Hi Po,
I also have the same question, but when i read the code, i find sth.

The main code is here:

  if (PREDICT_TRUE (table_index0 != ~0))

     {

       hash0 = vnet_buffer (b0)->l2_classify.hash;

       t0 = pool_elt_at_index (vcm->tables, table_index0);

       e0 = vnet_classify_find_entry (t0, h0, hash0, now);

       if (e0)

 {

   hits++;

   printf("flow classify hit!!\n");   

 }

       else

 {

   misses++;

   printf("flow classify miss!!\n");

   vnet_classify_add_del_session (vcm, table_index0,

 h0, ~0, 0, 0, 0, 0, 1);

   /* increment counter */

   vnet_classify_find_entry (t0, h0, hash0, now);

 }

     }
When hitting, it does nothing, or it will create a new session.

but I do not know the purpose of such implementation, it looks like the flow-classify has no effect.

The " set flow classify interface memif0/2 ip4-table 0" and "set int input acl intfc memif0/2 ip4-table 0" must match the classify session we created before.

This is my understanding.