According to the OpenFlow 1.3.5 spec, page 44 specifies the following:
Modify and delete commands can also be filtered by cookie value, if the cookie_mask field contains a value other than 0. This constraint is that the bits specified by the cookie_mask in both the cookie field of the flow mod and a flow entry’s cookie value must be equal. In other words, (flow entry.cookie&flow mod.cookie mask) == (flow mod.cookie&flow mod.cookie mask).
Now, using the Ryu python-based controller, I tried to delete a flow by specifying the flow's cookie value, but the procedure was not successful.
The following code is a test-example which I used.
from ryu.base.app_manager import RyuApp
from ryu.controller.dpset import EventDP
from ryu.controller.handler import MAIN_DISPATCHER
from ryu.controller.handler import set_ev_cls
from ryu.ofproto import ofproto_v1_3
from ryu.ofproto import ether, inet
class MPLS_Testing(RyuApp):
OFP_VERSIONS = [ofproto_v1_3.OFP_VERSION]
@set_ev_cls(EventDP, MAIN_DISPATCHER)
def switch_connect_event(self, ev):
ofp_parser = ev.dp.ofproto_parser
ofp = ev.dp.ofproto
datapath_obj = ev.dp
if ev.enter:
datapath_obj.send_msg( # Removes all flows registered in this switch.
ofp_parser.OFPFlowMod(
datapath=datapath_obj,
table_id=ofp.OFPTT_ALL,
command=ofp.OFPFC_DELETE,
out_port=ofp.OFPP_ANY,
out_group=ofp.OFPG_ANY,
)
)
add_label_flow = ofp_parser.OFPFlowMod(
datapath=datapath_obj,
cookie=1,
table_id=0,
command=ofp.OFPFC_ADD,
match=ofp_parser.OFPMatch(
in_port=1
),
instructions=[
ofp_parser.OFPInstructionActions(
ofp.OFPIT_APPLY_ACTIONS,
[
ofp_parser.OFPActionPushMpls(),
ofp_parser.OFPActionSetField(mpls_label=16),
]
),
ofp_parser.OFPInstructionGotoTable(table_id=1),
]
)
datapath_obj.send_msg(add_label_flow)
add_label_flow2 = ofp_parser.OFPFlowMod(
datapath=datapath_obj,
cookie=2,
table_id=1,
command=ofp.OFPFC_ADD,
match=ofp_parser.OFPMatch(
in_port=1
),
instructions=[
ofp_parser.OFPInstructionActions(
ofp.OFPIT_APPLY_ACTIONS,
[
ofp_parser.OFPActionPushMpls(),
ofp_parser.OFPActionSetField(mpls_label=12),
]
),
ofp_parser.OFPInstructionGotoTable(table_id=2),
]
)
datapath_obj.send_msg(add_label_flow2)
# Deletes flow with cookie equal to 2.
datapath_obj.send_msg(
ofp_parser.OFPFlowMod(
cookie=2,
cookie_mask=0xFFFFFFFFFFFFFFFF,
datapath=datapath_obj,
command=ofp.OFPFC_DELETE,
out_port=ofp.OFPP_ANY,
out_group=ofp.OFPG_ANY,
)
)
Can anyone tell me if OpenVSwitch 2.9 supports cookie match when deleting a flow from the tables? OpenFlow 1.3.5 spec clearly states that a Delete command could also filter flows using the cookie value, when the cookie_mask is different than zero. Currently, I'm kinda lost here.
I have figured out what was missing.
@pchaigno Thank you for your support.
It seems the table_id = OFPTT_ALL was missing from the OFPFlowMod
message. Ryu seems to default this value to zero, when initialising the object. Because of this, the OFPFlowMod message when used as a OFPFC_DELETE command, Ryu adds by default a table_id = 0 matching requirement.
So, when using Ryu, the proper message structure to remove a Flow with a cookie equal to 2 from the Switch, is:
ofp_parser.OFPFlowMod(
datapath=datapath_obj,
cookie=2,
cookie_mask=0xFFFFFFFFFFFFFFFF,
table_id=ofp.OFPTT_ALL,
command=ofp.OFPFC_DELETE,
out_port=ofp.OFPP_ANY,
out_group=ofp.OFPG_ANY
)
According to the standard, out_port needs to be equal to OFPP_ANY and the
out_group field needs to be equal to OFPG_ANY, otherwise both fields will be considered as a matching requirement.
It seems the table_id field follows almost the same logic, requiring a
table_id = OFPTT_ALL to match all tables.
I now consider this issue resolved.