Sorry for posting again. Can anybody help me in understanding this. On 16 May 2015 13:20, "Manik Sidana" <[email protected]> wrote:
> Hi All, > > I am new to GRE tunneling in OVS. I tried the below example > http://linuxmantra.com/2013/08/gre-tunneling-with-open-vswitch.html > and I was able to establish the tunnel between the two VMs on two > different physical machines. > > This link talks about creating isolated bridges br0 and br2 but I was > able to achieve it with a single bridge br2. > Now I want to understand the packet flow of how the actual > communication happens when VM1 pings VM2. > > 1. Data from VM1 reaches br2 through the tap interface. At this point, > the ARP entry is not learnt, so br2 broadcasts the packets and thus > the packet reaches gre0 interface on br2. > 2. Packet is encapsulated with GRE header. > 3. Now, how this packet reaches br0 and leaves the host machine from > eth0 is not clear. Who picks the encapsulated packet ? Is it the OVS > GRE kernel module ? If yes, then after the packet is encapsulated, is > the route for remote host applied ? > 4. Similarly when the packet reaches the destination host machine's > br0, is it the kernel module that checks GRE header and handsover it > to gre0 interface of br0 > > If its the kernel module doing all the wonders, how does it fetches > the packets. DOes this module takes over the linux networking stack. ? > > It would be great help if anybody can explain me the flow. > > Thanks >
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