Description
Title of Invention: COMMUNICATION SYSTEM, CONTROL
DEVICE, NODE CONTROLLING METHOD AND PROGRAM
Technical Field
[000 1] (CROSS-REFERENCE TO RELATED APPLICATIONS)
The present Application claims priority rights based upon JP Patent Application
No.2010-275668 filed in Japan on December 10, 2010. The total of the contents
disclosed in the Application of the senior filing date is to be incorporated by reference
into the present Application. This invention relates to a communication system, a
control device, a node controlling method and a program. More particularly, it relates
to a communication system which implements communication using a node that
processes a received packet in accordance with a processing rule matching to the
received packet. It also relates to a control device, a node controlling method and to a
program.
Background Art
[0002] Recently, a technique termed Open-Flow has been proposed (see Patent Literature 1
and Non Patent Literatures 1 and 2). The OpenFlow comprehends communication as
an end-to-end flow and effects path control, recovery from malfunctions, load dis
tribution and optimization on the flow-by-flow basis. The OpenFlow switch, whose
design statements are shown in Non Patent Literature 2, includes a secure channel for
communication with an OpenFlow controller that is to operate as control device. The
OpenFlow switch is in operation in accordance with a flow table the addition in or the
rewriting of which is commanded from time to time by the OpenFlow controller. In the
flow table, a set of a matching rule (header field) for matching against a packet header,
flow statistics information (Counters) and an action defining contents of processing, is
defined on the flow-by-flow basis (see Fig.21).
[0003] On receipt of a packet, the OpenFlow switch retrieves the flow table for an entry
having the matching rule that matches to the packet's header information (see the
header field of Fig.21). If, as a result of the retrieval, the entry that matches to the
incoming packet has been found, the OpenFlow switch updates the flow statistics in
formation (Counters). The OpenFlow switch also applies to the incoming packet the
contents of processing stated in an action field of the entry, such as transmission of the
packet via the specified port, flooding or discarding (drop). If, as a result of the above
mentioned retrieval, no entry matching to the incoming packet has been found, the
OpenFlow switch forwards the incoming packet to the OpenFlow controller, over the
secure channel, with a request to the controller to decide on a path for the packet based
upon the source as well as the destination of transmission of the incoming packet. The
OpenFlow switch then receives an implementing flow entry to update the flow table. In
this manner, the OpenFlow switch forwards the packet, using the entry stored in the
flow table as the set of processing rules.
Citation List
Patent Literature
[0004] PTL 1: International Patent Literature WO2008/ 095010A1
Non Patent Literature
[0005] NPL 1: Nick McKeown et al., "OpenFlow: Enabling Innovation in Campus Networks",
[online], [retrieved on October 6, 2010], Internet
NPL 2: "OpenFlow Switch Specification" Version 1.0.0. (Wire Protocol 0x01)
[retrieved on October 6, 2010], Internet
Summary
Technical Problem
[0006] The following analysis is given by the present invention. The above OpenFlow has
an advantage that the OpenFlow switch may be of a simplified configuration.
However, it also suffers a problem that, if once a heavy load is imposed on the
OpenFlow controller, referred to below as a 'control device', the high load state is
sustained. For example, it is supposed that the control device has fallen into a highload
state such that delay has been caused in path calculations or in setting the flow
entries, referred to below as 'processing rules', as requested by the OpenFlow switch,
referred to below as a 'node'. If the node that has made such request should receive a
succeeding packet of the same flow, it requests the control device to prepare a
processing rule. This further raises the load imposed on the control device, as a result
of which the forwarding performance of the entire communication system is dete
riorated. A similar phenomenon may arise in case requests for the control device to set
the processing rules are congested within a shorter time interval. It is felt that such
phenomenon may arise frequently especially in case of forwarding of video streams.
[0007] In view of the above depicted status of the art, it is an object of the present invention
to provide a communication system in which the tendency to sustention of the high
load state of the control device may be relaxed. It is also intended by the present
invention to provide a control device, a node controlling method and a program.
Solution to Problem
[0008] In one aspect of the present invention, there is provided a communication (network)
system comprising a plurality of (network) nodes and a control device. Each of the
nodes references, on receipt of a packet, a table including a plurality of processing
rules (or handling rules) concerning packet processing. Each of the nodes processes
(handles) the packet received in accordance with at least one of the processing rules
corresponding to the packet received. Each of the nodes transmits a processing rule
setting request (inquiry) in case the corresponding processing rule is not known. The
control device sets a packet processing rule in at least one of the nodes on receipt of
said processing rule setting request (inquiry). A request staying (suspending) means for
transiently staying (suspending) the setting request (inquiry) to the control device is
provided in at least one of the nodes. In an alternative mode of the first aspect, there is
provided a network system, comprising: a plurality of network nodes to refer to a table
including a plurality of packet handling rules, and to handle an incoming packet with at
least one of the packet handling rules, the one or more rules corresponding to the
incoming packet; and a control device to set a new packet handling rule to at least one
of the network nodes when the control device receives an inquiry from a network node
which receives a first packet that a corresponding rule is not included in the table,
wherein at least one of the network nodes comprises: a unit to suspend the inquiry to
the control device
[0009] In a second aspect of the present invention, there is provided a control device that
controls a plurality of nodes, each of which references, on receipt of a packet, a table
including a plurality of processing rules (or handling rules) concerning packet
processing. Each of the nodes processes (handles) the packet received in accordance
with at least one of the processing rules corresponding to the packet received. The
control device includes a means for receiving a processing rule setting request
transmitted from the node that received a packet the corresponding processing rule for
which is not known. The control device also includes a means for setting, on receipt of
the setting request, the processing rule for the packet for at least one of the nodes, and
a means for transmitting to at least one of the nodes a command to transiently stay the
setting request to the control device.
[0010] In a third aspect of the present invention, there is provided a communication method
in which a packet is processed based upon control by a control device that decides a
forwarding path for the packet. The method includes a step of referencing, on receipt
of the packet, a table including a plurality of processing rules (or handling rules)
concerning packet processing. The communication method also includes a step of
processing (handling) the packet received in accordance with at least one of the
processing rules corresponding to the packet received, and transmitting a processing
rule setting request in case the corresponding processing rule is not known. The com
munication method further includes a step of transiently staying (halting) the setting
request to the control device. The present method is bound up with a particular
machine, viz., a control device that controls the node by setting the processing rule.
[001 1] In a fourth aspect of the present invention, there is provided a communication node
in which a packet is processed based upon control by a control device that decides a
forwarding path for the packet. The communication node includes a means for ref
erencing, on receipt of the packet, a table including a plurality of processing rules (or
handling rules) concerning packet processing, for processing (handling) the packet
received in accordance with at least one of the processing rules corresponding to the
packet received, and for transmitting a processing rule setting request to the control
device in case the corresponding processing rule is not known. The communication
node further includes a means for receiving the setting of the processing rule for the
setting request from the control device, and a means for transiently staying the setting
request to the control device.
[0012] In a fifth aspect of the present invention, there is provided a program that allows a
control device, controlling a plurality of nodes, to reference a table, on receipt of a
packet, and to process the received packet in accordance with at least one of the
processing rules (or handling rules) corresponding to the packet received. The table
includes a plurality of processing rules concerning packet processing (handling). The
program allows the control device to execute the processing of receiving the
processing rule setting request transmitted from the node that received a packet the
corresponding processing rule for which is not known. The program also allows the
control device to execute the processing of setting a packet processing rule in at least
one of the nodes in case of receiving the setting request, and the processing of
transmitting to at least one of the nodes a command to transiently stay the setting
request to the control device. The program may be recorded on a computer-readable
recording medium. Viz., the present invention may be implemented as a computer
program product.
Advantageous Effects of Invention
[0013] According to the present invention, it is possible to moderate the tendency that a
control device, setting a processing (handling) rule in response to a request from the
node, might be kept in a high load state.
Brief Description of Drawings
[0014] [fig. 1]Fig. 1 is a schematic view for illustrating schemata of the present invention.
[fig.2]Fig.2 is another schematic view for illustrating schemata of the present
invention.
[fig.3]Fig.3 is a further schematic view for illustrating schemata of the present
invention.
[fig.4]Fig.4 is a further schematic view for illustrating schemata of the present
invention.
[fig.5]Fig.5 is a schematic view showing the configuration of a communication system
of an exemplary embodiment 1 of the present invention.
[fig.6]Fig.6 is a block diagram showing the configuration of a control device of the
exemplary embodiment 1 of the present invention.
[fig.7]Fig.7 is a block diagram showing the configuration of a node according to the
exemplary embodiment 1 of the present invention.
[fig.8]Fig.8 is a schematic view for illustrating the operation of the communication
system of an exemplary embodiment 1 of the present invention.
[fig.9]Fig.9 is a schematic view continuing from Fig.8.
[fig. 10] Fig. 10 is a schematic view continuing from Fig.9.
[fig. 1l]Fig. 11 is a schematic view for illustrating other processing rules set in the
control device of the exemplary embodiment 1 of the present invention
[fig. 12] Fig. 12 is a schematic view continuing from Fig. 11.
[fig. 13]Fig. 13 is a schematic view for illustrating the state in which a loop is formed as
a result of setting the processing rules of Fig. 12.
[fig. 14] Fig. 14 is a schematic view for illustrating the operation of a communication
system according to an exemplary embodiment 2 of the present invention.
[fig. 15]Fig. 15 is a schematic view for illustrating the operation of a communication
system according to an exemplary embodiment 3 of the present invention.
[fig. 16] Fig. 16 is a schematic view continuing from Fig. 15.
[fig.l7]Fig.l7 is a schematic view continuing from Fig. 16.
[fig. 18]Fig. 18 is a schematic view showing the configuration of a communication
system of an exemplary embodiment 4 of the present invention.
[fig. 19] Fig. 19 is a block diagram showing the configuration of a control device
according to the exemplary embodiment 4 of the present invention.
[fig.20]Fig.20 is a schematic view for illustrating the operation of the communication
system according to the exemplary embodiment 4 of the present invention.
[fig.21]Fig.21 is a block diagram showing the configuration of a flow entry shown in
Non Patent Literature 2.
Description of Embodiments
The outline of the present invention will be first discussed with reference to Figs.l to
4. It is noted that the reference numerals for relevant elements used in the drawings are
only for facility in understanding and are not intended to restrict the invention to the
mode shown in the drawings. The same applies for figures other than Figs.l to 4 as
well. The various figures are given only by way of illustration, such that, for example,
the number of nodes or the like components is not intended to restrict the present
invention to the particular numbers.
[0016] Fig. 1 shows the outline of the communication system (or network system) of the
present invention. The communication system includes network nodes (termed
generally "nodes" hereinafter) 210, 220 that store (hold) processing (handling) rules to
process (handle) incoming packets belonging to a preset flow and a control device 100
that sets the processing rules in response to requests (inquires) from these nodes 210,
220. The nodes 210, 220 process the incoming packet that has matched to the
processing rules. It is noted that the processing rules correspond to the flow entries in
the OpenFlow system.
[0017] Each of the nodes 210, 220 includes a table that stores the processing rules. Although
Fig. 1 shows a table owned by the node 210, the node 220 also has a similar table. The
node 210 receives, from a communication terminal A, a packet whose destination is a
communication terminal B. The node 210 compares a header part of the packet
received to the matching rule contained in the processing rule. In case there is the
processing rule having a matching rule that matches to the header part, the node 210
processes the packet in accordance with the processing rule. In case there is no
matching rule that matches to the header part, the node 210 transmits a processing rule
request to the control device 100. In short, in case of receipt of a packet, the corre
sponding processing rule for which has not been known, the node 210 sends a request
to set the processing rule for the unknown packet to the control device 100.
[0018] The control device 100 decides the forwarding path for the packet, having the
terminal B as the destination, in response to the setting request. The control device 100
sets in the node 210 the processing rule including an action(s) for the forwarding path
as decided. It is noted that the control device 100 similarly sets a processing rule,
including an action(s), for the packet having the terminal B as destination, in the node
220, in a manner not shown.
[0019] Referring to Fig.2, the operation of the node 210 comparing an incoming packet to a
table is specifically explained. The table stores a set of processing rules each of which
includes a matching rule and an action. The node 210 processes a received packet in
accordance with the processing rule corresponding to the received packet. The node
210 compares the contents of the header of the received packet to the matching rule of
each processing rule, as an example. If there is the processing rule including the
matching rule corresponding to the header, the node 210 processes the packet in ac
cordance with the processing rule. The table defines priorities as prescribed for the
processing rules. The priorities are determined, for instance, by the arraying rows of
the processing rules in the table. For example, the smaller the value of the row number
of the row in which a processing rule of interest is arrayed, the higher is the priority
accorded to the processing rule. In case there is a plurality of the processing rules
matched to the incoming packet, the node 210 processes the packet in accordance with
the processing rule of the higher priority.
[0020] Referring to Fig.3, the node 210 includes a processing rule memory 212 and a
request staying unit 2101, as does the node 220. In case there is no processing rule that
matches to the incoming packet in the table stored in the processing rule memory 212,
the node 210 transmits to the control device 100 a processing rule setting request for
the incoming packet. The request staying unit 2101 has the function to suspend, viz.,
transiently stay, the transmission of the setting request to the control device 100, even
in case there is no processing rule for the incoming packet. By this function, excessive
congestion of the processing rule setting requests may be forestalled in the control
device 100 to prevent the load on the controlling device 100 from increasing.
[0021] The request staying unit 2101 may stay a processing rule setting request at an
arbitrary timing. Or, the request staying unit may stay the processing rule setting
request at a preset cycle (interval), or in response to prevailing load states of the
control device 100. For example, the request staying unit 2101 may periodically
exchange messages with the control device, in which case the request staying unit
decides that the load on the control device 100 is increased if a message from the
control device 100 is delayed by more than a preset threshold value. Based on this
decision, the request staying unit stays the processing rule setting request.
[0022] Fig.4 shows an alternative illustrative configuration of the node 210. In this i l
lustrative configuration, the request staying unit 2101 stays transmission of the setting
requests to the control device 100 based upon the processing rules as set on the table.
In the processing rule memory 212, there are stored a first processing rule that provides
for contents of processing for the packet that matches to the matching rule, and a
second processing rule. The second processing rule provides that, on receipt of an
unknown packet not matched to any of the pre-existing matching rules, the request for
setting the corresponding processing rule to the control device 100 is to be suspended.
It is noted that the priority of the second processing rule in the table is set at a lower
value. The packet is configured to be matched to the second processing rule in case the
incoming packet is matched to none of the first processing rules, viz., in case the
incoming packet is an unknown packet.
[0023] In Fig.4, the matching rule of the second processing rule is "ANY". Viz., the
incoming packet matches to the second processing rule irrespectively of the header
contents of the incoming packet. The request staying unit 2101 processes the packet in
accordance with the second processing rule. Hence, the transmission of the setting
request from the node 210 to the control device 100 is stayed.
[0024] The request staying unit 2101 manages control so that, for example, when the load on
the control device 100 is high, the nodes 210, 220 will not request the control device to
set the processing rules. Specifically, the control device 100 may be provided with a
load monitoring means, and the second processing rule, providing that the setting
requests for the processing rules should be suppressed when the load tends to be
increased, such as when the load exceeds a preset threshold value, may be set. Or, the
node 210 may check the load applied to the control device 100.
[0025] The second processing rule provides for packet processing that is carried out without
dependency upon control managed by the control device 100. The request staying unit
2101 executes packet processing not dependent upon the forwarding path decided by
the control device 100, such as packet discarding.
[0026] The packet processing that is carried out without dependency upon control managed
by the control device 100 may be exemplified by packet processing decided by the
routing information exchanged in accordance with the routing protocol among
different nodes. By this second processing rule, the node 210 is able to autonomously
forward incoming packets without recourse to the control device 100.
[0027] The second processing rule may be set in the total of the nodes 210, 220, as shown in
Fig.4. It is however possible to select nodes where the second processing rule is to be
set. For example, such a node that might be more effective in suppressing the
processing rule setting request may be selected in consideration of load states of the
control device, the number of hosts (communication terminals) connected thereto or
the statistic information of the data traffic of each host. It is also possible for the
control device 100 to analyze the contents of the packets, the processing rule setting
requests for which have been made from the nodes, such as IP headers or TCP headers.
By so doing, it is possible to select such nodes that will be more effective in sup
pressing processing rule setting requests.
[0028]
An exemplary embodiment 1 of the present invention will now be explained with
reference to the drawings. Fig.5 depicts the configuration of the exemplary em
bodiment 1 of the present invention. Referring to Fig.5, the configuration includes a
node 210, communication terminals A and X are connected to, another node 220, com
munication terminals B, Y are connected to, and a control device 100. The control
device controls these nodes 210, 220 over a dedicated channel, indicated by broken
lines, for example, a secure channel in the OpenFlow system.
[0029] The control device 100 decides on a packet forwarding path on the packet flow basis.
The control device 100 sets in nodes lying on a packet forwarding path, out of the
nodes 201, 202, the processing rules for implementing packet forwarding along the
packet forwarding path. In the following explanation of the exemplary embodiment, it
is assumed that the control device 100 is an OpenFlow controller of Non Patent
Literature 2 capable of setting processing rules (flow entries) in the nodes 210, 220,
transmitting a buffered packet or collecting the statistic information (Counters). It is
noted that the control device 100 of the present invention is not limited to the
OpenFlow controller. Viz., the control device need not be a device configured in ac
cordance with the OpenFlow protocol, provided that the control device is able to
perform centralized management of packet forwarding by nodes exemplified by
switches. The same applies for exemplary embodiments other than the present
exemplary embodiment. It is noted that, in the figures referred to in the following ex
planation, the tables in which the processing rules are set are simplified as compared to
Figs. 1 to 4. In these simplified tables, the upper the position of the row in which each
processing rule is entered, the higher is the priority of the processing rule in question.
The same applies for exemplary embodiments other than the present exemplary em
bodiment.
[0030] Fig.6 depicts a block diagram showing the configuration of a control device
(controller) 100 operating as OpenFlow controller. Referring to Fig.6, the control
device (controller) 100 includes a processing rule memory 101 in which there are
stored the processing rules (flow entries) each made up of a matching rule, shown by
way of example in Fig.21, the flow statistic information (Counters), and an action(s),
inclusive of a timer value and the priority information. The controller 100 also includes
a topology management unit 103, a path/ action calculation unit 104, a processing rule
preparation unit 105, a control message processor 106 and a node communication unit
107 configured for doing communication with the nodes 210 to 240. The operation of
these components is the following.
[0031] The topology management unit 103 constructs and manages the network topological
information, based upon the relationship of interconnection of the nodes 210, 220 as
collected by the node communication unit 107.
[0032] The path/ action calculation unit 104 calculates the packet forwarding path and the
actions based upon the network topological information as constructed by the topology
management unit 103. The actions are executed by the nodes on the packet forwarding
path and include priorities and timer values as valid period of the processing rules.
[0033] The processing rule preparation unit 105 prepares the matching rule to identify the
packet belonging to a flow in question in response to a request from the node 210 or
220. The processing rule preparation unit puts the so prepared matching rule and the
action calculated by the path/ action calculation unit 104 together to form a processing
rule (flow entry) which is set in each of the nodes 210, 220. The processing rule
preparation unit 105 also registers the so formed processing rule (flow entry) in the
flow table of the processing rule memory 101 in order to allow for referencing at the
time of a request from the node 210 or 220 to set the processing rule (flow entry) a
second time.
[0034] The processing rule preparation unit 105 of the controller 100 of the present
exemplary embodiment also forms (and sets) a set of another processing rule (third
processing rule) having a valid period and a further processing rule (second processing
rule) on receipt of an unknown packet not belonging to any existing flows irre
spectively of a request from the node 210 or 220. The third processing rule provides
for contents of processing of having the nodes 210, 220 request the control device 100
to set a new processing rule. The second processing rule is lower in priority than the
third processing rule but does not have the valid period and allows discarding the
unknown packet not belonging to any existing flows on receipt of such unknown
packet. The processing rule preparation unit 105 also updates the processing rule
having the valid period (third processing rule) at a preset time interval to forestall ex
piration of the processing rule having the valid period (third processing rule). It is also
possible for each of the nodes 210, 220 to set for itself the second and third processing
rules in a flow table owned by each of the nodes 210, 220.
[0035] The control message processor 106 analyzes a control message, received from the
node 210 or 220, to deliver the control message information to relevant processing
means within the control device (controller) 100. For example, on receipt from the
node 210 or 220 of a message requesting a setting of the processing rule (Packet-In),
the control message processor 106 checks to see whether or not the set of processing
rules (flow entries) relevant to such flow has been registered in the processing rule
memory 101. If the set of processing rules has not been registered, the control message
processor asks the path/ action calculation unit 104 to prepare a new set of processing
rules (flow entries).
[0036] A computer program that allows the respective components (processing means) of
the control device (controller) 100, shown in Fig.6, to execute the above mentioned
processing operations with the aid of the hardware of a computer composing the
controller 100, may also be used.
[0037] Fig.7 depicts a block diagram showing the configuration of a node 210 operating as
OpenFlow switch. Referring to Fig.7, the node 210 includes a processing rule memory
212 that stores the processing rule(s), as set by the controller, and a packet processor
211. The packet processor 211 retrieves the processing rule(s) matched to the incoming
packet from the processing rule memory 212 to process the incoming packet. The
above applies for the node 220 as well. For the node 210 (220), the OpenFlow switch,
shown in Non Patent Literature 2, may be used, the entire disclosure where of is in
corporated herein by reference thereto.
[0038] The valid period may be set for the processing rules stored in the processing rule
memory 212. The nodes 210, 220 are configured to delete the processing rule(s),
whose valid period has lapsed, from the processing rule memory 212.
[0039] Further, it is possible to set priorities for the processing rules stored in the processing
rule memory 212. The nodes 210, 220 execute contents of processing provided for in
the processing rule of higher priority among the processing rules matched to the
incoming packets. Examples of the priorities that may be used include those that are
able to be set in the action field (Priority) of the processing rules of Non Patent
Literature 2 (see Non Patent Literature 2, page 27, '5.3.3 Modify State Messages').
Such a method may also be used in which the processing rules are stored in the
processing rule memory 212 in the order of the falling priorities and in which retrieval
is commenced from the processing rule of higher priority to select a first matching
processing rule.
[0040] The operation of the present exemplary embodiment will now be described in detail
with reference to Figs.8 to 12. It is assumed that, in connection with a pre-known flow
(communication from a communication terminal A to a communication terminal B), a
forwarding path for forwarding a packet from the node 210 to the node 220 has been
calculated and that the corresponding first processing rule has been set in each of the
nodes 210, 220, as shown in Fig. 8.
[0041] It is noted that an N'th processing rule {matching rule: XXX; action: YYY} in the
drawing denotes that, when a packet that has matched to the matching rule 'XXX' is
received, the processing 'YYY' is to be carried out. On the other hand, a 'pre-known
flow' in the drawing denotes a flow a processing rule for which is included in the flow
table. For example, on receipt of a packet belonging to a pre-known flow from the
communication terminal A to the communication terminal B, for example, a packet
whose header includes the information that the destination is the communication
terminal B, the node 210 of Fig.8 may transmit the packet via its port the node 220 is
connected to. In similar manner, on receipt of a packet belonging to the pre-known
flow addressed from the communication terminal A to the communication terminal B,
the node 220 performs contents of processing of transmitting the packet via its port the
communication terminal B is connected to. By so doing, the packet, transmitted from
the communication terminal A, may be delivered to the communication terminal B.
[0042] The control device 100 sets second and third processing rules in the nodes 210, 220,
at the time of setting the above mentioned first processing rule or based upon e.g., the
statistics information as collected from the nodes 210, 220. The valid period of the
third processing rule is P seconds. It is noted that the contents of the second processing
rule are such that, if a packet received is one belonging to an unknown flow, viz., a
flow matched to none of the pre-existing processing rules (first processing rules) as
held (stored) by the nodes, such packet is to be discarded. This, however, is only by
way of illustration, such that it is not mandatory that the action of the second
processing rule is to be packet discarding. On the other hand, there is no valid period
set to the second processing rule, such that, if P seconds have elapsed as from the time
point of setting the second processing rule, the second processing rule is not deleted by
the nodes 210, 220. It is however possible to set a valid period longer than that of the
third processing rule of P seconds as the valid period for the second processing rule.
[0043] The contents of the third processing rule are such that, if a packet received is one
belonging to an unknown flow, viz., the packet received is matched to none of the pre
existing processing rules (first processing rules) as held by the node, a processing rule
setting request message (Packet-In) is to be transmitted to the control device 100. Also,
a valid period of P seconds is set for the third processing rule, such that, if P seconds
have elapsed as from its setting time point, the third processing rule is to be deleted
(dropped) by the nodes 210, 220.
[0044] The control device 100 then performs a third processing rule update operation at a
preset time interval not longer than P seconds, as shown in Fig.9. Thus, if, as long as
the control device 100 updates the third processing rule within this preset time period,
a packet belonging to an unknown flow is detected by the node 210 or 220, the
unknown packet matches to the third processing flow. The node 210 or 220 thus
transmits a processing rule setting request message (Packet-In) to the control device
100.
[0045] For example, if the node 210 has received a packet from the communication terminal
X to the communication terminal Y, the node transmits to the control device a
processing rule setting request message (Packet-In) for the packet addressed from the
communication terminal X to the communication terminal Y. On receipt of the
processing rule setting request message (Packet-In), the control device 100 calculates
the path of forwarding the packet addressed from the communication terminal X to the
communication terminal Y, while setting the processing rule for implementing the
forwarding path (first processing rule). This implements the forwarding of the packet
from the communication terminal X to the communication terminal Y.
[0046] If subsequently the control device 100 is excessively loaded, by some reason or
other, thus causing delay in updating the third processing rule, the third processing rule
is deleted in the node 210 or 220, as shown in Fig. 10. Since the third processing rule
has been deleted, the packet belonging to the unknown flow matches to the second
processing rule. Hence, even if the node 210 or 220 detects a packet belonging to the
unknown flow, the node 210 or 220 does not transmit the processing rule setting
request message (Packet-In) to the control device 100, but discards the received packet
in accordance with the second processing rule.
[0047] Hence, if the control device 100 is under a high load, processing rule setting request
messages (Packet-In) are suppressed. When the load has subsequently been lowered,
the control device 100 sets the third processing rule in each of the nodes 210, 220,
thereby restoring the state to that shown in Fig.9.
[0048] Viz., with the present exemplary embodiment, it becomes possible to suppress the
processing rule setting requests from the nodes 210, 220 in case of excessive loading
of the control device 100.
[0049] In the foregoing explanation, it is assumed that the processing rule setting request
messages (Packet-In) are to be issued for all unknown flows. It is however also
possible to have certain specified data traffics discarded as a principle or not discarded
provided that certain conditions are set in the matching rule of each of the second and
third processing rules.
[0050] In addition, it has been explained in the foregoing that the second processing rule
provides for contents of processing defining that the packet in question is to be
discarded. It is however possible to use the second processing rule providing for packet
queuing or packet forwarding to other nodes.
[0051] For example, the second processing rule may be so set that the packet received is to
be forwarded to a node 230 controlled by a control device 100A distinct from the
control device 100, as shown in Fig. 11. If the load on the control device 100 is
increased, the node 220, which has received a new packet from the communication
terminal Y, forwards the received packet to the node 230 in accordance with the
second processing rule, as indicated by a thick broken line in Fig.l 1. The node 230,
which received the packet, sends a processing rule setting request message (Packet-In)
not to the control device 100 but to the control device 100A, as indicated by a thick
broken line in Fig.l 1. The load on the control device 100 may thus be relieved.
[0052] The control device 100A then sets a processing rule to process the packet sent from
the communication terminal Y (first processing rule), in the node 230, as shown in
Fig. 12. A packet addressed from the communication terminal Y to the processing
terminal A may thus be forwarded on a forwarding path via nodes 220, 230 and 210, as
indicated by a broken line in Fig. 12.
[0053]
An exemplary embodiment 2 of the present invention will now be explained with
reference to the drawings. The second processing rule, providing for an action of
forwarding a received packet to the node 230, controlled by the control device different
from the control device for the node 220, may be set, as explained with reference to
Figs. 11 and 12. However, if the second processing rule similar to that set in the node
220 is set in the node 210, as shown in Fig. 13, the received packet might possibly be
returned from the node 210 to the node 230. The exemplary embodiment 2 of the
present invention provides for a configuration in which it is possible to suppress such
packet looping from occurring. Since the present exemplary embodiment 2 may be im
plemented by a configuration equivalent to that of the exemplary embodiment 1,
described above, the following explanation will be centered on the points of difference
from the exemplary embodiment 1.
[0054] Fig. 14 illustrates the operation of a communication system according to the
exemplary embodiment 2 of the present invention. The present exemplary embodiment
differs from the exemplary embodiment 1 in that, in the present exemplary em
bodiment 2, the processing of rewriting a vlan tag (VLAN ID) before forwarding the
packet to the next hop is added to a second processing rule, and a fourth processing
rule to discard a packet whose vlan tag (VLAN ID) has been rewritten is set.
Otherwise, the first and third processing rules may be the same as those in the
exemplary embodiment 1.
[0055] By so doing, the packet returned from the node 230, the packet was once forwarded
to, may positively be discarded at the node 220, as shown in Fig. 13. It is of course
possible to set the fourth processing rule providing for queuing the packets or
forwarding them to other nodes, instead of discarding the packets, as explained in the
above mentioned exemplary embodiment 1.
[0056] In the foregoing, it has been explained that a packet that has looped back is dis
criminated by rewriting a packet's vlan tag (VLAN ID) before forwarding the packet to
the next hop. However, the information indicating that the packet is that forwarded by
the own node may be written in an any field not used in the so rewritten packet, such
as MAC address (source or destination of transmission), EtherType or an IP address
(source or destination of transmission).
[0057]
An exemplary embodiment 3 of the present invention, in which a control device is to
execute a further operation, will be explained with reference to the drawings. Since the
present exemplary embodiment 3 may be implemented by a configuration equivalent
to that of the exemplary embodiment 1, described above, the following explanation
will be centered on the points of difference from the exemplary embodiment 1.
[0058] On detecting a flow addressed from the communication terminal Y to the commu
nication terminal X, the node 220 transmits a processing rule setting request message
(Packet- In) to the control device 100, in accordance with the third processing rule, as
shown in Fig. 15. It is assumed that the flow addressed from the communication
terminal Y to the communication terminal X is such a flow that corresponding
processing rule setting request messages (Packet- In) would be produced at a high
frequency after the incoming of a new packet, for example, moving picture con
figuration data traffics.
[0059] It is supposed that the control device 100 of the present exemplary embodiment has
concluded that the flow as the subject of the processing rule setting request message
(Packet- In) is such a flow that corresponding processing rule setting request messages
(Packet-In) would be produced at a high frequency. In such case, the control device
100 sets a fifth processing rule in the node 220 as the source of transmission of the
processing rule setting request message (Packet-In). The fifth processing rule provides
that the flow addressed from the communication terminal Y to the communication
terminal X is to remain discarded for a preset time period of Q seconds, and is set in
the node 220 as the source of transmission of the processing rule setting request
message (Packet-In), as shown in Fig. 16.
[0060] After setting the fifth processing rule, the control device 100 calculates a packet
forwarding path for the flow addressed from the communication terminal Y to the
communication terminal X, while setting the first processing rule, as shown in Fig. 17.
After the end of the setting of the first processing rule, the packet transmitted from the
communication terminal Y is delivered via the nodes 220, 210 to the communication
terminal X.
[0061] In the present exemplary embodiment, described above, any succeeding packets from
the communication terminal Y remain discarded for the preset time period (Q seconds)
in the node 220. Thus, should the delay be caused in the control device 100 in
connection with the calculations of the packet forwarding path or with the setting of
the processing rules, there is no fear of the processing rule setting request messages
(Packet-In) occurring at a higher frequency.
[0062] In the foregoing, it has been explained that the fifth processing rule is to be set for the
flow for which the processing rule setting request messages are likely to be produced at
a higher frequency. However, there are cases where it is known from the outset that
path calculations by the control device 100 or the setting of the first processing rule
would be time-consuming in consideration of the network topology or the number of
the nodes. In such case, the fifth processing rule of causing the succeeding packets to
be discarded for a preset time may, as a principle, be set.
[0063] In the above explanation, the contents for processing of the fifth processing rule are
to command for executing packet discarding. As an alternative, the contents for
processing of the fifth processing rule may also be for packet queuing or the like.
[0064]
An exemplary embodiment 4 of the present invention, in which the configuration of
the control device has partially been changed, will now be described with reference to
the drawings. The following explanation of the exemplary embodiment 4 will be
centered on the points of difference of the exemplary embodiment from the exemplary
embodiment 1.
[0065] Fig. 18 depicts the configuration of the exemplary embodiment 4 of the present
invention. Referring to Fig. 18, the configuration includes a node 210, a communication
terminal A is connected to, a node 220, a communication terminal B is connected to,
and a node 230, a contents server is connected to. In addition, the configuration
includes a control device 100B that controls these nodes 210 to 230 over a secure
channel indicated by broken lines.
[0066] Fig. 19 depicts a block diagram showing the configuration of a control device 100B
of the present exemplary embodiment. The present control device differs from the
control device 100 of the exemplary embodiment 1, shown in Fig.6, in including a
statistic information collection unit 108.
[0067] The statistic information collection unit 108 is a means for collecting the statistic in
formation, collected from one processing rule to another, from the nodes 210 to 230
via the control message processor 106 and the node communication unit 107.
[0068] In the control device 100B of the present exemplary embodiment, provided with the
statistic information collection unit 108, such a flow for which it is desired to suppress
the processing rule setting request is specified for a node where it is desired to suppress
the processing rule setting request, based upon the collected statistic information. The
control device 100B thus sets the above mentioned second to fifth processing rules.
[0069] It is supposed that, as an example, the proportion of a video stream from the contents
server to the communication terminal B is high in the node 220 for a certain time zone,
as shown in Fig.20. In such case, the control device 100B sets a group of the second
and third processing rules, or the fifth processing rule, in advance, in the nodes 220 and
230 for the time zone in question.
[0070] It is thus possible with the present exemplary embodiment to set in advance the
processing rule that might suppress the processing rule setting request, in consideration
of temporal or local traffic variations or of constraints in the traffic.
[0071] Although the description has been made of preferred exemplary embodiments of the
present invention, such exemplary embodiments are given only by way of illustration
and are not intended to limit the scope of the present invention. Viz., further modi
fications, substitutions or adjustments may be made without departing from the basic
technical concept of the present invention. For example, the number of the nodes or the
communication terminals as well as the network configuration in the above described
exemplary embodiments has been simplified to assist in understanding of the present
invention, and may be varied to meet practical needs.
[0072] Moreover, as explained in the above exemplary embodiments, the particular nodes
where the second to fifth processing rules are set may optionally be set from the per
spective of efficiently suppressing processing rule setting requests. For example, if
there are further nodes between the nodes 210, 220 shown in Fig.l, and it is desirable
to suppress processing rule setting requests from these further nodes, a group of the
second and third processing rules may be set for these further nodes. If the nodes
provided between the nodes 210, 220 are not connected to the external communication
terminals, with the frequency of occurrence of the processing rule setting requests from
these non-connected nodes being not that high, there is no necessity to set the group of
the second and third processing rules for these interposed nodes.
[0073] On the other hand, it has been explained in the above exemplary embodiments that
valid period are to be provided for the third and fifth processing rules. These valid
period may be of fixed values, or may also be varied depending upon the time zone or
on the species of the data traffics. For example, the valid period of the third processing
rule may be made shorter the higher the load on the control device. The valid period
may also be made longer little by little such as in the case of slow start in TCP
(Transmission Control Protocol).
[0074] The valid period may also be changed subject to analysis of the contents of the
packet as well as the processing rule setting request for which has been received from a
node, such as IP header or the TCP header.
[0075] Preferred forms of the present invention will now be summarized as follows.
(Mode 1)
A communication system comprising:
a node that holds a first processing rule, providing for contents of processing of a
packet belonging to a preset flow, and that processes an incoming packet matching to
the processing rule; and
a control device that sets a first processing rule in the node in response to a request
from the node;
the control device setting a second processing rule in the node; the second processing
rule being applied in case of a high load on the control device and providing for
contents of processing of suppressing a processing rule setting request at the time of
receipt of an unknown packet belonging to none of existing flows.
(Mode 2)
The communication system according to mode 1, wherein,
the control device sets, in the node, a third processing rule applied with priority to the
second processing rule; the third processing rule providing for contents of processing
of having the node request the control device to set the first processing rule on receipt
of a packet matched to a preset matching rule.
(Mode 3)
The communication system according to mode 2, wherein,
the third processing rule provides for contents of processing of having the node
request the control device to set the first processing rule at the time of receiving an
unknown packet belonging to none of existing flows, and for the valid period thereof;
the second processing rule being applied in case of delay in an operation of updating
the third processing rule by the control device.
(Mode 4)
The communication system according to any one of modes 1 to 3, wherein
the contents of processing of the second processing rule are for one out of discarding
the received packet, forwarding the received packet to another node and queuing the
received packets.
(Mode 5)
The communication system according to any one of modes 1 to 4, wherein,
as the contents of processing of the second processing rule, rewriting a header of the
received packet and forwarding the header-rewritten packet to another node are set;
and wherein,
on receipt of the header-rewritten packet from the another node, a fourth processing
rule is set; the fourth processing rule providing for one selected from the group
consisting of discarding the received packet, forwarding the received packet to another
node and queuing the received packets.
(Mode 6)
The communication system according to any one of modes 3 to 5, wherein,
the higher the loading state of the control device, the shorter is the valid period of the
third processing rule as set by the control device.
(Mode 7)
The communication system according to any one of modes 1 to 6, wherein,
the control device is connected to a plurality of nodes; and wherein
the higher the loading state of the control device, the greater is the number of the nodes
in which the second processing rules are set.
(Mode 8)
The communication system according to any one of modes 1 to 7, wherein,
the control device includes a means (unit) for monitoring the load state thereof; and
wherein,
the control device sets the second processing rule in the node in response to the load
state of the control device.
(Mode 9)
The communication system according to any one of modes 3 to 8, wherein,
the control device changes the valid period of the third processing rule based upon the
traffic information as collected from the node.
(Mode 10)
The communication system according to any one of modes 1 to 9, wherein,
the control device is connected to a plurality of nodes; and wherein,
the node where the second processing rule is set or the flow as the subject of the
second processing rule is decided based upon the traffic information as collected from
the nodes.
(Mode 11)
The communication system according to any one of modes 1 to 10, wherein,
a fifth processing rule is set in the node that requested setting the first processing rule;
the fifth processing rule providing for contents of processing of having the node
discard or queue succeeding packets of the same flow for a preset time period.
(Mode 12)
A control device connected to a node that holds a first processing rule providing for
contents of processing of a packet belonging to a preset flow, and that processes an
incoming packet matching to the processing rule; wherein
the control device sets in the node a second processing rule applied in case of a high
load on the control device; the second processing rule providing for contents of
processing of suppressing a processing rule setting request in case of receiving an
unknown packet belonging to none of existing flows.
(Mode 13)
The control device according to mode 12, wherein,
a third processing rule is set in the node; the third processing rule being applied with
priority to the second processing rule; the third processing rule providing for contents
of processing of having the node request the control device to set the first processing
rule on receipt of a packet matching to a preset matching rule.
(Mode 14)
The control device according to mode 13, wherein,
the third processing rule provides for contents of processing of having the node request
the control device to set a processing rule at the time of receipt of an unknown packet
belonging to none of pre-existing flows; the third processing rule also providing for a
preset valid period thereof;
the second processing rule being applied as a result of delay caused in the update
operation of the third processing rule by the control device.
(Mode 15)
The control device according to any one of modes 12 to 14, wherein,
the contents of processing of the second processing rule provide for one selected from
the group consisting of discarding the received packet, forwarding the received packet
to another node and queuing the received packets.
(Mode 16)
The control device according to any one of modes 12 to 15, wherein,
as the contents of processing of the second processing rule, rewriting a header of the
received packet and forwarding the header-rewritten packet to another node are set;
and wherein,
a fourth processing rule is set; the fourth processing rule providing, on receipt of the
header-rewritten packet from the another node, for one out of discarding the received
packet, forwarding the received packet to another node and queuing the received
packets.
(Mode 17)
The control device according to any one of modes 14 to 16, wherein,
the higher the loading state of the control device, the shorter is the valid period of the
third processing rule set by the control device.
(Mode 18)
The control device according to any one of modes 12 to 17, wherein,
the control device is connected to a plurality of nodes; and wherein
the higher the loading state of the control device, the greater is the number of the nodes
in which the second processing rules are set.
(Mode 19)
The control device according to any one of modes 12 to 18, wherein,
the control device includes a means (unit) for monitoring the load state thereof; and
wherein,
the control device sets the second processing rule in the node in response to the load
state thereof.
(Mode 20)
The control device according to any one of modes 14 to 19, wherein,
the control device changes the valid period of the third processing rule based upon the
traffic information as collected from the node.
(Mode 21)
The control device according to any one of modes 12 to 20, wherein,
the control device is connected to a plurality of nodes; and wherein,
the node where the second processing rule is set or the flow as the subject of the
second processing rule is decided based upon the traffic information as collected from
the nodes.
(Mode 22)
The control device according to any one of modes 12 to 21, wherein,
a fifth processing rule providing that the node that requested setting the first processing
rule is to execute discarding or queuing succeeding packets of the same flow for a
preset time period is set.
(Mode 23)
A method for controlling a node by a control device connected thereto; the node
staying a first processing rule providing for contents of processing for a packet
belonging to a preset flow; the node processing an incoming packet that matches to the
processing rule; the method comprising:
a step of setting in the node a first processing rule in response to a request from the
node; and
a step of setting a second processing rule in the node; the second processing rule being
applied in case of a load on the control device being high; the second processing rule
providing for contents of processing of suppressing a processing rule setting request in
case of receiving an unknown packet belonging to none of existing flows.
(Mode 24)
A program executed by a computer forming a control device connected to a node that
holds a first processing rule providing for contents of processing for a packet
belonging to a preset flow and that processes an incoming packet matching to the
processing rule; the program comprising:
a processing of setting in the node a first processing rule in response to a request from
the node; and
a processing of setting a second processing rule in the node; the second processing rule
being applied in case of a load on the control device being high; the second processing
rule providing for contents of processing of suppressing a processing rule setting
request in case of receiving an unknown packet belonging to none of existing flows.
The disclosure of the aforementioned Patent Literature and the Non Patent Literatures
is incorporated herein by reference thereto. The particular exemplary embodiments or
examples may be modified or adjusted within the gamut of the entire disclosure of the
present invention, inclusive of claims, based on the fundamental technical concept of
the invention. Further, a variety of combinations or selection of elements disclosed
herein may be made within the framework of the claims. Viz., the present invention
may cover a wide variety of modifications or corrections that may occur to those
skilled in the art in accordance with the entire disclosure of the present invention,
inclusive of claims and the technical concept of the present invention.
Reference Signs List
100, 100A, 100B: control device (controller)
101: processing (handling) rule memory
103: topology management unit
104: path/ action calculation unit
105: processing (handling) rule preparation unit
106: control message processor
107: node communication unit
108: statistic information collection unit
210 to 230: (network) nodes
211: packet processor
212: processing (handling) rule memory
2101: request staying unit
PCT/JP2011/004783
Claims
A communication system comprising:
a plurality of nodes; each of said nodes on receipt of a packet ref
erencing a table including a plurality of processing rules concerning
packet processing; each of said nodes processing the packet received in
accordance with at least one of said processing rules corresponding to
the packet received; each of said nodes transmitting a processing rule
setting request in case the corresponding processing rule is not known;
and
a control device setting a packet processing rule in at least one of said
nodes on receipt of said processing rule setting request;
at least one of said nodes including request staying means for
transiently staying said setting request to the control device.
The communication system according to claim 1, wherein
said request staying means processes the received packet in accordance
with a second processing rule that provides for packet processing for
transiently staying said setting request to said control device.
The communication system according to claim 1 or 2, wherein
at least one of said nodes holds a third processing rule in said table;
said third processing rule being applied with priority to said second
processing rule and providing that said setting request is to be
transmitted to said control device.
The communication system according to claim 3, wherein
said third processing rule provides for contents of processing that said
setting request is to be transmitted on receipt of a packet a corre
sponding processing rule for which is not known; said third processing
rule also providing for a preset valid period thereof;
said control device updating said third processing rule at a preset time
interval.
The communication system according to any one of claims 2 to 4,
wherein,
said second processing rule provides for packet processing executed
without dependency upon control by said control device.
The communication system according to any one of claims 2 to 4,
wherein
said at least one of said nodes holds in said table said second processing
rule that provides for rewriting of a header of said received packet and
PCT/JP2011/004783
for forwarding of said received packet to another one of said nodes,
at least one of said nodes also holding in said table a fourth processing
rule that provides for packet processing executed without dependency
upon control by said control device on receipt of the header-rewritten
packet from said another node.
The communication system according to any one of claims 1 to 6,
wherein,
said request staying means transiently stays said setting request to said
control device in response to a load on said control device.
The communication system according to any one of claims 4 to 7,
wherein,
the valid period of said third processing rule is adjusted in response to
the load on said control device.
The communication system according to any one of claims 2 to 8,
wherein,
said control device increases the number of nodes where said second
processing rule is set in response to the load on the own device.
The communication system according to any one of claims 2 to 9,
wherein,
said control device includes means for monitoring the load state of own
control device;
said control device setting said second processing rule in said node in
response to the load state of own control device.
The communication system according to any one of claims 2 to 10,
wherein,
at least one of said nodes includes means for monitoring the load state
of said control device;
said second processing rule being set in at least one of said nodes in
response to said load state.
The communication system according to any one of claims 4 to 11,
wherein,
said control device changes the valid period of said third processing
rule based upon the traffic information collected from said node or the
packet received from said node.
The communication system according to any one of claims 2 to 12,
wherein,
said control device decides the node where said second processing rule
is set or attribute of the packet as a subject of said second processing
WO 2012/077259 PCT/JP2011/004783
rule based upon the traffic information collected from said node or the
packet received from said node.
[Claim 14] The communication system according to any one of claims 1 to 13,
wherein,
a fifth processing rule is set in the node that transmitted said setting
request; said fifth processing rule providing that said node that
transmitted said setting request is to carry out discarding or queuing of
succeeding packets of the same attribute as that of the received packet
for a preset time period.
[Claim 15] A control device that controls a plurality of nodes; each of said nodes
on receipt of a packet referencing a table including a plurality of
processing rules concerning packet processing; each of said nodes
processing the packet received in accordance with at least one of said
processing rules corresponding to the packet received;
said control device comprising:
means for receiving a processing rule setting request transmitted from
the node that received a packet the corresponding processing rule of
which is not known;
means for setting, on receipt of said setting request, the processing rule
for the packet for at least one of said nodes; and
means for transmitting to at least one of said nodes a command to
transiently stay said setting request to said control device.
[Claim 16] The control device according to claim 15, further comprising:
means for setting, in at least one of said nodes, a second processing rule
providing for packet processing of transiently staying said setting
request to said control device.
[Claim 17] The control device according to claim 15 or 16, further comprising:
means for setting a third processing rule in at least one of said nodes;
said third processing rule being applied with priority to said second
processing rule and providing that said setting request is to be
transmitted to said control device.
[Claim 18] The control device according to claim 17, wherein,
said third processing rule provides for contents of processing that said
setting request is to be transmitted at the time of receipt of a packet a
corresponding processing rule for which is not known; said third
processing rule also providing a preset valid period thereof;
said control device including means for updating said third processing
rule at a preset time interval.
PCT/JP2011/004783
The control device according to any one of claims 16 to 18, wherein,
said second processing rule includes means for prescribing packet
processing executed without dependency upon the control by said
control device.
The control device according to any one of claims 16 to 18, further
comprising:
means for setting said second processing rule in at least one of said
nodes; said second processing rule providing for rewriting of a header
of said received packet and for forwarding of said header-rewritten
packet to another one of said nodes; and
means for setting, in at least one of said nodes, a fourth processing rule
on receipt of said header-rewritten packet from said another one of said
nodes; said fourth processing rule providing for packet processing
executed without dependency upon the control by said control device.
The control device according to any one of claims 15 to 20, further
comprising:
means for transmitting to at least one of said nodes a command for
transiently staying said setting request to said control device in
response to a load state in said control device.
The control device according to any one of claims 18 to 21, further
comprising:
means for adjusting the valid period of said third processing rule in
response to a load state in said control device.
The control device according to any one of claims 16 to 22, further
comprising:
means for increasing the number of nodes where said second
processing rule is set in response to the load state of the control device.
The control device according to any one of claims 16 to 23, further
comprising:
means for monitoring the load state of own control device; and
means for setting said second processing rule in said nodes in response
to the load state of the own control device.
The control device according to any one of claims 18 to 24, further
comprising:
means for changing the valid period of said third processing rule based
upon the traffic information collected from said node or the packet
received from said node.
The control device according to any one of claims 16 to 25, further
WO 2012/077259 PCT/JP2011/004783
comprising:
means for deciding the node where said second processing rule is set or
the attributes of a packet as a subject of said second processing rule,
based upon the traffic information collected from said node or the
packet received from said node.
[Claim 27] The control device according to any one of claims 15 to 26, wherein,
a fifth processing rule is set in the node that transmitted said setting
request; said fifth processing rule providing that said node that
transmitted said setting request is to carry out discarding or queuing of
succeeding packets of the same attribute as that of the packet received
for a preset time period.
[Claim 28] A communication method in which a packet is processed based upon
control by a control device that decides a forwarding path for said
packet; said communication method comprising the steps of:
referencing, on receipt of the packet, a table including a plurality of
processing rules concerning packet processing;
processing the packet received in accordance with at least one of said
processing rules corresponding to the packet received and transmitting
a processing rule setting request to said control device in case the corre
sponding processing rule is not known; and
transiently staying said setting request to the control device.
[Claim 29] A communication node in which a packet is processed based upon
control by a control device that decides a forwarding path for said
packet; said communication node comprising:
means for referencing, on receipt of the packet, a table including a
plurality of processing rules concerning packet processing, processing
the packet received in accordance with at least one of said processing
rules corresponding to the packet received and transmitting a
processing rule setting request to said control device in case the corre
sponding processing rule is not known;
means for receiving the setting of the processing rule for said setting
request from said control device; and
request staying means for transiently staying said setting request to the
control device.
[Claim 30] A program that allows a control device, controlling a plurality of nodes,
to reference a table including a plurality of processing rules concerning
packet processing, on receipt of a packet, and to process the received
packet in accordance with at least one of said processing rules correWO
2012/077259 PCT/JP2011/004783
sponding to said packet received; said program allowing said control
device to execute:
a processing of receiving the processing rule setting request transmitted
from a node that received the packet a corresponding processing rule
for which is not known;
a processing of setting the packet processing rule in at least one of said
nodes in case of receiving said setting request; and
a processing of transmitting to at least one of said nodes a command to
transiently stay said setting request to said control device.
[Claim 31] A network system, comprising:
a plurality of network nodes to refer to a table including a plurality of
packet handling rules, and to handle an incoming packet with at least
one of the packet handling rules, the one or more rules corresponding to
the incoming packet; and
a control device to set a new packet handling rule to at least one of the
network nodes when the control device receives an inquiry from a
network node which receives a first packet that a corresponding rule is
not included in the table,
wherein at least one of the network nodes comprises:
a unit to suspend the inquiry to the control device.