Network system including radio network using MPLS

After a first base station connects to a first mobile terminal, a first GW (gateway) receives a request for connection between the first mobile terminal and a second GW and identifiers of the second GW and the first mobile terminal and transmits identifiers of the first mobile terminal and the first GW to the second GW. The second GW transmits an MPLS allocation flag to the first GW. The first GW transmits an MPLS allocation signal including an identifier of the first mobile terminal to the second GW via a second NW (network) apparatus. The first base station receives an identifier of the first GW and the MPLS allocation flag from the first GW via a management server and transmits the MPLS allocation signal including the identifier of the first mobile terminal to the first GW via a first NW apparatus.

CLAIM OF PRIORITY

The present application claims priority from Japanese patent application JP 2011-002018 filed on Jan. 7, 2011, the content of which is hereby incorporated by reference into this application.

FIELD OF THE INVENTION

The present invention relates to a network system and more particularly to a network system including a radio network using MPLS.

BACKGROUND OF THE INVENTION

A radio access network accommodates a base station and a mobile gateway using the UMTS (Universal Mobile Telecommunications System) technology and the EV-DO (Evolution Data Only) technology referred to as 3.5G. The radio access network generally provides an IP tunnel between the base station and the mobile gateway according to the IP tunnel link technology. User data is transmitted through the IP tunnel.

Widely known technologies for providing the IP tunnel include GTP (GPRS Tunnelling Protocol) specified in 3GPP (3rd Generation Partnership Project) and PMIP (Proxy Mobile IP) specified in IETF (Internet Engineering Task Force), for example. The IP tunnel is provided between the base station and the mobile gateway or between a first mobile gateway connected to a mobile access network and a second mobile gateway included in a service network. The IP tunnel is used for mobility management of terminals.

An ordinary IP network routes IP packets in units of subnetworks to which an IP address assigned to a terminal belongs. Accordingly, the terminal cannot move out of the subnetwork without changing the IP address assigned to the terminal. An IP tunnel technology represented by Mobile IP solves this problem.

The IP tunnel technology such as Mobile IP distributes a Care of Address (CoA) to the network. The Care of Address provides an IP address that differs from the IP address assigned to the mobile terminal and indicates an IP address corresponding to the current position of the mobile terminal. The IP tunnel technology encapsulates an IP packet for communication with the mobile terminal by providing the IP packet with an IP header whose destination address stores the Care of Address. The encapsulated IP packet is transferred to the mobile terminal at the destination in order to ensure the terminal mobility.

For this reason, the IP tunnel is mainly used for mobility control over radio access networks at the present time (e.g., refer to “TS 29.274, 3GPP Evolved Packet System (EPS); Evolved General Packet Radio Service (GPRS) Tunnelling Protocol for Control plane (GTPv2-C); Stage 3” and “IETF RFC 5213: Proxy Mobile IPv6”).

On the other hand, communication speeds proceed to increase for the radio technology used for mobile terminals and base stations. The LTE/SAE system provides a communication speed of 100 Mbps. The LTE-Advanced system, expected to be a next-generation LTE/SAE radio system, will provide a communication speed over 100 Mbps.

To respond to increasing communication speeds, the radio access network (RAN) is requested to not only provide faster IP packet transfer but also apply the MPLS (Multi Protocol Labeling Switch) technology to the radio access network and replace the IP tunnel with an MPLS path. This is because the MPLS can ensure QoS for IP packets.

There is proposed a technology of replacing a Mobile IP tunnel with an MPLS tunnel (e.g., refer to Integration of Mobile IP and Multi-Protocol Label Switching ICC 2001, June 2001). Further, there is proposed a technology of providing the MPLS path from an exit node to an entry node when the mobile terminal is connected to the base station (e.g., refer to Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2008-518532).

However, the MPLS path is installed when an LSR (Label Switch Router) between nodes maintains label switch information hop by hop. The path configuration requires updating the label switch information maintained in all LSRs to be traveled. Generally, the radio access network accommodates as many as over 1,000,000 mobile terminals. A label resource in the MPLS network might be greatly consumed and the MPLS network performance might degrade if all the mobile terminals are supplied with independent label switch paths.

SUMMARY OF THE INVENTION

Many label switch paths are needed if a radio access network uses the MPLS for each mobile terminal or bearer in order to accelerate the network. The use of the MPLS for the radio access network generally degrades the network performance compared to an MPLS network in VPN.

All LSRs placed between the base station and gateways might be switched if a hand-over is performed between the mobile terminal and the base station. A process is needed for the hop-by-hop LSR, thus extending the time to complete the hand-over.

It is therefore an object of the present invention to decrease network performance degradation due to distribution of MPLS labels, fast complete hand-over by fast switching an LSR between the base station and the gateway, and provide a highly efficient mobile MPLS network.

The following describes a representative example of the present invention. A network system includes: plural mobile terminals; plural base stations connected to the mobile terminals by radio; a first gateway connected to the base stations via plural first network apparatuses; a second gateway connected to the first gateway via plural second network apparatuses; and a management server connected to the base stations and the first gateway. A first of the mobile terminals is connected to a first of the base stations and the first base station transmits a request for connection with the first mobile terminal to the management server. The first gateway thereafter receives a first signal from the management server, the first signal being configured to include a request for connection between the first mobile terminal and the second gateway, an identifier of the second gateway, and an identifier of the first mobile terminal. The first gateway transmits a second signal to a destination specified by the identifier of the second gateway included in the first signal, the second signal being configured to include the identifier of the first mobile terminal included in the first signal and an identifier of the first gateway. The second gateway transmits a third signal to a destination specified by the identifier of the first gateway included in the second signal, the third signal being configured to include the identifier of the second gateway and an MPLS allocation flag indicating allocation of an MPLS path to a route between the first mobile terminal and the second gateway. Based on the MPLS allocation flag included in the third signal, the first gateway transmits a fourth signal for MPLS path allocation to a destination specified by the second gateway included in the third signal via the second network apparatuses, the fourth signal being configured to include the identifier of the first mobile terminal. The first base station receives a fifth signal from the first gateway via the management server, the fifth signal being configured to include the identifier of the first gateway and the MPLS allocation flag. Based on the MPLS allocation flag included in the fifth signal, the first base station transmits a sixth signal for MPLS path allocation to a destination specified by the identifier of the first gateway included in the fifth signal via the first network apparatuses, the sixth signal being configured to include the identifier of the first mobile terminal. After the first mobile terminal is connected to the second base station, the second base station transmits a seventh signal for MPLS allocation to plural third network apparatuses provided to a route for communication between the second base station and the first gateway, the seventh signal being configured to include the identifier of the first mobile terminal.

An embodiment of the present invention can prevent the network performance from degrading without distributing many MPLS labels.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1,2, and3show basic processes that provide a radio network with IP tunnels.

FIG. 1is a block diagram showing a basic radio network according to a first embodiment of the invention.

The radio network shown inFIG. 1is called LTE/SAE (Long Term Evolution/System Architecture Evolution) and is equivalent to the radio access network specified in 3GPP. The radio network shown inFIG. 1includes UE101, eNB102, MME103, S-GW104, P-GW105, PCRF120, and a service network107.

The UE101is a mobile terminal. The eNB (enhanced Node B)102is a base station. The MME (Mobility Management Entity)103is a mobility management server that performs position management and authentication processes for the UE101. The UE101communicates with the eNB102by radio.

The S-GW (Serving GW)104is a first mobile gateway functioning as an anchor point in the radio access network. The P-GW (Packet Data Network GW)105is a second mobile gateway functioning as an entry to the service network.

An HSS106(Home Subscriber Server) is a subscriber data server that distributes data and/or user profiles for authenticating the UE101to the MME103or performs position management.

A PCRF (Policy and Charging Enforcement Function)120is a server that manages a user profile for each user of the UE101and provides a QoS policy control function and/or a charging function. The user of the UE101signifies a user associated with each UE101or bearer.

The service network107is equivalent to a core network that provides the UE101with a mail service and/or a web access service.

FIG. 2is a sequence diagram showing a basic communication process using an IP tunnel for the radio network according to the first embodiment of the invention.

The sequence diagram inFIG. 2shows an example process of setting an IP tunnel for transferring user data when the UE101connects with the service network107in the radio network shown inFIG. 1.

The UE101issues a request to connect with the service network107and establishes a radio link with the eNB102(1401). The UE101transmits a connection request message to the MME103via the eNB102(1402and1403).

The MME103receives the connection request message from the UE101and acquires authentication data corresponding to the UE101as a sender of the connection request message and data about an encryption key used by the UE101from the HSS106. The MME103authenticates the UE101based on the acquired data (1404).

The MME103registers the position of the UE101to the HSS106if the authentication at sequence1404is successful (1405). The MME103acquires profile information about a subscriber stored in the HSS106from it. The MME103thereby acquires information indicating the service network107as a connection destination of the UE101and information indicating the P-GW105as a connection destination included in the service network107(1406).

Based on the acquired information indicating the P-GW105, the MME103requests the S-GW104to make connection with the P-GW105and the UE101as connection points to the service network107(1407). At sequence1407, the MME103transmits an identifier for uniquely identifying the UE101or the bearer to the S-GW104.

When receiving the connection request from the MME103, the S-GW104transmits a session establishment request to the P-GW105based on connection information (including the information indicating the P-GW105) contained in the received connection request (1408). The session establishment request at sequence1408contains information indicating a GTP tunnel that transmits a packet addressed to the UE101from the P-GW105to the S-GW104.

The information indicating the GTP tunnel, to be transmitted to the P-GW105at sequence1408, contains an endpoint IP address of the GTP tunnel, that is, a reception IP address for the S-GW104and a TEID (Tunnel Endpoint Identifier). The TEID uniquely identifies the GTP tunnel. The session establishment request at sequence1408contains the TEID that uniquely indicates the GTP tunnel provided for a transmission path from the P-GW105to the S-GW104.

The GTP tunnel is unique for each UE101or bearer. The TEID is also unique for each UE101or bearer.

The P-GW105receives the session establishment request from the S-GW104and then transmits a session establishment response to the S-GW104that transmitted the session establishment request (1409). The session establishment response at sequence1409contains information indicating a GTP tunnel used to transmit the packet transmitted from the UE101to the service network107via the S-GW104and the P-GW105in succession.

The information indicating the GTP tunnel, to be transmitted to the S-GW104at sequence1409, contains an endpoint IP address of the GTP tunnel, that is, an IP address of the P-GW105and the TEID for identifying the GTP tunnel. The TEID contained in the session establishment response at sequence1409contains another TEID that uniquely indicates a GTP tunnel used to transmit a packet from the S-GW104to the P-GW105.

The S-GW104receives the session establishment response from the P-GW105and then transmits a session establishment response to the MME103(1410). The session establishment response at sequence1410contains information indicating a GTP tunnel used to transmit the packet transmitted from the UE101further from the eNB102to the service network107via the S-GW104and the P-GW105. The information indicating the GTP tunnel at sequence1410contains an endpoint IP address of the GTP tunnel, that is, an IP address of the S-GW104and the TEID that uniquely identifies a GTP tunnel for transmitting a packet from the eNB102to the S-GW104.

The MME103receives the session establishment response from the S-GW104and then transmits an Initial Context Setup/Attach Accept message to the eNB102in order to notify the eNB102and the UE101that connection between the eNB102and the P-GW105is ready to be established (1411).

The message transmitted to the eNB102at sequence1411contains information indicating the GTP tunnel notified from the S-GW104at sequence1410. That is, the message contains the IP address of the S-GW104and the TEID that uniquely indicates the GTP tunnel for transmitting a packet from the eNB102to the S-GW104.

The eNB102receives the Initial Context Setup/Attach Accept message from the MME103and then reestablishes the radio link connection with the UE101(1412and1413). The eNB102then transmits an Initial Context Setup Response to the MME103(1414).

The message transmitted at sequence1414contains information indicating a GTP tunnel used to transfer a packet addressed to the UE101from the S-GW104to the eNB102. Specifically, the information indicating the GTP tunnel at sequence1414contains an endpoint IP address of the GTP tunnel, that is, an IP address of the eNB102and the TEID that uniquely identifies a GTP tunnel for transmitting a packet from the S-GW104to the eNB102.

The UE101further transmits an Attach Accept message to the MME103and thereby notifies the MME103that the connection with the service network107has been established (1415).

The MME103issues a Modify Bearer Request message to transmit the information indicating the GTP tunnel transmitted from the eNB102at sequence1414to the S-GW104(1416). The S-GW104receives the Modify Bearer Request message from the MME103and then issues a Modify Bearer Response message to respond to the MME103(1417).

The above-mentioned procedure establishes the GTP tunnel between the eNB102and the S-GW104and the GTP tunnel (1418) between the S-GW104and the P-GW105. The packet addressed to the UE101from the service network107is transmitted to the UE101via the P-GW105, the S-GW104, and the eNB102. The packet addressed to the service network107from the UE101is transmitted to the service network107via the eNB102, the S-GW104, and the P-GW105.

FIG. 3is an explanatory diagram showing basic protocol stacks for the eNB102, the S-GW104, and the P-GW105to be used with GTP tunnels according to the first embodiment of the invention.

FIG. 3shows protocol stacks used for the radio network shown inFIG. 1. The protocol stacks for the eNB102, the S-GW104, and the P-GW105contain an IP505and a payload506in common. The protocol stacks for the eNB102and the S-GW104contain L1/L2 (501), IP502, UDP503, and GTP504because the eNB102and the S-GW104communicate with each other. The protocol stacks for the S-GW104and the P-GW105contain L1/L2 (507), IP508, UDP509, and GTP510because the S-GW104and the P-GW105communicate with each other.

Each protocol stack shown inFIG. 3is equivalent to the header attached to a packet to be transmitted or received in the radio network.

The payload506is equivalent to a payload attached to a packet.

The IP505is equivalent to an IP header. The eNB102, the S-GW104, and the P-GW105transmit or receive a packet that contains the IP header for storing an IP address.

If a packet is addressed to the UE101, the IP header attached to the packet stores the IP address allocated to the UE101as a reception destination IP address. If a packet is transmitted from the UE101, the IP header stores the IP address allocated to the UE101as a transmission destination IP address.

L1/L2 (501) and L1/L2 (507) indicate the physical layer and the data link layer (Layer1/Layer2). The L1/L2 (501) is used between the eNB102and the S-GW104. The L1/L2 (507) is used between the S-GW104and the P-GW105.

The IP502is equivalent to an IP header in the GTP tunnel for packets transmitted and received between the eNB102and the S-GW104. The IP508is equivalent to an IP header in the GTP tunnel for packets transmitted and received between the S-GW104and the P-GW105.

The UDP503is equivalent to a UDP header in the GTP tunnel for packets transmitted and received between the eNB102and the S-GW104. The UDP509is equivalent to a UDP header in the GTP tunnel for packets transmitted and received between the S-GW104and the P-GW105.

The GTP504is equivalent to a GTP header indicating the GTP tunnel between the eNB102and the S-GW104. The GTP510is equivalent to a GTP header indicating the GTP tunnel between the S-GW104and the P-GW105. The GTP header contains the TEID that uniquely indicates each GTP tunnel.

Of packets received from the eNB102, the S-GW104replaces the headers indicating the IP502, the UDP503, and the GTP504corresponding to the GTP tunnel between the eNB102and the S-GW104with the headers indicating the IP508, the UDP509, and the GTP510corresponding to the GTP tunnel between the S-GW104and the P-GW105. The S-GW104transmits the packets having the replaced headers to the P-GW105.

Of packets received from the P-GW105, the S-GW104replaces the headers indicating the IP508, the UDP509, and the GTP510corresponding to the GTP tunnel between the S-GW104and the P-GW105with the headers indicating the IP502, the UDP503, and the GTP504corresponding to the GTP tunnel between the eNB102and the S-GW104. The S-GW104transmits the packets having the replaced headers to the eNB102.

The following describes a process of providing the above-mentioned GTP tunnel with an MPLS path.

FIG. 4is a block diagram showing a radio network according to the first embodiment of the invention.

The radio network according to the embodiment includes the UE101, the eNB102(102-1through102-3), the MME103, the S-GW104, the P-GW105, the PCRF120, the service network107, a radio access network108, LSR1 (109-1), and LSR2 (109-2). In the following description, the LSR1 (109-1) and the LSR2 (109-2) are generically referred to as LSR109.

The UE101is a mobile terminal. The eNB (enhanced Node B)102is abase station. The MME (Mobility Management Entity)103is a mobility management server that performs position management and authentication processes for the UE101. The UE101communicates with the eNB102by radio.

The S-GW (Serving GW)104is a first mobile gateway functioning as an anchor point in the radio access network. The P-GW (Packet Data Network GW)105is a second mobile gateway functioning as an entry to the service network.

The PCRF120is a server that manages a user profile for each user using the UE101and provides the QoS policy control function and/or the charging function.

The HSS106(Home Subscriber Server) is a subscriber data server that distributes data and/or user profiles for authenticating the UE101to the MME103or performs position management. The service network107is equivalent to a core network that provides the UE101with a mail service and/or a web access service.

The radio access network108is provided between the eNB102and the P-GW105. The LSR109is a router node for packet transfer and provides the LSR (Label Switching Router) function for MPLS.

The UE101, the eNB102(102-1through102-3), the MME103, the S-GW104, the P-GW105, the PCRF120, the service network107, the LSR1 (109-1), and the LSR2 (109-2) are computers each having a processor. The processor performs a program loaded into the memory to implement the corresponding function.

FIG. 5is a block diagram showing a physical configuration of the S-GW104and the LSR109according to the first embodiment of the invention.

The S-GW104and the LSR109each include a CPU901, memory902, nonvolatile memory903, an interface904, and a label switch processing portion905.

The CPU901includes at least one processor. The CPU901performs a program stored in the memory902.

The memory902stores a program loaded from the nonvolatile memory903. The CPU901accesses and performs the program stored in the memory902. The memory902also stores MPLS FIB to be described later and IP tunnel information after the MPLS is applied.

The nonvolatile memory903is equivalent to flash memory, for example. The nonvolatile memory903stores programs performed by the CPU901and configuration information for performing programs.

The interface904is equivalent to a network interface for communication through a network in the radio access network108. The interface904receives packets from the other apparatuses such as the eNB102and the LSR109. The interface904stores a received packet in the memory902or transmits it to the label switch processing portion905.

The label switch processing portion905processes a packet supplied with the MPLS header.

FIG. 6is a sequence diagram showing an MPLS path allocation procedure according to the first embodiment of the invention.

A process from sequences1101to1107inFIG. 6is equal to that from sequences1401to1407inFIG. 2. The following description starts from sequence1108.

The S-GW104receives the connection request from the MME103and then transmits a session establishment request to the P-GW105based on the information about connection to the service network107contained in the received connection request (1108). The session establishment request at sequence1108contains: information indicating a GTP tunnel used for transferring the packet addressed to the UE101from the P-GW105to the S-GW104; and an identifier for the UE101or the bearer that requested the connection via the eNB102-1and the MME103.

The information indicating the GTP tunnel, to be transmitted to the P-GW105at sequence1108, contains an endpoint IP address of the GTP tunnel, that is, a reception IP address for the S-GW104and the TEID. The TEID contained in the session establishment request at sequence1108uniquely indicates a GTP tunnel provided between the S-GW104and the P-GW105.

The embodiment applies MPLS paths to a network using GTP tunnels and therefore allocates fixed MPLS paths between apparatuses including the eNB102-1, the S-GW104, and the P-GW105functioning as endpoints of the GTP tunnels. The MPLS header replaces a header that stores information equivalent to the TEID for the GTP tunnel. Instead of the TEID, an MPLS label is distributed to each of the apparatuses including the eNB102-1, the LSR109, the S-GW104, and the P-GW105.

When receiving the MPLS header, the LSR109and the S-GW104can identify each tunnel between the apparatuses by stacking the distributed MPLS label onto the fixed MPLS path. The replacement with the MPLS header will be described with reference to an explanatory diagram showing protocol stacks to be described.

The P-GW105receives the session establishment request at sequence1108and then extracts the identifier for the UE101or the bearer contained in the session establishment request. The P-GW105determines the QoS policy specific to the UE101or the bearer based on the extracted identifier.

The P-GW105extracts the identifier indicating the UE101or the bearer from the transmitted session establishment request. Based on the extracted identifier, for example, the P-GW105acquires a user class (information indicating a user priority), QoS policy supplied to a user, and/or charging information allocated to the user from the PCRF120. Based on the acquired information, the P-GW105settles the QoS policy corresponding to the UE101or the bearer. The user here is assumed to use the UE101or the bearer.

Alternatively, the P-GW105may settle the QoS policy corresponding to the UE101or the bearer based on static policy such as APN (Access Point Name) that is previously stored and is allocated to each service network, for example. In this case, the information such as APN used for the UE101may be contained in the session establishment request at sequence1108and may be transmitted to the P-GW105via the S-GW104.

The QoS policy to be settled here ensures specified traffic in the daytime and provides best-effort traffic at night, for example.

Based on the settled QoS policy, the P-GW105settles the maximum bit rate and/or the guaranteed bandwidth allocated to each UE101or bearer. The P-GW105may allocate the maximum bit rate and/or the guaranteed bandwidth to the UE101or the bearer for upstream or downstream communication thereof.

The P-GW105compares the settled maximum bit rate and/or guaranteed bandwidth with a predetermined threshold value maintained in the P-GW105. A comparison result might indicate that the settled maximum bit rate and/or guaranteed bandwidth is greater than the predetermined threshold value. In such a case, particularly high QoS is needed for the UE101or the bearer requested for connection. The P-GW105settles to allocate an MPLS path for the UE101or the bearer requested for communication or for upstream or downstream communication of the UE101or the bearer.

The information acquired from the PCRF120might indicate that a high priority is provided for the UE101or the bearer requested for connection. In such a case, the P-GW105may settle to allocate an MPLS path to the UE101or the bearer provided with a high priority.

An MPLS path may be allocated while a session is established or if the total amount of actual traffic after the session establishment exceeds a threshold value.

The P-GW105then transmits the session establishment response at sequence1109to the S-GW104to transmit, to the same, the result acquired after reception of the session establishment request at sequence1108, that is, the information indicating whether to allocate an MPLS path between the S-GW104and the P-GW105.

The session establishment response at sequence1109contains not only information indicating the GTP tunnel used for packets transmitted from the UE101to the service network107via the S-GW104and the P-GW105in succession, but also a flag indicating allocation of an MPLS path for downstream communication of the UE101or the bearer requested for connection.

The P-GW105generates the flag indicating the MPLS path allocation corresponding to a route to which the MPLS path is allocated. That is, the flag indicating the MPLS path allocation contains another flag indicating the MPLS path allocation corresponding to the UE101or the bearer and still another flag indicating the MPLS path allocation corresponding to upstream or downstream communication of the UE101or the bearer.

The information indicating the GTP tunnel, to be transmitted to the P-GW104at sequence1109, contains an endpoint IP address of the GTP tunnel, that is, an IP address for the P-GW105and the TEID for identifying the GTP tunnel from the S-GW104to the P-GW105.

The session establishment response received from the P-GW105at sequence1109might contain the flag indicating the MPLS path allocation for downstream communication of the UE101or the bearer requested for connection. In this case, the S-GW104starts a procedure to establish the MPLS path for transmitting a packet to the S-GW104from the P-GW105.

The MPLS establishment procedure according to the embodiment uses LDP (Label Distribution Protocol), CR-LDP (Constraint-Routing LDP), or RSVP (Resource Reservation Protocol)-TE, for example.

The S-GW104receives the session establishment response at sequence1109and then transmits a label allocation message to the LSR2 (109-2) so as to be transmitted to the P-GW105(1121). The S-GW104thereby distributes the MPLS label corresponding to the GTP tunnel for downstream communication allocated at sequence1108to the LSR2 (109-2) on the route corresponding to the GTP tunnel between the P-GW105and the S-GW104.

The label allocation message at sequence1121is transmitted to the destination indicated by the identifier for the P-GW105contained in the session establishment response at sequence1109. As a result, the label allocation message at sequence1121is transferred along the route corresponding to the GTP tunnel from the P-GW105to the S-GW104. WhileFIG. 6shows one LSR2 (109-2), the embodiment may use plural LSR2's (109-2).

The label allocation message at sequence1121contains the FEC (Forwarding Equivalence Class) information for MPLS in order to make correspondence between the MPLS path and the GTP tunnel. The FEC information contains the IP address of the S-GW104as an endpoint of the GTP tunnel and the TEID for identifying the GTP tunnel from the P-GW105to the S-GW104.

The FEC information contained in the label allocation message at sequence1121may further contain: an identifier indicating the UE101; an identifier indicating the APN; IP addresses of the P-GW105and the UE101; or an identifier uniquely indicating the UE101or the bearer such as IMSI (International Mobile Subscriber Identity) or bearer ID.

The P-GW105may transmit a label allocation request message to the LSR2 (109-2) parallel to sequence1121in order to request the LSR2 (109-2) to allocate an MPLS path (1120). The P-GW105can fast allocate the MPLS path by transmitting the label allocation request message at sequence1120.

The label allocation request message at sequence1120contains the FEC information similarly to the label allocation message at sequence1121. The label allocation request message at sequence1102is transmitted to the destination indicated by the identifier for the S-GW104used at sequence1109. As a result, the label allocation request message at sequence1120is transferred along the packet transfer route corresponding to the GTP tunnel from the P-GW105to the S-GW104.

The LSR2 (109-2) is positioned along the route corresponding to the GTP tunnel from the P-GW105to the S-GW104. The LSR2 (109-2) does not transfer the received label allocation request message to further LSR2 (109-2) or the S-GW104if the FEC contained in the received label allocation request message is already stored in the memory902or is equal to the FEC contained in the received label allocation message.

The LSR2 (109-2) transfers the label allocation message transmitted from the S-GW104at sequence1121and transmits it to the P-GW105(1122). As a result, the MPLS label containing the FEC information is distributed to the LSR2 (109-2) along the route corresponding to the GTP tunnel from the P-GW105to the S-GW104to establish a downstream MPLS path1123from the P-GW105to the S-GW104.

After sequence1108, the P-GW105might determine allocation of the MPLS path to upstream communication from the UE101or the bearer requested for connection. In this case, the P-GW105transmits the label allocation message to the LSR2 (109-2) so as to be addressed to the S-GW104(1125). As a result, the P-GW105distributes the MPLS label corresponding to the upstream GTP tunnel allocated at sequence1109to the LSR2 (109-2) along the route corresponding to the GTP tunnel between the P-GW105and the S-GW104.

The label allocation message at sequence1125is transmitted to the destination indicated by the identifier for the S-GW104used at sequence1109. As a result, the label allocation message at sequence1125is transferred along the route corresponding to the GTP tunnel from the S-GW104to the P-GW105.

Similarly to sequence1121, the label allocation message at sequence1125contains the FEC information for making correspondence between the MPLS path and the GTP tunnel. The FEC information contains the IP address of the P-GW105as an endpoint of the GTP tunnel and the TEID for identifying the GTP tunnel from the S-GW104to the P-GW105.

The FEC information contained in the label allocation message at sequence1125may further contain: an identifier indicating the UE101; an identifier indicating the APN; IP addresses of the P-GW105and the UE101; or an identifier uniquely indicating the UE101or the bearer such as IMSI (International Mobile Subscriber Identity) or bearer ID.

The S-GW104may transmit a label allocation request message to the LSR2 (109-2) parallel to sequence1125in order to request the LSR2 (109-2) to allocate an MPLS path (1124). The S-GW104can fast allocate the MPLS path by transmitting the label allocation request message.

The label allocation request message at sequence1124contains the FEC information similarly to the label allocation message at sequence1125. The label allocation request message at sequence1124is transmitted to the destination indicated by the identifier for the P-GW105. As a result, the label allocation request message at sequence1124is transferred along the route corresponding to the GTP tunnel from the S-GW104to the P-GW105.

The LSR2 (109-2) is positioned along the route corresponding to the GTP tunnel between the S-GW104and the P-GW105. The LSR2 (109-2) does not transfer the received label allocation request message to further LSR2 (109-2) or the P-GW105if the FEC contained in the received label allocation request message is already stored in the memory902or is equal to the FEC contained in the received label allocation message.

The LSR2 (109-2), positioned along the route corresponding to the GTP tunnel from the S-GW104to the P-GW105, transfers the label allocation message transmitted from the P-GW105at sequence1125and transmits it to the S-GW104(1126). As a result, the MPLS label containing the FEC information is distributed to the LSR2 (109-2) along the route corresponding to the GTP tunnel from the S-GW104to the P-GW105to establish an upstream MPLS path1127from the S-GW104to the P-GW105.

The process from sequences1110to1117inFIG. 6is equal to the process from sequences1410to1417inFIG. 2. Differences will be described below. The GTP tunnel1118equals the GTP tunnel1418.

Information for MPLS path allocation is added to not only the session establishment response transmitted from the S-GW104to the MME103at sequence1110, but also an Initial Context Setup Request message transmitted from the MME103to the eNB102-1at sequence1111.

That is, the session establishment response at sequence1110and the Initial Context Setup Request message at sequence1111contain: the information indicating the GTP tunnel used to transmit a packet transmitted from the UE101from the eNB102to the service network107via the S-GW104and the P-GW105; and a flag indicating allocation of an MPLS downstream communication path for the UE101or the bearer requested for connection.

The information indicating the GTP tunnel at sequences1110and1111contains an endpoint IP address of the GTP tunnel, that is, an IP address for the S-GW104and the TEID for identifying the GTP tunnel from the eNB102to the S-GW104.

The Initial Context Setup Request message received from the MME103at sequence1111might contain the flag indicating the MPLS path allocation for downstream communication of the UE101or the bearer requested for connection. In this case, the eNB102-1starts a procedure to establish the MPLS path for transmitting a packet to the eNB102-1from the S-GW104.

The eNB102-1receives the Initial Context Setup Request message at sequence1111and then transmits the label allocation message to the LSR1 (109-1) so as to be transmitted to the S-GW104(1131). As a result, the eNB102-1distributes the MPLS label corresponding to the downstream GTP tunnel allocated at sequence1116to the LSR1 (109-1) along the route corresponding to the GTP tunnel between the S-GW104and the eNB102-1.

The label allocation message at sequence1131is transmitted to the destination indicated by the IP address for the S-GW104contained in the session establishment response at sequence1111. As a result, the label allocation message at sequence1131is transferred along the route corresponding to the GTP tunnel from the S-GW104to the eNB102-1. WhileFIG. 6shows one LSR1 (109-1), the embodiment may use plural LSR1's (109-1).

The label allocation message at sequence1131contains MPLS FEC information for making correspondence between an MPLS path and a GTP tunnel. The FEC information contains an identifier (e.g., IP address) of the UE101allocated by the MME103, an identifier (e.g., MAC address) specific to the UE101, or a bearer ID, and a TEID for identifying the GTP tunnel from the S-GW104to the eNB102-1.

The FEC information contained in the label allocation message at sequence1131may further contain: an identifier indicating the APN used for the UE101to communicate with the service network107; or an identifier uniquely indicating the UE101or the bearer such as IP addresses of the P-GW105and the UE101.

The S-GW104may transmit a label allocation request message to the LSR1 (109-1) parallel to sequence1131in order to request the LSR1 (109-1) to allocate an MPLS path (1130). The S-GW104can fast allocate the MPLS path by transmitting the label allocation request message at sequence1120.

The label allocation request message at sequence1130contains the FEC information similarly to the label allocation message at sequence1131. The label allocation request message at sequence1130is transmitted to the destination indicated by the identifier for the eNB102-1transmitted at sequence1116. As a result, the label allocation request message at sequence1130is transferred along the packet transfer route corresponding to the GTP tunnel from the S-GW104to the eNB102-1.

The LSR1 (109-1) is positioned along the route corresponding to the GTP tunnel between the S-GW104and the eNB102-1. The LSR1 (109-1) does not transfer the received label allocation request message to further LSR1 (109-1) or the eNB102-1if the FEC contained in the received label allocation request message is already stored in the memory902or is equal to the FEC contained in the received label allocation message.

The LSR1 (109-1), positioned along the route corresponding to the GTP tunnel from the S-GW104to the eNB102-1, transfers the label allocation message transmitted from the eNB102-1at sequence1131and transmits it to the S-GW104(1132). As a result, the MPLS label containing the FEC information is distributed to the LSR1 (109-1) along the route corresponding to the GTP tunnel from the S-GW104to the eNB102-1to establish a downstream MPLS path1133from the S-GW104to the eNB102-1.

The session establishment response at sequence1109might contain the flag indicating allocation of an MPLS path to upstream communication from the UE101or the bearer requested for connection. In this case, the S-GW104transmits the label allocation message to the LSR1 (109-1) so as to be transmitted to the eNB102-1(1135). As a result, the S-GW104distributes the MPLS label corresponding to the upstream GTP tunnel allocated at sequences1110and1111to the LSR1 (109-1) along the route corresponding to the GTP tunnel between the eNB102-1and the S-GW104.

The label allocation request message at sequence1135is transmitted to the destination indicated by the identifier for the eNB102-1transmitted at sequence1116. As a result, the label allocation request message at sequence1135is transferred along the route corresponding to the GTP tunnel from the eNB102-1to the S-GW104.

Similarly to sequence1131, the label allocation message at sequence1135contains the FEC information for making correspondence between the MPLS path and the GTP tunnel. The FEC information contains the IP address of the S-GW104and the TEID for identifying the GTP tunnel from the eNB102-1to the S-GW104.

The FEC information contained in the label allocation message at sequence1131may further contain: an identifier indicating the APN used for the UE101to communicate with the service network107; IP addresses of the P-GW105and the UE101; or an identifier such as a bearer ID uniquely indicating the UE101or the bearer.

The eNB102-1may transmit a label allocation request message to the LSR1 (109-1) parallel to sequence1135in order to request the LSR1 (109-1) to allocate an MPLS path (1134). The S-GW104can fast allocate the MPLS path by transmitting the label allocation request message.

The label allocation request message at sequence1134contains the FEC information similarly to the label allocation message at sequence1135. The label allocation request message at sequence1134is transmitted to the destination indicated by the identifier for the eNB102-1. As a result, the label allocation request message at sequence1134is transferred along the route corresponding to the GTP tunnel from the eNB102-1to the S-GW104.

The LSR1 (109-1) is positioned along the route corresponding to the GTP tunnel between the eNB102-1and the S-GW104. The LSR1 (109-1) does not transfer the received label allocation request message to further LSR1 (109-1) or the S-GW104if the FEC contained in the received label allocation request message is already stored in the memory902or is equal to the FEC contained in the received label allocation message.

The LSR1 (109-1), positioned along the route corresponding to the GTP tunnel from the eNB102-1to the S-GW104, transfers the label allocation message transmitted from the S-GW104at sequence1135and transmits it to the eNB102-1(1136). As a result, the MPLS label containing the FEC information is distributed to the LSR1 (109-1) along the route corresponding to the GTP tunnel from the eNB102-1to the S-GW104to establish an upstream MPLS path1137from the eNB102-1to the S-GW104.

Sequences1120to1122and sequences1124to1126allocate an MPLS path between the S-GW104and the P-GW105and may be performed parallel to sequences1110to1117that allocate a GTP tunnel between the eNB102-1and the S-GW104. This can fast allocate the MPLS path.

The GTP tunnel is included in the IP tunnel. According to the embodiment, application of the MPLS to a GTP tunnel is synonymous with application of the MPLS to an IP tunnel. If the embodiment applies the MPLS to the IP tunnel, the TEID is replaced by the identifier that uniquely indicates the IP tunnel.

FIG. 7is an explanatory diagram showing protocol stacks for the eNB102, the S-GW104, and the P-GW105according to the first embodiment of the invention.

FIG. 7shows protocol stacks available when an MPLS path is established. The protocol stacks shown inFIG. 7correspond to headers attached to packets that are transmitted and received.

The IP505and the payload506are equal to those shown inFIG. 3and correspond to the IP header and the payload attached to a packet transmitted or received from the UE101. L1/L2 (501) and L1/L2 (507) indicate the physical layer and the data link layer (Layer1/Layer2). The L1/L2 (501) is used between the eNB102and the S-GW104. The L1/L2 (507) is used between the S-GW104and the P-GW105.

An MPLS601is equivalent to the MPLS header attached to a packet exchanged between the eNB102-1and the LSR1 (109-1). An MPLS602is equivalent to the MPLS header attached to a packet exchanged between the LSR1 (109-1) and the S-GW104.

An MPLS603is equivalent to the MPLS header attached to a packet exchanged between the S-GW104and the LSR2 (109-2). An MPLS604is equivalent to the MPLS header attached to a packet exchanged between the LSR2 (109-2) and the P-GW105.

The LSR109and the S-GW104replace headers corresponding to the MPLS's601through604with labels. That is, the LSR109and the S-GW104replace the contents of the headers corresponding to the MPLS's601through604attached to a packet with the labels distributed by the label allocation message and the label allocation request message at sequences1121,1122,1125,1126,1131,1132,1135, and1136. As a result, the packet is transferred within the radio access network108.

For example, a packet might store an identifier (a value equivalent to the TEID) for each IP tunnel in each of the MPLS headers corresponding to the MPLS's601through604. In such a case, each LSR109and the S-GW104can compare an FEC type703and an FEC value704maintained in themselves with the IP tunnel identifier contained in the packet and determine which MPLS path the packet passes through.

FIG. 8is an explanatory diagram showing an FIB for the MPLS according to the first embodiment of the invention.

FIG. 8exemplifies an MPLS FIB (Forwarding Information Base) maintained in the LSR109or the S-GW104. The FIB contains an input port701, an input label702, an FEC type703, an FEC value704, an output port705, and an output label706.

The input port701indicates a reception port corresponding to the MPLS path. The input label702indicates a reception label corresponding to the MPLS path.

The FEC type703indicates the attribute of a packet accommodated to the MPLS path. That is, the FEC type703indicates what type of UE101or bearer transmitted the packet. The type includes an identifier that uniquely indicates the UE101or the bearer.

For example, the FEC type703stores: the address indicated by IPv4 or IPv6; the subnet indicated by IPv4 or IPv6; the IP address of an apparatus as a reception endpoint of the GTP tunnel and the TEID of the GTP tunnel; the IP address of the UE101and the address of P-GW or HA (Home Agent); the IP address of the UE101and the identifier of a service network such as APN used by the UE101; and the identifier such as IMSI (International Mobile Subscriber Identity) and/or a bearer ID.

The FEC value704stores a value corresponding to the FEC type703. That is, the FEC value704stores a value for the identifier indicated by the FEC type703. One MPLS FIB may maintain plural FEC types703and FEC values704.

The FEC type703and the FEC value704store the FEC information contained in the label allocation message and the label allocation request message at sequences1121,1122,1125,1126,1131,1132,1135, and1136.

The output port705indicates an output port corresponding to the MPLS path. The output label706indicates an output label corresponding to the MPLS path. The MPLS FIB inFIG. 8may store predetermined values or dynamically store values in accordance with the MPLS label allocation signaling inFIG. 6(including the label allocation message and the label allocation request message shown inFIG. 6).

The LSR109receives a packet and then references the MPLS FIB maintained in itself. The LSR109determines whether the FIB contains entries for the input port701and the input label702that match the input port for the received packet and the MPLS label maintained in the received packet. If the FIB contains matching entries, the LSR109replaces the MPLS label maintained in the packet with the output label706for the matching entry. The LSR109transmits the packet from the interface904for a port specified by the output port705.

FIG. 9is a flowchart showing a process of the P-GW105after reception of a session establishment request according to the first embodiment of the invention.

The P-GW105receives a session establishment response from the S-GW104at sequence1108(1001). The P-GW105then determines whether the static policy previously stored in the P-GW105is used for the service network corresponding to the APN used by the UE101or the bearer requested for connection via the eNB102-1, the MME103, and the S-GW104(1002).

The static policy previously stored in the P-GW105might not be used for the service network corresponding to the APN used by the UE101or the bearer requested for connection. In this case, the P-GW105requests the PCRF120to transmit the user class and/or the QoS policy of the UE101or the bearer requested for connection (1003).

After step1003, the P-GW105receives the user class and/or the QoS policy from the PCRF120. The P-GW105settles the maximum bit rate and/or the guaranteed bandwidth of the UE101or the bearer requested for connection based on the received user class and/or QoS policy (1004).

At step1002, the static policy previously stored in the P-GW105might be used for the service network corresponding to the APN used by the UE101. In this case, the P-GW105extracts the user class and/or the QoS policy stored in the P-GW105. The P-GW105settles the maximum bit rate and/or the guaranteed bandwidth of the UE101or the bearer requested for connection based on the extracted user class and/or QoS policy (1005).

After step1004or1005, the P-GW105determines whether the user class acquired at step1003or1005indicates a high priority (1006). If the user class indicates a high priority, the P-GW105proceeds to step1008to allocate an MPLS path based on the user class.

At step1006, the user class acquired at step1003or1005might not indicate a high priority. In this case, the P-GW105determines whether the maximum bit rate and/or the guaranteed bandwidth settled at step1004or1005is greater than a threshold value previously maintained in the P-GW105(1007). The P-GW105thereby determines whether to allocate an MPLS path to the UE101or the bearer requested for connection.

At step1007, the settled maximum bit rate and/or guaranteed bandwidth might be smaller than or equal to the threshold value previously maintained in the P-GW105. In this case, the P-GW105determines not to allocate an MPLS path to the UE101or the bearer requested for connection because high QoS is unneeded for the UE101or the bearer requested for connection. The P-GW105then transmits a normal session establishment response to the S-GW104(1013). This is equivalent to sequence1409inFIG. 2.

After step1013, the UE101, the eNB102, the MME103, and the S-GW104establish an IP tunnel for data communication (1014). This is equivalent to sequences1410to1417inFIG. 2.

At step1007, the settled maximum bit rate and/or guaranteed bandwidth might be greater than the threshold value previously maintained in the P-GW105. In this case, the P-GW105determines to allocate an MPLS path to the UE101or the bearer requested for connection because high QoS is needed for the UE101or the bearer requested for connection (1008). The P-GW105transmits a session establishment response supplied with the flag for MPLS path establishment to the S-GW104(1009). This is equivalent to sequence1109inFIG. 6.

After step1009, the UE101, the eNB102-1, the MME103, and the S-GW104generate an IP tunnel for data communication (1010). This is equivalent to sequences1110to1117in FIG.6. After step1010, the eNB102-1, the S-GW104, and the P-GW105transmit an MPLS path, a label allocation message, and a label allocation request message to the LSR109connected to themselves (1011). After step1011, each LSR109stores the label in the label switch processing portion905(1012).

As mentioned above, the MPLS path allocation is determined in accordance with the UE101or the bearer. The MPLS path allocation may be determined in accordance with the upstream or downstream communication for the UE101or the bearer if the static policy previously maintained in the P-GW105or the QoS policy maintained in the PCRF120is settled for the upstream or downstream communication.

The first embodiment can uniquely settle a route between the eNB102and the P-GW105by allocating an MPLS path between endpoints of the IP tunnel. The MPLS label is not distributed to unnecessary LSR109.

The MPLS path is allocated to the route for each UE101or bearer accommodated to the IP tunnel. It is therefore possible to prevent degradation of the MPLS network performance and insufficiency of resources due to distribution of many label switch paths to all the LSRs109in the radio access network108.

The QoS policy is acquired for each UE101or bearer. It is therefore possible to determine the UE101or bearer requiring an MPLS path and efficiently apply the MPLS.

Second Embodiment

The following describes hand-over operations of the UE101according to the second embodiment of the invention.

FIG. 10is a sequence diagram showing a hand-over process of the UE101according to the second embodiment of the invention.

The sequence diagram inFIG. 10shows a process after completion of the process from sequences1101to1136inFIG. 6. InFIG. 10, the eNB102-1represents a base station as a hand-over origin. The TeNB102-2represents the eNB102as a hand-over destination. The eNB102-1at the beginning of the sequence inFIG. 10is equivalent to the eNB102-1after the process inFIG. 6has been performed up to sequence1136.

MPLS paths before hand-over (HO) include1133,1123,1137, and1127. The eNB102-1as an HO origin transmits a Measurement Control message to the UE101and thereby requests the UE101to report a radio state at the transmission of the Measurement Control message and information indicating the eNB102from which the UE101receives signals (1802).

After sequence1802, the UE101transmits a Measurement Report message to notify the eNB102-1of the radio state at the reception of the Measurement Control and the information about the eNB102from which the LTE101receives signals (1803). The information about the eNB102includes information such as the radio field strength of a signal the UE101receives from the eNB102, position information about the UE101, and/or a distance from the nearest eNB102.

The eNB102-1as the HO origin settles the TeNB102-2as an HO destination based on the received Measurement Report message. The eNB102-1transmits an HO Request message to the TeNB102-2in order to request the settled TeNB102-2as the HO destination to prepare for HO (1804).

The HO Request message contains information about a bearer with which the eNB102-1as the HO origin and the UE101are communicating. The information about the communicating bearer includes, for example, an identifier for uniquely identifying the UE101allocated by the MME103, an identifier specific to the UE101, a bearer ID corresponding to each bearer, information about an IP tunnel corresponding to the bearer, and information indicating whether an MPLS path is used for the IP tunnel.

After sequence1804, the TeNB102-2as the HO destination transmits an HO Request Ack message to the eNB102-1to notify completion of the HO preparation, if done (1805). The eNB102-1as the HO origin receives the HO Request Ack message and then transmits an HO Command message to the UE101in order to perform the HO (1806).

After sequence1806, the UE101is assumed to successfully establish a radio link to the TeNB102-2as the HO destination and then transmits an HO Confirm message to the TeNB102-2(1807). The TeNB102-2receives the HO Confirm message and then notifies the MME103of successful HO and requests it to switch the IP tunnel (1808).

After sequence1808, the MME103transmits a Modify Bearer Request message to the S-GW104to notify that the HO occurs between the UE101and the eNB102and the IP tunnel needs to be switched (1813).

The S-GW104receives the Modify Bearer Request message and then returns the Modify Bearer Response message to respond to the MME103(1814).

The MME103receives the Modify Bearer Response message and then transmits a Path Switch Ack message to notify the TeNB102-2as the HO destination that the IP tunnel has been switched successfully (1815). As a result, an IP tunnel1816is established.

The TeNB102-2as the HO destination starts switching the MPLS path simultaneously with the IP tunnel switching process (equivalent to sequences1813to1815). According to the second embodiment, the MPLS path switching during HO is not performed on all the LSR1s (109-1) that are travelled from the TeNB102-2to the S-GW104as endpoints of the IP tunnel. The MPLS path switching just needs to be performed only on the LSR1 (109-1) between the TeNB102-2and the LSR1 (109-1) as a junction (branch point) between the earlier MPLS and the new MPLS path. This makes it possible to reduce the time needed to switch the MPLS path.

The TeNB102-2as the HO destination transmits a label distribution message to the directly connected LSR1 (109-1) (1809). The label distribution message is addresses to the S-GW104and switches the downstream MPLS path from the S-GW104to the TeNB102-2. An LDP signal is used to transmit the label distribution message to the LSR1 (109-1).

The label distribution message at sequence1809stores the information contained in the HO Request message at sequence1804. In order to switch the MPLS path, the label distribution message stores the identifier allocated by the MME103for identifying the UE101, the identifier specific to the UE101, the bearer ID, and the destination address of the MPLS path (i.e., the address of the S-GW104as an endpoint of the IP tunnel).

The TeNB102-2as the HO destination also transmits a label distribution request message to the directly connected LSR1 (109-1) (1810). The label distribution request message is addresses to the S-GW104and switches the upstream MPLS path from the TeNB102-2to the S-GW104. An LDP signal is used to transmit the label distribution request message to the LSR1 (109-1).

Similarly to the label distribution message at sequence1809, the label distribution request message at sequence1810stores the information contained in the HO Request message at sequence1804. In order to switch the MPLS path, the label distribution request message stores the identifier allocated by the MME103for identifying the UE101, the identifier specific to the UE101, the bearer ID, and the destination address of the MPLS path (i.e., the address of the S-GW104as an endpoint of the IP tunnel).

The label distribution message at sequence1809and the label distribution request message at sequence1810are transmitted to the LSR1 (109-1) along the route from the TeNB102-2to the S-GW104. These messages are received and processed in the LSR1s (109-1) and then are transmitted to the next LSR1 (109-1) along the route to the S-GW104.

Each LSR1 (109-1) receives the label distribution message at sequence1809and the label distribution request message at sequence1810and then searches the MPLS FIB (seeFIG. 8) maintained in itself. The LSR1 (109-1) determines whether its FIB contains information that matches the information contained in the label distribution message and the label distribution request message.

If containing matching information, the LSR1 (109-1) is to be used as a junction (branch point) and therefore stops further transfer of the label distribution message and the label distribution message. The LSR1 (109-1) updates the MPLS FIB (seeFIG. 8) maintained in itself based on the information contained in the received label distribution message and label distribution request message.

Specifically, the LSR1 (109-1) receives the label distribution message at sequence1809and then extracts entries for the FEC type703and the FEC value704corresponding to identifiers contained in the label distribution message from the FIB maintained in the LSR1 itself. The LSR1 (109-1) updates the input port701and the input label702for the extracted entries to values corresponding to those contained in the label distribution message.

The LSR1 (109-1) receives the label distribution request message at sequence1810and then extracts entries for the FEC type703and the FEC value704corresponding to identifiers contained in the label distribution request message from the FIB maintained in the LSR1 itself. The LSR1 (109-1) updates the output port705and the output label706for the extracted entries to a port and a label corresponding to the new MPLS path. The LSR1 (109-1) stores the updated label in the label distribution request message. The LSR1 (109-1) then transfers the label distribution request message to the next LSR1 (109-1) along the route to have transmitted the label distribution request message toward the transmission origin (i.e., TeNB102-2) of the message.

Sequence1809establishes the downstream MPLS path1811. Sequences1810and1820establish the upstream MPLS path1812.

The MPLS path presetting (equivalent to sequence1809) may start when the TeNB102-2receives the HO Request message (equivalent to sequence1804) for allowing the TeNB102-2to prepare for HO in the MPLS path switching procedure. In this case, the TeNB102-2may receive the HO Confirm message indicating the completion of HO from the UE101(equivalent to sequence1807) and then may command the LSR1 (109-1) as a junction (branch point) to completely switch the MPLS path.

FIG. 11is a flowchart showing a process of the LSR109during hand-over according to the second embodiment of the invention.

The LSR1 (109-1) receives an LDP signal and then starts the process inFIG. 11(1201). After step1201, the LSR1 (109-1) analyzes the received LDP signal and determines whether the LDP signal indicates downstream switching, that is, the LDP signal contains the label distribution message (1202).

If the received LDP signal contains the label distribution request message, the LSR1 (109-1) determines to allow the received LDP signal to perform the process at step1203and later (1203). The LSR1 (109-1) determines whether the FEC type703and the FEC value704in its FIB store the same value as information contained in the label distribution request message (1204and1205).

The LSR1 (109-1) is not defined as a junction (branch point) if its FIB does not store the same value as information contained in the label distribution request message. The LSR1 (109-1) transmits the label distribution request message (upstream switch request) to the next LSR1 (109-1) between the TeNB102-2and the S-GW104(1206).

The LSR1 (109-1) is defined as a junction (branch point) if its FIB stores the same value as information contained in the label distribution request message. If the HO changes the MPLS path, the LSR1 (109-1) between another LSR1 (109-1) as a junction and the S-GW104need not update the already stored MPLS label corresponding to the UE101.

At step1205, the LSR1 (109-1) might find that its FIB stores the same value as information contained in the label distribution request message. In this case, the LSR1 (109-1) stops transmitting the LDP signal (label distribution request message) to the next LSR1 (109-1) along the route to the S-GW104(1207).

After step1207, the LSR1 (109-1) extracts an FIB entry matching the information contained in the label distribution request message. The LSR1 (109-1) updates the extracted FIB entries corresponding to the output port705and the output label706to equivalents the LSR1 (109-1) allocated for the changed path (1208). After step1208, the LSR1 (109-1) uses an LDP (upstream switching) signal to transmit a label distribution message containing the changed label to the transmission origin of the LDP switch request (label distribution request message) (1209).

After step1209, the LSR1 (109-1) between another LSR1 (109-1) as a junction and the TeNB102-2might receive the LDP (upstream switching) signal and then updates its FIB based on the received FEC information and the output port and the output label the relevant LSR1 (109-1) allocated for the changed path. That LSR1 (109-1) then transmits a response to the transmission origin of the LDP switch request (label distribution request message).

In this manner, the TeNB102-2distributes the MPLS label for the newly allocated upstream MPLS path to the LSR1 (109-1) between the TeNB102-2and the LSR1 (109-1) as a junction (branch point). As a result, the upstream MPLS path1812is established.

At step1202, the LSR1 (109-1) might receive an LDP signal that does not contain the label distribution request message. In this case, the LSR1 (109-1) determines whether the received LDP signal requests downstream switching, that is, whether the LDP signal contains the label distribution message (1210).

If the received LDP signal contains the label distribution message, the LSR1 (109-1) determines to allow the received LDP signal to perform the process at1211and later (1211). The LSR1 (109-1) determines whether the FEC type703and the FEC value704in its FIB store the same value as information contained in the label distribution message (1212and1213).

The LSR1 (109-1) is defined as a junction (branch point) if its FIB stores the same value as information contained in the label distribution request message. At step1213, the LSR1 (109-1) might be determined that its FIB stores the same value as information contained in the label distribution request message. In this case, the LSR1 (109-1) then stops transmitting the LDP signal to the next LSR1 (109-1) along the route to the S-GW104.

The LSR1 (109-1) extracts an FIB entry matching the information contained in the label distribution message. The LSR1 (109-1) updates the input port701and the input label702corresponding to the extracted FIB entries to the information contained in the received label distribution message (1214).

At step1213, the LSR1 (109-1) might be determined that its FIB does not store the same value as information contained in the label distribution request message. In this case, the LSR1 (109-1) configures a new MPLS path. That is, the LSR1 (109-1) creates a new entry in the FIB and stores a value corresponding to the downstream MPLS path in the new entry (1215).

Specifically, at step1215, the LSR1 (109-1) stores values contained in the label distribution message in the FEC type703and the FEC value704as new entries. The values include the identifier allocated by the MME103for identifying the UE101, the identifier specific to the UE101, the bearer ID corresponding to each bearer, and the destination address of the MPLS path (i.e., the address of the S-GW104as an endpoint of the IP tunnel).

After step1215, the LSR1 (109-1) transmits an LDP signal containing the label distribution message to the next LSR1 (109-1) along the route to the S-GW104(1216).

The process at steps1211to1216establishes the downstream MPLS path1811from the LSR1 (109-1) as a junction to the TeNB102-2.

At step1210, the LDP signal might contain neither the label distribution message nor the label distribution request message. In this case, the LSR1 (109-1) performs the other MPLS signal processes (1217).

The first and second embodiments are available with the same UE101, eNB102, MME103, S-GW104, P-GW105, LSR109, and PCRF120.

The embodiment has allocated the MPLS path in accordance with the IP tunnel establishment procedure. In addition, the embodiment can establish the MPLS path according to the same procedure as that shown inFIG. 6if the transitional apparatus (equivalent to S-GW104) between the P-GW105and the eNB102is uniquely determined and a route between the eNB102and the transitional apparatus and a route between the transitional apparatus and the P-GW105are uniquely determined for the UE101or the bearer separately from each other.

During hand-over, the second embodiment switches the MPLS path on the route from the eNB102to the S-GW104. This eliminates the need to distribute an MPLS label to the LSR109that is included in the route from the eNB102to the P-GW105and need not switch the MPLS path. The MPLS network can be operated efficiently.

The embodiment extracts the LSR1 (109-1) that is included between the eNB102and the S-GW104and is assumed to be a junction between the route before hand-over and the route after hand-over. The embodiment updates the MPLS path between the extracted LSR1 (109-1) as a junction and the eNB102. This makes it possible to fast update the MPLS path during hand-over and efficiently operate the mobile MPLS network.

In general, the eNB102connected to the UE101before hand-over is positioned geographically near the eNB102connected to the UE101after hand-over. In many cases, a route connecting the eNB102to the S-GW104before hand-over share many LSR1s (109-1) with a route connecting the eNB102to the S-GW104after hand-over. Therefore, it is possible to highly efficiently operate the mobile MPLS network by switching the MPLS path due to hand-over up to the LSR1 (109-1) functioning as a junction.

The embodiment can uniquely settle a route to which the MPLS is allocated. This makes it possible to decrease the network performance degradation due to MPLS label distribution. The embodiment fast switches an MPLS label for the LSR109between the eNB102and the P-GW105or the S-GW104. This makes it possible to fast complete the hand-over and highly efficiently operate the mobile MPLS network.