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

[Dmita Levy]

I'm testing OVS 1.04 on a Virtualbox VM running Ubuntu 12.04 LTS with 1024
MB of RAM 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. 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.

On Thu, Aug 15, 2013 at 1:14 AM, Ben Pfaff <blp at nicira.com> wrote:

> On Wed, Aug 14, 2013 at 11:28:05PM -0400, Dmita Levy wrote:
> > Our research meeting today ended on the question of whether or not it
> would
> > be possible or system breaking to tunnel to a large number of hosts using
> > OVS. So I threw my JSON RPC tunnel creator into a loop and around 234 on
> > bridge0 decided to stop. That being said I noticed with the ovs-vsctl
> show
> > command I did not see 234 gre ports (at a glance). My question is, how
> many
> > GRE ports can an OVS bridge have and what kind of system resources does a
> > GRE tunnel port use?
>
> In OVS 1.10 and later, a tunnel port has pretty minimal requirements.
> At a guess, a few thousand should not be a problem.
>
> Tunnel monitoring (CFM or BFD) is more expensive than tunnels
> themselves.
>
> If you think there's a bug causing ports not to be created, please
> report it.  But ovs-vsctl just reports what's in the OVSDB database, and
> OVSDB is pretty well tested, so we would need some real details.
>
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