[ovs-discuss] How many GRE Ports can an OVS bridge have?

[Ben Pfaff]

On Thu, Aug 15, 2013 at 01:58:52AM -0400, Dmita Levy wrote:
> I'm testing OVS 1.04 on a Virtualbox VM running Ubuntu 12.04 LTS with 1024
> MB of RAM 

You've mentioned "OVS 1.04" before.  There is no such version.  I
guess you mean 1.4.0.

> and I have to say that after 780 GRE port additions OVS shows no
> signs of slow down. We were initially trying to create a kind of GRE tunnel
> convergence between hosts when the network is first brought online where
> every host would have a tunnel interface to every other OVS host but that
> idea doesn't seem to scale well. The problem is due to the Bridge table
> becoming massive and parsing a MONITOR response, extracting UUID info etc
> gets increasingly slower.

Are you retrieving the entire database repeatedly?  The "monitor"
feature offers incremental updates, so that adding or removing ports
should not be expensive.

> Not an OVS issue but interesting to me none the
> less. So we will have to go the route of dynamic tunnel creation and
> deletion when tunneling is not in use but OVS makes one heck of an
> encapsulator when paired with JSON RPC and OpenFlow.

Another option with sufficiently new OVS is creating only one tunnel
with key=flow and then distinguishing between tunnels only in the flow
table.