[ovs-dev] Openflow 1.4: Eviction mechanism implementation

Ben Pfaff blp at nicira.com
Fri Aug 22 15:23:38 UTC 2014

On Fri, Aug 22, 2014 at 05:17:32PM +0530, Saloni Jain wrote:
> Kindly validate following approach for implementation of eviction
> mechanism and vacancy events as specified in openflow specification
> 1.4.  According to specification eviction and vacancy events are set
> through table_mod messages.
> Based on this scenerio, there are two cases:
> CASE 1: When both Eviction and Vacancy Events are set.

> When the remaining space in flow table decreases to vacancy_down, a vacancy down event is generated and sent to the controller. 
> This will start Eviction mechanism on the switch. 
> Eviction will be performed on the basis of "importance" or "lifetime" or both. If "importance" flag is the only flag set, flow entry with less importance will be deleted and comparison is done between the current vacancy and vacancy_up value. 

I don't understand this linkage between vacancy and eviction.  I
understand eviction to occur when a flow table is full.  Can you point
out the OpenFlow specification text that says that eviction should occur
based on configured vacancy?

OVS already has a configurable eviction policy.  This should be part of
the mechanism.

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