[ovs-discuss] MVRP in OVS

Ben Pfaff blp at nicira.com
Thu Mar 27 22:36:46 UTC 2014


If ovs-vswitchd writes a column, instead of responding to it, then it
doesn't reconfigure when that column changes.  (We have a number of
these "status" columns.)  It is also easy to mark a column as
"ephemeral", which means that the column contents doesn't get written to
disk or persist.  So none of that necessarily disqualifies this
information from being kept in the database.

On Thu, Mar 27, 2014 at 03:32:33PM -0700, Howard Tsai wrote:
> Our application doesn't need to expose MVRP state to a controller. However,
> my concern of storing MVRP state in OVSDB is that, at least theoretically,
> VLAN topology changes can happen frequently (as well as changes in other
> MRP participant state, i.e., MMRP, MSRP, once these MRP-family protocols
> are implemented.) As ovs-vswitchd is currently implemented, if I understand
> it correctly, a change in OVSDB will trigger reconfiguration of every Open
> Flow port, which is quite expensive. MVRP state don't need to persist
> across switch restart. Moreover, LACP/STP state are not in OVSDB, either.
> In this case, is storing MVRP state in OVSDB still a good choice?
> 
> Thanks,
> Howard
> 
> 
> On Thu, Mar 27, 2014 at 2:36 PM, Ben Pfaff <blp at nicira.com> wrote:
> 
> > On Thu, Mar 27, 2014 at 10:41:40AM -0700, Howard Tsai wrote:
> > > One thing I am curious about is the exposure of current VLAN topology
> > from
> > > ovs-vswitchd.
> > >
> > > Currently, ofbundle registers a set of callback functions with MVRP. MVRP
> > > calls these functions to adjust VLAN membership. I.e., OVSDB doesn't have
> > > the current VLAN topology declared by MVRP. To compensate, I implemented
> > a
> > > unixctl cmd "mvrp/show" to show MVRP state.
> > >
> > > My questions are:
> > > 1. Is this the preferred way to expose protocol state? Any
> > > suggestion/pseudo standard on output formatting?
> >
> > Is the VLAN topology something that a controller would likely be
> > interested in?  If so, then I think that exposing it in OVSDB, perhaps
> > as a column in the Port or Interface table, would be appropriate.  (I
> > don't know much about MVRP, so I don't know what is correct
> > conceptually.)
> >
> > If the VLAN topology goes in the database we probably don't need it via
> > unixctl.
> >
> > > 2. It seems that OF-Config should be extended to include MVRP as one of
> > > OpenFlow Port Feature and VLAN configuration in OpenFlow Port State.  Any
> > > thought on that?
> >
> > Do you mean OF-Config or OVSDB?  Open vSwitch doesn't include an
> > OF-Config implementation.  I think we already covered OVSDB, above.
> >



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