[ovs-dev] Issue with OVS lacp-fallback-ab option

Ben Pfaff blp at ovn.org
Mon Oct 8 20:15:34 UTC 2018


I think I see a problem in the implementation of bonding when
recirculation is available.  Are you able to try out a patch?  If so,
try the following.  It is not a good way to solve the issue, but it
should illustrate whether recirculation is the problem.

diff --git a/ofproto/bond.c b/ofproto/bond.c
index f87cdba7908f..bb6a80411de5 100644
--- a/ofproto/bond.c
+++ b/ofproto/bond.c
@@ -927,7 +928,7 @@ bond_recirculation_account(struct bond *bond)
 static bool
 bond_may_recirc(const struct bond *bond)
 {
-    return bond->balance == BM_TCP && bond->recirc_id;
+    return bond->balance == BM_TCP && bond->recirc_id && false;
 }
 
 static void


On Fri, Oct 05, 2018 at 04:45:21AM +0000, Arun Navasivasakthivelsamy wrote:
> Also, ofproto/trace is suggesting that the packet will be hashed to a slave (instead of just to the active port) with lacp-fallback-ab option.
> 
> This is with active-backup bond mode:
> 
> 
> [root at frankfurter02-4 ~]# ovs-appctl ofproto/trace br0 in_port=6,dl_dst=28:99:3a:08:7a:cf
> 
> Bridge: br0
> 
> Flow: in_port=6,vlan_tci=0x0000,dl_src=00:00:00:00:00:00,dl_dst=28:99:3a:08:7a:cf,dl_type=0x0000
> 
> 
> Rule: table=0 cookie=0 priority=0
> 
> OpenFlow actions=NORMAL
> 
> forwarding to learned port
> 
> 
> Final flow: unchanged
> 
> Megaflow: recirc_id=0,in_port=6,vlan_tci=0x0000/0x1fff,dl_src=00:00:00:00:00:00,dl_dst=28:99:3a:08:7a:cf,dl_type=0x0000
> 
> Datapath actions: 5
> 
> 
> This is with balance-tcp with lacp-fallback-ab mode (LACP is not negotiated):
> 
> 
> [root at frankfurter02-4 ~]# ovs-appctl ofproto/trace br0 in_port=6,dl_dst=28:99:3a:08:7a:cf
> 
> Bridge: br0
> 
> Flow: in_port=6,vlan_tci=0x0000,dl_src=00:00:00:00:00:00,dl_dst=28:99:3a:08:7a:cf,dl_type=0x0000
> 
> 
> Rule: table=0 cookie=0 priority=0
> 
> OpenFlow actions=NORMAL
> 
> forwarding to learned port
> 
> 
> Final flow: unchanged
> 
> Megaflow: recirc_id=0,in_port=6,vlan_tci=0x0000/0x1fff,dl_src=00:00:00:00:00:00,dl_dst=28:99:3a:08:7a:cf,dl_type=0x0000
> 
> Datapath actions: hash(hash_l4(0)),recirc(0x1)
> 
> From: Arunkumar Navasiva <arunkum.navasiv at nutanix.com<mailto:arunkum.navasiv at nutanix.com>>
> Date: Thursday, October 4, 2018 at 4:18 PM
> To: "ovs-dev at openvswitch.org<mailto:ovs-dev at openvswitch.org>" <ovs-dev at openvswitch.org<mailto:ovs-dev at openvswitch.org>>
> Subject: Issue with OVS lacp-fallback-ab option
> 
> Hello folks,
> 
> We’re seeing an issue with lacp-fallback-ab option on ovs 2.5/2.6/2.8. It looks like when LACP is not enabled on the TOR switch ports, OVS on the centos server is not falling back cleanly to active-backup, and continues to send some portions of the traffic through the backup interface (we’ve seen this occur with various TOR vendor switches).  Please see the attached screenshot which shows that some traffic still hashes to backup interface. We looked at the TOR forwarding table, and MAC addresses of VMs running on this server flaps between the two corresponding TOR switch ports of the bond . I’m still in the early stages of debugging this, but wanted to reach out to you to see if this is already a known issue? If not, any help on how to debug this further will be helpful.
> 
> 
> Thanks
> -Arun
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