Description
Title of Invention: COMMUNICATION PATH CONTROL
SYSTEM, PATH CONTROL DEVICE, COMMUNICATION
PATH CONTROL METHOD, AND PATH CONTROL
PROGRAM
Technical Field
[0001] The present invention relates to a communication path control system, a path control
device, a communication path control method, and a path control program for con
trolling a communication path.
Background Art
[0002] A technology called OpenFlow is proposed in recent years (see Non Patent Lit
eratures (NPL) 1 and 2). OpenFlow is a technology that treats communication as an
end-to-end flow, and performs path control, failure recovery, load distribution, opti
mization, and the like on a flow-by-flow basis.
[0003] In a network where communication is performed using OpenFlow (hereafter referred
to as an OpenFlow network), an OpenFlow switch and an OpenFlow controller are
used. The OpenFlow switch functions as a packet transmitting device. The OpenFlow
controller functions as a path control device.
[0004] The OpenFlow switch includes a secure channel used for communication with the
OpenFlow controller, and operates according to a flow table for which an add in
struction or a rewrite instruction is appropriately sent from the OpenFlow controller via
the secure channel.
[0005] Fig. 15 is an explanatory diagram showing an ordinary flow table. In the flow table, a
combination including: a rule for matching (Header Fields) used for comparison
against a packet header; flow statistic information (Counters); and an action (Actions)
defining a process for a packet is defined for each flow.
[0006] For example, upon receiving a packet, the OpenFlow switch searches the flow table
for an entry including a rule for matching that matches header information of the
received packet. In the case where the entry matching the received packet is found as a
result of the search, the OpenFlow switch updates the flow statistic information
(Counters). In this case, the OpenFlow switch also performs a process (e.g. sending the
packet from a designated port, flooding, discard) defined in an action field of the entry,
on the received packet.
[0007] In the case where the entry matching the received packet is not found as a result of
searching the flow table, on the other hand, the OpenFlow switch transmits the
received packet to the OpenFlow controller via the secure channel. Thus, the
OpenFlow switch queries about a process for the packet. For instance, the OpenFlow
switch requests the OpenFlow controller to determine a path of the received packet
based on a source and a destination of the received packet, receives the determined
entry, and updates the flow table. Hence, the OpenFlow switch transmits the packet, by
using the entry stored in the flow table as a process rule.
[0008] Note that the OpenFlow controller also has a function of collecting the flow statistic
information (Counters) that is updated each time a packet is processed. This function is
also called a visualization function.
[0009] A system in which a switch transmits a packet based on a flow table controlled by a
controller is described in Patent Literature (PTL) 1. In the system described in PTL 1,
when the switch receives a packet not found in the flow table, the switch transmits the
packet to the controller. When the switch receives a packet found in the flow table, the
system transmits the packet based on the flow table.
[0010] Fig. 16 is an explanatory diagram showing an example of an ordinary packet flow in
the OpenFlow network. A packet flow in the network described in each of PTL 1, NPL
1, and NPL 2 is described below, with reference to Fig. 16.
[001 1] In the case where a terminal 310 sends the first data packet to a terminal 320, the data
packet is first sent to a packet transmitting device 210 connected to the terminal 320
(step S901). Upon receiving the packet, the packet transmitting device 210 searches a
flow table for an entry including a rule for matching (also referred to as a comparison
rule or a matching key) that matches header information of the received packet.
[0012] However, since the received packet is the first packet, there is no corresponding entry
in the flow table. Accordingly, the packet transmitting device 210 buffers the received
packet, and then sends a control message indicating that a new flow is detected
(hereafter also referred to as an information message about detecting a new flow or a
Packet-In message), to a path control device (controller) 100 (step S902).
[0013] The Packet-In message includes information necessary for identifying the flow (e.g. a
MAC (Media Access Control) address, an IP (Internet Protocol) address, a port number
(for both the source and the destination)) and information indicating a receiving port of
the packet.
[0014] It is assumed here that the packet transmitting device 210 buffers the received packet
and sends the information necessary for identifying the flow to the path control device
(controller) 100, but there is also an instance where the packet transmitting device 210
sends the received packet itself to the path control device (controller) 100.
[0015] Upon receiving the Packet-In message, the path control device (controller) 100
creates a comparison rule (matching key) of a new entry from the received message,
and determines a timer value applied to the entry. Information created as the
comparison rule is, for instance, the information from "InPort" to "TCP/UDP src port"
shown as an example in Fig. 15.
[0016] The path control device (controller) 100 further checks a location of the terminal 320
as the destination based on the received message, and computes a packet transmission
route from the terminal 310 to the terminal 320. It is assumed here that, as a result of
transmission route computation, the transmission route of transmitting the packet in the
order of the packet transmitting device 210 -> a packet transmitting device 220 -> a
packet transmitting device 230 is computed.
[0017] Next, the path control device (controller) 100 creates an entry in which an action
defining transmission according to the computed transmission route and the timer
value are set for a packet that matches the comparison rule (matching key) of the new
entry, for each of the packet transmitting devices 210 to 230. The path control device
(controller) 100 notifies each of the packet transmitting devices 210 to 230 of the
created entry, using a FlowMod message (step S903). The FlowMod message
mentioned here is a message used when the controller requests the switch to register,
change, or delete a flow. Upon receiving the FlowMod message, each of the packet
transmitting devices 210 to 230 sets the received entry in the flow table.
[0018] Having completed the setting of the entry, the packet transmitting device 210
transmits the buffered packet to the packet transmitting device 220, according to the set
entry (step S904-1). The packet transmitting devices 220 and 230 on the transmission
route through which the packet is to be transmitted have already set the entry, so that
the packet is transmitted to the packet transmitting device 220 and then to the packet
transmitting device 230, and eventually arrives at the terminal 320 (steps S904-2 and
S904-3).
[0019] Subsequently, in the case of sending a packet from the terminal 310 to the terminal
320, the packet is transmitted in the order of the packet transmitting device 210 -> the
packet transmitting device 220 -> the packet transmitting device 230 according to the
transmission route (steps S905-1 to S905-4), and arrives at the terminal 320.
Citation List
Patent Literature
[0020] PTL 1: Domestic re-publication of PCT International Application No.
WO2008/095010
Non Patent Literature
[0021] NPL 1: Nick McKeown, and seven others, "OpenFlow: Enabling Innovation in
Campus Networks", [online], [search on July 6, 2010], Internet , March 14, 2008
NPL 2: "OpenFlow Switch Specification", Version 1.0.0. (Wire Protocol 0x01)
[search on July 6, 2010], Internet , December 31,
2009
Summary of Invention
Technical Problem
[0022] As described above, in the OpenFlow network, the OpenFlow switch receives a data
packet. In the case where an entry corresponding to the received packet is not found in
the flow table, the OpenFlow switch transmits the received packet to the OpenFlow
controller via the secure channel. Thus, the OpenFlow switch queries about an action
for the data packet. This query is also referred to as Packet-In.
[0023] The OpenFlow controller determines a path of the received packet, based on in
formation indicating a source and a destination of the received packet. The OpenFlow
controller sends the determined path information (hereafter also referred to as
FlowMod) to all OpenFlow switches on the path, using a secure channel formed
according to TCP (Transmission Control Protocol), SSL (Secure Sockets Layer), or the
like.
[0024] That is, the OpenFlow network can be regarded as a network in which the OpenFlow
controller and the OpenFlow switch exchange (send/receive) control messages to
thereby enable a data packet to arrive at its destination. Therefore, when the number of
flows increases, the number of control messages sent/received between the OpenFlow
controller and the OpenFlow switch increases, too. This raises a possibility of putting
significant pressure on network bandwidth.
[0025] Fig. 17 is an explanatory diagram showing another example of a packet flow in the
OpenFlow network. Steps S201-1 to S202 in which the path control device 100
receives the Packet-In message from the packet transmitting device and computes the
transmission route are the same as steps S901 to S902 in Fig. 16.
[0026] Having completed the computation of the transmission route, the path control device
(controller) 100 creates the entry in which the action defining transmission according
to the computed transmission route and the timer value are set for a packet that
matches the comparison rule (matching key) of the new entry, for each of the packet
transmitting devices 210 to 230. The path control device (controller) 100 notifies each
of the packet transmitting devices 210 to 230 of the created entry, using the FlowMod
message (steps S203-1, S203-2, and S203-3).
[0027] Suppose here that, when notifying each of the packet transmitting devices 210 to 230
of the created entry, the FlowMod message to the packet transmitting device 210 (the
FlowMod message sent in step S203-1) and the FlowMod message to the packet
transmitting device 230 (the FlowMod message sent in step S203-3) arrive at the
packet transmitting devices 210 and 230 respectively, but the FlowMod message to the
packet transmitting device 220 (the FlowMod message sent in step S203-2) does not
arrive at the packet transmitting device 220 due to a packet loss, a delay, or the like
caused by network congestion.
[0028] Having received the FlowMod message and completed the setting of the entry in the
flow table, the packet transmitting device 210 transmits the buffered packet to the
packet transmitting device 220, according to the set entry (step S201-2). Upon
receiving the data packet from the packet transmitting device 210, the packet
transmitting device 220 searches the flow table for an entry including a comparison
rule (matching key) that matches the header information of the packet. However, since
the FlowMod message does not arrive at the packet transmitting device 220, there is no
corresponding entry in the flow table. Accordingly, the packet transmitting device 220
buffers the received packet, and then sends an information message about detecting a
new flow (Packet-In message) to the path control device (controller) 100 (step S204).
[0029] Upon receiving the Packet-In message, the path control device (controller) 100
creates a comparison rule (matching key) of a new entry based on the received in
formation, and determines a timer value applied to the entry. Information created as the
comparison rule is, for instance, the information from "InPort" to "TCP/UDP src port"
shown as an example in Fig. 15. The path control device (controller) 100 further
checks the location of the terminal 320 as the destination based on the received in
formation, and computes a packet transmission route from the terminal 310 to the
terminal 320. It is assumed here that, as a result of transmission route computation, the
transmission route of transmitting the packet in the order of the packet transmitting
device 220 -> the packet transmitting device 230 is computed.
[0030] Next, the path control device (controller) 100 creates an entry in which an action
defining transmission according to the computed transmission route and the timer
value are set for a packet that matches the comparison rule (matching key) of the new
entry, for each of the packet transmitting devices 220 and 230. The path control device
(controller) 100 notifies each of the packet transmitting devices 220 and 230 of the
created entry, using a FlowMod message (steps S205-1 and S205-2).
[0031] The packet transmitting devices 220 and 230 each successfully receive the FlowMod
message, and set the received entry in the flow table. As a result of setting the entry in
this way, the terminal 320 can receive the data packet.
[0032] However, the FlowMod message received by the packet transmitting device 230 in
step S203-3 and the FlowMod message received by the packet transmitting device 230
in step S205-2 are the same message, because they relate to the entry for the same data
packet. This means that the packet transmitting device 230 receives the same message
twice from the path control device 100.
[0033] Sending/receiving such a redundant control packet has a possibility of causing a
decrease in use efficiency of the network. In the examples shown in Figs. 16 and 17,
there are three packet transmitting devices between the terminal 310 and the terminal
320. However, an increase in the number of packet transmitting devices between the
terminals (i.e. an increase in hop count) can lead to a further increase in the number of
unnecessary control packets. Sending/receiving such unnecessary control packets is
likely to impact the network and decrease the use efficiency of the network.
[0034] In view of this, an exemplary object of the present invention is to provide a commu
nication path control system, a path control device, a communication path control
method, and a path control program that can reduce the number of packets used for
communication path control.
Solution to Problem
[0035] A communication path control system according to an exemplary aspect of the
present invention is a communication path control system comprising: a packet
transmitting device for transmitting a received packet based on a packet transmission
rule which is a rule defining a transmission method of the packet; and a path control
device for controlling a communication path of the packet, by instructing the packet
transmitting device to apply the packet transmission rule, wherein the packet
transmitting device includes process querying means for querying the path control
device about a process for the received packet, and wherein the path control device
includes packet transmitting device determining means for, when receiving the query
about the process for the packet from the packet transmitting device, determining a
packet transmitting device that is to apply the packet transmission rule determined
according to the packet, based on whether or not the query about the process for the
packet is a first-time query.
[0036] A path control device according to an exemplary aspect of the present invention is a
path control device comprising packet transmitting device determining means for,
when receiving a query about a process for a packet from a packet transmitting device
that transmits a received packet based on a packet transmission rule which is a rule
defining a transmission method of the packet, determining a packet transmitting device
that is to apply the packet transmission rule determined according to the packet, based
on whether or not the query about the process for the packet is a first-time query.
[0037] A communication path control method according to an exemplary aspect of the
present invention is a communication path control method wherein a packet
transmitting device for transmitting a received packet based on a packet transmission
rule which is a rule defining a transmission method of the packet queries a path control
device for controlling a communication path of the packet, about a process for the
received packet, and wherein, when receiving the query about the process for the
packet from the packet transmitting device, the path control device determines a packet
transmitting device that is to apply the packet transmission rule determined according
to the packet, based on whether or not the query about the process for the packet is a
first-time query.
[0038] A path control program according to an exemplary aspect of the present invention is
a path control program for causing a computer to execute a packet transmitting device
determining process of, when receiving a query about a process for a packet from a
packet transmitting device that transmits a received packet based on a packet
transmission rule which is a rule defining a transmission method of the packet, de
termining a packet transmitting device that is to apply the packet transmission rule de
termined according to the packet, based on whether or not the query about the process
for the packet is a first-time query.
Advantageous Effects of Invention
[0039] According to the present invention, the number of packets used for communication
path control can be reduced.
Brief Description of Drawings
[0040] [fig. 1]Figure 1 is a block diagram showing an example of a communication path
control system in Exemplary Embodiment 1 of the present invention.
[fig.2]Figure 2 is a block diagram showing an example of a packet transmitting device.
[fig.3]Figure 3 is a block diagram showing an example of a path control device in
Exemplary Embodiment 1.
[fig.4]Figure 4 is a flowchart showing an example of an operation of the path control
device.
[fig.5]Figure 5 is a block diagram showing an example of a path control device in
Exemplary Embodiment 2 of the present invention.
[fig.6]Figure 6 is an explanatory diagram showing an example of a packet flow in an
OpenFlow network.
[fig.7]Figure 7 is an explanatory diagram showing an example of a communication
path control system in Example 1 of the present invention.
[fig.8]Figure 8 is a flowchart showing an example of an operation of a path control
device.
[fig.9]Figure 9 is an explanatory diagram showing an example of an operation of de
termining a packet transmitting device that is to be notified of a process rule
[fig. 10]Figure 10 is an explanatory diagram showing an example of network topology
information.
[fig. 11]Figure 11 is an explanatory diagram showing an example of a packet flow in
the OpenFlow network.
[fig. 12]Figure 12 is an explanatory diagram showing an example of an operation of de
termining a packet transmitting device.
[fig. 13]Figure 13 is a block diagram showing an example of a minimum structure of a
communication path control system according to the present invention.
[fig. 14]Figure 14 is a block diagram showing an example of a minimum structure of a
path control device according to the present invention.
[fig.l5]Figure 15 is an explanatory diagram showing a flow table.
[fig. 16]Figure 16 is an explanatory diagram showing an example of a packet flow in
the OpenFlow network.
[fig.l7]Figure 17 is an explanatory diagram showing an example of a packet flow in
the OpenFlow network.
Description of Embodiments
[0041] The following describes exemplary embodiments of the present invention with
reference to drawings.
[0042] Exemplary Embodiment 1
Fig. 1 is a block diagram showing an example of a communication path control
system in Exemplary Embodiment 1 of the present invention. The communication path
control system in Exemplary Embodiment 1 includes a path control device 100, packet
transmitting devices 210 to 230, and terminals 310 and 320. Note, however, that the
number of packet transmitting devices and the number of terminals are not limited to
the numbers shown as an example in Fig. 1. The number of packet transmitting devices
may be one, two, or four or more. The number of terminals may be three or more.
[0043] Each of the packet transmitting devices 210 to 230 is a device that, when receiving a
packet, transmits the received packet based on a predetermined rule. This rule is also
referred to as a packet transmission rule. For example, the packet transmitting device is
realized by a router, a switch, or the like.
[0044] Fig. 2 is a block diagram showing an example of the packet transmitting device 210.
Since the packet transmitting devices 220 and 230 have the same structure as the
packet transmitting device 210, their description is omitted. The packet transmitting
device 210 includes a control message sending/receiving unit 2 11, a flow table storage
unit 212, and a packet management unit 213.
[0045] The control message sending/receiving unit 211 has a function of communicating
with the path control device 100. That is, the control message sending/receiving unit
2 11 sends/receives a control message to/from the path control device 100.
[0046] The flow table storage unit 212 stores a flow table. In the flow table, a combination
including: a rule for matching (Header Fields) used for comparison against a packet
header; flow statistic information (Counters); and an action (Actions) defining a
process for a packet is defined for each flow. This combination is hereafter also
referred to as a process rule (flow entry). For instance, the information shown as an
example in Fig. 15 is included in the flow table.
[0047] The packet management unit 213 manages a received packet based on an action
included in the flow table. In detail, when the packet transmitting device 210 receives a
packet, the packet management unit 213 searches the flow table stored in the flow table
storage unit 212 for a process rule (flow entry) including a comparison rule (matching
key) that matches the received packet. In the case where the flow entry that matches
the received packet is found as a result of the search, the packet management unit 213
performs a process (e.g. sending the packet from a designated port, flooding, discard)
defined in an action field of the flow entry, on the received packet.
[0048] In the case where the entry that matches the received packet is not found in the flow
table, the packet management unit 213 sends a control message indicating that a new
flow is detected (i.e. an information message about detecting a new flow) to the path
control device 100, thereby querying about a process for the packet.
[0049] The path control device 100 is a device that performs path control in the network
managed by the path control device 100. In detail, the path control device 100 is a
device that controls a packet communication path, by instructing a packet transmitting
device to apply a packet transmission rule. In Exemplary Embodiment 1, the path
control device 100 manages the packet transmitting devices 210 to 230. Fig. 3 is a
block diagram showing an example of the path control device 100. The path control
device 100 includes a control message destination determining unit 101, a topology
management unit 102, a path/action computing unit 103, a communication unit 104, a
control message management unit 105, and a terminal location storage unit 106.
[0050] The communication unit 104 has a function by which the path control device 100
communicates with the packet transmitting devices 210 to 230. That is, the commu
nication unit 104 sends/receives a packet to/from the packet transmitting devices 210
to 230.
[0051] The topology management unit 102 creates network topology information based on
connection relations of the packet transmitting devices 210 to 230 collected via the
communication unit 104, and stores the created topology information. The topology in
formation mentioned here is information indicating a connection configuration in
which a packet transmitting device connects with another device. For example, the
topology management unit 102 collects information of a path table held in each of the
packet transmitting devices 210 to 230, and creates the network topology information
based on the path table. Note, however, that the method of creating the network
topology information is not limited to this. The topology management unit 102 may
receive network topology information from another path control device 100 and store
the received network topology information.
[0052] The terminal location storage unit 106 stores terminal location information. For
example, the terminal location storage unit 106 stores a database of location in
formation such as an IP address. The terminal location information may be stored in
the terminal location storage unit 106 beforehand by an administrator or the like. Alter
natively, whenever the path control device 100 receives location information from
another path control device, the received location information may be stored in the
terminal location storage unit 106. For example, the terminal location storage unit 106
is realized by a magnetic disk or the like.
[0053] The path/action computing unit 103 computes an action to be executed by the packet
transmitting devices 210 to 230 and a packet transmission route, as a process rule (flow
entry). In detail, the path/action computing unit 103 specifies locations of a source
terminal and a destination terminal from the location information stored in the terminal
location storage unit 106, and computes a transmission route of a packet based on the
network topology information managed by the topology management unit 102. The
path/action computing unit 103 also determines a process (action) to be executed on
the packet by each packet transmitting device on the transmission route. An arbitrary
method may be used as the method of determining the action. For example, in the case
where the path/action computing unit 103 successfully computes the transmission
route, the path/action computing unit 103 may determine that an action of transmitting
the packet is to be executed. For a packet of a predetermined type, on the other hand,
the path/action computing unit 103 may determine that a predetermined action such as
discarding the packet, transmitting the packet to a predetermined device, or the like is
to be executed.
[0054] The control message destination determining unit 101 determines a packet
transmitting device that is to be notified of the process rule (flow entry), from among
the packet transmitting devices on the path computed by the path/action computing
unit 103. In detail, the control message destination determining unit 101 determines the
packet transmitting device that is to be notified of the flow entry (i.e. that is to apply
the flow entry), based on whether or not a query about a process for the packet from a
packet transmitting device is a first-time query.
[0055] The control message management unit 105 analyzes a control message received from
the packet transmitting devices 210 to 230, and passes the control message to a corre
sponding unit in the path control device 100. For example, in the case of receiving an
information message about detecting a new flow from any of the packet transmitting
devices 210 to 230, the control message management unit 105 requests the path/action
computing unit 103 to create a new process rule (flow entry).
[0056] The control message destination determining unit 101, the topology management unit
102, the path/action computing unit 103, the communication unit 104, and the control
message management unit 105 are realized by a CPU of a computer operating
according to a program (path control program). For example, the program may be
stored in a storage unit (not shown) in the path control device 100, with the CPU
reading the program and, according to the program, operating as the control message
destination determining unit 101, the topology management unit 102, the path/action
computing unit 103, the communication unit 104, and the control message
management unit 105. Alternatively, the control message destination determining unit
101, the topology management unit 102, the path/action computing unit 103, the com
munication unit 104, and the control message management unit 105 may be each
realized by dedicated hardware.
[0057] The following describes an operation of the communication path control system in
Exemplary Embodiment 1, with reference to Fig. 16.
[0058] When the terminal 310 sends a data packet to the packet transmitting device 210 and
the packet transmitting device 210 receives the packet (step S901), the packet
management unit 213 searches the flow table for an entry including a comparison rule
(matching key) that matches header information of the received packet. However,
since the received packet is the first packet, there is no corresponding entry in the flow
table. Accordingly, the packet management unit 213 buffers the received packet, and
then sends an information message about detecting a new flow to the path control
device 100 (step S902).
[0059] The information message about detecting a new flow includes information necessary
for identifying the flow (e.g. a MAC address, an IP address, a port number (for both
the source and the destination)) and information indicating a receiving port of the
packet.
[0060] It is assumed here that the packet transmitting device 210 buffers the received packet
and sends the information necessary for identifying the flow to the path control device
100, but the packet transmitting device 210 may send the received packet itself to the
path control device 100.
[0061] An operation when the path control device 100 receives the information message
about detecting a new flow is described below. Fig. 4 is a flowchart showing an
example of the operation of the path control device 100.
[0062] When the path control device 100 receives the information message about detecting a
new flow from the packet transmitting device 210 (step S1501 in Fig. 4), the path/
action computing unit 103 computes a path of the packet, and determines an action of
each packet transmitting device located on the path (step S1502). Following this, the
control message destination determining unit 101 determines a packet transmitting
device as a destination that is to be notified of a process rule including the action, from
among the packet transmitting devices on the path (step S1503).
[0063] In detail, when the information message about detecting a new flow is received, the
control message destination determining unit 101 determines whether or not the packet
transmitting device sending the information message is the first packet transmitting
device from the source terminal of the data packet. For example, the control message
destination determining unit 101 may reference the network topology information and
determine whether or not the device sending the data packet to the packet transmitting
device is the terminal or not, based on information included in the information message
about detecting a new flow, namely, the identifier of the packet transmitting device and
the port number of the port at which the packet transmitting device receives the data
packet.
[0064] In the case where the packet transmitting device sending the information message
about detecting a new flow is the first packet transmitting device from the source
terminal of the data packet, the control message destination determining unit 101 de
termines to notify the process rule to all packet transmitting devices on the path
computed by the path/action computing unit 103. In the case where the packet
transmitting device sending the information message about detecting a new flow is not
the first packet transmitting device, on the other hand, the control message destination
determining unit 101 determines to notify the process rule only to the packet
transmitting device sending the information message about detecting a new flow. The
control message destination determining unit 101 sends the process rule to the de
termined control message destination (step S1504).
[0065] When each of the packet transmitting devices 210 to 230 receives the process rule
from the path control device 100, the control message sending/receiving unit 2 11 sets
the received entry in the flow table. The packet management unit 213 then transmits
the buffered packet to the packet transmitting device 220, according to the set entry
(step S904-1 in Fig. 16). The packet transmitting devices 220 and 230 on the
transmission route through which the packet is to be transmitted have already set the
entry, so that the packet is transmitted to the packet transmitting device 220 and then to
the packet transmitting device 230, and eventually arrives at the terminal 320 (steps
S904-2 and S904-3).
[0066] As described above, according to Exemplary Embodiment 1, the control message
sending/receiving unit 211 in a packet transmitting device queries the path control
device 100 about a process for a received packet. When receiving the query about the
process for the received packet from the packet transmitting device, the control
message destination determining unit 101 in the path control device 100 determines a
packet transmitting device that is to apply a packet transmission rule determined
according to the packet, based on whether or not the query about the process for the
packet is a first-time query.
[0067] In detail, the control message destination determining unit 101 determines the packet
transmitting device that is to apply the packet transmission rule, based on whether or
not the packet transmitting device making the query is the first packet transmitting
device on a path through which the packet is to be transmitted. According to such a
structure, the number of packets used for communication path control can be reduced.
Since it is possible to avoid sending a redundant control packet from the OpenFlow
controller to the OpenFlow switch, an improvement in network use efficiency, a
reduction in control packet sending load in the OpenFlow controller, and a reduction in
control packet management load in the OpenFlow switch can be expected.
[0068] Exemplary Embodiment 2
The following describes a communication path control system in Exemplary Em
bodiment 2 of the present invention. The communication path control system in
Exemplary Embodiment 2 includes the path control device 100, the packet transmitting
devices 210 to 230, and the terminals 310 and 320, too, as shown as an example in Fig.
1.
[0069] The path control device 100 is a device that performs path control in the network
managed by the path control device 100, as in Exemplary Embodiment 1. In
Exemplary Embodiment 2, the path control device 100 manages the packet
transmitting devices 210 to 230. The path control device 100 in Exemplary Em
bodiment 2 is a device having additional functions to the path control device 100 in
Exemplary Embodiment 1.
[0070] Fig. 5 is a block diagram showing an example of the path control device 100 in
Exemplary Embodiment 2. The path control device 100 in Exemplary Embodiment 2
includes the control message destination determining unit 101, the topology
management unit 102, the path/action computing unit 103, the communication unit
104, the control message management unit 105, the terminal location storage unit 106,
a flow entry storage unit 107, and a flow entry management unit 108.
[0071] That is, the path control device 100 in Exemplary Embodiment 2 differs from the
path control device 100 in Exemplary Embodiment 1, in that the functions of the flow
entry storage unit 107 and the flow entry management unit 108 are added.
[0072] The communication unit 104 has a function by which the path control device 100
communicates with the packet transmitting devices 210 to 230.
[0073] The topology management unit 102 creates network topology information based on
connection relations of the packet transmitting devices 210 to 230 collected via the
communication unit 104, and stores the created topology information. The method of
creating and storing the topology information is the same as that in Exemplary Embodiment
1. The terminal location storage unit 106 stores terminal location in
formation. The information stored in the terminal location storage unit 106 is the same
as that in Exemplary Embodiment 1. For example, the terminal location storage unit
106 is realized by a magnetic disk or the like.
[0074] The path/action computing unit 103 computes an action to be executed by the packet
transmitting devices 210 to 230 and a packet transmission route, as a process rule (flow
entry). In detail, the path/action computing unit 103 specifies locations of a source
terminal and a destination terminal and computes a transmission route of a packet,
from the network topology information managed by the topology management unit
102 and the location information stored in the terminal location storage unit 106. The
path/action computing unit 103 also determines a process (action) to be executed on
the packet by the packet transmitting devices 210 to 230 on the transmission route.
[0075] The control message destination determining unit 101 determines a packet
transmitting device that is to be notified of the process rule (flow entry), from among
the packet transmitting devices on the path computed by the path/action computing
unit 103. In detail, according to a determination result of the flow entry management
unit 108 described later, the control message destination determining unit 101 de
termines the packet transmitting device that is to be notified of the flow entry (i.e. that
is to apply the flow entry), based on whether or not a query about a process for the
packet from a packet transmitting device is a first-time query.
[0076] The control message management unit 105 analyzes a control message received from
the packet transmitting devices 210 to 230, and passes the control message information
to a corresponding unit in the path control device (controller) 100. For example, in the
case of receiving an information message about detecting a new flow (Packet-In) from
any of the packet transmitting devices 210 to 230, the control message management
unit 105 requests the path/action computing unit 103 to create a new process rule (flow
entry).
[0077] The flow entry storage unit 107 stores a flow entry. In detail, the flow entry storage
unit 107 stores a database of a flow entry. For example, the flow entry storage unit 107
is realized by a magnetic disk or the like. As shown as an example in Fig. 15, the flow
entry storage unit 107 stores a process rule (flow entry) including a comparison rule
(rule for matching), an action (including a timer value), and flow statistic information.
[0078] The flow entry management unit 108 creates a comparison rule (matching key),
based on the information received from the node (packet transmitting device). The
flow entry management unit 108 also stores the flow entry computed by the path/action
computing unit 103, in the flow entry storage unit 107. When doing so, the flow entry
management unit 108 determines whether or not the flow entry is already stored in the
flow entry storage unit 107. In the case where the flow entry is already stored in the
flow entry storage unit 107, the flow entry management unit 108 determines that the
query about the process for the received packet is not the first-time query. In the case
where the flow entry is not stored in the flow entry storage unit 107, on the other hand,
the flow entry management unit 108 determines that the query about the process for the
received packet is the first-time query. The flow entry management unit 108 notifies
the control message destination determining unit 101 of the determination result.
[0079] Moreover, in response to a request to add or update a process rule (flow entry) from
the packet transmitting devices 210 to 230, the flow entry management unit 108
instructs to set the process rule (flow entry) in the flow table storage unit 212.
[0080] The control message destination determining unit 101, the topology management unit
102, the path/action computing unit 103, the communication unit 104, the control
message management unit 105, and the flow entry management unit 108 are realized
by a CPU of a computer operating according to a program (path control program). Al
ternatively, the control message destination determining unit 101, the topology
management unit 102, the path/action computing unit 103, the communication unit
104, the control message management unit 105, and the flow entry management unit
108 may be each realized by dedicated hardware.
[0081] Each of the packet transmitting devices 210 to 230 is a device that, when receiving a
packet, transmits the received packet based on a predetermined rule, as in Exemplary
Embodiment 1. The packet transmitting devices 210 to 230 in Exemplary Embodiment
2 have the same structure as shown as an example in Fig. 2. That is, the packet
transmitting device 210 in Exemplary Embodiment 2 includes the control message
sending/receiving unit 211, the flow table storage unit 212, and the packet management
unit 213.
[0082] The control message sending/receiving unit 211 has a function of communicating
with the path control device 100.
[0083] The flow table storage unit 212 stores a flow table. In the flow table, a combination
including: a rule for matching (Header Fields) used for comparison against a packet
header; flow statistic information (Counters); and an action (Actions) defining a
process for a packet is defined for each flow, as in Exemplary Embodiment 1 (see Fig.
15).
[0084] The packet management unit 213 searches the flow table storage unit 212 for a
process rule (flow entry) including a comparison rule (matching key) that matches a
received packet, and performs a process (e.g. transmitting the packet to a designated
port, flooding, discard) defined in an action field of the process rule (flow entry).
[0085] The following describes an operation of the communication path control system in
Exemplary Embodiment 2. Fig. 6 is an explanatory diagram showing an example of a
packet flow in the OpenFlow network.
[0086] When the terminal 310 sends a data packet to the packet transmitting device 210 and
the packet transmitting device 210 receives the packet (step S1401), the packet
management unit 213 searches the flow table for an entry including a comparison rule
(matching key) that matches header information of the received packet. However,
since the received packet is the first packet, there is no corresponding entry in the flow
table. Accordingly, the packet management unit 213 buffers the received packet, and
then sends an information message about detecting a new flow to the path control
device 100 (step S1402).
[0087] The information message about detecting a new flow includes information necessary
for identifying the flow (e.g. a MAC address, an IP address, a port number (for both
the source and the destination)) and information indicating a receiving port of the
packet.
[0088] It is assumed here that the packet transmitting device 210 buffers the received packet
and sends the information necessary for identifying the flow to the path control device
100, but the packet transmitting device 210 may send the received packet itself to the
path control device 100.
[0089] An operation when the path control device 100 receives the information message
about detecting a new flow is described below, with reference to Fig. 4.
[0090] When the path control device 100 receives the information message about detecting a
new flow from the packet transmitting device 210 (step S1501 in Fig. 4), the path/
action computing unit 103 computes a path of the packet, and determines an action of
each packet transmitting device located on the path (step S1502). Following this, an
operation of determining a packet transmitting device as a destination that is to be
notified of a process rule including the action from among the packet transmitting
devices on the path is carried out in the path control device 100 (step S1503).
[0091] First, the flow entry management unit 108 extracts the information for identifying the
flow, from the information message about detecting a new flow. When registering an
entry corresponding to the flow in the flow entry storage unit 107, the flow entry
management unit 108 determines whether or not the flow entry is already stored in the
flow entry storage unit 107.
[0092] In the case where the flow entry is already stored in the flow entry storage unit 107,
the control message destination determining unit 101 determines to notify the process
rule only to the packet transmitting device sending the information message about
detecting a new flow. In the case where the flow entry is not stored in the flow entry
storage unit 107, on the other hand, the control message destination determining unit
101 determines to notify the process rule to all packet transmitting devices on the path
computed by the path/action computing unit 103. The control message destination de
termining unit 101 notifies the process rule to the determined control message destination
(step S1504).
[0093] When each of the packet transmitting devices 210 to 230 receives the process rule
from the path control device 100, the control message sending/receiving unit 2 11 sets
the received entry in the flow table. The packet management unit 213 then transmits
the buffered packet to the packet transmitting device 220, according to the set entry
(step S1404-1 in Fig. 6). The packet transmitting devices 220 and 230 on the
transmission route through which the packet is to be transmitted have already set the
entry, so that the packet is transmitted to the packet transmitting device 220 and then to
the packet transmitting device 230, and eventually arrives at the terminal 320 (steps
S1404-2 and S1404-3). Subsequently, in the case of sending a packet from the terminal
310 to the terminal 320, the packet is transmitted in the order of the packet transmitting
device 210 -> the packet transmitting device 220 -> the packet transmitting device 230
according to the transmission route (steps S1405-1 to S1405-4), and arrives at the
terminal 320.
[0094] As described above, according to Exemplary Embodiment 2, based on whether or not
a packet transmission rule corresponding to a packet for which a query about a process
is made is stored in the flow entry storage unit 107, the control message destination de
termining unit 101 determines a packet transmitting device that is to apply the packet
transmission rule. According to such a structure, too, the number of packets used for
communication path control can be reduced.
Example 1
[0095] The following describes the present invention by way of specific examples.
However, the scope of the present invention is not limited to the following. Example 1
corresponds to the communication path control system in Exemplary Embodiment 1 of
the present invention.
[0096] Fig. 7 is an explanatory diagram showing an example of a communication path
control system in Example 1 of the present invention. The communication path control
system in Example 1 includes the two terminals 310 and 320, the three packet
transmitting devices 210 to 230 between the terminals 310 and 320, and the path
control device 100 for controlling the network. Note that a one-digit number shown on
either side of each of the packet transmitting devices 210 to 230 is a port number of a
port in the device, and a three-digit number assigned to each of the packet transmitting
devices 210 to 230 is an identifier of the device.
[0097] A communication path control system intended for the OpenFlow network is
described in Example 1. The path control device 100 corresponds to a device that
includes, in the OpenFlow controller, a function of determining a packet transmitting
device to be notified of a process rule (flow entry). Meanwhile, each packet
transmitting device corresponds to the OpenFlow switch. The following describes an
operation of the communication path control system in Example 1, with reference to
Fig. 16.
[0098] When the terminal 310 sends a data packet to the packet transmitting device 210 and
the packet transmitting device 210 receives the packet (step S901), the packet
management unit 213 searches the flow table for an entry including a comparison rule
(matching key) that matches header information of the received packet. However,
since the received packet is the first packet, there is no corresponding entry in the flow
table. Accordingly, the packet management unit 213 buffers the received packet, and
then sends an information message about detecting a new flow (Packet-In message) to
the path control device 100 (step S902).
[0099] The Packet-In message includes information necessary for identifying the flow (e.g. a
MAC address, an IP address, a port number (for both the source and the destination))
and information indicating a receiving port of the packet.
[0100] It is assumed here that the packet transmitting device 210 buffers the received packet
and sends the information necessary for identifying the flow to the path control device
100, but the packet transmitting device 210 may send the received packet itself to the
path control device 100.
[0101] An operation when the path control device 100 receives the Packet-In message is
described below. Fig. 8 is a flowchart showing an example of the operation of the path
control device 100.
[0102] When the path control device 100 receives the Packet-In message from the packet
transmitting device 210 (step S301), the path/action computing unit 103 computes a
path of the packet, and determines an action of each packet transmitting device located
on the path (step S302). Following this, the control message destination determining
unit 101 determines a packet transmitting device as a destination that is to be notified
of a process rule including the action, from among the packet transmitting devices on
the path (step S303). The control message destination determining unit 101 notifies a
FlowMod message to the determined control message destination (step S304).
[0103] Fig. 9 is an explanatory diagram showing an example of an operation of determining
the packet transmitting device to be notified of the process rule. Step S303 is described
in detail below, with reference to Fig. 9.
[0104] When the Packet-In message is received, the control message destination determining
unit 101 determines whether or not the packet transmitting device sending the Packet-
In message is the first packet transmitting device from the source terminal of the data
packet. In Example 1, this determination is performed using the identifier of the packet
transmitting device sending the Packet-In message and, from among port numbers
specified from the Packet-In message, the port number of the port (hereafter also
referred to as Input Port) at which the packet transmitting device receives the data
packet (step S401). Note that the method of determination is not limited to the deter
mination method using the port number and the identifier of the packet transmitting
device described in Example 1. Any other method is applicable so long as whether or
not the packet transmitting device sending the Packet- In message is the first packet
transmitting device from the source terminal of the data packet can be determined.
[0105] In the communication path control system shown as an example in Fig. 7, the
identifier of the packet transmitting device 210 is "210", and the Input Port is "1".
Suppose here that the topology management unit 102 computes network topology in
formation from the identifiers and the port numbers in the path control device 100
shown as an example in Fig. 7, and holds the computed network topology information.
Fig. 10 is an explanatory diagram showing an example of network topology in
formation computed by the topology management unit 102. In the example shown in
Fig. 10, a square denotes a terminal, and a circle denotes a packet transmitting device.
A three-digit number below the square or the circle is an identifier of the device, and a
one-digit number on either side of the square or the circle is a port number.
[0106] The control message destination determining unit 101 accesses the topology
management unit 102 (step S402), and determines whether or not a device connected
to the packet transmitting device is another packet transmitting device (step S403).
Here, the control message destination determining unit 101 checks a device connected
to the port of the port number "1" of the device identified by the identifier "210", from
the network topology information shown as an example in Fig. 10. In the example
shown in Fig. 10, the device connected to the port of the port number "1" of the packet
transmitting device 210 is the terminal 310. Thus, the control message destination de
termining unit 101 detects that the device adjacent to the packet transmitting device
210 is the terminal 310 (step S403: N). The control message destination determining
unit 101 accordingly notifies the process rule (path information) to all packet
transmitting devices on the path computed by the path/action computing unit 103 (step
405).
[0107] In the case where the device adjacent to the packet transmitting device 210 is another
packet transmitting device (step S403: Y), on the other hand, the control message des
tination determining unit 101 notifies the process rule only to the packet transmitting
device sending the Packet-In message (step S404). An operation in the case where the
device adjacent to the packet transmitting device is another packet transmitting device
will be described later.
[0108] Having determined the destination of the FlowMod message, the control message
destination determining unit 101 sends the FlowMod message to the packet
transmitting devices 210 to 230 (step S903 in Fig. 16). The packet management unit
213 transmits the buffered packet to the packet transmitting device 220, according to
the set entry (step S904-1 in Fig. 16). The packet transmitting devices 220 and 230 on
the transmission route through which the packet is to be transmitted have already set
the entry, so that the packet is transmitted to the packet transmitting device 220 and
then to the packet transmitting device 230, and eventually arrives at the terminal 320
(steps S904-2 and S904-3).
[0109] The following describes a situation where step S404 (i.e. an operation in the case
where the device sending the data packet to the packet transmitting device is another
packet transmitting device) in Fig. 9 is performed. Fig. 11 is an explanatory diagram
showing an example of a packet flow in the OpenFlow network.
[01 10] In the case where the terminal 310 sends the first data packet to the terminal 320, the
data packet is first sent to the packet transmitting device 210 connected to the terminal
320 (step S1301-1). When the packet transmitting device 210 receives the packet, the
packet management unit 213 searches the flow table for an entry including a
comparison rule (matching key) that matches header information of the received
packet.
[0111] However, since the received packet is the first packet, there is no corresponding entry
in the flow table. Accordingly, the control message sending/receiving unit 211 buffers
the received packet, and then sends an information message about detecting a new flow
(Packet-In message) to the path control device (controller) 100 (step S1302).
[01 12] The Packet-In message includes information necessary for identifying the flow (e.g. a
MAC address, an IP address, a port number (for both the source and the destination))
and information indicating a receiving port of the packet.
[01 13] It is assumed here that the packet transmitting device 210 buffers the received packet
and sends the information necessary for identifying the flow to the path control device
(controller) 100, but the control message sending/receiving unit 2 11 may send the
received packet itself to the path control device (controller) 100.
[01 14] When the path control device (controller) 100 receives the Packet-In message, the
path/action computing unit 103 creates a comparison rule (matching key) of a new
entry from the received message, and determines a timer value applied to the entry. In
formation created as the comparison rule is, for instance, the information from "InPort"
to "TCP/UDP src port" shown as an example in Fig. 15.
[01 15] The path/action computing unit 103 further checks the location of the terminal 320 as
the destination based on the received message, and computes a packet transmission
route from the terminal 310 to the terminal 320. It is assumed here that, as a result of
transmission route computation, the transmission route of transmitting the packet in the
order of the packet transmitting device 210 -> the packet transmitting device 220 ->
the packet transmitting device 230 is computed.
[0116] Next, the path/action computing unit 103 creates an entry in which an action defining
transmission according to the computed transmission route and the timer value are set
for a packet that matches the comparison rule (matching key) of the new entry, for
each of the packet transmitting devices 210 to 230. The control message destination
determining unit 101 notifies each of the packet transmitting devices 210 to 230 of the
created entry, using a FlowMod message (steps S1303-1, S1303-2, S1303-3).
[01 17] Suppose here that the FlowMod message to the packet transmitting device 210 (the
FlowMod message sent in step SI303-1) and the FlowMod message to the packet
transmitting device 230 (the FlowMod message sent in step S1303-3) arrive at the
packet transmitting devices 210 and 230 respectively, but the FlowMod message to the
packet transmitting device 220 (the FlowMod message sent in step SI303-2) does not
arrive at the packet transmitting device 220 due to a packet loss, a delay, or the like
caused by network congestion.
[0118] When the packet transmitting device 210 receives the FlowMod message and the
packet management unit 213 completes the setting of the entry in the flow table, the
packet management unit 213 transmits the buffered packet to the packet transmitting
device 220, according to the set entry (step S1301-2). When the packet transmitting
device 220 receives the data packet from the packet transmitting device 210, the packet
management unit 213 in the packet transmitting device 220 searches the flow table for
an entry including a comparison rule (matching key) that matches the header in
formation of the packet. However, since the FlowMod message does not arrive at the
packet transmitting device 220, there is no corresponding entry in the flow table. Ac
cordingly, the control message sending/receiving unit 2 11 in the packet transmitting
device 220 buffers the received packet, and then sends an information message about
detecting a new flow (Packet-In message) to the path control device (controller) 100
(step SI304).
[01 19] When the path control device (controller) 100 receives the Packet-In message, the
path/action computing unit 103 creates a comparison rule (matching key) of a new
entry based on the received information, and determines a timer value applied to the
entry. Information created as the comparison rule is, for instance, the information from
"InPort" to "TCP/UDP src port" shown as an example in Fig. 15. The path/action
computing unit 103 further checks the location of the terminal 320 as the destination
based on the received information, and computes a packet transmission route from the
terminal 310 to the terminal 320. It is assumed here that, as a result of transmission
route computation, the transmission route of transmitting the packet in the order of the
packet transmitting device 220 -> the packet transmitting device 230 is computed.
[0120] Next, the control message destination determining unit 101 determines a destination
of a FlowMod message. An operation of determining the destination of the FlowMod
message is described below, with reference to Fig. 9.
[0121] After the path/action computing unit 103 computes the path, the control message des
tination determining unit 101 determines whether or not the packet transmitting device
sending the Packet-In message is the first packet transmitting device from the source
terminal of the data packet. In Example 1, this determination is performed using the
identifier of the packet transmitting device sending the Packet-In message and, from
among port numbers specified from the Packet-In message, the port number of the port
at which the packet transmitting device receives the data packet (step S401). Note that
the method of determination is not limited to the determination method using the port
number and the identifier of the packet transmitting device described in Example 1.
Any other method is applicable so long as whether or not the packet transmitting
device sending the Packet-In message is the first packet transmitting device from the
source terminal of the data packet can be determined.
[0122] In the communication path control system shown as an example in Fig. 7, the
identifier of the packet transmitting device 220 is "220", and the Input Port is "1".
Suppose here that the topology management unit 102 computes network topology in
formation from the identifiers and the port numbers in the path control device 100
shown as an example in Fig. 7, and holds the computed network topology information.
Also suppose that the network topology information computed by the topology
management unit 102 is the information shown as an example in Fig. 10.
[0123] The control message destination determining unit 101 accesses the topology
management unit 102 (step S402), and determines whether or not a device connected
to the packet transmitting device is another packet transmitting device (step S403).
Here, the control message destination determining unit 101 checks a device connected
to the port of the port number "1" of the device identified by the identifier "220", from
the network topology information shown as an example in Fig. 10. In the example
shown in Fig. 10, the device connected to the port of the port number "1" of the packet
transmitting device 220 is the packet transmitting device 210. Thus, the control
message destination determining unit 101 detects that the device adjacent to the packet
transmitting device 220 is the packet transmitting device 210 (step S403: Y). The
control message destination determining unit 101 accordingly notifies the process rule
only to the packet transmitting device 220 sending the Packet-In message (step 404).
[0124] The OpenFlow network is a network in which, when a data packet arrives at a packet
transmitting device, the packet transmitting device queries the path control device
about a path of the packet, and the path control device notifies each packet transmitting
device of an action for the packet so that the data packet can arrive at its intended des
tination device. Hence, in the case where the packet transmitting device 220 receives
the data packet from a device (i.e. a packet transmitting device, the packet transmitting
device 210 in Example 1) which is not a terminal, it means that the path control device
100 has already sent the FlowMod message for the data packet to the packet
transmitting device 220.
[0125] There is an instance where a query is made from the packet transmitting device 220
despite the fact that the FlowMod message has already been sent to the packet
transmitting device 220. This occurs in such a case where the FlowMod message from
the path control device 100 arrives at the packet transmitting device 220 before the
data packet from the packet transmitting device 210, or where the FlowMod message
from the path control device 100 is lost. In this case, the path control device 100 does
not need to send the path information to all packet transmitting devices on the
transmission route, and only needs to send the path information to the packet
transmitting device 220 again.
[0126] Therefore, the control message destination determining unit 101 sends the FlowMod
message only to the packet transmitting device 220, as shown in Fig. 11 (step S1305-1
in Fig. 11). The packet management unit 213 transmits the buffered packet to the
packet transmitting device 230, according to the set entry (step S1301-3). Hence, the
packet is transmitted to the packet transmitting device 230, and eventually arrives at
the terminal 320 (step SI301-4).
[0127] As described above, in Example 1, the control message destination determining unit
101 references the network topology in the topology management unit 102, and checks
the device connected to the port at which the packet transmitting device receives the
data packet, based on the information of the packet transmitting device sending the
Packet-In message and the port number of the port at which the packet transmitting
device receives the data packet.
[0128] In the case where another packet transmitting device is connected to the port at which
the packet is received, it means that the path control device 100 has already sent the
FlowMod message to each packet transmitting device on the path. In this case, the path
control device 100 only needs to send the FlowMod message to the packet transmitting
device sending the Packet-In message. In the case where a terminal (e.g. a terminal)
which is not a packet transmitting device is connected to the port at which the packet is
received, on the other hand, the path control device 100 sends the FlowMod message
to all packet transmitting devices on the path.
[0129] By the path control device 100 determining the FlowMod destination device
according to the packet transmitting device sending the Packet-In message in this
manner, it is possible to avoid sending a redundant control packet from the path control
device 100 to a packet transmitting device. According to such a structure, an im
provement in network use efficiency, a reduction in control packet sending load in the
path control device, and a reduction in control packet management load in the packet
transmitting device can be expected.
Example 2
[0130] The following describes Example 2 of the present invention. Example 2 corresponds
to the communication path control system in Exemplary Embodiment 2 of the present
invention.
[0131] In Example 2 of the present invention, a database (i.e. the flow entry storage unit
107) for holding a flow entry is provided in the path control device 100 and, based on
whether or not path information of a flow for which a query is received is stored in the
database, whether or not the flow is a new flow is determined.
[0132] In the communication path control system in Example 1 of the present invention,
whether or not the flow is a new flow is determined using the topology information.
The communication path control system in Example 2 of the present invention differs
from the communication path control system in Example 1, in that whether or not the
flow is a new flow is determined using the flow entry database.
[0133] A communication path control system intended for the OpenFlow network is
described in Example 2, as in Example 1. That is, the OpenFlow controller corresponds
to the path control device 100 in Exemplary Embodiment 2. In other words, the path
control device 100 corresponds to a device that includes, in the OpenFlow controller, a
function of determining a packet transmitting device to be notified of a process rule
(flow entry). Meanwhile, the OpenFlow switch corresponds to each packet transmitting
device in Exemplary Embodiments 1 and 2.
[0134] The communication path control system in Example 2 of the present invention is
described below, with reference to Fig. 1. The communication path control system in
Example 2 includes the two terminals 310 and 320, the three packet transmitting
devices 210 to 230 between the terminals 310 and 320, and the path control device 100
for controlling the network. The following describes an operation of the commu
nication path control system in Example 2, with reference to Fig. 16.
[0135] When the terminal 310 sends a data packet to the packet transmitting device 210 and
the packet transmitting device 210 receives the packet (step S901), the packet
management unit 213 searches the flow table for an entry including a comparison rule
(matching key) that matches header information of the received packet. However,
since the received packet is the first packet, there is no corresponding entry in the flow
table. Accordingly, the packet management unit 213 buffers the received packet, and
then sends an information message about detecting a new flow (Packet-In message) to
the path control device 100 (step S902).
[0136] The Packet-In message includes information necessary for identifying the flow (e.g. a
MAC address, an IP address, a port number (for both the source and the destination))
and information indicating a receiving port of the packet.
[0137] It is assumed here that the packet transmitting device 210 buffers the received packet
and sends the information necessary for identifying the flow to the path control device
100, but the packet transmitting device 210 may send the received packet itself to the
path control device 100.
[0138] An operation when the path control device 100 receives the Packet-In message is
described below, with reference to Fig. 8.
[0139] When the path control device 100 receives the Packet-In message from the packet
transmitting device 210 (step S301), the path/action computing unit 103 computes a
path of the packet, and determines an action of each packet transmitting device located
on the path (step S302). Following this, the control message destination determining
unit 101 determines a packet transmitting device as a destination that is to be notified
of a process rule including the action, from among the packet transmitting devices on
the path (step S303). The control message destination determining unit 101 notifies a
FlowMod message to the determined control message destination (step S304).
[0140] After the control message destination determining unit 101 notifies the path in
formation to the packet transmitting device determined as the control message des
tination, the flow entry management unit 108 registers the path information in the flow
entry storage unit 107. Note that, in the case where a process rule is deleted in the
packet transmitting device, the path control device 100 may delete path information of
a corresponding flow from the flow entry storage unit 107.
[0141] Fig. 12 is an explanatory diagram showing an example of an operation of de
termining the packet transmitting device to be notified of the process rule. Step S303
for determining the packet transmitting device as the control message destination is
described in detail below, with reference to Fig. 12.
[0142] When the path control device 100 receives the Packet-In message, first the flow entry
management unit 108 extracts an element (header) for specifying the data packet (step
S1201). For example, in the case where a flow is identified by a 5-tuple, the flow entry
management unit 108 checks the 5-tuple of the data packet.
[0143] The flow entry management unit 108 then references the flow entry storage unit 107,
to check whether or not a flow entry corresponding to the flow exists (step S1202). In
the case where the flow entry does not exist in the flow entry storage unit 107 as a
result of the check (step S1202: N), it means that the flow is a new flow. Accordingly,
the control message destination determining unit 101 determines to notify the process
rule to all packet transmitting devices on the path computed by the path/action
computing unit 103, and sends the process rule to the determined control message des
tination (step S1204).
[0144] In the case where the flow entry exists in the flow entry storage unit 107 (step S1202:
Y), on the other hand, the control message destination determining unit 101 determines
to notify the process rule only to the packet transmitting device sending the Packet-In
message (step S1203). An operation in the case where the flow entry exists in the flow
entry storage unit 107 will be described later.
[0145] Having determined the destination of the FlowMod message in this way, the control
message destination determining unit 101 sends the FlowMod message to the packet
transmitting devices 210 to 230 (step S903 in Fig. 16).
[0146] The packet management unit 213 transmits the buffered packet to the packet
transmitting device 220, according to the set entry (step S904-1 in Fig. 16). The packet
transmitting devices 220 and 230 on the transmission route through which the packet is
to be transmitted have already set the entry, so that the packet is transmitted to the
packet transmitting device 220 and then to the packet transmitting device 230, and
eventually arrives at the terminal 320 (steps S904-2 and S904-3).
[0147] The following describes a situation where step S1203 (i.e. an operation in the case
where the received packet is not a new flow) in Fig. 12 is performed, with reference to
Fig. 11.
[0148] In the case where the terminal 310 sends the first data packet to the terminal 320, the
data packet is first sent to the packet transmitting device 210 connected to the terminal
320 (step S1301-1). When the packet transmitting device 210 receives the packet, the
packet management unit 213 searches the flow table for an entry including a
comparison rule (matching key) that matches header information of the received
packet.
[0149] However, since the received packet is the first packet, there is no corresponding entry
in the flow table. Accordingly, the control message sending/receiving unit 211 buffers
the received packet, and then sends an information message about detecting a new flow
(Packet-In message) to the path control device (controller) 100 (step S1302).
[0150] The Packet- In message includes information necessary for identifying the flow (e.g. a
MAC address, an IP address, a port number (for both the source and the destination))
and information indicating a receiving port of the packet.
[0151] It is assumed here that the packet transmitting device 210 buffers the received packet
and sends the information necessary for identifying the flow to the path control device
(controller) 100, but the control message sending/receiving unit 2 11 may send the
received packet itself to the path control device (controller) 100.
[0152] When the path control device (controller) 100 receives the Packet-In message, the
path/action computing unit 103 creates a comparison rule (matching key) of a new
entry from the received message, and determines a timer value applied to the entry. In
formation created as the comparison rule is, for instance, the information from "InPort"
to "TCP/UDP src port" shown as an example in Fig. 15.
[0153] The path/action computing unit 103 further checks the location of the terminal 320 as
the destination based on the received message, and computes a packet transmission
route from the terminal 310 to the terminal 320. It is assumed here that, as a result of
transmission route computation, the transmission route of transmitting the packet in the
order of the packet transmitting device 210 -> the packet transmitting device 220 ->
the packet transmitting device 230 is computed.
[0154] Next, the path/action computing unit 103 creates an entry in which an action defining
transmission according to the computed transmission route and the timer value are set
for a packet that matches the comparison rule (matching key) of the new entry, for
each of the packet transmitting devices 210 to 230. The control message destination
determining unit 101 notifies each of the packet transmitting devices 210 to 230 of the
created entry, using a FlowMod message (steps S1303-1, S1303-2, S1303-3).
[0155] Suppose here that the FlowMod message to the packet transmitting device 210 (the
FlowMod message sent in step SI303-1) and the FlowMod message to the packet
transmitting device 230 (the FlowMod message sent in step S1303-3) arrive at the
packet transmitting devices 210 and 230 respectively, but the FlowMod message to the
packet transmitting device 220 (the FlowMod message sent in step SI303-2) does not
arrive at the packet transmitting device 220 due to a packet loss, a delay, or the like
caused by network congestion.
[0156] When the packet transmitting device 210 receives the FlowMod message and the
packet management unit 213 completes the setting of the entry in the flow table, the
packet management unit 213 transmits the buffered packet to the packet transmitting
device 220, according to the set entry (step S1301-2). When the packet transmitting
device 220 receives the data packet from the packet transmitting device 210, the packet
management unit 213 in the packet transmitting device 220 searches the flow table for
an entry including a comparison rule (matching key) that matches the header in
formation of the packet. However, since the FlowMod message does not arrive at the
packet transmitting device 220, there is no corresponding entry in the flow table. Ac
cordingly, the control message sending/receiving unit 2 11 in the packet transmitting
device 220 buffers the received packet, and then sends an information message about
detecting a new flow (Packet-In message) to the path control device (controller) 100
(step SI304).
[0157] When the path control device (controller) 100 receives the Packet-In message, the
path/action computing unit 103 creates a comparison rule (matching key) of a new
entry based on the received information, and determines a timer value applied to the
entry. Information created as the comparison rule is, for instance, the information from
"InPort" to "TCP/UDP src port" shown as an example in Fig. 15. The path/action
computing unit 103 further checks the location of the terminal 320 as the destination
based on the received information, and computes a packet transmission route from the
terminal 310 to the terminal 320. It is assumed here that, as a result of transmission
route computation, the transmission route of transmitting the packet in the order of the
packet transmitting device 220 -> the packet transmitting device 230 is computed.
[0158] Next, the path control device (controller) 100 determines a destination of a FlowMod
message. When the path control device 100 receives the Packet-In message, first the
flow entry management unit 108 extracts an element (header) for specifying the data
packet (step S1201 in Fig. 12). For example, in the case where a flow is identified by a
5-tuple, the flow entry management unit 108 checks the 5-tuple of the data packet.
[0159] The flow entry management unit 108 then references the flow entry storage unit 107,
to check whether or not a flow entry corresponding to the flow identified by the 5-tuple
exists (step S1202). In the case where the flow entry exists in the flow entry storage
unit 107 as a result of the check (step S1202: Y), it means that the flow is not a new
flow. Accordingly, the control message destination determining unit 101 determines to
notify the process rule only to the packet transmitting device sending the information
message about detecting a new flow, and sends the process rule to the determined
control message destination (step S1203).
[0160] Thus, the control message destination determining unit 101 sends the FlowMod
message only to the packet transmitting device 220, as shown in Fig. 11 (step S1305-1
in Fig. 11). Upon receiving the FlowMod message, the packet management unit 213
transmits the buffered packet to the packet transmitting device 230, according to the set
entry (step S1301-3). Hence, the packet is transmitted to the packet transmitting device
230, and eventually arrives at the terminal 320 (step SI30 1-4).
[0161] The following describes a minimum structure of the present invention. Fig. 13 is a
block diagram showing an example of a minimum structure of a communication path
control system according to the present invention. The communication path control
system according to the present invention comprises: a packet transmitting device 80
(e.g. the packet transmitting devices 210 to 230) for transmitting a received packet
based on a packet transmission rule which is a rule defining a transmission method of
the packet; and a path control device 90 (e.g. the path control device 100) for con
trolling a communication path of the packet, by instructing the packet transmitting
device 80 to apply the packet transmission rule.
[0162] The packet transmitting device 80 includes process querying means 8 1 (e.g. the
control message sending/receiving unit 2 11) for querying the path control device 90
about a process (e.g. an action) for the received packet.
[0163] The path control device 90 includes packet transmitting device determining means 9 1
(e.g. the control message destination determining unit 101) for, when receiving the
query about the process for the packet from the packet transmitting device 80, de
termining the packet transmitting device 80 that is to apply the packet transmission
rule determined according to the packet, based on whether or not the query about the
process for the packet is a first-time query.
[0164] According to such a structure, the number of packets used for communication path
control can be reduced.
[0165] Moreover, the packet transmitting device determining means 9 1 may determine the
packet transmitting device that is to apply the packet transmission rule, based on
whether or not the packet transmitting device making the query is a first packet
transmitting device on a path through which a terminal device (e.g. the terminal 310)
communicating to another device sends the data packet.
[0166] Moreover, the path control device 90 may include packet transmission rule storage
means (e.g. the flow entry storage unit 107) for storing the packet transmission rule set
in the packet transmitting device, wherein the packet transmitting device determining
means 9 1 (e.g. the control message destination determining unit 101, the flow entry
management unit 108) determines the packet transmitting device that is to apply the
packet transmission rule, based on whether or not the packet transmission rule corre
sponding to the packet for which the query about the process is made is stored in the
packet transmission rule storage means.
[0167] Moreover, the path control device 90 may include topology storage means (e.g. the
terminal location storage unit 106) for storing topology (e.g. network topology) which
is information indicating a connection configuration in which the packet transmitting
device connects with another device, wherein the packet transmitting device de
termining means 91: determines whether or not the packet transmitting device making
the query about the process for the packet is the first packet transmitting device on the
path, based on the topology and, from among information included in the packet, an
identifier of the packet transmitting device making the query and an identifier (e.g.
Input Port) of a receiving port of the packet transmitting device at which the query is
received; and, based on a result of the determination, determines the packet
transmitting device that is to apply the packet transmission rule.
[0168] Moreover, the packet transmitting device determining means 9 1 may: determine that
all packet transmitting devices on a path of the data packet sent by a terminal device
(e.g. the terminal 310) communicating to another device are to apply the packet
transmission rule, in the case where the query about the process for the packet is the
first-time query; and determine that the packet transmitting device making the query is
to apply the packet transmission rule, in the case where the query about the process for
the packet is not the first-time query.
[0169] Fig. 14 is a block diagram showing an example of a minimum structure of a path
control device according to the present invention. The path control device shown as an
example in Fig. 14 is the same as the path control device 90 shown as an example in
Fig. 13. According to such a structure, too, the number of packets used for communication
path control can be reduced.
[0170] While the invention has been particularly shown and described with reference to
exemplary embodiments thereof, the invention is not limited to these embodiments. It
will be understood by those of ordinary skill in the art that various changes in form and
details may be made therein without departing from the spirit and scope of the present
invention as defined by the claims.
[0171] This application is based upon and claims the benefit of priority from Japanese patent
application No. 2010-277204, filed on December 13, 2010, the disclosure of which is
incorporated herein in its entirety by reference.
Industrial Applicability
[0172] The present invention is preferably applied to a communication path control system
for controlling a communication path.
Reference Signs List
[0173] 100 path control device
101 control message destination determining unit
102 topology management unit
103 path/action computing unit
104 communication unit
105 control message management unit
106 terminal location storage unit
107 flow entry storage unit
108 flow entry management unit
210 to 230 packet transmitting device
211 control message sending/receiving unit
212 flow table storage unit
213 packet management unit
310, 320 terminal

PCT/JP2011/004587
Claims
[Claim 1]A communication path control system comprising:
a packet transmitting device for transmitting a received packet based on
a packet transmission rule which is a rule defining a transmission
method of the packet; and
a path control device for controlling a communication path of the
packet, by instructing the packet transmitting device to apply the packet
transmission rule,
wherein the packet transmitting device includes
process querying means for querying the path control device about a
process for the received packet, and
wherein the path control device includes
packet transmitting device determining means for determining a packet
transmitting device that is applied the packet transmission rule decided
according to the packet, based on whether or not the query about the
process for the packet is a first-time query, when receiving the query
about the process for the packet from the packet transmitting device.
[Claim 2]The communication path control system according to claim 1, wherein
the packet transmitting device determining means determines the
packet transmitting device that is applied the packet transmission rule,
based on whether or not the packet transmitting device making the
query is a first packet transmitting device on a path through which a
terminal device communicating to another device sends the data packet.
[Claim 3] he communication path control system according to claim 1, wherein
the path control device includes
packet transmission rule storage means for storing the packet
transmission rule set in the packet transmitting device, and
wherein the packet transmitting device determining means determines
the packet transmitting device that is applied the packet transmission
rule, based on whether or not the packet transmission rule corre
sponding to the packet for which the query about the process is made is
stored in the packet transmission rule storage means.
[Claim 4]The communication path control system according to claim 2, wherein
the path control device includes
topology storage means for storing topology which is information in
dicating a connection configuration in which the packet transmitting
device connects with another device, and
WO 2012/081145 PCT/JP2011/004587
wherein the packet transmitting device determining means: determines
whether or not the packet transmitting device making the query about
the process for the packet is the first packet transmitting device on the
path, based on the topology and, from among information included in
the packet, an identifier of the packet transmitting device making the
query and an identifier of a receiving port of the packet transmitting
device at which the query is received; and, based on a result of the de
termination, determines the packet transmitting device that is applied
the packet transmission rule.
[Claim 5] The communication path control system according to any one of claims
1 to 4, wherein the packet transmitting device determining means de
termines that all packet transmitting devices on a path of the data
packet sent by a terminal device communicating to another device are
applied the packet transmission rule, in the case where the query about
the process for the packet is the first-time query, and determines that
the packet transmitting device making the query is applied the packet
transmission rule, in the case where the query about the process for the
packet is not the first-time query.
[Claim 6] A path control device comprising
packet transmitting device determining means for, when receiving a
query about a process for a packet from a packet transmitting device
that transmits a received packet based on a packet transmission rule
which is a rule defining a transmission method of the packet, de
termining a packet transmitting device that is applied the packet
transmission rule determined according to the packet, based on whether
or not the query about the process for the packet is a first-time query.
[Claim 7] A communication path control method wherein a packet transmitting
device for transmitting a received packet based on a packet
transmission rule which is a rule defining a transmission method of the
packet queries a path control device for controlling a communication
path of the packet, about a process for the received packet, and
wherein, when receiving the query about the process for the packet
from the packet transmitting device, the path control device determines
a packet transmitting device that is applied the packet transmission rule
determined according to the packet, based on whether or not the query
about the process for the packet is a first-time query.
[Claim 8] The communication path control method according to claim 7, wherein
the path control device determines the packet transmitting device that is
WO 2012/081145 PCT/JP2011/004587
applied the packet transmission rule, based on whether or not the
packet transmitting device making the query is a first packet
transmitting device on a path of the data packet sent by a terminal
device communicating to another device.
[Claim 9] The communication path control method according to claim 7, wherein
the path control device determines the packet transmitting device that is
applied the packet transmission rule, based on whether or not the
packet transmission rule corresponding to the packet for which the
query about the process is made is stored in packet transmission rule
storage means for storing the packet transmission rule set in the packet
transmitting device.
[Claim 10] A path control program for causing a computer to execute
a packet transmitting device determining process of, when receiving a
query about a process for a packet from a packet transmitting device
that transmits a received packet based on a packet transmission rule
which is a rule defining a transmission method of the packet, de
termining a packet transmitting device that is applied the packet
transmission rule determined according to the packet, based on whether
or not the query about the process for the packet is a first-time query.