[ovs-dev] [PATCH v6 1/2] Avoid packet drop on LACP bond after link up

Nitin Katiyar nitin.katiyar at ericsson.com
Thu Jun 6 06:40:19 UTC 2019



> -----Original Message-----
> From: Ben Pfaff [mailto:blp at ovn.org]
> Sent: Tuesday, June 04, 2019 11:39 PM
> To: Nitin Katiyar <nitin.katiyar at ericsson.com>
> Cc: ovs-dev at openvswitch.org; Manohar Krishnappa Chidambaraswamy
> <manukc at gmail.com>
> Subject: Re: [ovs-dev] [PATCH v6 1/2] Avoid packet drop on LACP bond after
> link up
> 
> On Sun, Jun 02, 2019 at 04:06:34PM +0000, Nitin Katiyar wrote:
> > Problem:
> > ========
> > During port DOWN->UP of link (slave) in a LACP bond, after receiving
> > the LACP PDU with SYNC set for both actor and partner, the bond-slave
> > remains "disabled" until OVS main thread runs LACP state machine and
> > eventually "enables" the bond-slave. With this, we have observed
> > delays in the order of 350ms and packets are dropped in OVS due to
> > bond-admissibility check (packets received on slave in "disabled" state are
> dropped).
> 
> I had to think about this a bit.  Is the following alternate statement of the
> problem also correct?
Yes, that's correct. Do you want me to update the patch with the following in problem statement?
> 
> The OVS state machine that enables and disables bond slaves runs in the OVS
> main thread.  The OVS code that processes received LACP packets runs in a
> different thread.  Until now, when the latter processes a LACP PDU that
> should enable a slave, the slave was only enabled when the main thread was
> able to run the state machine.   In some cases this led to delays of up to
> 350ms when the main thread was busy or not scheduled, which led to
> corresponding delays in which packets were dropped due to the bond-
> admissibility check.


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