[ovs-discuss] What is the mechanism of GRE tunnel implement by OVS?

Jesse Gross jesse at nicira.com
Tue Nov 30 02:15:09 UTC 2010


On Fri, Nov 26, 2010 at 7:16 PM, 陈文龙 <qzchenwl at gmail.com> wrote:
> For example,
> (Host ip: 1.1.1.1) OVS1 gre remote_ip:2.2.2.2
> (Host ip: 2.2.2.2) OVS2 gre remote_ip:1.1.1.1
> If OVS1 wants to send a packet to OVS2 through gre tunnel, does it send the
> packet to 2.2.2.2:<certain port>?
> And when OVS2 receives a packet from 2.2.2.2:<certain port>, that means it
> is a packet go through the tunnel.
> Is that right? And what is the certain port?

GRE is an IP based protocol that is used for encapsulation of packets,
so the mechanism literally is GRE.  What you described is correct,
with the exception that there is no port number involved - that is
part of TCP/UDP which are not used here.  GRE runs directly on top of
IP.




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