[ovs-discuss] GRE packet forwarding questions

Romain Lenglet romain at midokura.jp
Mon Aug 16 02:58:27 UTC 2010


My understanding when using a 'gre' vport is that:
- the next hop to send a GRE packet is determined by looking up the Linux
routing table;
- each GRE packet is sent through the Linux in-kernel router for forwarding.
Is that right?
If so, I assume that this behavior is inherited from the original gre

It would be nice:
- not to look up the Linux routing table, and to rely solely on the ovsdb
config for the port and/or the flow definitions / actions to determine the
next hop for GRE packets;
- to have all GRE packets just forwarded to another vport (of another
datapath or of the same datapath), like a patch vport, without going through
the Linux routing.

That would make it very easy to separate the encapsulated traffic and the
non-encapsulated traffic into different datapaths, and to concentrate all
the control into OpenFlow controllers without having to setup Linux routing.
And I think it may make the gre vport implementation simpler.

What are the plans regarding the gre vport implementation?
Is there any plan to make gre vports behave more like patch vports, to
simplify the control of GRE forwarding and have more control over it in the

Best regards,
Romain Lenglet
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