[ovs-dev] Openflow 1.4: Eviction mechanism implementation

[Ben Pfaff]

On Mon, Sep 08, 2014 at 04:53:57PM +0530, Saloni Jain wrote:
> 1. Setting eviction using table-mod messages should not disturb the
> current ovs eviction configuration mechanism(without implementation
> of openflow specification 1.4). That means, if eviction is to be
> performed on the basis of lifetime only, then it should be
> configured via ovs-vsctl create table... command(overflow-policy
> evict) and if it is to be performed on the basis of importance only,
> then it should be configured via ovs-ofctl mod-table... command ?

Right.

> 2. As per the openflow specs 1.4, section 7.3.4.1 (Page 72) ????
> "The OFPTMPT_EVICTION property usually cannot be modified using a
> OFP_TABLE_MOD request, because the eviction mechanism is switch
> defined, and this property is usually only used in a
> OFPMP_TABLE_DESC multipart reply to inform the controller about the
> eviction mechanism used."
> 
> By this, does it imply that if eviction for lifetime is set by
> ovs-vsctl create command, then the table property cannot be modified
> for eviction via importance using ovs-ofctl mod-table command. That
> is for a given table, eviction can be configured only once either
> via lifetime(ovs-vsctl create..) or importance (by table-mod
> messages...)?

This paragraph only means that OFPTMPT_EVICTION announces what forms
of eviction the switch supports.  It does not configure what kinds of
eviction are in use.  In other words, with OVS as written today the
"lifetime" and "other" bits would always be set, because those are the
kinds of eviction that OVS implements, and after your work is done all
three bits will be set.