[ovs-dev] [PATCH v9 net-next 4/7] openvswitch: add layer 3 flow/port support
Jiri Benc
jbenc at redhat.com
Fri May 20 09:20:04 UTC 2016
On Fri, 20 May 2016 18:12:05 +0900, Simon Horman wrote:
> 1. push_eth adds an Ethernet header with all-zero addresses and
> the Ethernet type as determined from skb->protocol which is in
> turn determined by the tunnel header (we have discussed that
> bit before).
>
> In principle it is pushed when needed. And this happens automatically
> as controlled by user-space.
>
> It is possible to modify the Ethernet addresses using a custom rule.
> (I need to exercise that more often.)
>
> 2. For the GRE part of the scenario above it is important to know that with
> the accompanying user-space patch set OvS user-space the user-space
> representation of a vport (from now on simply vport) may be "layer3" or
> not.
>
> This allows OvS user-space to determine if an Ethernet header should be
> present or not on receive. And if it needs to be present or not on
> transmit. This allows it to automatically use pop_eth and push_eth to
> control the presence of an Ethernet header so its there when it needs to
> be and not when it doesn't.
>
> So if a GRE vport is "layer3" then no Ethernet header should be
> present on transmit, regardless of where the packet came from. And
> conversely if the GRE vport is not "layer3" then an Ethernet header
> should be present.
I think this works for me. Thanks a lot for answering my questions!
> 3. With regards to the mirroring part of your connection, I need to check
> on that and possibly its broken. But my thinking is that a mirroring
> vport would regarded in the same way as any other vport in this respect
> and the presence of the "layer3" flag would control whether an Ethernet
> header is present or not.
>
> It may be the case that its not possible to use a tunnel vport as a
> mirroring vport. And as all other vports currently do not support
> "layer3" then currently an Ethernet header would always be present
> on output to a mirror.
We can just require a mirror port to be always L2 and output the L3
packets with zero Ethernet addresses. For mirroring, this should be
okay(?)
Jiri
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