[ovs-discuss] How to set up GRE tunnel on openvswitch?

[Ethan Jackson]

> Sorry I have so many questions. I couldn't find a detailed
> documentation on how this tunneling feature works and still unclear
> about the concept. If any of you have worked on tunneling, could you
> please kindly shed lights on this? Thank you so much!

Configuration of tunnels is documented thoroughly in the
ovs-vswitchd.conf.db man page.  They are pretty straight forward, when
traffic is output to a tunnel, it is encaped, and then forwarded to
the remote_ip configured in the database.

Ethan


>
> Yimin
>
> On Fri, May 25, 2012 at 10:20 AM, YIMIN CHEN <ymchen.nbzj at gmail.com> wrote:
>> Hi,
>>
>> I am trying to understand the GRE tunnel feature on openvswitch, and
>> found the following document on the networkstatic.net/. I have some
>> questions after the instructions that would appreciate your
>> clarification!
>>
>> --------------------------------------------
>> Open vSwitch 1 configuration
>> --------------------------------------------
>> #ifconfig eth0 192.168.1.155 netmask 255.255.255.0
>> #ifconfig eth0 up
>> #ovs-vsctl add-br br1
>>
>> That creates the bridge and logical BVI. Ifconfig –a will now show a
>> new interface named br1.
>>
>> #ifconfig br1 10.1.1.1 netmask 255.255.255.0
>>    * br1 is now the gateway for your VM DCI interface. That would
>> likely be one of a few connections or part of a 802.1q trunk.
>>
>> #ifconfig br1 up #ovs-vsctl add-port br1 gre1 — set interface gre1
>> type=gre options:remote_ip=192.168.1.152
>>
>> --------------------------------------------
>> Open vSwitch 2 configuration
>> --------------------------------------------
>> #ifconfig eth0 192.168.1.152 netmask 255.255.255.0
>> #ifconfig eth0 up
>> #ovs-vsctl add-br br1
>> #ifconfig br1 10.1.1.2 netmask 255.255.255.0
>> #ifconfig br1 up
>> #ovs-vsctl add-port br1 gre1 — set interface gre1 type=gre
>> options:remote_ip=192.168.1.152
>>
>>    * Now spin up your VM. I use the following to boot Ubuntu off CD
>>
>>
>> Here is my questions/confusions regarding the feature:
>> 1) How is br1 and eth0 related? Is eth0 not part of br1? or just br1
>> using eth0 to tunnel the packets? When ovs is started, eth0 is already
>> part of br0. What is the difference between br0 and br1? br1 is a
>> tunnel between switches and br0 is virtual bridge for VMs on the same
>> switch?
>> 2) In the example, switch 1 and switch 2's eth0 address configs are
>> different, but in the add-port command, the remote_ip was same, was
>> that a mistake? should remote_ip same as the configured eth0 ip?
>>
>> Appreciate your helps! If there is a better documentation about how
>> the feature works and how to setup, would you please give me a
>> pointer?
>>
>> Thanks!
>> Yimin
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