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

Arun Navasivasakthivelsamy arunkum.navasiv at nutanix.com
Fri Oct 5 04:45:21 UTC 2018


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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