[ovs-discuss] Slowness on neighbour learning

Mika Väisänen mika.vaisanen at gmail.com
Thu Apr 6 18:57:21 UTC 2017


Hello,

Is it normal OVS behaviour that neighbour update (MAC moving from OVS switch port to another) can cause 100-500 ms break to traffic? Is there any way to configure it to be faster?

In my case a Linux host is connected with two bonded Ethernets to server running OVS 2.5.2 switch. When I change the active bonding slave from the Linux host, it causes 100-500 ms break to traffic between the Linux host and other hosts on the network. In case I run the same test with HW switch, there is no noticeable traffic break at all. 

While investigating this, I found some strangeness in the way how MAC is learned by OVS. In the following example I have moved the active slave from interface eno3 to eno4.  It seems correct (hander51), but then revalidator56 updates the MAC to be found from the old port again:

2017-04-06T09:51:25.179Z|00339|ofproto_dpif_xlate(handler51)|DBG|bridge swu0: learned that 02:11:61:61:70:25 is on port eno4 in VLAN 4
2017-04-06T09:51:25.179Z|00344|ofproto_dpif_xlate(handler51)|DBG|bridge swu0: learned that 02:11:61:61:70:25 is on port eno4 in VLAN 5
2017-04-06T09:51:25.179Z|00349|ofproto_dpif_xlate(handler51)|DBG|bridge swu0: learned that 02:11:61:61:70:25 is on port eno4 in VLAN 64
2017-04-06T09:51:25.247Z|00065|ofproto_dpif_xlate(revalidator56)|DBG|bridge swu0: learned that 02:11:61:61:70:25 is on port eno3 in VLAN 4
2017-04-06T09:51:25.247Z|00066|ofproto_dpif_xlate(revalidator56)|DBG|bridge swu0: learned that 02:11:61:61:70:25 is on port eno3 in VLAN 5
2017-04-06T09:51:25.249Z|00067|ofproto_dpif_xlate(revalidator56)| DBG |bridge swu0: learned that 02:11:61:61:70:25 is on port eno4 in VLAN 4
 
Why is revalidator refreshing old neighbour information? Could it be causing the slowness or is it totally irrelevant?


BR, Mika



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