Ovs-Vsctl Gre Tunnel

Hi I woud like to know the process for the GRE (Generic Routing Encapsulation) tunnels with OVS as I would like to use the same?

[Pathak]

OVS can utilize GRE burrows between hosts as a method for epitomizing activity and making an overlay system. OpenStack Quantum can (and leverages) this usefulness, truth be told, to independent distinctive "occupant systems" from each other.

the procedure of designing OVS to construct a GRE passage to fabricate an overlay system between two hypervisors running KVM.

This procedure has 3 fundamental steps:

Make a disengaged span for VM network.

Make a GRE burrow endpoint on each hypervisor.

Include a GRE interface and set up the GRE burrow.

These strides expect that you've as of now introduced OVS on your Linux conveyance of decision.

Auditing the Topology

The realistic beneath demonstrates the fundamental topology of what we have going ahead here:

Topology diagram

We have two hypervisors (CentOS 6.3 and KVM, for this situation), both running OVS (a more seasoned rendition, adaptation 1.7.1). Each hypervisor has one OVS connect that has no less than one physical interface connected with the extension (appeared as br0 associated with eth0 in the chart). As a feature of this procedure, you'll make the other inward interfaces (the tep and gre interfaces, and also the second, separated scaffold to which VMs will associate. You'll then make a GRE burrow between the hypervisors and test VM-to-VM availability.



Making an Isolated Bridge

The initial step is to make the separated OVS extension to which the VMs will associate. Then call this a "confined extension" on the grounds that the scaffold has no physical interfaces appended. (Side note: this thought of a detached scaffold is genuinely regular in OpenStack and NVP situations, where it's generally called the combination span. The idea is the same.)

The summon is exceptionally straightforward, really:

ovs-vsctl include br br2

Yes, that is it. Don't hesitate to substitute an alternate name for br2 in the order above, in the event that you like, however simply make note of the name as you'll need it later.

To make things simpler for myself, once I'd made the confined scaffold then make a libvirt system for it with the goal that it was dead-simple to append VMs to this new disengaged span.

Designing the GRE Tunnel Endpoint

The GRE burrow endpoint is an interface on each hypervisor that will, as the name suggests, serve as the endpoint for the GRE burrow. The reason in making a different GRE burrow endpoint is to particular hypervisor administration activity from GRE movement, hence taking into consideration an engineering that may influence a different administration system (which is ordinarily viewed as a prescribed practice).

To make the GRE burrow endpoint, I'm going to utilize the same procedure I portrayed in my post on running host administration movement through OVS. In particular, we'll make an inside interface and allocate it an IP address.

To make the inward interface, utilize this summon:

ovs-vsctl include port br0 tep0 - set interface tep0 type=internal

In your surroundings, you'll substitute br2 with the name of the disconnected scaffold you made before. You could likewise utilize an alternate name than tep0. Since this name is basically for human utilization just, utilize what sounds good to you. Since this is a passage endpoint, tep0 sounded good to me.

Once the inner interface is set up, allocate it with an IP address utilizing ifconfig or ip, whichever you favor. Regardless it getting used to utilizing ip (more on that in a future post, in all likelihood), so it tends to utilize if config, similar to this:

on the off chance that config tep0 192.168.200.20 netmask 255.255.255.0

Clearly, you'll need to utilize an IP tending to plan that bodes well for your surroundings. One imperative note: don't utilize the same subnet as you've allocated to different interfaces on the hypervisor, or else you can't control that the GRE passage will start (or end) on the interface you indicate. This is on the grounds that the Linux steering table on the hypervisor will control how the activity is directed.

Setting up the GRE Tunnel

By this point, you've made the disengaged span, set up the GRE burrow endpoints, and tried availability between those endpoints. You're presently prepared to build up the GRE burrow.

Utilize this charge to add a GRE interface to the disconnected extension on each hypervisor:
ovs-vsctl include port br2 gre0 - set interface gre0 type=gre \
options:remote_ip=<GRE burrow endpoint on other hypervisor>

Substitute the name of the segregated scaffold you made before here for br2 and don't hesitate to utilize an option that is other than gre0 for the interface name. I think utilizing gre as the base name for the GRE interfaces bodes well, however keep running with what bodes well.