[ovirt-users] questions on OVN

[Lance Richardson]

> From: "Gianluca Cecchi" <gianluca.cecchi at gmail.com>
> To: "Marcin Mirecki" <mmirecki at redhat.com>
> Cc: "Ovirt Users" <users at ovirt.org>
> Sent: Thursday, February 16, 2017 4:40:46 AM
> Subject: Re: [ovirt-users] questions on OVN
> 
> On Thu, Feb 16, 2017 at 9:54 AM, Marcin Mirecki < mmirecki at redhat.com >
> wrote:
> 
> 
> 
> OVN is aleady using GENEVE, VXLAN or STT tunnels (the user can choose any),
> so the isolation is already assured.
> The scripts provided by ovirt configure a geneve tunnel.
> You are free so override this manually to vxlan or stt if you want, let me
> know if you need any howto info.
> 

A small correction/clarification: for hypervisor-hypervisor tunnels, the
only tunnel encapsulations that are currently supported are GENEVE and STT.
The rationale is explained in detail at
http://openvswitch.org/support/dist-docs/ovn-architecture.7.html in the
"Design Decisions" section.  VXLAN tunnels are supported for hypervisor-gateway
tunnels only.


> yes, please.
> I have used in the mean time the vdsm-tool command that takes care of
> creating the default geneve tunnel
> In my case
> vdsm-tool ovn-config 10.4.168.80 10.4.168.81
> 
> but I would like to know how to manually use other types too.
> I watched the deep dive demo about ovn but at the bottom of the related slide
> there are three lines that should be equivalent to the above command,
> something like
> 
> ovs-vsctl set open ? external-ids:ovn-remote=tcp: 10.4.168.80:6642
> ovs-vsctl set open ? external-ids:ovn-encap=type=geneve
> ovs-vsctl set open ? external-ids:ovn-encap-ip=10.4.168.81
> 
> The ? character seems a dot or a comma, I have not understood the syntax....
> (what are the accepted words for type= in the second line?)
> 

The syntax here is "ovs-vsctl set <table> <record> <column>[:<key>]=<value>...".
In this case, the table name is "Open_vSwitch", "open" can be used as a
shorthand because the table name is not case-sensitive and prefixes of
the table name are accepted as long as they are unique.

The "." character specifies the record name as explained in the ovs-vsctl man
page at http://openvswitch.org/support/dist-docs-2.5/ovs-vsctl.8.txt:

       Open_vSwitch
              Global  configuration  for an ovs-vswitchd.  This table contains
              exactly one record, identified by specifying  .  as  the  record
              name.

Valid settings for external-ids:ovn-encap-type= are given in the ovn-controller
man page http://openvswitch.org/support/dist-docs-2.5/ovn-controller.8.txt:

              external_ids:ovn-encap-type
                     The  encapsulation type that a chassis should use to con‐
                     nect to this node.  Multiple encapsulation types  may  be
                     specified  with  a  comma-separated  list.   Each  listed
                     encapsulation type will be paired with ovn-encap-ip.

                     Supported tunnel types  for  connecting  hypervisors  are
                     geneve and stt.  Gateways may use geneve, vxlan, or stt.

                     Due to the limited amount of metadata in vxlan, the capa‐
                     bilities and performance of connected  gateways  will  be
                     reduced versus other tunnel formats.

Hope this helps,

    Lance

> Thanks again,
> Gianluca
> 
> 
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