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List:       openvswitch-discuss
Subject:    [ovs-discuss] ifindex of datapath
From:       motonori () shin ! do (Motonori Shindo)
Date:       2014-11-26 23:24:27
Message-ID: 28B6A52E-E13E-4C23-8F97-5A07105D6EFD () shin ! do
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Ben,

Oh I din't come up with this idea. Thanks a lot!

As to the current Engine ID and Engine Type, I agree with you. There must be a better \
way, or simply defaults to 0 regardless to the type of datapath as we can explicitly \
set these values anyway.

Regards,

—
Motonori Shindo

2014/11/27 1:53、Ben Pfaff <blp at nicira.com> のメール：

> On Wed, Nov 26, 2014 at 11:01:57PM +0900, Motonori Shindo wrote:
> > Is there any way to know the ifindex of datapath (ova-system) by using
> > ovs-vsctl/dpctl/appctl ?
> 
> "cat /sys/class/net/ovs-system/ifindex" will show you, although I
> understand it is not one of the tools you mention.
> 
> > I also noticed that switch.xml says:
> > 
> > <column name="engine_id">
> > Engine ID to use in NetFlow messages.  Defaults to datapath index
> > if not specified.
> > </column>
> > 
> > <column name="engine_type">
> > Engine type to use in NetFlow messages.  Defaults to datapath
> > index if not specified.
> > </column>
> > 
> > but this is only true in the case of netlink. If OVS is run in user
> > space these are derived from the hash based on datapath name, I think.
> 
> Here's some better documentation of the current situation, but the
> current situation just looks crazy to me.  I think we should probably do
> something different:
> 
> <column name="engine_id">
> Engine ID to use in NetFlow messages.  The value used depends on
> the datapath in use.  Kernel-based datapaths use the ifindex of
> the datapath device, e.g. the ifindex of <code>ovs-system</code>
> (this can change from one boot to the next or even more often if
> the Open vSwitch kernel module is unloaded and reloaded or if
> the datapath is otherwise deleted).  The userspace datapath uses
> 8 bits of an internally generated hash of the datapath name (for
> a given Open vSwitch architecture and version, this is a
> constant).
> </column>
> 
> <column name="engine_type">
> Engine type to use in NetFlow messages.  The value used depends
> on the datapath in use.  Kernel-based datapaths use the ifindex
> of the datapath device (the same value as <ref
> column="engine_id"/>.  The userspace datapath uses 8 bits of an
> internally generated hash of the datapath name (but the bits
> used are different from <ref column="engine_id"/>.
> </column>


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