy way to
> test if the GRE tunnel is working?

You're trying to ping between two
 different subnets.  You need a
router in between to do that.
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