[ovs-discuss] GRE tunnel - no ping reply

[krishna kumar]

No, 108.x.x.x is the access point in my home. The 198.168.x.x is the subnet to which the VM is attached. OVS is running in the VM.
The GRE packet arriving at 108.x.x.x cannot reach OVS in 192.168.x.x unless forwarded using DNAT. 
The router at 108.x.x.x does not support GRE.
 

________________________________
 From: Jesse Gross <jesse at nicira.com>
To: krishna kumar <ipower2 at yahoo.com> 
Cc: "discuss at openvswitch.org" <discuss at openvswitch.org> 
Sent: Friday, March 1, 2013 2:53 PM
Subject: Re: [ovs-discuss] GRE tunnel - no ping reply
 
On Fri, Mar 1, 2013 at 2:04 PM, krishna kumar <ipower2 at yahoo.com> wrote:
> 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.

I don't understand why you are using NAT here.  Isn't 108 the subnet
of the GRE endpoint and 192.168 the subnet of the host inside the
tunnel?
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