[ovs-discuss] Interval /transmission timer for particular MPs in CFM

Sun Mar 18 16:49:50 UTC 2012

CFM works on the basis of an interface.  Configuring CFM on br0 is not
useful because the CFM packets transmitted on br0 do not go anywhere.

There are various ways that you could avoid using two physical machines
to set up CFM, but CFM is more useful in the presence of two (or more)
physical machines.

I do not see cfm_remote_mpid mentioned in ovs-vsctl(8).  Please let me
know where you saw this recommendation, so that we can correct the
documentation.

OVS will place the remote MPs for which it receives CFM packets in
cfm_remote_mpids, for a manager to read.

On Sun, Mar 18, 2012 at 09:03:02PM +0530, edward wilson wrote:
> Hi,
> 
> After installing and configuring OVS, br0 will be there.
> 1. is that mean I have to use its physical interface with which br0
> attached like eth0.
> 2. is that mean I have to use 2 physical OVS machines at least for cfm
> set-up.
> 3. configuration of cfm_remote_mpid ,I got from ovs-vsctl config book. so
> my command would be now:-
> ovs-vsctl set Interface br0 cfm_mpid=1
> then how a machine will identify its remote MPs.
> 
> -Ed
> 
> 
> 
> On Sat, Mar 17, 2012 at 2:30 AM, Ben Pfaff <blp at nicira.com> wrote:
> 
> > cfm_remote_mpids (note the "s") is not a column that you as a user
> > write.  It is a column that ovs-vswitchd writes.
> >
> > Ordinarily one would configure CFM on a physical interface or a
> > tunnel.  br0 is an internal interface.
> >
> > On Fri, Mar 16, 2012 at 09:19:44AM +0530, edward wilson wrote:
> > > OVS version 1.2.2
> > >
> > > following commands run on machine-
> > >
> > > first mahine-
> > > ovs-vsctl set Interface br0 cfm_mpid=1 cfm_remote_mpid=2
> > >
> > > second machine--
> > >  ovs-vsctl set Interface br0 cfm_mpid=2 cfm_remote_mpid=1
> >  >
> > > -Ed
> > >
> > >
> > >
> > > On Fri, Mar 16, 2012 at 8:53 AM, edward wilson
> > > <edward.wilson2601 at gmail.com>wrote:
> > >
> > > >
> > > >
> > > > First machine-
> > > >
> > > > ovs-appctl cfm/show br0
> > > >
> > > > MPID 1: fault recv_fault
> > > >
> > > >                  Interval: 1000ms
> > > >
> > > >                 Next CCM tx: 403ms
> > > >
> > > >                 Next fault check: 2744ms
> > > >
> > > >
> > > >
> > > > Remote MPID 2: fault
> > > >
> > > >                 Recv since check: false
> > > >
> > > >
> > > >
> > > > Second machime-
> > > >
> > > > ovs-appctl cfm/show br0
> > > >
> > > > MPID 2: fault recv_fault
> > > >
> > > >                  Interval: 1000ms
> > > >
> > > >                 Next CCM tx: 403ms
> > > >
> > > >                 Next fault check: 2744ms
> > > >
> > > >
> > > >
> > > > Remote MPID 1: fault
> > > >
> > > >                 Recv since check: false
> > > >
> > > > -Ed
> > > >
> > > >  On Thu, Mar 15, 2012 at 10:12 PM, Ben Pfaff <blp at nicira.com> wrote:
> > > >
> > > >> Maybe you should show us your configuration.  It seems likely that
> > > >> there is just some misunderstanding.
> > > >>
> > > >> On Thu, Mar 15, 2012 at 05:30:19PM +0530, edward wilson wrote:
> > > >> > when I am creating cfm between two ovs ( one physical and other VM
> > on
> > > >> same
> > > >> > machine) , CCM packet are with RDI bit set.
> > > >> > connection is not making between MPs.
> > > >> > both are on same bradcast domain.
> > > >> >
> > > >> > tried with two physical machines with OVS by giving same vlan id,
> > but
> > > >> > result is same.
> > > >> >
> > > >> > -ed
> > > >> >
> > > >> > On Sat, Feb 18, 2012 at 2:27 AM, Ethan Jackson <ethan at nicira.com>
> > > >> wrote:
> > > >> >
> > > >> > >   > Ed- same broadcast domain , you mean- I have to assign all
> > MPs in
> > > >> one
> > > >> > > vlan
> > > >> > > > or same network should be provided.
> > > >> > >
> > > >> > > The CFM module sends multicast CCMs on the interface upon which
> > it's
> > > >> > > configured.  Presumably, multicast/broadcasts packets egressing
> > this
> > > >> > > interface can reach some set of other hosts on the network.  This
> > set
> > > >> > > can be restricted by using VLANs or other strategies.  How this is
> > > >> > > done precisely, is out of the scope of the CFM module.  The
> > important
> > > >> > > thing is, when the CFM module broadcasts CCMs, all other MPs that
> > > >> > > these CCMs reach need to have the same transmission interval.
> > > >> > >
> > > >> > > >> > 2) along with that I want to know how can I see the current
> > timer
> > > >> > > value
> > > >> > > >> > by
> > > >> > > >> > any show command for particular MPids, I didn' tfind any
> > command
> > > >> for
> > > >> > > >> > this.
> > > >> > > >>
> > > >> > > >> ovs-appctl cfm/show will give you information about currently
> > > >> configured
> > > >> > > >> CFM.
> > > >> > >
> > > >> > > The CFM module doesn't maintain a separate timer for each remote
> > MP.
> > > >> > > Instead it maintains one timer that triggers at an interval of 3.5
> > > >> > > times the transmission interval.  When the CFM module receives a
> > CCM
> > > >> > > from a remote MP, it sets a flag for this remote MP indicating the
> > > >> > > reception.   When the timer triggers, any MPs which are not
> > flagged
> > > >> > > are considered unreachable and removed.  All of this information
> > (the
> > > >> > > timers, the set of reachable MPs, the reception flag) is available
> > > >> > > from the ovs-appctl cfm/show command.
> > > >> > >
> > > >> > > It's also worth noting that we don't implement the full 802.1ag
> > > >> > > specification.  We implement a much simplified version which
> > maintains
> > > >> > > the packet format, but is quite a bit less sophisticated than the
> > > >> > > standard.
> > > >> > >
> > > >> > > Ethan
> > > >> > >
> > > >> > >
> > > >> > >
> > > >> > > >
> > > >> > > >
> > > >> > > > Ed- this command shows the configured CFM,my doubt was when CCM
> > > >> received
> > > >> > > > then timer gets restarted then how can I check /verfiy this that
> > > >> timer
> > > >> > > has
> > > >> > > > been restarted for a MP or MPs
> > > >> > > >>
> > > >> > > >>
> > > >> > > >> Ethan
> > > >> > > >>
> > > >> > > >>
> > > >> > > >>
> > > >> > > >> >
> > > >> > > >> > Regards,
> > > >> > > >> > Ed
> > > >> > > >> >
> > > >> > > >> > _______________________________________________
> > > >> > > >> > discuss mailing list
> > > >> > > >> > discuss at openvswitch.org
> > > >> > > >> > http://openvswitch.org/mailman/listinfo/discuss
> > > >> > > >> >
> > > >> > > >
> > > >> > > >
> > > >> > >
> > > >>
> > > >> > _______________________________________________
> > > >> > discuss mailing list
> > > >> > discuss at openvswitch.org
> > > >> > http://openvswitch.org/mailman/listinfo/discuss
> > > >>
> > > >>
> > > >
> >