Method and system for avoiding new flow packet flood from data plane to control plane of a network device
A mechanism is provided by which communication is reduced between a data plane of a network device and a control plane associated with that network device upon introduction of a new flow. A holding table is provided for every active flow table in the data plane. The holding table holds flow contexts for new flows not found in the associated active flow table, while awaiting flow information from the control plane. Each flow context includes a queue of subsequent data packets associated with the flow, which are held from the control plane pending receipt of the flow information from the control plane. A timeout mechanism compensates for packet loss between the network device and control plane. When the data plane receives the flow information from the control plane, the data plane then processes all the queued packets, deletes the flow context, and enters the data into an associated flow table.
1. A system for transmitting a data packet in a data network, the system comprising:
a network controller configured to provide data flow information to one or more network devices; and
a network device, coupled to the network controller, wherein the network device further comprises
a data port, coupled to a data network, and configured to receive a data packet comprising information identifying a data flow associated with the data packet,
a flow table memory storing one or more flow tables and one or more holding tables,
a first processor, coupled to the data port, and configured to
determine whether the information identifying the data flow associated with the data packet matches an entry in a flow table stored in the flow table memory,
provide the data packet to a second processor if the information identifying the data flow associated with the data packet fails to match any entry in any flow table stored in the flow table memory, and
the second processor configured to
determine whether the information identifying the data flow associated with the data packet matches an entry in a holding table stored in the flow table memory,
transmit the data packet to the network controller, if the information identifying the data flow associated with the data packet fails to match any entry in the holding table, wherein the holding table comprises identifying information associated with data packets previously transmitted to the network controllers, and
store the data packet in a flow context queue associated with the matching entry in the holding table, if the information identifying the data flow associated with the data packet matches an entry in the holding table, wherein
the flow context queue is stored in the flow table memory, and
the flow context queue comprises data packets awaiting processing instructions for a flow corresponding to each data packet.
2. The system of claim 1 wherein the second processor is further configured to:
store a matching flow context in the holding table wherein the matching flow context matches the information identifying the data flow associated with the data packet, if the information identifying the data flow associated with the data packet fails to match any entry in the holding table; and
store the data packet in association with a flow context matching the information identifying the data flow associated with the data packet.
3. The system of claim 2 wherein the second processor is further configured to:
start a life timer associated with the data flow associated with the data packet in response to storing the matching flow context in the holding table; and
store life timer information in a timer information table memory coupled to the second processor.
4. The system of claim 3 wherein the second processor is further configured to:
delete the matching flow context from the holding table, if the life timer associated with the data flow associated with the data packet expires prior to receiving, from the network controller, a response associated with the data flow.
5. The system of claim 2 wherein the second processor is further configured to:
start a reminder timer associated with the data flow associated with the data packet in response to transmitting the data packet to the network controller; and
transmit a second data packet associated with the data flow associated with the data packet in response to the reminder timer expiring prior to receiving, from the controller, a response associated with the data flow.
6. The system of claim 2 , wherein
the data port of the network device is configured to receive a second data packet comprising information identifying the data flow associated with the data packet; and
the second processor is further configured to
determine whether the information identifying the data flow associated with the second data packet matches an entry in the holding table stored in the flow table memory, and
store the second data packet in a flow context queue associated with the matching entry in the holding table, wherein the flow context queue is stored in the flow table memory.
7. The system of claim 6 wherein the second processor is further configured to:
check if a reminder timer associated with the data flow associated with the second data packet in response to transmitting the data packet to the network controller has expired; and
transmit the second data packet to the network controller in response to the reminder timer expiring.
8. The system of claim 2 wherein the network device further comprises:
a second data port, communicatively coupled to a control network, and configured to transmit the data packet to the network controller over the control network.
9. The system of claim 8 wherein the network device further comprises:
a third data port, coupled to the control network, and configured to receive a flow offload from the network controller;
a third processor, coupled to the third data port and the flow table memory, and configured to
add a flow entry to a corresponding flow table, wherein the flow entry includes information within the flow offload, and
remove the matching flow context associated with the flow offload from the holding table.
10. The system of claim 9 wherein the network device is further configured to:
process the data packet using the flow entry; and
process any additional data packets associated with the data flow associated with the data packet using the flow entry, wherein the additional data packets were stored in a flow context queue associated with the data flow associated with the data packet.
11. A method for determining a flow for a data packet of a stream of packets received at a network device, the method comprising:
comparing, by a first processor, information identifying a data flow associated with the data packet with entries stored in one or more flow tables stored in a flow table memory of a data switch; and
if there are no matching entries stored in the one or more flow tables for the information identifying the data flow associated with the data packet, then
comparing, by a second processor, the information identifying the data flow associated with the data packet with entries stored in a holding table stored in the flow table memory,
transmitting, using a rate limiting interface, the data packet from the network device to a network controller, if the information identifying the data flow associated with the data packet fails to match any entry in the holding table, wherein
the holding table comprises identifying information for data flows associated with previously received data packets that have already been transmitted to the network controller, and
storing, by the second processor, the data packet in a flow context queue associated with the matching entry in the holding table, if the information identifying the data flow associated with the data packet matches an entry in the holding table, wherein
the flow context queue is stored in the flow table memory, and
the flow context queue comprises data packets awaiting processing instructions for a flow corresponding to each data packet.
12. The method of claim 11 further comprising:
storing a matching flow context entry in the holding table wherein the matching flow context entry comprises information matching the information identifying the data flow associated with the data packet, if the information identifying the data flow associated with the data packet fails to match any entry in the holding table; and
storing the data packet in association with a flow context matching the information identifying the data flow associated with the data packet.
13. The method of claim 12 further comprising:
starting a life timer associated with the data flow associated with the data packet in response to storing the matching flow context in the holding table; and
storing information associated with the life timer in a timer table memory.
14. The method of claim 13 further comprising:
deleting the matching flow context entry from the holding table if the life timer associated with the data flow associated with the data packet expires prior to receiving, at the network device from the network controller, a response associated with the data flow.
15. The method of claim 13 further comprising:
starting a reminder timer associated with the data flow associated with the data packet in response to transmitting the data packet to the network controller; and
transmitting a second data packet associated with the data flow associated with the data packet in response to the reminder timer expiring prior to receiving, at the network device from the network controller, a response associated with the data flow, wherein a time associated with the reminder timer is less than a time associated with the life timer.
16. The method of claim 12 further comprising:
determining whether information identifying a data flow associated with a second data packet matches an entry in the holding table stored in the flow table memory; and
storing the second data packet in a flow context queue associated with the matching entry in the holding table, wherein the flow context queue is stored in the flow table memory.
17. The method of claim 16 further comprising:
checking if a reminder timer associated with the data flow associated with the second data packet in response to transmitting a previous data packet to the network controller has expired; and
transmitting the second data packet to the network controller in response to the reminder timer having expired.
18. The method of claim 12 further comprising:
receiving a flow offload from the network controller wherein the flow offload corresponds to the data flow associated with the data packet;
adding a flow table entry to a corresponding flow table wherein the flow table entry includes information comprised within the flow offload; and
removing the matching flow context associated with the flow offload from the holding table.
19. The method of claim 18 further comprising:
processing the data packet using the flow table entry; and
processing any additional data packets associated with the data flow associated with the data packet using the flow entry, wherein the additional data packets were stored in a flow context queue associated with the data flow associated with the data packet.