[ovs-discuss] Port satturation?

Vladimir Nikolić vladimir.nikolic at amis.si
Tue Oct 11 22:53:13 UTC 2011

VM1 does not know MAC address of syslog server. VM1 sends arp message to
ff:ff:ff:ff:ff:ff requesting answer for (syslog server ip).
Syslog server responds with its MAC address, VM1 insert an entry for
syslog server into its own ARP table for 1200 seconds. Until that time
expires, VM1 does not send broadcast message, it sends only syslog UDP
packets to syslog server MAC address. Switch should know that syslog
server MAC is not on its ports, and should not send that traffic to port
vif2.0 (xapi2).


On 12. 10. 2011 00:34, Jesse Gross wrote:
> 2011/10/11 Vladimir Nikolić <vladimir.nikolic at amis.si>:
>> Yes, there are occasionally arp records (showed by tcpdump on VM2), but
>> there is 1000x more records for unicast traffic between VM1 and syslog
>> server. I can see that traffic on VM2 (vif2.0) and xapi2 interface
>> (tcpdump).
> Yes, the problem is that the vast majority of the time the traffic is
> unidirectional.  This means that the switch doesn't know where the
> destination is and it floods.  This is simply how switches work,
> nothing specific to Open vSwitch.

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