Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L45/00—Routing or path finding of packets in data switching networks
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L45/00—Routing or path finding of packets in data switching networks
  • H04L45/50—Routing or path finding of packets in data switching networks using label swapping, e.g. multi-protocol label switch [MPLS]
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W40/00—Communication routing or communication path finding
  • H04W40/34—Modification of an existing route
  • H04W40/36—Modification of an existing route due to handover

Definitions

• the invention generally relates to packet data transmission in wireless networks, such as cellular mobile networks and wireless local area networks, and in particular to protocols providing the routing of packet data through the core network of the wireless network.
• a mobile data terminal such as a mobile phone or a portable personal computer
• MH mobile data terminal
• Packet data in this context may contain hypertext markup language (HTML) documents or coded audio and video signals like voice over Internet protocol, video conferencing signals or video streaming.
• HTTP hypertext markup language
• coded audio and video signals like voice over Internet protocol, video conferencing signals or video streaming.
• uncontrolled delay or even loss of data packets in the transmission can impact the practical use up to complete uselessness.
• QoS quality of service
• the wireless network consists of a so called core network and a plurality of radio access network (RAN) domains providing wireless connection between the mobile host and the core network.
• the core network has an external connection through a gateway (GW) to other networks, like for example the world wide Internet.
• GW gateway
• a scenario is considered, in which multi-protocol label switching (MPLS) is deployed as a transport technology between the gateway (GW) and the radio access network domains.
• MPLS-based tunnels between the GW and the RAN domains are set up deploying traffic engineering (TE) options of MPLS signalling.
• TE traffic engineering
• a tunnel is a virtual connection between two nodes of a network, wherein payload data is encapsulated with lower layer protocol headers and transmitted over the network, in order to provide a transparent point-to-point connection.
• the data packets destined to a roaming MH are tunnelled in such MPLS- based tunnel over the core network.
• Mobility management solutions for data communication for example in second generation (Global System for Mobile Communication, GSM) and third generation (Universal Mobile Telecommunications System, UMTS) cellular networks, are proprietary and technology specific.
• the Internet Engineering Task Force (IETF) has standardized mobility management within Internet protocol-(IP)-based networks known as Mobile Internet protocol (MIP).
• IP routing uses the packet's IP address as information about the destination point, i.e. the IP address determines unambiguously the geographical point of attachment.
• MIP extends the classical IP routing with the mobile host's possibility to be associated with two IP addresses: a static "home” address and a dynamic "care-of-address" (CoA), which reflects the MH's current point of attachment. More detailed information about the functionality of MIP can be found in C. Perkins et. al., "IP Mobility Support for IPv4", RFC 3344, August 2002.
• the MPLS concept employs two distinct functional planes: control plane and forwarding plane.
• control plane standard routing protocols are used to exchange information between routers to build and maintain a forwarding table.
• standard protocols are for example "open shortest path first" (OSPF) and border gateway protocol (BGP).
• OSPF open shortest path first
• BGP border gateway protocol
• FEC forwarding equivalent class
• LSR Label Switch Router
• the MPLS described above has still the hop-by-hop forwarding paradigm inherited from standard IP routing.
• traffic engineering (TE) capabilities for MPLS can be deployed.
• the requirements for TE- MPLS are defined in D. Awduche, J. Malcolm, J. Agogbua, M. O'Dell, J. McManus, "Requirements for Traffic Engineering Over MPLS", RFC 2702, September 1999. These capabilities can be used to optimise the utilization of network resources and to enhance traffic oriented performance characteristics.
• a LSP set up by TE functionality is called TE-LSP or LSP tunnel, since the flow along an LSP is completely identified by the label applied at the ingress node of the path.
• MPLS is generic rather than proprietary transport technique, however, mobility is not available in the specifications.
• Several recent publications have considered the deployment of MPLS in mobile networks. Whereas F. Chiussi, D. Khotimsky, and S. Krishnan, “A Network Architecture for MPLS-Based Micro-Mobility", in Proc. of the Wireless Communications and Networking Conference (WCNC), March 2002 and T. Yang, Y. Dong, Y. Zhang, and D. Makrakis, "Practical Approaches for Supporting Micro Mobility with MPLS", in Proc. of the International Conference on Telecommunications (ICT), June 2002 consider micro-mobility within the mobile operator's network, the proposal described in Z. Ren, C.-K. Tham, C.-C. Foo, C.-C.
• bi-directional MPLS tunnels can be used to connect the Gateway and the NoA.
• the setup of bi-directional LSPs is described in detail in R. Dube, M. Costa, "Bi-directional LSPs for classical MPLS", Internet Draft, Work in Progress (in context of "classical” MPLS) and L. Berger et.al., "Generalized Multi- Protocol Label Switching (GMPLS) Signalling Resource Reservation Protocol-Traffic Engineering (RSVP-TE) Extensions", RFC 3473, January 2003 (in context of Generalized MPLS), which differ only in the message format rather than the procedures for the LSP setup.
• GPLS Generalized Multi- Protocol Label Switching
• RSVP-TE Signalling Resource Reservation Protocol-Traffic Engineering
• the term "initiator” is used to represent the LSR that initiates LSP setup and the term “terminator” to represent the LSR at the other end of the LSP.
• the ingress LSR in case of uni-directional tunnel corresponds to initiator and the egress LSR corresponds to terminator.
• uni-directional tunnels will be regarded and the terms ingress and egress LSR will be used for the ease of explanation. However, this is not to be understood as limiting, and the described procedures can be applied to bidirectional tunnels as well.
• the method for setup of bi-directional MPLS tunnels provides means for both symmetric and asymmetric tunnels. Having a voice service or video conferencing, a symmetric bi-directional tunnel can be preferable. In contrary, when the bi-directional tunnel is used to support video streaming, an asymmetric tunnel, where the bandwidth for the upstream path is lower than in the downstream path, can optimally fit to the traffic requirements.
• the method according to the invention does not impact the procedures for set up symmetric/asymmetric tunnels.
• the MPLS architecture does not assume a single label distribution protocol, and thus, in the control plane different signalling protocols like Label Distribution Protocol (LDP) and Resource Reservation Protocol (RSVP) can be used.
• RSVP was designed to fulfil the Integrated Services (IntServ) concept for implementing QoS in standard IP-based networks.
• IntServ Integrated Services
• RSVP-TE Integrated Services
• the extended RSVP is known as RSVP-TE and it is described in detail in D. Awduche, L. Berger, D. Gan, T. Li, V. Srinivasan, G. Swallow, "RSVP-TE: Extensions to RSVP for LSP Tunnels", RFC 3209, December 2001.
• the extended RSVP protocol supports the instantiation of explicitly routed LSPs, with or without resource reservations. It also supports smooth rerouting of LSP tunnels, pre-emption, and loop detection.
• RSVP-TE is considered as an exemplary signalling protocol. However, it is understood that the invention can also be applied to other particular protocols providing data tunnels in a packet switched network.
• RSVP-TE Two mechanisms are currently available in RSVP-TE, which allow to perform changes on existing LSP tunnels. These mechanisms are:
• a packet switched communications network utilizes a mobile specific label edge router (MLER) configured with mobility management functionality.
• MLER supports the handing over of a call from a label switched path to a first MLER associated with a currently serving radio base station to another label switched path for a second MLER associated with a target base station.
• paths are available between Label Edge Router (LER) and BS.
• the Label Edge Router changes the MPLS header of the data packets destined to the old base station with MPLS labels targeting the new base station.
• CA2292252 proposes a segmentation of the LSP within the MPLS domain, where an intermediate LER changes the packet's header. This requires extended functionality of the intermediate LER. Therefore a simplified method is needed with minimum additional requirements to intermediate nodes of the core network.
• WO0045560A2 "PUBLIC MOBILE DATA COMMUNICATIONS NETWORK" is an example of a public mobile access network using a home/foreign agent model where the home and foreign agents transfer data packets over the public mobile access network via a data tunnel.
• the Mobile IP packets are carried using MPLS LSPs.
• the home agent is located at a point of presence near to Internet backbone and each base station has implemented foreign agent functionality.
• a data tunnel is established between the home agent and one of the foreign agents.
• WO0045560A2 assumes Mobile IP that runs over MPLS LSP. This requires extended functionality from the mobile host. Therefore a method is needed which relieves the mobile host largely from mobility management tasks.
• a unique MPLS label is assigned to each terminal.
• This MPLS label allows unambiguous addressing of the data packets to the terminal.
• the routers tunnel the information packets, using either the MPLS or another tunnelling protocol. This provides a method for the end terminal to notify a MPLS router about its unique MPLS label. Then the MPLS router tunnels the data packets to the end terminal using label stacking.
• WO2003030467A2 assumes that each terminal has a unique MPLS label allowing the tunnelling from ingress point to the mobile host. This requires an adaptation of the signalling in the radio access network. Therefore there is a need for a method which does not include the mobile host in the MPLS functionality.
• MPLS packet- switched network with possibility to provide QoS (especially relevant for real-time services) and TE. Since the MH roams between BSs (and consequently between ARs), the egress LSR terminating the MPLS tunnel may change during handover. In such a scenario an appropriate method to provide mobility to the MH is needed.
• Currently known schemes for employing mobility in MPLS are based on Mobile IP and require that the MH accepts a new IP address when it registers at the new AR.
• a method comprising the steps of (a) setting up a first multi-protocol label switching tunnel from an ingress node to a first egress node serving a first radio access network domain and, if the mobile host moves from a service area of the first radio access network domain to a service area of a second radio access network domain, (b) setting up a second multiprotocol label switching tunnel from the ingress node to a second egress node serving the second radio access network domain, the mobile host having an IP address in step (b) identical with an IP address assigned to the mobile host in step (a).
• the method of setting up a new tunnel to the second (new) egress node instead of re-routing the existing tunnel provides the advantage of compatibility with existing resource reservation protocols, as the tunnel end point address is a part of the tunnel identifier.
• the mobility handling is simplified because it can be managed in the ingress node without requiring additional functionality in intermediate nodes and the requirement on the functionality of the MH is reduced.
• the second MPLS tunnel may have a quality of service parameter equal to a quality of service parameter of the first MPLS tunnel. This ensures that the quality of service does not change when the MH moves inside the service area of the wireless network.
• the difference between identifiers of the first and second MPLS tunnels is only a tunnel end point address. This provides the advantage of simplified signalling and reduces traffic necessary for signalling in the core network.
• the second MPLS tunnel is built up before the first MPLS tunnel is torn down. This embodiment provides the advantage of improved reliability avoiding the risk of loss of data packages.
• the setup of the second MPLS tunnel may be initiated from the first egress node.
• This embodiment provides the advantage of simplified signalling, as the first (old) egress node has all information necessary to request the setup of a new tunnel to the second (new) egress node.
• the method may comprise the steps of (c) informing the first egress node about the handover; (d) sending, by the first egress node, (d1 ) an acknowledgement for attachment to the second egress node, and (d2) a message to the ingress node with information about the second egress node; (e) starting, by the ingress node, upon reception of the message specified in (d2), the setup of a second multi-protocol label switching tunnel to the second egress node; (f) completing, by the second egress node, after receiving the acknowledgement as specified in (d1 ) and signalling from the ingress node concerning the setup of the second multi-protocol label switching tunnel, handover procedures in the network; (g) switching, by the ingress node, traffic from the first to the second tunnel when a tunnel setup acknowledge is received; and (h) tearing down the first tunnel by the ingress node.
• This embodiment provides the advantage of quick and reliable signalling while requiring only one element in the protocol, which is not part of the current standard and has to be newly introduced.
• step (c) comprises (d) informing, by the mobile host, the second egress node about the IP address of the mobile host and an IP address of the first egress node; and (c2) requesting, by the second egress node, an authorization from the first egress node.
• the message in step (d2) is a dedicated message in a resource reservation protocol. This embodiment provides the advantage of compatibility with existing protocols. In still another embodiment the message in step (d2) contains a dedicated object in a resource reservation protocol. This embodiment provides the advantage of compatibility with existing protocols while at the same time minimising signalling traffic, as identical elements common to both tunnels are not repeated in step (d2).
• the first egress node is informed in step (c) about the handover and about an identifier of the second egress node by the mobile host.
• This embodiment may work also in cases where there is no direct communication between first and second egress node possible over the core network, for example with loosely coupled radio access network domains.
• the ingress node checks in step (e) for other available tunnels to the mobile host via the first egress node and starts a set up of a tunnel to the second egress node for each such tunnel.
• This embodiment has the advantage of greatly reducing signalling between the first egress node and the ingress node, because the first egress node has to send the message in step (d2) only once for all existing tunnels to the same MH.
• the setup of the second multi-protocol label switching tunnel is initiated from the second egress node.
• the method may comprise the steps of (i) informing, by the mobile host, the first egress node about an IP address of the second egress node; (k) sending context information from the first egress node to the second egress node; (I) sending a request from the second egress node to the ingress node to set up the second multi-protocol label switching tunnel; (m) starting, by the ingress node, upon reception of the request specified in (c), the setup of the second multi-protocol label switching tunnel to the second egress node; (n) completing, by the second egress node, after receiving signalling from the ingress node concerning the setup of the second multi-protocol label switching tunnel, handover procedures in the network; (o) switching, by the ingress node, traffic from the old tunnel to the second tunnel when a tunnel setup acknowledge is received; and (p) tearing down the old tunnel by the ingress node.
• This embodiment provides the advantage of quick and reliable signalling while requiring only one element
• the request in step (I) may be a dedicated message in a resource reservation protocol. This embodiment provides the advantage of compatibility with existing protocols.
• the request in step (I) may be a dedicated object in a resource reservation protocol.
• This embodiment provides the advantage of compatibility with existing protocols while at the same time minimising signalling traffic, as identical elements common to both tunnels are not repeated in step (I).
• the ingress node checks in step (m) for other available tunnels to the mobile host via the first egress node and starts a set up of a second tunnel for each such tunnel.
• This embodiment has the advantage of greatly reducing signalling between the first egress node and the ingress node, because the first egress node has to send the message in step (I) only once for all existing tunnels to the same MH.
• the wireless network is a cellular network. This embodiment provides the advantage of compatibility with existing cellular networks.
• the wireless network is a wireless local area network. This embodiment provides the advantage of compatibility with existing local area networks.
• a telecommunication system comprises a multi-protocol label switching network with a plurality of label switching routers forming nodes of said network, one of said nodes being configured as ingress node to provide connection to an external packet switched network; a mobile host having an Internet protocol address and being configured to receive packet data; a plurality of radio access network domains, each of said radio access network domains being configured to provide wireless connection between one of said nodes and said mobile host, said network being configured to set up a first multi-protocol label switching tunnel from said ingress node to a first egress node connecting a first radio access network domain belonging to a first service area where said mobile host is located, and, if the mobile host changes its location from said first service area of said first radio access network domain to a second service area of a second radio access network domain, to set up a second multi-protocol label switching tunnel from said ingress node to a second egress node connecting said second radio access network domain, wherein said mobile host does not change said Internet protocol address
• a telecommunication system provides the advantage that it can be obtained by upgrade of existing systems, due to the compatibility with existing resource reservation protocols. There is no requirement for additional functionality in intermediate nodes and the requirement on the functionality of the MH is reduced.
• an apparatus forming a first egress node of a multi-protocol label switching network being configured to receive packet data from an ingress node of said network through a multi-protocol label switching tunnel and forward said packet data to a mobile host via a first radio access network domain, is further adapted to carry out the steps of sending, upon receiving information about a handover of said mobile host from said first radio access network domain to a second radio access network domain, an acknowledgement message to a second egress node connecting said second radio access network domain; and sending a message to said ingress node with information about said second egress node.
• An apparatus can advantageously serve as egress node in a telecommunication system according to the preceding embodiment.
• an apparatus forming an ingress node from an external packet switched network to a multi-protocol label switching network being configured to receive packet data from said external network and forward said packet data to a mobile host via a multi-protocol label switching tunnel, a first egress node of the multi-protocol label switching network, and a first radio access network domain, is further adapted to carry out the steps of starting, upon reception of a message from said first egress node with information about a second egress node connecting a second radio access network domain, into which the location of said mobile host is handed over, a setup of a second multi-protocol label switching tunnel to said second egress node; switching, upon reception of a tunnel setup acknowledge from said second egress node, traffic from said first to said second tunnel; and tearing down said first tunnel.
• An apparatus according to this embodiment can advantageously serve as ingress node (gateway) in a telecommunication system according to another embodiment of this invention.
• Figure 1 shows an exemplary architecture of a wireless network.
• Figure 2 illustrates a handover of a mobile host between two egress nodes of the core network.
• FIG 3 illustrates the protocol stacks in the entities shown in Figure 2.
• Figure 4 depicts the signalling flow between the entities involved in the handover procedure when the setup of the new MPLS tunnel is initiated from the first (old) egress node.
• Figure 5 shows an alternative to the signalling flow shown in Figure 4.
• Figure 6 shows the signalling flow between the entities involved in the handover procedure when the setup of the new MPLS tunnel is initiated by the second (new) egress node.
• Figure 7 illustrates a procedure for handling multiple tunnels to a mobile host
• Figure 8 shows the format of a MPLS tunnel identifier.
• Figure 9 shows the format of a SESSION_ATTRIBUTE object in RSVP-TE.
• Figure 10 shows the constitution of a PATH message in RSVP-TE.
• Figure 11 shows a possibility for a new message in RSVP-TE requesting the setup of a new MPLS tunnel from the ingress node.
• Figure 12 shows a possibility for a new object in RSVP-TE requesting the setup of a new MPLS tunnel from the ingress node.
• FIG. 1 gives an example of a network structure 100 where TE MPLS is deployed in a wireless network consisting of core network 113 and radio access network (RAN).
• RAN radio access network
• WLAN wireless local area network
• 3G 3rd Generation
• 4G 4th Generation
• Each of the different radio access technologies is organized regionally in radio access domains managed by an access router (AR).
• the ARs are connected to the Core network 113 through a Core Edge Router (CER).
• CER Core Edge Router
• 3G and 4G access domains 104, 105 are connected to CER2 8.
• the MPLS tunnel 4 or 5 is set up between an ingress LSR 1 in the mobile network (e.g. Gateway, GW) and an egress LSR 2 or 3, e.g. NoA (AR or base station, BS).
• the packets destined to a MH 6 are encapsulated at the ingress LSR 1 (i.e. MPLS label is added to the IP header), transported over the previously set up MPLS tunnel 4, de-capsulated at the egress LSR 2 and transported further according to the native IP address 7.
• the GW 1 performs also the functionality of Foreign Agent (FA) as described in the MIP specification RFC 3344, and thus, it can assign a CoA address 7 to a foreign MH 6 which is then valid within the whole mobile network 100.
• FA Foreign Agent
• the egress LSR 2 is implemented in the NoA, where the MH 6 needs to authenticate at handover.
• the NoA is AR, but in other scenarios is can be a BS.
• the MH 6 does not support MPLS.
• the MPLS tunnel is terminated at the AR, since the packet transport within the radio access domain 104 is assumed to be performed in Layer 2 and one radio access domain forms a kind of Local Area Network (LAN).
• LAN Local Area Network
• the MH 6 is a mobile computing device like for example a notebook or 3G's User Equipment (UE) etc.
• the MH 6 is connected via wireless link with a BS 113, which terminates the wireless communication and assures wire line packet-switched oriented connection with further entities in the mobile network.
• the BS might be the last entity, which terminates the MPLS tunnel 4.
• the network builds up a new LSP 5 to the second egress node 3.
• the MH's location database is not distributed in the network, but rather concentrated in the ingress LSR, where the database is created and maintained.
• the ingress LSR can map each incoming data packet to a MPLS tunnel based on the IP address.
• the mobile host 6 has a wireless connection to the old egress LSR 2, which receives data packets from the gateway or ingress LSR 1 over a first tunnel or LSP 4.
• the LSP passes one intermediate LSR 8, which may be the core edge router.
• LSP 4 might pass a plurality of such intermediate LSRs.
• the MH 6 has a wireless connection to the new egress LSR 3.
• a new LSP 5 is built up from ingress LSR 1 to the new egress LSR 2 and the data traffic is switched from LSP 4 to LSP 5.
• the old LSP 4 may be torn down.
• FIG. 3 illustrated the protocol stack in the data plane of a MPLS network.
• 301 is the protocol stack of the gateway 1 , 302 belongs to the intermediate LSR 8, 303 to the respective egress LSR 2 or 3, and 304 to the mobile host 6. Every pair of neighbouring nodes in the network maintains a bidirectional data connection 305, 306 in the MPLS protocol plane.
• the MPLS tunnel 307 is a virtual point-to-point connection from ingress node 1 to egress node 2 or 3. It is implemented by sending encapsulated data packets hop-wise over the MPLS data connections 305 and 306.
• the egress node 2 or 3 forwards the received data packets to the MH 6, for example through a connection 308 in layer 2 of the radio access network protocol.
• Figure 4 shows an illustrative example of a method to set up a new MPLS tunnel from the ingress node to a new egress node to which the mobile host is handed over, initiated by the old egress node where the mobile host has been attached so far.
• the embodiment described in Figure 4 exhibits the advantage that the old egress node has exact knowledge of the (1 ) MH's authorization and connection session parameter, (2) MPLS tunnel's ingress node, (3) tunnel traffic parameters and (4) the IP address of the new egress node.
• a detailed description of the steps for setting up the new MPLS tunnel are described as follows:
• the MH When the MH detects in step 401 a new NoA (will be the new egress LSR), the MH requires in step 402 authentication and informs it about its own IP address and the IP address of the current (old) NoA (old egress LSR).
• the new egress LSR does not know, if the MH is authorized for using the network resources, and therefore, it requests in step 403 an authorization from the old egress LSR, which still serves the MH.
• Extensible Authentication Protocol represents one possibility how the communication can proceed between MH and new egress LSR, as well as between new egress LSR and old egress LSR.
• the old egress LSR When receiving a request from the new egress LSR, the old egress LSR checks in step 404 its database. If the MH is currently served (i.e. also authorized and active tunnels are established from the Gateway) by the old egress LSR, the LSR initiates two activities to enable the handover: (i) it sends an acknowledgement for attachment 405 to the new egress LSR and (ii) it sends a message 406 to the ingress LSR with an update of the new egress LSR.
• the latter message includes e.g. the IP addresses of the new egress LSR and of the MH.
• the ingress LSR needs the information about the concerned MH because it should update its database, where the incoming IP packets are classified to the MPLS tunnels according the MH's IP address.
• the ingress LSR At receiving the update message from the egress LSR, the ingress LSR starts in step 407 the setup of a new TE tunnel to the new egress LSR with the same parameter as the old tunnel. During the setup procedure, the ingress LSR still sends the MH's traffic on the old tunnel.
• the new egress LSR After receiving the acknowledgement for attachment and the tunnel setup signalling, the new egress LSR completes the handover procedures in the RAN in order to accomplish the whole handover of the MH.
• the tunnel setup acknowledgement 408 when the tunnel setup acknowledgement 408 is received by the ingress LSR, it switches in step 409 the traffic from the old to the new tunnel and tears down the old tunnel in step 410.
• the old egress LSR can obtain the new egress LSR's identifier (e.g. IP address) by the MH as shown in step 501.
• the MH can inform the old egress LSR about the new NoA (new egress LSR) and consequently the old egress LSR initiates the signalling to the ingress LSR.
• An advantage of the methods described in figures 4 and 5 is that the old egress LSR can directly signal the identifier (e.g. IP address) of the new egress LSR's to the ingress LSR, which speeds up the procedure by saving the delay of additional signalling, which would otherwise be necessary.
• the identifier e.g. IP address
• FIG. 6 illustrates another embodiment of the invention, where the signalling initiated by the new egress LSR.
• the new and old egress LSRs communicate with each other in order to exchange traffic context parameters, like for example the existing tunnel traffic parameters.
• the traffic context parameters are called PDP context.
• the new egress LSR sends periodically a broadcast message.
• a router advertisement message is sent every 3 seconds.
• the MH informs in step 602 the old egress node about the IP address of the new egress node.
• the old egress LSR communicates the traffic context in step 603 to the new egress LSR.
• the new egress LSR is informed about the identifier (IP address) of the ingress LSR, which is a part of the MPLS tunnel parameter contained in the context.
• IP address IP address
• the new egress LSR can contact the ingress LSR in step 604 and require the setup of a new MPLS tunnel to the new egress LSR.
• the signalling is completed by steps 605 to 608 in the same way as described before in connection with figure 4.
• a setup of one MPLS tunnel per user is regarded.
• the method can also be applied in cases, in which one user is connected via multiple tunnels to the gateway. This is the case when the tunnels are set up per application because different applications may have different QoS requirements.
• a user of a MH connected to the gateway via multiple tunnels moves to new NoA, then one of the methods described above can be applied for each of the tunnels separately.
• this process can be optimised in another embodiment with the exemplary procedure shown in figure 7.
• the ingress LSR receives a notification message from the old egress LSR to establish one new tunnel to the new egress LSR, the ingress LSR starts procedure 700.
• step 701 a new list is created having the existing MPLS tunnel specified in the request message as first entry.
• the ingress LSR checks its database in step 702 for other available tunnels to the same user. Other tunnels found as a result of this search are added to the list.
• step 703 the ingress node sets up a new MPLS tunnel to the new egress LSR for the first entry in the list, which is deleted in step 704.
• step 705 it is checked whether the list is empty. If this is the case, the procedure is terminated in step 706. Otherwise it jumps back to step 703 to treat the next entry in the list.
• an exemplary data structure 800 is shown, which unambiguously identifies an MPLS tunnel. It comprises two objects from the RSVP- TE protocol, namely a SESSION object 801 and a SENDER_TEMPLATE or FILTER_SPEC object 802.
• the SESSION object 801 contains the IP address 803 of the tunnel end point, i.e. the egress node of the network, a tunnel identifier 805 and an extended tunnel identifier 806.
• Field 804 has no meaning in the context of the present invention and may be filled with zeroes.
• the SENDER_TEMPLATE or FILTER_SPEC object contains the IP address of the tunnel sender, i.e. the ingress node of the network, and the tunnel identifier 809.
• Field 808, again, is filled with zeroes.
• the structure in figure 8 is only an example of a data structure identifying a tunnel. Other structures could be thought of serving the same purpose.
• Figure 9 shows the data structure of a SESSION_ATTRIBUTE object 900 in RSVP- TE as an example of a data structure conveying QoS information.
• Fields 901 to 903 are optional and not explained in further detail.
• Field 904 specifies the priority of the tunnel in comparison to other traffic with respect to taking resources and can assume a value between 0 and 7.
• Field 905 specifies the priority of the tunnel for holding resources.
• the flags 906 are control switches concerning the routing of the tunnel and are not regarded in detail in this context.
• Field 908 contains a null padded session name and field 907 the length of this name. In other protocols other structures than that shown in figure 9 could serve the same purpose of specifying the quality of service of the tunnel.
• Figure 10 illustrates the structure of a RSVP-TE PATH message 1000, which is sent by the ingress node in order to built up a new tunnel, like for example in steps 407 and 605 of figure 4 and 6, respectively. It contains the SESSION object 801 explained in conjunction with figure 8, the SESSION__ATTRIBUTE object 900 from figure 9 and the SENDER_TEMPLATE object from figure 8.
• the EXPLICIT_ROUTE object contains subobjects defining network nodes which should or must be passed by the route of the tunnel. Other fields of the PATH message 1000 are not explained in more detail.
• the difference of the identifier between the old and new tunnel is only the tunnel end point address 803. This means that the same SENDER_TEMPLATE and FILTER_SPEC objects 802 together with the modified SESSION 801 and EXPLICIT_ROUTE 1005 objects are sent with the Path message 1000 along the path of the new MPLS tunnel. Since the mobile operator has a perfect knowledge of the network's topology, the route for the new tunnel can advantageously be determined fast.
• FIG. 11 illustrates an exemplary proposal for a possible structure of such a message 1100.
• message 1100 may contain besides a header 1101 only the old SESSION object with the IP address of the old egress node and the new SESSION object with the IP address of the new egress node.
• message 1100 can be kept advantageously short.
• object 1200 (normally included in the Path message) in the protocol is used for the request of the setup of a new tunnel, is illustrated in an example in figure 12.
• object 1200 is obtained by an extension of SESSION object 801 , to which the IP address 1201 of the new egress node is appended.
• the procedures described in figures 4 to 6 allow seamless mobility for the MH, because the connection with the correspondent counterpart is kept alive during handovers. These handovers can be between base stations within both the same or different access technologies.
• the described handover procedures in the core network assure the mobility of the tunnels, and may fulfil this mobility in a fast manner without packet losses. This is achieved by the principle of "make-before- brake", as the new MPLS tunnel is set up before the traffic is switched on the new tunnel, and last the old tunnel is torn down.
• the proposed method uses the same tunnel parameter as in the old tunnel. Another benefit of the proposed method is that its deployment requires no changes in the implementation of the signalling protocols apart from ingress and egress LSR. That is, no changes in the intermediate LSRs are necessary. Further, the proposed method makes widely use of available RSVP-TE signalling and minimises necessary modifications.
• Another benefit of the methods described above is that there is no need to implement the micro-mobility Mobile IP in the network entities except in the Gateway and the MH. Since most of the routers distributed on the market now are MPLS-capable, the embodiments presented above can be implemented with handover procedures only on the network side. Signalling and processing effort is reduced compared to micro- mobility MIP extensions. Further the MH is relieved from mobility management tasks, which are taken over by the network equipment. This enables a reduction of processing power and consequently leads to lower power consumption, smaller batteries and smaller MH.

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• 2004
  • 2004-03-31 EP EP04724585A patent/EP1730901A1/de not_active Withdrawn
  • 2004-03-31 WO PCT/EP2004/003421 patent/WO2005096556A1/en not_active Application Discontinuation
  • 2004-03-31 CN CNA2004800426668A patent/CN1926822A/zh active Pending
  • 2004-03-31 BR BRPI0418648-6A patent/BRPI0418648A/pt not_active IP Right Cessation

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