Added vnode_id column to the interfaces table which indicates which vnode

that an interface of an allocated node belongs to. Value is NULL when
the pnode is not allocated to an experiment.

sql/database-create.sql

@@ -461,6 +461,7 @@ CREATE TABLE interfaces (
   current_speed enum('100','10','1000') NOT NULL default '100',
   duplex enum('full','half') NOT NULL default 'full',
   rtabid smallint(5) unsigned NOT NULL default '0',
+  vnode_id varchar(32) default NULL,
   PRIMARY KEY  (node_id,card,port),
   KEY mac (mac),
   KEY IP (IP)

sql/database-migrate.txt

@@ -1166,4 +1166,10 @@ last_net_act,last_cpu_act,last_ext_act);
 
 1.209: Go back to revision 202 and change a bit.
 
+1.210: Add vnode_id column in the interfaces table to indicate which
+       vnode in an allocated experiment that the interface belongs
+       to. This is useful when multiple jail vnodes are hosted on a
+       physical node. 
+
+       alter table interfaces add vnode_id varchar(32) default NULL;