WO2008058479A1 - Procédé et système pour éviter une circulation en rond de support de transport - Google Patents

Procédé et système pour éviter une circulation en rond de support de transport Download PDF

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Publication number
WO2008058479A1
WO2008058479A1 PCT/CN2007/070915 CN2007070915W WO2008058479A1 WO 2008058479 A1 WO2008058479 A1 WO 2008058479A1 CN 2007070915 W CN2007070915 W CN 2007070915W WO 2008058479 A1 WO2008058479 A1 WO 2008058479A1
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address
domain
communication
entity
information
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PCT/CN2007/070915
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English (en)
French (fr)
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Shibi Huang
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Huawei Technologies Co., Ltd.
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Publication of WO2008058479A1 publication Critical patent/WO2008058479A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
    • H04L65/1066—Session management
    • H04L65/1069—Session establishment or de-establishment
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
    • H04L65/10—Architectures or entities
    • H04L65/1016—IP multimedia subsystem [IMS]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
    • H04L65/80—Responding to QoS

Definitions

  • the present invention relates to a communication technology, and more particularly to a technique for avoiding bearer media bypass during communication.
  • NGN Next Generation Network
  • IP network technology such as voice, video, and multimedia
  • IPv4 networks are IPv4 networks. Due to the tight IPv4 address, operators use a large number of private IPv4 addresses in the access network during network planning. Therefore, there are a large number of enterprises that use private IP addresses in practical applications.
  • the phenomenon of accessing NGN to the network The foregoing networking schemes and requirements lead to the overlap of IP addresses and spaces between different networks in the NGN network.
  • the access network and the core network of the same carrier may be different. Network address and/or port translation is required when interworking between carrier core networks.
  • IPv6 network applications there are networking situations where IPv4 networks and IPv6 networks coexist, and network address translation and/or port translation are also required when IPv4 and IPv6 networks are interworking.
  • the NGN network when the NGN network is deployed, the IP address space overlaps and/or the IP version conversion of the IP bearer network is required. Therefore, the NGN network needs to perform network address translation and/or port conversion when interworking. .
  • the NGN network uses SIP, H.323, H.248 and other application signaling protocols at the signaling control level.
  • the media stream connection address of the underlying IP bearer layer is through the signaling control layer SIP, H.323, H.248, etc.
  • the protocol is dynamically negotiated. Therefore, when the NGN network performs network address and/or port conversion, the media stream connection address and/or port negotiated in the signaling protocol needs to be converted. That is to say, the implementation of the network address and/or port translation function of the NGN service flow needs to be completed by the service control plane conversion entity and the media bearer plane conversion entity.
  • NAPT Network Address Translation
  • Bearer layer by changing the media message
  • the address and/or port number implements the network address and/or port translation function and the media transfer function
  • the NAPT proxy function entity belongs to the service control layer, and completes the address in the application signaling message body according to the address binding information created by the NAPT execution function entity. / or port modification
  • NAPT control function entity belonging to the bearer control layer, performs NAPT policy control according to the address binding information obtained from the NAPT proxy function entity.
  • IP Multimedia Subsystem Application Layer Gateway Functional Entity IMS-ALG, IP Multimedia Subsystem - Application Level Gateway
  • TrGW Translation Network Functional Entity
  • the IMS-ALG is equivalent to integrating the functions of the ITU-T defined NAPT proxy function entity and the NAPT control function entity
  • TrGW is equivalent to the ITU-T defined NAPT execution function entity.
  • FIG. 1 a flow chart of address translation between two IPv4 UEs in the IPv6 IMS core network communication process, and the address translation process includes :
  • Step 101 The user 1 (UE1) sends a session description protocol (SDP offer, Session Description Protocol offer) to the IMS-ALG1, and the SDP offer message carries the IPv4 address (IPv4-l) and the port P1 of the media connection of the UE1. ;
  • SDP offer Session Description Protocol
  • IPv4-l IPv4 address
  • Step 102 The IMS-ALG1 sends an IP address binding request carrying the IPv4-l and the port P1 to the TrGW1.
  • Step 103 TrGW1 selects an IPv6 address IPv6-l and port P61 from the address pool, binds IPv4-l, PI, and IPv6-l, P61, and returns an IP address carrying IPv6-l and P61 to IMS-ALG1. Binding response
  • Step 104 IMS-ALG1 replaces IPv4-l and port P1 in the SDP offer message with the IPv6-1 and port P61 returned from the TrGW1, and forwards the SDP offer message to the IMS-ALG2 of the session terminating party;
  • Step 105 The IMS-ALG2 sends an IP address binding request carrying the media connection address IPv6-1 and port P61 to the TrGW2.
  • Step 106 TrGW2 selects an IPv4 address IPv4-12 and port P12 from the address pool, binds IPv4-12, P12, and IPv6-1, P61, and returns an IP address carrying IPv4-12 and P12 to IMS-ALG1.
  • UE2 session terminator user 2
  • Step 108 The UE2 sends an SDP answer response message to the IMS-ALG2, where the SDP answer message carries the IPv4 address of the UE2 media connection, IPv4-2 and port P2.
  • Step 109 IMS-ALG2 sends an IP address binding request carrying IPv4-2 and port P2 to TrGW2.
  • Step 110 TrGW2 selects an IPv6 address IPv6-2 and port P62 from the address pool, binds IPv4-2, P2, and IPv6-2, P62, and returns an IP address carrying IPv6-2 and P62 to IMS-ALG1. Binding response
  • Step 111 IMS-ALG2 replaces the IPv4-2 address and port P2 in the SDP answer message with the IPv6-2 and port P62 returned from the TrGW2, and forwards the SDP answer message to the IMS-ALG1 of the session termination party;
  • Step 112 IMS-ALG1 sends an IP address binding request carrying IPv6-2 and port P62 to TrGW1.
  • Step 113 TrGW1 selects an IPv4 address IPv4-21 and port P21 from the address pool, binds IPv4-21, P21, and IPv6-2, P62, and returns an IP address carrying IPv4-21 and P21 to IMS-ALG1. Binding response
  • Step 114 IMS-ALG1 replaces IPv6-2 and port P62 in the SDP answer message with the address returned from TrGW1, IPv4-21 and port P21, and forwards the SDP message to the session termination party UE1.
  • Step 115 The UE1 sends a real time transport protocol (RTP) voice media packet 1 to the UE2, where the source IP address is the IP address ⁇ 4-1 of the UE1, the port is the PI, and the destination IP address is based on the previous signaling protocol.
  • RTP real time transport protocol
  • the IP address of the UE2, IPv4-21 and port P21, are known in the negotiation. Since IPv4-21 is allocated to TrGW1, this message is finally routed to TrGW1.
  • Step 116 After receiving the RTP 4 message 1, the TrGW1 replaces the source IP address IPv4-l and port P1 with the address IPv6-l and port P61, and the destination IP address IPv4-21 according to the established address binding information. Port P21 is replaced with the address IPv6-2 and port P62, and the IPv6 RTP packet is constructed and forwarded, and finally reaches TrGW2; Step 117: After receiving the RTP message 1, the TrGW2 replaces the source IP address IPv6-l and port P61 with the address IPv4-12 and port P12, and the destination IP address IPv6-2 and port P62 according to the established address binding information. Replace with IPv4-2 and port P2, construct an IPv4 RTP message and forward it, and finally reach UE2;
  • Step 118 The UE2 sends the RTP voice media message 2 to the UE1, where the source IP address is the IP address of the UE2, the IPv4-2 and the port P2, and the destination IP address is the IP address of the UE1, which is known according to the previous signaling protocol negotiation. 12 and port P12, since IPv4-12 is allocated to TrGW2, this message is finally routed to TrGW2;
  • Step 119 After receiving the RTP message 2, the TrGW2 replaces the IPv4 source address IPv4-2 and the port P2 with the address IPv6-2 and port P62, and the destination IP address IPv4- 12 and port according to the established address binding information. P12 is replaced with the address IPv6-l and port P61. The IPv6 RTP packet is constructed and forwarded, and finally reaches TrGWl.
  • Step 120 After receiving the RTP packet 2, the TrGW1 replaces the source IP address IPv6-2 and port P62 with the address IPv4-21 and port P21, and the destination IP address IPv6-l and port P61 according to the established address binding information. Replace with the address IPv4-l and port P1, construct the IPv4 RTP file and forward it, and finally reach UE1.
  • the ETSI standard specification defines functional entities that implement IP address and/or port translation, including: Application Function Entity (AF), Service-based Policy Decision Function (SPDF), and Border Gateway. BGF, Border Gateway Function.
  • AF Application Function Entity
  • SPDF Service-based Policy Decision Function
  • BGF Border Gateway Function.
  • AF is equivalent to the NAPT proxy functional entity defined by ITU-T
  • SPDF is equivalent to the NAPT control functional entity defined by ITU-T
  • BGF is equivalent to the NAPT executive functional entity defined by ITU-T.
  • the principles and procedures for implementing IP address and/or port translation are similar to those defined by ITU-T and related standard specifications in the 3GPP standards organization, and are not described here.
  • the network address and/or port conversion process defined in the above-mentioned ITU-T, 3GPP, and ETSI standards organization standard specifications is a NAPT conversion signaling processing entity of the service control layer, such as a NAPT proxy functional entity, an IMS-ALG functional entity. Or an entity such as an AF function entity, which triggers a NAPT conversion execution function entity of a bearer layer across different IP address domains, such as a NAPT execution function entity, a TrGW function entity, or a BGF function entity to perform network address and/or port conversion functions.
  • IP address domain In an NGN network, different network entities in an IP address domain that can be directly routed by the same IP.
  • interworking since the pair of ⁇ conversion signaling processing entities and the ⁇ media conversion execution entity are only responsible for the network address and/or port translation of the adjacent two interworking IP domains, it is not known that the final two interworking network entities are actually in the same IP.
  • the IP address field can be directly routed. After the network address and/or port is translated by multiple times, the media stream needs to be relayed by multiple NAPT media conversion execution entities, so that the original media plane can perform direct IP addressing. In the case of the situation, an unnecessary media roundabout problem was carried out.
  • UE1 and UE2 are in the same directly routable IPv4 address domain.
  • UE1 and UE2 can directly perform routing and interworking through IP addresses IPv4-l and IPv4-2, but according to the foregoing implementation.
  • the technical solution and process of IP address and/or port conversion, after multiple IPv4 and IPv6 conversions, media interworking between UE1 and UE2 must perform multiple address translation and media relay through TrGW1 and TrGW2, thus, on the one hand The media communication delay is increased.
  • the media stream that can be directly interoperable needs to perform unnecessary address conversion and traverse the IPv6 core network through TrGW1 and TrGW2, resulting in great waste of network resources.
  • the problem to be solved by the present invention is to provide a method and system for avoiding the bypass of the bearer media, so that different users of the IP domain directly routable by the same IP can directly communicate with each other, thereby avoiding unnecessary media path bypass.
  • the embodiment of the present invention provides a method for avoiding bearer media bypass, which includes:
  • the IP domain negotiation initiating entity sends the IP domain negotiation receiving entity to send the IP domain information carrying the communication initiator.
  • IP domain negotiation request ;
  • the IP domain negotiation receiving entity sends an IP domain negotiation request response to the IP domain negotiation initiating entity; determining that the IP domain negotiation request response indicates that the IP domain of the communication initiator is the same as the IP domain of the communication receiving end;
  • the communication initiator and the communication receiver negotiate to obtain the media connection IP address and/or port information of the peer end, and the communication parties communicate by direct routing.
  • An embodiment of the present invention further provides a system for avoiding bearer media bypass, which includes:
  • the IP domain negotiation initiating entity sends an IP domain negotiation request carrying the IP domain information of the communication initiator; the IP domain negotiation receiving entity receives the IP domain negotiation request sent by the IP domain negotiation initiating entity, and according to the IP domain negotiation request, The IP domain negotiation sending entity sends an IP domain negotiation request response; the network address and/or port conversion signaling processing entity forwards the communication if the IP domain negotiation request response is the IP domain of the communication initiator and the IP domain of the communication receiver is the same The media connection IP address and/or port information of the terminal and the receiving end are sent to the opposite end.
  • An embodiment of the present invention further provides an IP domain negotiation initiation/reception entity, including:
  • the IP domain information addition and deletion module is configured to: when the SDP offer message is sent from the terminal, the IP domain information of the media endpoint is added to the SDP offer; when the SDP offer message is forwarded to the terminal, the corresponding IP domain information is deleted.
  • the embodiment of the present invention further provides a network address and/or port conversion signaling processing entity, including: a third packet processing module, configured to: when receiving an SDP answer message, if the media connection IP address domain information in the packet If the SDP offer packet is the same as the corresponding SDP offer packet, the SDP reply packet is directly forwarded. If the corresponding SDP offer packet has been applied for the IP address binding, the corresponding IP address resource binding is released.
  • a third packet processing module configured to: when receiving an SDP answer message, if the media connection IP address domain information in the packet If the SDP offer packet is the same as the corresponding SDP offer packet, the SDP reply packet is directly forwarded. If the corresponding SDP offer packet has been applied for the IP address binding, the corresponding IP address resource binding is released.
  • the method for avoiding bearer media bypass and the system thereof provided by the embodiments of the present invention can be used to know whether different users that are in communication are in an IP domain that can be directly routed. If different clients are in an IP domain that can be directly routed by the same IP, the communication is cancelled. Binding between the IP address and/or port of the initiator and the translation gateway address and/or port, so that the user can directly communicate with each other, thereby avoiding unnecessary bearer media path bypass, thereby shortening communication time and Save network processing resources
  • the method and system for avoiding the bearer of the media are provided in the embodiment of the present invention, and further, whether the conversion gateway of the user access network with different IP domains is in the same IP domain, and if so, The binding between the conversion gateway of the access network of the user end and the other translation gateway addresses and/or ports in the bearer media forwarding path is removed, which reduces the path bypass between the bearer media conversion gateways, thereby shortening the communication time and saving the time. Network processing resources.
  • 1 is a flow chart of performing address translation in the communication process of two IPv4 UEs in the IPv6 IMS core network
  • FIG. 2 is a schematic diagram of an embodiment of the present invention for avoiding a bearer media bypass system
  • FIG. 3 is a flow chart of an embodiment of a method for avoiding bearer media bypass in accordance with the present invention.
  • FIG. 5 is a signaling flowchart of another embodiment of the method for avoiding bearer media bypass in the IMS architecture
  • FIG. 6 is a signaling flowchart of another embodiment of the method for avoiding bearer media bypass in the IMS architecture
  • FIG. 7 is a signaling flowchart of a fourth preferred embodiment of the method for avoiding bearer media bypass in the IMS architecture
  • FIG. 8 is a signaling flowchart of a fifth preferred embodiment of the method for avoiding bearer media bypass in the IMS architecture
  • FIG. 9 is a signaling flowchart of a sixth preferred embodiment of the method for avoiding bearer media bypass in the IMS architecture
  • FIG. 10 is a signaling flowchart of a seventh preferred embodiment of the IMS architecture for the method for avoiding bearer media bypass in the present invention.
  • the NGN network when there are multiple network addresses and/or port transitions when interworking between different network entities in the IP address domain that can be directly routed by the same IP, a pair of NAPT conversion signaling processing entities and NAPT media conversion are performed.
  • the entity is only responsible for the network address and/or port translation of the two adjacent interworking IP domains. It is not known that the two interworking network entities are actually in the IP address domain that can be directly routed by the same IP, so that multiple network addresses and/or After the port is converted, the media stream also needs to be relayed by multiple NAPT media conversion execution entities, so that the original media stream can be directly IP-based. In the case of interoperability, unnecessary media detours were carried out.
  • the key to solve this problem is to let multiple NAPT conversion signaling processing entities and NAPT media conversion execution entities between two interworking network entities know that the two interworking network entities are actually in the IP address domain that can be directly routed by the same IP.
  • the network address and/or port of the bearer layer media stream is converted to implement direct IP addressing interworking of the media plane.
  • the present invention provides a method and system for avoiding bearer media rounding.
  • the present invention will be described in detail below with reference to the accompanying drawings.
  • FIG. 2 is a schematic structural diagram of a preferred embodiment of the present invention for avoiding a bearer media bypass system.
  • the present invention avoids a bearer media bypass system comprising two communication network entities 20 and 21, two signaling relays 22 and 23 respectively connected to the communication network entities 20 and 21, located in the signaling relays 22 and 23 A plurality of NAPT conversion signaling processing entities 24, 26, and 28, and a plurality of NAPT media conversion execution entities 25, 27, and 29 connected to the NAPT conversion signaling processing entities 24, 26, and 28, respectively.
  • the communication network entity 20 or the signaling relay 22 issues an IP domain negotiation request to the communication network entity 21 or the signaling relay 23, and provides IP domain information of the communication network entity 20, the communication network
  • the entity 21 or the signaling relay 23 sends the same response to the IP domain to the communication network entity 20 or the signaling relay 22, the NAPT conversion signaling processing entities 24, 26 and 28 not for the network address of the bearer medium and/or The ports are converted so that the communication network entities 20 and 21 can communicate directly.
  • the communication network entities 20 and 21, the signaling relays 22 and 23, and the NAPT conversion signaling processing entities 24, 26, and 28 all need to perform corresponding function extensions, and the functions of the specific extensions will be described later.
  • the signaling relay is a Proxy Call Session Control Function Entity (P-CSCF)
  • P-CSCF Proxy Call Session Control Function Entity
  • IMS-ALG IMS Application Gateway Function Entity
  • TrGW conversion gateway function entity
  • FIG. 3 is a flowchart of a preferred embodiment of a method for avoiding carrying media bypass in the present invention.
  • the specific process includes the following steps:
  • Step 301 The IP domain negotiation initiating entity sends an IP domain negotiation request carrying the IP domain negotiation initiation entity IP domain information to the IP domain negotiation receiving entity, where the IP domain negotiation initiation entity is a communication initiator network entity or a signaling relay entity.
  • the IP domain negotiation receiving entity is a communication receiving network entity or a signaling relay entity;
  • Step 302 The IP domain negotiation receiving entity receives the IP domain negotiation sent by the IP domain negotiation initiating entity. And sending, to the communication initiator, an IP domain negotiation request response that carries the IP domain information of the communication initiator; Step 303: If the IP domain negotiation request response indicates that the IP domain of the communication initiator is the same as the IP domain of the communication receiver, the communication initiator Negotiating with the communication receiving end to obtain the media connection IP address and/or port information of the opposite end. The communication parties then communicate via direct routing.
  • the NAPT conversion signaling processing entity exists between the IP domain negotiation initiating entity and the IP domain negotiation receiving entity.
  • the NAPT conversion signaling processing entity in the foregoing method may be a NAPT proxy function entity, an IMS-ALG function entity or an AF function in a network address and/or port conversion process defined in ITU-T, 3GPP, ETSI standards organization standard specifications.
  • An entity such as an entity. The above method is further described below in the various cases of the IMS network architecture defined by 3GPP, how to solve the media roundabout problem.
  • the following is an example of how to use the present invention to avoid the unnecessary IP address translation process of the bearer medium in the IMS network networking when two user terminals in the same address domain that can be directly IP-addressed communicate with each other.
  • the method for avoiding bearer media forwarding in the present invention is applied to a signaling flowchart of a first preferred embodiment in an IMS architecture, where UE1 and UE2 are two user terminals to be communicated; P-CSCF1 and P -CSCF2 is a proxy call session control function entity for accessing the user terminals UE1 and UE2 to the IMS core network, respectively; the IMS-ALG i entity and the TrGW i entity represent multiple network address and/or port translation functions on the interworking path of the two communication terminals. Multiple pairs of IMS-ALG and TrGW entities; SIP protocol is used between each network entity at the signaling level; network address and/or port translation control is implemented between each IMS-ALG and the corresponding TrGW through the Ix interface.
  • the specific process includes:
  • Step 401 UE1 sends an SDP offer message carrying the media connection IP address IP-0 of UE1 to the P-CSCF1;
  • Step 402 The P-CSCF1 expands the SDP offer message, adds the IP domain negotiation information, for example, increases the IP address domain information D-abc where the media connection IP address IP-o is located, and forwards the extended SDP offer message to IMS-ALG-I in the signaling path;
  • IP address domain information Examples of IP domain negotiation information included in row c of D-abc are as follows:
  • c ⁇ network type> ⁇ addresstype> ⁇ connectionaddress> ⁇ domainidentify> , the above network type (network type), address type (address type), connection address (connection)
  • the address is an existing definition of the existing SDP protocol
  • the IP domain identifier is a new definition that indicates the IP domain identifier to which the communication end belongs. This parameter field is optional in the SDP standard and can be global. Uniquely identify each IP domain that can be directly routed by the same IP, so that the communicating parties can judge whether the two communicating parties are in the IP address domain directly routable by the same IP according to the identifier.
  • IP domain ID value rule is as follows: When the IP address field of the communication end is the IPv4 public network IP address field, the value is IP4PUB. When the IP address field of the communication end is the IPv6 public network IP address field, The value is IP6PUB. When the IP address field of the communication end is a private network address or a public network private address field, it can be represented by a legal domain name.
  • the host name part indicates that the domain in which the host name belongs is in the same IP.
  • the IP address field that can be directly routed such as abc.sz.gd.cn, indicates the IP address field abc that is directly routed by the same IP in the sz.gd.cn domain.
  • the negotiation process of the IP domain can be performed by using an offer/answer mode of the SDP.
  • the IP domain carried by the c-line in the SDP offer is the IP domain of the provider, and the C-line carried in the SDP answer
  • the IP domain identifier is the IP domain in which the responder is located. When the two IP domain identifiers are the same, the provider and the responder are in the IP address domain that the same IP can directly route.
  • the IP domain in which the user terminal is located is determined by the operator during network planning, so the UE generally has no IP domain information, and thus can access the first network side signaling entity of the IMS network by the user terminal.
  • the function of the P-CSCF is extended. For example, when the SDP message sent from the terminal is received, the IP address negotiation information is added to the SDP. The P-CSCF can forward the SDP message to the user terminal. The IP domain negotiation information in the SDP packet is deleted. The P-CSCF can obtain the IP domain information corresponding to each terminal through static configuration or querying from the IP access network.
  • Step 403 The IMS-ALG i sends an IP address binding request carrying the IP-o to the TrGW i.
  • Step 405 IMS-ALG-i replaces the IP-o address in the SDP offer message with the returned IP-i address, and forwards the SDP offer message to the P-CSCF2 of the receiver.
  • Step 406 The P-CSCF2 deletes the IP address domain information D-abc in the SDP offer 4, and forwards the SDP offer message to the UE2;
  • Step 407 The UE2 sends the media connection carrying the UE2 in the SDP answer message to the P-CSCF2. IP address IP-d;
  • Step 408 The P-CSCF2 adds the IP address domain information D-abc in which the media connection IP address IP-d is located in the SDP answer message, and forwards the SDP answer to the IMS-ALG-i in the signaling path.
  • IMS-ALG-i finds that the SDP offer is the same as the IP address domain information D-abc in the SDP answer, and knows that the two communicating parties are in the IP address domain that the same IP can directly route, so the IP-o and IP are sent to the TrGW_i. -i address binding application;
  • Step 410 TrGW-i sends a splicing success response to the IMS-ALG-i to cancel the IP address binding;
  • Step 411 IMS-ALG-i forwards the SDP answer message to P-CSCF1 while releasing the IP address binding operation;
  • Step 412 The P-CSCF1 deletes the IP address domain information D-abc in the SDP answer message, and forwards the SDP answer message to UE1.
  • Step 413 The P-CSCF1 re-initiates the SDP offer message carrying the media connection IP address IP-o of the UE1.
  • the media connection IP address information IP-o of the UE1 in the first SDP offer message sent by the UE1 may be changed by the intermediate IMS-ALG_i entity, so that the last obtained IP address information of the UE2 is not the actual media connection of the UE1.
  • IP address, as in the previous process, the media connection IP address of the UE1 obtained by the UE2 through the SDP offer message is the IP address IP-i modified by the IMS-ALG-i entity; to ensure that the UE2 can obtain the actual media connection IP address of the UE1.
  • - ⁇ , ⁇ -CSCF1 again initiates an SDP offer message carrying the media connection IP address IP-o of UE1.
  • Step 414 The IMS-ALG-i forwards the SDP offer directly according to the previous IP address domain negotiation result, and knows that the two communication parties are in the IP address domain that can be directly routed by the same IP address, and the IP domain in the SDP offer packet does not change.
  • the message is sent to P-CSCF2;
  • Step 415 The P-CSCF2 forwards the SDP offer message to the UE2, and the UE2 changes the media connection address of the UE1 from the previously negotiated IP-i to IP-o;
  • Step 416 UE2 returns an SDP answer to the P-CSCF2.
  • Step 417 P-CSCF2 returns SDP answer to TrGW i;
  • Step 418 TrGW I returns SDP answer to P-CSCF1;
  • UE1 knows that the UE2 is in an address domain that can be directly routed, and UE1 and UE2 can directly communicate through the address information of the peer end. Because each IMS-ALG in the path knows the IP address field of the same IP according to the previous IP address domain negotiation result, and the current SDP answer does not change the IP domain, the SDP answer message is not specially processed. When the SDP offer message arrives at the P-CSCF1, the P-CSCF1 knows that it is responding to the SDP offer message initiated by the previous P-CSCF1, and no longer forwards the SDP answer to the UE1.
  • the P-CSCF and the IMS-ALG functional entity in the IMS architecture defined by the 3GPP are extended.
  • the P-CSCF when forwarding the SDP offer message from the terminal, the IP address domain information of the media endpoint is added to the SDP offer; when the SDP offer is forwarded to the terminal, the corresponding IP is deleted first. Address domain information; when receiving the SDP answer of the communication peer, if the negotiated media connection IP address domain information is the same, the SDP offer message is sent exactly the same as the previous SDP offer message; When the packet is received, it is not forwarded to the UE.
  • the SDP answer message is received, if the media connection IP address field information and the corresponding SDP offer message in the message are the same, the SDP answer message is forwarded directly, if the corresponding SDP offer message is sent. If you have applied for the resource binding of the IP address, the corresponding IP address resource binding is released.
  • the SDP packet is received, if the IP address domain information negotiation has been performed and the IP address fields of both ends are consistent, if the current SDP is available. If the IP address field information of the message is the same as the IP address field information of the previous negotiation, the corresponding SDP message is directly forwarded.
  • the media connection IP address information IP-o of the UE1 in the first SDP offer message sent by the UE1 may be changed by the intermediate IMS-ALG i entity, so that the last obtained IP address information of the UE2 is not the actual media connection IP of the UE1. address.
  • the P-CSCF1 has to initiate an SDP negotiation process again, which will cause the session establishment time to increase, and the P-CSCF1 needs to proxy the UE1 to initiate the second SDP negotiation.
  • the P-CSCF1 inserts the IP domain negotiation information in the SDP, and avoids losing the original SDP offer message sent by the UE1 due to the modification of the media connection address information in the SDP by the intermediate IMS-ALG entity.
  • the media connection address information, the P-CSCF 1 can extend the SDP protocol to copy the media connection address information in the message to the new extension domain.
  • the following is an example of how to use the present invention to avoid unnecessary IP address translation of a bearer medium and shorten the session establishment time when the two users in the same address domain that can be directly IP-addressed communicate with each other in the IMS network.
  • Specific process Referring to FIG. 5, a signaling flowchart of a second preferred embodiment of the IMS architecture is provided. The specific process includes:
  • Step 501 UE1 sends an SDP offer message carrying the media connection IP address IP-0 of UE1 to the P-CSCF1;
  • Step 502 The P-CSCF1 extends the SDP offer message, and adds the IP domain negotiation information, for example, the IP address domain information D-abc in which the media connection IP address IP-o is located, and the original media in the SDP offer is copied.
  • the address information IP-o is connected to the original address and port (Original Address and Port) parameter field, and the extended SDP offer message is forwarded to the IMS-ALG-I in the signaling path; the extended SDP includes the c line
  • Examples of IP domain negotiation information and original media connection address information are as follows:
  • the original address and the port parameter field are newly extended in order to retain the original media connection address information in the SDP message sent by the user terminal.
  • this parameter may also represent each m line media stream in the SDP.
  • Raw port information An example of the value of an original address and port parameter field is: IPv4—l/portl/port2, where IPv4—1 is the original IPv4 address, ortl is the media connection port given in the first m line of this session, port2 is The media connection port given in the second m line in this session.
  • Step 503 The IMS-ALG i sends an IP address binding request carrying the IP-o to the TrGW i.
  • Step 504 The TrGW i selects a free address IP-i from the address pool, and binds the IP-i and the IP-o. And return an IP address binding response carrying the IP-i to the IMS-ALG i;
  • Step 505 IMS-ALG-i replaces the IP-o address of the media connection address in the SDP offer message with the returned IP-i address, and forwards the IP address domain information D-abc and the original media connection address information IP-o. SDP offer message to the recipient's P-CSCF2;
  • Step 506 The P-CSCF2 knows that the two communication parties are in the IP address domain that can be directly routed by the same IP address according to the IP address domain information D-abc, and replaces the media connection address IP-i address in the SDP offer message with the original media connection address IP- o, deleting the IP address domain information D-abc and the original media connection address information IP-o in the SDP offer message, and forwarding the SDP offer message to the UE2;
  • Step 507 The UE2 sends the media connection carrying the UE2 in the SDP answer message to the P-CSCF2. IP address IP-d;
  • Step 508 The P-CSCF2 adds the IP address domain information D-abc in which the media connection IP address IP-d is located in the SDP answer message, and forwards the SDP answer to the IMS-ALG-i in the signaling path.
  • IMS-ALG-i finds that the SDP offer is the same as the IP address domain information D-abc in the SDP answer, and knows that the two communicating parties are in the IP address domain that the same IP can directly route, so the IP-o and IP are sent to the TrGW_i. -i address binding application;
  • Step 510 The TrGW-i sends a response to the IMS-ALG-i to cancel the IP address binding.
  • Step 512 The P-CSCF1 deletes the IP address domain information D-abc in the SDP answer message, and forwards the SDP answer message to UE1.
  • UE1 learns that the UE2 is in an address domain that can be directly routed, and UE1 and UE2 can directly communicate through the address information of the peer end.
  • the functions of the P-CSCF and the IMS-ALG functional entity in the IMS architecture defined by the 3GPP are also extended.
  • the specific extended functions are not described here.
  • the TrGWs of the access network at both ends are in the same IP address domain on the core network side after the IP address translation, if there are multiple pairs of IMS between the TrGWs of the two ends accessing the network-
  • the ALG entity and the TrGW entity need to perform IP address domain information negotiation between the P-CSCFs of the access network and the core network where the access network TrGW is located. Therefore, the extended SDP needs to carry the terminal address domain negotiation information and the address domain negotiation information of the core network where the access network TrGW is located, and the extension method is similar to the foregoing methods in FIG. 4 and FIG. 5, and details are not described herein.
  • the following is an example of how to use the present invention in an IMS network, when two clients are not in the same IP address domain, but the TrGWs of the access networks at both ends are in the same IP address domain on the IMS core network side after IP address translation. Avoid media bypass between TrGWs that access the network at both ends.
  • the method for avoiding the bearer of the media is applied to the signaling flowchart of the third preferred embodiment in the IMS architecture, and the specific process includes:
  • Step 601 The UE1 sends the SDP offer message carrying the media connection IP address IP-o of the UE1 to the P-CSCF/IMS-ALG1;
  • Step 602 The P-CSCF/IMS-ALG1 sends an IP address binding request carrying the IP-o to the TrGW1.
  • Step 603 The TrGW1 selects a free address IP-11 from the address pool, binds the IP-11 and the IP-o, and returns an IP address binding response carrying the IP-11 to the P-CSCF/IMS-ALG1.
  • Step 604 The P-CSCF/IMS-ALG1 replaces the IP-o address in the SDP offer message with the returned IP-11 address, and adds the IP address field in which the IP-o and IP- 11 are located in the SDP offer 4 message.
  • Information D1 and D2 and copy IP-o and IP-11 to the newly extended SDP parameter domain for backup, forward SDP message, and finally reach IMS-ALG-i;
  • Step 605 IMS-ALG-i sends an IP address binding request carrying IP-11 to TrGW-i.
  • Step 607 IMS-ALG-i replaces the IP-o address in the SDP offer message with the returned IP-i address, forwards the SDP offer message, and finally reaches the receiving party's P-CSCF/IMS-ALG2;
  • Step 608 The P-CSCF/IMS-ALG2 knows that the IP access network of the communication network is not in the same IP address domain, but the core network where the access network TrGW is located is in the same IP address domain, according to the IP address domain information D2 in the SDP packet. D2, the access network still needs to perform IP address translation, and sends an IP address binding request carrying IP-11 to TrGW2;
  • TrGW2 selects a free address IP-12 from the address pool, binds IP-12 and IP-11, and returns an IP address binding response carrying IP-12 to P-CSCF/IMS-ALG2.
  • P-CSCF/IMS-ALG2 replaces the IP connection address in the SDP offer message with
  • IP-12 delete the IP address domain information D1 and D2 and the backup address information IP-o and IP-11, forward the SDP to the UE2;
  • Step 611 The UE2 sends the SDP answer message carrying the media connection IP address IP-d of the UE2 to the P-CSCF/IMS-ALG2;
  • Step 612 The P-CSCF/IMS-ALG2 sends an IP address binding request carrying the IP-d to the TrGW2.
  • TrGW2 selects a free address IP-22 from the address pool, binds IP-d and IP-22, and returns an IP address binding response carrying IP-22 to P-CSCF/IMS-ALG2.
  • P-CSCF/IMS-ALG2 replaces the IP connection address in the SDP answer message with IP-22, and add IP-d and IP-22 IP address domain information D3 and D2 in the message, forward SDP packets, and finally reach IMS-ALG-i;
  • Step 615 The IMS-ALG-i finds that the IP address domain information in the SDP offer and the SDP answer has the same D2, and knows that the two communication parties are in the IP address domain that can be directly routed by the same IP, and therefore sends the IP- 11 and the TrGW-i. IP-i address binding application;
  • Step 616 The TrGW-i sends a response to the IMS-ALG-i to cancel the IP address binding.
  • Step 618 The P-CSCF/IMS-ALG1 knows that the IP access network is not in the same IP address domain, but the core network where the access network TrGW is located is the same according to the IP address domain information D3 and D2 in the SDP answer message. IP address domain D2, the access network still needs to perform IP address translation, and sends an IP address binding request carrying IP-22 to TrGW2;
  • Step 619 The TrGW1 selects a free address IP-21 from the address pool, binds the IP-21 and the IP-22, and returns an IP address binding response carrying the IP-21 to the P-CSCF/IMS-ALG1.
  • IP-21 delete the IP address domain information D3 and D2, and forward the SDP 4 message to UE1.
  • UE1 learns that the UE2 is in an address domain that can be directly routed, and UE1 and UE2 can directly communicate through the address information of the peer end.
  • the P-CSCF/IMS-ALG function unified entity and the IMS-ALG independent functional entity in the IMS architecture defined by the 3GPP need to be extended.
  • the functions of the P-CSCF/IMS-ALG functional unity entity are extended as follows:
  • the SDP packet from the terminal is forwarded, if the media connection IP address is given in the SDP, the IP address domain information in which the terminal media connection IP address is located and the IP address on the core network side after the IP address translation binding are added in the SDP Address domain information;
  • the SDP offer message When forwarding the SDP offer message from the terminal, if the IP address and port information of the media connection are given in the SDP, the IP address and port information of the copy media connection and the translated IP address and port information are forwarded to the present.
  • the SDP original address and the port parameter domain extended by the patent are backed up; when the SDP offer message is forwarded to the terminal, if the core network IP address domain information in the SDP packet is consistent with the local core network IP address domain information, the Backup the IP address of the peer core network side and Or the port first performs an IP address binding request, and the media connection address and or the port replacement IP address in the packet are bound to the address and or the port returned by the response; if the SDP address is in the terminal IP address domain information and the local terminal If the IP address field information is the same, the media connection address and port in the packet are replaced with the media connection address and port of the peer terminal carried in the original address and port parameter domain.
  • the SDP packet When the SDP packet is forwarded to the terminal, if the SDP packet contains the IP address domain information and/or the original address and/or port information, the corresponding IP address domain information and/or the original address and port information are deleted before forwarding. ;
  • the media connection address and port information in the SDP are not replaced if the address fields of the two terminals are the same. If the corresponding SDP offer packet has been applied for the IP address resource binding, the corresponding IP address is released. Address resource binding;
  • the IP address domain information of the current SDP is the same as the IP address domain information of the previous negotiation.
  • the media connection address and or port information in the SDP are not replaced;
  • the IMS-ALG specified in the standard specifications such as 3GPP 29.162, 23.228 is implemented. Functional process.
  • IMS-ALG independent functional entity The functions of the IMS-ALG independent functional entity are extended as follows:
  • the SDP packet is directly received. Forward the corresponding SDP packet;
  • Figure 4 and Figure 5 and Figure 6 show two specific embodiments of the two IP addresses of the same IP version of the IMS core network to avoid bearer media bypass.
  • the following example illustrates the IMS network networking.
  • the IP version used by the IMS core network is different, how to use the present invention to avoid carrying media into the media The process of converting unnecessary IP versions.
  • the method for avoiding bearer media bypass is applied to a signaling flowchart of a fourth preferred embodiment in an IMS architecture, where an IMS core network uses IPv6, and UE1 and UE2 are in an IPv4 address domain.
  • the specific process includes:
  • Step 701 UE1 sends an SDP offer message carrying the media connection IP address IPv4-l and port P1 of UE1 to the P-CSCF1;
  • Step 702 The P-CSCF1 extends the SDP offer 4, adds the IP address domain information D-1 where the IPv4-l is located, and copies the original media connection address IPv4-l and the port P1 to the local in the SDP offer message.
  • the newly extended original address and ports parameter field in the patent method forwards the extended SDP offer message to IMS-ALG1;
  • Step 703 The IMS-ALG1 sends an application for binding the address IPv4-l and the port P1 to the TrGW1.
  • Step 704 TrGW1 selects a free address IPv6-l and port P61 from the address pool, binds IPv4-l/P1 and IPv6-l/P61, and returns an IP carrying IPv6-l/P61 to IMS-ALG1. Address binding response;
  • Step 705 IMS-ALG1 replaces the media connection address IPv4-l and port P1 in the SDP offer message with the returned address IPv6-l and port P61, and forwards the IP address domain information D-1 and the original media connection address IPv4. -l and the SDP offer message of port P1, and finally reach the IMS-ALG2 of the receiver;
  • Step 706 The IMS-ALG2 sends an address binding request to the TrGW2 carrying the address IPv6-l and the port P61.
  • TrGW2 selects a free address IPv4-12 and port P12 from the address pool, binds IPv4-12/P12 and IPv6-l/P61, and returns an IP carrying IPv4-12/P12 to IMS-ALG2. Address binding response;
  • Step 708 The IMS-ALG2 sets the media connection address in the SDP offer message to the IPv6-l and the port.
  • P61 is replaced with the returned address IPv4-12 and port P12, and forwards the SDP offer message carrying the IP address domain information D-1 and the original media connection address IPv4-l and port P1, and finally reaches the P-CSCF2 of the receiver;
  • Step 709 The P-CSCF2 knows that the communication parties are in the same IP according to the IP address domain information D-1. In the IP address field of the direct route, replace the media connection address IPv4-12 and port P12 in the SDP offer message with the original media connection address IPv4-l and port P1, and delete the IP address domain information D-1 in the SDP offer message. And the original media connection address IPv4-l and port P1, forward the SDP offer message to the UE2; Step 710: The UE2 sends the SDP answer message to the P-CSCF2 to carry the media connection address IPv4-2 and port P2 of the UE2;
  • Step 711 The P-CSCF2 adds the IP address domain information D- 1 of the media connection IP address of the IPv4-2 in the SDP answer message, and forwards the SDP answer message to the IMS-ALG2.
  • Step 712 The IMS-ALG2 finds that the SDP offer is the same as the IP address domain information D-1 in the SDP answer, and knows that the two communicating parties are in the IP address domain directly routable by the same IP, and therefore sends the IPv4-12/P12 and IPv6- to the TrGW2. l/P61 address binding application;
  • Step 713 TrGW2 sends a detachment of the IP address binding success message to the IMS-ALG2.
  • Step 715 The IMS-ALG1 finds that the SDP offer is the same as the IP address domain information D-1 in the SDP answer, and knows that the two communicating parties are in the IP address domain that can be directly routed by the same IP, and therefore sends the IPv4-l/Pl and IPv6- to the TrGW1. l/P61 address binding application;
  • Step 716 The TrGW1 sends a detachment of the IP address binding success response to the IMS-ALG1.
  • Step 717 The IMS-ALG1 forwards the SDP answer message and finally reaches the P-CSCF1 while releasing the IP address binding operation.
  • Step 718 The P-CSCF 1 deletes the IP address domain information D-1 in the SDP answer, and forwards the SDP answer message carrying the media connection address of the UE2, the IPv4-2 and the port P2, to the UE1.
  • UE1 learns that the UE is in the same IPv4 address domain as the UE, and UE1 and UE2 directly communicate through the address information of the peer.
  • the following is an example of how to use the present invention to avoid the unnecessary IP address translation process of the bearer medium when the two clients are in the same private IP addressable private network in the IMS network.
  • FIG. 8 is a schematic flowchart of a fifth preferred embodiment of the IMS architecture.
  • the UE1 and the UE2 are in the same private network.
  • the specific processes include:
  • Step 801 The UE1 sends an SDP offer message to the P-CSCF/IMS-ALG1 to carry the UE1.
  • Step 802 The P-CSCF/IMS-ALG1 sends an address binding application carrying the address IP-1 to the TrGW1.
  • Step 803 The TrGW1 selects a free address IP-lr from the address pool, binds the IP-1 and the IP-lr, and returns an IP address binding response carrying the IP-lr to the P-CSCF/IMS-ALG1.
  • Step 804 The P-CSCF/IMS-ALG1 extends the SDP offer message, adds the IP address domain information D-1 where the IP-1 is located, and copies the original media connection address IP-1 in the SDP packet to the new extension.
  • the original address and ports parameter field replaces the media connection address IP-1 in the SDP offer message with the returned address IP-lr, forwards the extended SDP offer message, and finally reaches the UE2 side.
  • P-CSCF/IMS-ALG2 The P-CSCF/IMS-ALG2;
  • Step 805 The P-CSCF/IMS-ALG2 knows that the two communication parties are in the IP address domain directly routed by the same IP according to the IP address domain information D-1, and replaces the media connection address IP-lr in the SDP offer message with the original media connection. Address IP-1, deleting the IP address domain information D-1 and the original media connection address IP-1 in the SDP offer message, and forwarding the SDP offer message to the UE2;
  • Step 806 UE2 sends an SDP answer message carrying the media connection address IP-2 of UE2 to the P-CSCF/IMS-ALG2;
  • Step 807 The P-CSCF/IMS-ALG2 adds the IP address domain information D-1 of the media connection IP address IP-2 in the SDP answer message, forwards the SDP answer text, and finally reaches the P-CSCF/IMS-ALG1;
  • Step 808 The P-CSCF/IMS-ALG1 finds that the SDP offer is the same as the IP address domain information D-1 in the SDP answer, and knows that the two communicating parties are in the IP address domain that can be directly routed by the same IP, so the IP-1 and the release of the IP-1 are sent to the TrGW1. IP-lr address binding application;
  • Step 809 The TrGW1 sends a de-IP address binding success response to the P-CSCF/IMS-ALG1.
  • Step 810 The P-CSCF/IMS-ALG1 deletes the IP address domain information D-1 in the SDP answer text, and forwards the media carrying the UE2. Connect the SDP answer message of address IP-2 to UE1.
  • UE1 knows that the UE2 is in the same direct addressable private network, and UE1 and UE2 directly communicate through the address information of the peer end.
  • the following example illustrates how to use the present invention to avoid carrying media when the two roaming terminals of the same carrier in the same IP addressable address domain are interworking in the IMS network.
  • the necessary IP address and port conversion process is necessary.
  • a signaling flowchart of a sixth preferred embodiment of the IMS architecture is applied to a method for avoiding bearer media bypass, where the P-CSCF1 is in a visited place 1, a visited place 1 network, and a home domain network. Interworking needs to be performed by IBCF1 and TrGW1 that integrate IMS-ALG1 functions. P-CSCF2 is in visited area 2. When the visited network 2 and the home network are interworking, IBCF2 and TrGW2 with IMS-ALG2 function are required to communicate. The roaming users UE1 and UE2 are in the same address domain that can be directly IP-addressed.
  • the specific process includes:
  • Step 901 UE1 sends an SDP offer message carrying the media connection IP address IP-1 and port P1 of UE1 to the P-CSCF1.
  • Step 902 The P-CSCF1 expands the SDP offer text, adds the IP address domain information D-1 where the IP-1 is located, and copies the original media connection address IP-1 and the port P1 in the SDP packet to the newly extended original address. And the port parameter field, forwarding the extended SDP offer message, and finally reaching the IMS-ALG1;
  • Step 903 The IMS-ALG1 sends an address binding request carrying the address IP-1 and the port P1 to the TrGW1;
  • Step 904 TrGWl selects a free address IP-11 and port P11 from the address pool
  • IP-1/P1 and IP-11/P11 are bound, and the IP address binding response carrying IP-11/P11 is returned to IMS-ALG1;
  • Step 905 IMS-ALG1 replaces the media connection address IP-1 and port P1 in the SDP offer message with the returned address IP-11 and port P11, and forwards the IP address domain information D-1 and the original media connection address IP. -1 and the SDP offer message of the port P1, and finally reach the IMS-ALG2 of the receiver;
  • Step 906 The IMS-ALG2 sends an address binding request carrying the address IP-11 and the port P11 to the TrGW2;
  • Step 907 TrGW2 selects a free address IP-22 and port P22 from the address pool, binds IP-11/P11 and IP-22/P22, and returns an IP carrying IP-22/P22 to IMS-ALG2. Address binding response;
  • Step 908 IMS-ALG2 replaces the media connection address IP-11 and port P11 in the SDP offer message with the returned address IP-22 and port P22, and carries the IP address domain information D-1 and the original media connection address IP. -1 and the SDP offer of the port P1, and finally reach the P-CSCF2 of the receiver; Step 909: The P-CSCF2 knows that the two parties are in the same IP according to the IP address domain information D-1. In the IP address field of the direct route, replace the media connection address IP-22 and port P22 in the SDP offer message with the original media connection address IP-1 and port P1, and delete the IP address domain information D-1 in the SDP offer message. The IP address and the port P1 are connected to the original media, and the SDP offer is forwarded to the UE2.
  • Step 910 UE2 sends an SDP answer message carrying the media connection address IP-2 and port P2 of UE2 to the P-CSCF2.
  • Step 911 The P-CSCF2 expands the SDP answer message, increases the IP address domain information D-1 of the media connection IP address IP-2, forwards the SDP answer message, and finally reaches the IMS-ALG2 in the signaling path;
  • Step 912 The IMS-ALG2 finds that the SDP offer is the same as the IP address domain information D-1 in the SDP answer, and knows that the two communicating parties are in the IP address domain that can be directly routed by the same IP, and therefore sends the IP-11/P11 and IP- to the TrGW2. 22/P22 address binding application;
  • Step 913 TrGW2 sends a detachment of the IP address binding success message to IMS-ALG2.
  • Step 915 IMS-ALG1 discovers IP address domain information in SDP offer and SDP answer
  • D-1 is the same. It knows that the two communicating parties are in the IP address domain that can be directly routed by the same IP. Therefore, the application for unbinding IP-1/P1 and IP-11/P11 addresses is sent to TrGW1.
  • Step 916 The TrGW1 sends a detachment of the IP address binding success response to the IMS-ALG1.
  • Step 917 The IMS-ALG1 forwards the SDP answer message and finally reaches the P-CSCF1 while releasing the IP address binding operation.
  • Step 918 The P-CSCF1 deletes the IP address domain information D-1 in the SDP answer message, and forwards the SDP answer message carrying the media connection address IP-2 of the UE2 and the port P2 to the UE1.
  • the roaming terminal UE1 learns that it is in the same addressable address domain as the roaming terminal UE2, and UE1 and UE2 directly communicate through the address information of the opposite end.
  • the IP domain negotiation initiator initiates the IP domain negotiation request and carries the IP address and/or the port negotiation information.
  • the IP domain negotiation initiator and the IP domain negotiate the IMS-ALG entity in the interworking path of the receiver. It is not known whether the two ends of the communication are in the same IP domain, so an IP address binding request is sent to the TrGW.
  • the IP domain negotiation initiator and the IP domain negotiation receiver may also perform IP domain negotiation first, and then send the IP address and/or port after the negotiation is completed. If the IP domain negotiation result is the same as the IP address of the two ends of the communication, the IP address binding operation may not be performed.
  • a signaling flowchart of a seventh preferred embodiment of the IMS architecture is provided.
  • the specific process includes:
  • Step 1001 UE1 sends an SDP offer message carrying the media connection IP address IP-1 of UE1 to the P-CSCF/IMS-ALG1;
  • Step 1002 The P-CSCF/IMS-ALG1 sends an SDP offer message carrying the IP address domain information D-1 where the IP-1 is located, and finally reaches the P-CSCF/IMS-ALG2 on the UE2 side;
  • Step 1003 The P-CSCF/IMS-ALG2 returns an SDP answer message of the IP address domain information D-1 where the UE2 is located, and finally reaches the P-CSCF/IMS-ALG1 of the UE1 side;
  • Step 1004 The P-CSCF/IMS-ALG1 knows that the two communication parties are in the IP address domain that can be directly routed by the same IP address according to the IP address domain information D-1, and the IP address binding operation is not performed, and the P-CSCF/IMS-ALG1 sends the SDP offer.
  • the packet carries the media connection IP address IP-1 of UE1. If there are other IMS-ALGs in the communication path, they will know that the two communication parties are in the IP address domain directly routed by the same IP according to the previous IP domain negotiation result. Perform the IP address binding operation, and the SDP offer finally arrives at the P-CSCF/IMS-ALG2 on the UE2 side;
  • Step 1005 The P-CSCF/IMS-ALG2 knows according to the result of the previous IP domain negotiation that the two communication parties are in the IP address domain that can be directly routed by the same IP, and the IP address binding operation is not performed, and the SDP offer message is directly forwarded to the UE2;
  • Step 1006 UE2 returns an SDP answer message carrying the media connection IP address IP-2 of UE2.
  • Step 1007 The P-CSCF/IMS-ALG2 knows that the two communication parties are in the IP address domain that can be directly routed by the same IP according to the previous IP domain negotiation result, and directly forwards the SDP answer message, and finally reaches the P-CSCF/IMS-ALG1 on the UE1 side;
  • Step 1008 The P-CSCF/IMS-ALG1 knows that the two communication parties are in the IP address domain that can be directly routed by the same IP according to the result of the previous IP domain negotiation, and directly forwards the SDP answer message to UE1.
  • UE1 obtains the media connection address of UE2 as IP-2 through the SDP negotiation message, and UE2 also obtains the media connection address of UE1 as IP-1 through SDP negotiation, because both terminals are in the same Direct IP addressing private network, the subsequent communication terminals can use the pair
  • the media connection address information of the terminal directly performs media communication, which avoids unnecessary communication between the two communication media streams through TrGW1 and TrGW2 for multiple unnecessary IP address conversion and media relay, shortens the media communication delay, and saves network processing resources such as TrGW.
  • the receiving entity has performed the IP domain negotiation, and the IP domain of the communication initiator and the communication receiver is the same, because the communication initiator and the communication receiver negotiate When the IP address and/or other media connection attributes outside the port, such as codec negotiation, the media connection IP address and/or port information also needs to be carried.
  • the network address and/or port conversion signaling processing function entity Directly forwarding the media connection IP address and/or port information to the peer end.
  • the method and system for avoiding bearer media bypass provided by the embodiments of the present invention can directly communicate with media interworking between different network entities in a directly addressable IP address domain, thereby avoiding unnecessary bearer media path bypass and shortening. Communication time and network processing resources are saved.
  • the method and system for avoiding bearer media detour provided by the embodiments of the present invention can reduce communication between different network entities with the same IP domain of the conversion gateway of the access network, although the IP address domains are different.
  • the path between the bearer media conversion gateways is reduced, the communication time is shortened, and the network processing resources are saved.

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Description

避免承载媒体迂回的方法及系统
本申请要求于 2006 年 11 月 17 日提交中国专利局、 申请号为 200610145189.9、 发明名称为 "避免承载媒体迂回的方法及其系统"的中国专利 申请的优先权， 其全部内容通过引用结合在本申请中。
技术领域
本发明涉及一种通信技术，尤其是一种通信过程中避免承载媒体迂回的技 术。
背景技术
目前，下一代电信网络 (NGN, Next Generation Network)通过使用 IP网络技 术， 承载、 控制和业务层相分离的体系架构， 来提供语音、 视频、 多媒体等丰 富的电信业务。 很多运营商现有的 IP网络都是 IPv4网络， 由于 IPv4地址紧 张， 运营商在网络规划时在接入网大量釆用私网 IPv4地址， 因此实际应用中 存在大量釆用私网 IP地址的企业网接入 NGN的现象。前述组网方案和需求导 致了 NGN网络组网中不同网络之间存在 IP地址空间重叠的情况，为了实现不 同网络之间的 IP互通和路由， 在同一运营商的接入网和核心网或不同运营商 核心网之间互通时需要进行网络地址和 /或端口转换。 随着 IPv6网络应用的引 入， 存在着 IPv4网络和 IPv6网络共存的组网情况， 而在 IPv4和 IPv6网络互 通时也需要进行网络地址转换和 /或端口转换。综上所述，在 NGN网络组网时， 由于存在前述 IP承载网络的 IP地址空间重叠的情况和 /或 IP版本转换的情况， 因此导致 NGN网络互通时需要进行网络地址转换和 /或端口转换。
NGN网络在信令控制层面釆用 SIP、 H.323、 H.248等应用信令协议， 底 层 IP承载层的媒体流连接地址是通过信令控制层面 SIP、 H.323、 H.248等信 令协议动态协商， 因此在 NGN网络进行网络地址和 /或端口转换时， 需要对信 令协议里协商的媒体流连接地址和 /或端口进行转换。也就是说 NGN业务流的 网络地址和 /或端口转换功能的实现需要业务控制面转换实体和媒体承载面转 换实体一起配合完成。
在 ITU-T 标准草案中，给出了 NGN的网络地址转换 (NAT, Network Adress Translation)和 /或网络地址端口转换 (NAPT, Network Address Port Translation)的 逻辑功能架构， 其中， NAPT执行功能实体属于承载层， 通过更改媒体报文的 地址和 /或端口号实现网络地址和 /或端口转换功能和媒体中转功能； NAPT代 理功能实体属于业务控制层，根据 NAPT执行功能实体创建的地址绑定信息完 成应用信令消息体中的地址和 /或端口的改动； NAPT 控制功能实体， 属于承 载控制层， 根据从 NAPT代理功能实体处获得的地址绑定信息， 执行 NAPT 策略控制。
3GPP技术标准规范中定义了实现 IP地址和 /或端口转换的功能实体主要 包括： IP 多媒体子系统应用层网关功能实体（IMS-ALG, IP Multimedia Subsystem - Application Level Gateway)和转换网络功能实体 (TrGW, Translation GateWay)。 其中 IMS-ALG相当于集成了 ITU-T定义的 NAPT代理功能实体 和 NAPT控制功能实体两个实体的功能，而 TrGW相当于 ITU-T定义的 NAPT 执行功能实体。下面举例说明对 3GPP相关标准规范中的地址和 /或端口转换的 过程， 请参阅图 1 , 两个 IPv4用户端在 IPv6的 IMS核心网通信过程中进行地 址转换的流程图， 其地址转换过程包括：
步骤 101 : 用户 1(UE1)向 IMS-ALG1发送会话描述协议媒体流建立请求 (SDP offer, Session Description Protocol offer) , SDP offer报文中携带 UE1媒 体连接的 IPv4地址 (IPv4-l)和端口 P1 ;
步骤 102: IMS-ALG1向 TrGWl发送携带 IPv4-l和端口 P1的 IP地址绑 定请求；
步骤 103: TrGWl从地址池中选择一个 IPv6地址 IPv6-l和端口 P61 , 把 IPv4-l、 PI和 IPv6-l、 P61进行绑定， 并向 IMS-ALG1返回携带 IPv6-l和 P61 的 IP地址绑定响应；
步骤 104: IMS-ALG1把 SDP offer报文中的 IPv4-l和端口 P1替换为从 TrGWl返回的 IPv6-l和端口 P61 , 并转发所述 SDP offer报文到达会话终止方 的 IMS-ALG2;
步骤 105: IMS-ALG2向 TrGW2发送携带媒体连接地址 IPv6- 1和端口 P61 的 IP地址绑定请求；
步骤 106: TrGW2从地址池中选择一个 IPv4地址 IPv4-12和端口 P12,把 IPv4-12、 P12和 IPv6-l、 P61进行绑定， 并向 IMS-ALG1返回携带 IPv4-12和 P12的 IP地址绑定响应； 步骤 107: IMS-ALG2把 SDP offer报文中的 IPv6-l和端口 P61替换为返 回的地址 IPv4-12和端口 P12,并转发 SDP offer 4艮文最终到达会话终止方用户 2(UE2);
步骤 108: UE2向 IMS-ALG2发送 SDP answer响应 4艮文， SDP answer 报文中携带 UE2媒体连接的 IPv4地址 IPv4-2和端口 P2。
步骤 109: IMS-ALG2向 TrGW2发送携带 IPv4-2和端口 P2的 IP地址绑 定请求；
步骤 110: TrGW2从地址池中选择一个 IPv6地址 IPv6-2和端口 P62, 把 IPv4-2、 P2和 IPv6-2、 P62进行绑定， 并向 IMS-ALG1返回携带 IPv6-2和 P62 的 IP地址绑定响应；
步骤 111： IMS-ALG2把 SDP answer报文中的 IPv4-2地址和端口 P2替换 为从 TrGW2返回的 IPv6-2和端口 P62,转发 SDP answer报文最终到达会话终 止方的 IMS-ALG1 ;
步骤 112: IMS-ALG1向 TrGWl发送携带有 IPv6-2和端口 P62的 IP地址 绑定请求；
步骤 113: TrGWl从地址池中选择一个 IPv4地址 IPv4-21和端口 P21 ,把 IPv4-21、 P21和 IPv6-2、 P62进行绑定， 并向 IMS-ALG1返回携带 IPv4-21和 P21的 IP地址绑定响应；
步骤 114: IMS-ALG1把 SDP answer报文中的 IPv6-2和端口 P62替换为 从 TrGWl返回的地址 IPv4-21和端口 P21 , 转发 SDP报文最终到达会话终止 方 UE1 ;
步骤 115: UE1发送实时传输协议 (RTP, Real time Transport Protocol)语音 媒体报文 1给 UE2, 其中源 IP地址为 UE1的 IP地址 ΙΡν4-1 , 端口为 PI , 目 的 IP地址为根据前面信令协议协商中得知的 UE2的 IP地址 IPv4-21和端口 P21 , 由于 IPv4-21分配给 TrGWl , 因此这个报文最终路由到 TrGWl；
步骤 116: TrGWl收到 RTP 4艮文 1后， 根据已经建立的地址绑定信息， 把源 IP地址 IPv4-l和端口 P1替换为的地址 IPv6-l和端口 P61 , 目的 IP地址 IPv4-21和端口 P21替换为地址 IPv6-2和端口 P62, 构造 IPv6的 RTP报文并 转发， 最终到达 TrGW2; 步骤 117: TrGW2收到 RTP报文 1后， 根据已经建立的地址绑定信息， 把源 IP地址 IPv6-l和端口 P61替换为地址 IPv4-12和端口 P12, 目的 IP地址 IPv6-2和端口 P62替换为 IPv4-2和端口 P2, 构造 IPv4的 RTP报文并转发， 最终到达 UE2;
步骤 118: UE2发送 RTP语音媒体报文 2给 UE1 , 其中源 IP地址为 UE2 的 IP地址 IPv4-2和端口 P2, 目的 IP地址为根据前面信令协议协商中得知的 UE1的 IP地址 IPv4-12和端口 P12 , 由于 IPv4-12分配给 TrGW2 , 因此这个报 文最终路由到 TrGW2;
步骤 119: TrGW2收到 RTP报文 2后, 根据已经建立的地址绑定信息， 4巴源 IP地址 IPv4-2和端口 P2替换为地址 IPv6-2和端口 P62 , 目的 IP地址 IPv4- 12和端口 P12替换为地址 IPv6-l和端口 P61 , 构造 IPv6的 RTP报文并 转发， 最终到达 TrGWl ;
步骤 120: TrGWl收到 RTP报文 2后， 根据已经建立的地址绑定信息， 把源 IP地址 IPv6-2和端口 P62替换为地址 IPv4-21和端口 P21 , 目的 IP地址 IPv6-l和端口 P61替换为地址 IPv4-l和端口 P1 , 构造 IPv4的 RTP 文并转 发， 最终到达 UE1。
ETSI标准规范定义了实现 IP地址和 /或端口转换的功能实体主要包括：应 用功能实体 (AF, Application Function) , 基于业务的策略决策功能功能实体 (SPDF, Service-based Policy Decision Function)和边界网关功能功能实体 (BGF, Border Gateway Function)。其中 AF相当于 ITU-T定义的 NAPT代理功能实体， SPDF相当于 ITU-T定义的 NAPT控制功能实体， 而 BGF相当于 ITU-T定义 的 NAPT执行功能实体。其实现 IP地址和 /或端口转换的原理和流程和 ITU-T 以及 3GPP标准组织中相关标准规范定义的类似， 这里不再赘述。
上述 ITU-T、 3GPP、 ETSI各标准组织标准规范中定义的网络地址和 /或端 口转换流程中， 是由业务控制层的 NAPT转换信令处理实体， 如 NAPT代理 功能实体、 IMS-ALG功能实体或 AF功能实体等实体， 触发承载层跨不同 IP 地址域的 NAPT转换执行功能实体， 如 NAPT执行功能实体、 TrGW功能实 体或 BGF功能实体等实体来完成网络地址和或端口转换的功能实现。
在 NGN组网中， 当处于同一 IP可直接路由的 IP地址域的不同网络实体 间互通时， 由于一对 ΝΑΡΤ转换信令处理实体和 ΝΑΡΤ媒体转换执行实体仅 负责相邻的两互通 IP域的网络地址和 /或端口转换， 并不了解最终两个互通网 络实体实际处于同一 IP可直接路由的 IP地址域， 这样通过多次的网络地址和 /或端口转换后， 媒体流也需要经过多个 NAPT媒体转换执行实体进行媒体中 继， 导致本来媒体面可以进行直接 IP寻址互通的情况下却进行了不必要的媒 体迂回问题。
例如图 1中，假设 UE1和 UE2处于同一个可直接路由的 IPv4地址域，在 承载媒体互通上 UE1和 UE2本来可以通过 IP地址 IPv4-l和 IPv4-2进行直接 路由和互通， 但根据前述实现 IP地址和 /或端口转换的技术方案和流程， 经过 多次 IPv4和 IPv6转换之后 , UE1和 UE2之间的媒体互通必须经过 TrGWl和 TrGW2进行多次的地址转换和媒体中继， 这样， 一方面增加了媒体通信时延， 另外一方面导致本来可以直接互通的媒体流需要通过 TrGWl和 TrGW2进行 不必要的地址转换和穿越 IPv6核心网络， 造成网络资源的极大浪费。
再如 IMS网络组网应用中， 漫游到中国移动的德国 T-Mobile用户和中国 移动本地用户通信时， 本来两终端可以直接通过中国移动的 IP 载网进行媒 体互通， 但由于中国移动的 IMS网络和德国 T-Mobile的网络不能进行直接互 通， 如果釆用前述实现 IP 地址和或端口转换的技术方案和流程实现德国 T-Mobile漫游用户和中国移动本地用户之间多次的 IP地址和或端口转换进行 互通通信时， 将造成不必要的媒体迂回到德国 T-Mobile的 IP承载网以及多次 的地址转换过程， 导致通信时延的增加和网络资源的浪费。
综上所述， 有必要提出一种网络地址和 /或端口转换时避免承载媒体迂回 的方法及系统。
发明内容
本发明要解决的问题在于提供一种避免承载媒体迂回的方法及系统，使处 于同一 IP可直接路由的 IP域的不同用户端之间可以直接进行通信，避免不必 要的媒体路径迂回。
为解决上述技术问题， 本发明的目的是通过以下技术方案实现的： 本发明实施例提供一种避免承载媒体迂回的方法， 其包括：
IP域协商发起实体向 IP域协商接收实体发送携带通信发起端 IP域信息的 IP域协商请求；
IP域协商接收实体向 IP域协商发起实体发送 IP域协商请求响应； 确定 IP域协商请求响应表示通信发起端的 IP域与通信接收端的 IP域相 同； 之后，
所述通信发起端和所述通信接收端协商获得对端的媒体连接 IP地址和 /或 端口信息， 通信双方之间通过直接路由进行通信。
本发明实施例还提供一种避免承载媒体迂回的系统， 其包括：
IP域协商发起实体， 发送携带通信发起端 IP域信息的 IP域协商请求； IP域协商接收实体， 接收从 IP域协商发起实体发送的 IP域协商请求， 并 根据所述 IP域协商请求， 向 IP域协商发送实体发送 IP域协商请求响应； 网络地址和 /或端口转换信令处理实体， 如果 IP域协商请求响应为通信发 起端的 IP域与通信接收端的 IP域相同， 则转发所述通信发起端和接收端的媒 体连接 IP地址和 /或端口信息至对端。
本发明实施例还提供一种 IP域协商发起 /接收实体， 包括：
IP域信息增删模块， 用于转发来自终端的 SDP offer报文时， 在 SDP offer 中增加媒体端点所处的 IP域信息； 在转发 SDP offer报文给终端时， 删除相应 的 IP域信息。
本发明实施例还提供一种网络地址和 /或端口转换信令处理实体， 包括： 第三报文处理模块， 用于接收到 SDP answer报文时， 如果报文中的媒体 连接 IP地址域信息和相应的 SDP offer报文一致则直接转发 SDP answer报文， 如果相应的 SDP offer报文已经申请了 IP地址的资源绑定， 则释放相应的 IP 地址资源绑定。
本发明实施例提供的避免承载媒体迂回的方法及其系统，可以获知进行通 信的不同用户端是否处于可以直接路由的 IP域， 如果不同用户端处于同一 IP 可直接路由的 IP域，则解除通信发起端的 IP地址和 /或端口与转换网关地址和 /或端口之间的绑定， 使所述用户端之间可以直接进行通信， 避免了不必要的 承载媒体路径迂回， 从而缩短了通信时间和节省了网络处理资源
另夕卜， 本发明实施例提供的避免承载媒体迂回的方法及其系统， 进一步可 以获知 IP域不同的用户端接入网的转换网关是否处于相同的 IP域， 如果是， 则解除用户端的接入网的转换网关与承载媒体转发路径中其他转换网关地址 和 /或端口之间的绑定， 减少了承载媒体转换网关之间的路径迂回， 从而缩短 了通信时间和节省了网络处理资源。
附图说明
图 1为现有技术两个 IPv4用户端在 IPv6的 IMS核心网通信过程中进行地 址转换的流程图；
图 2为本发明避免承载媒体迂回系统实施例的示意图；
图 3为本发明避免承载媒体迂回的方法实施例的流程图；
图 4为本发明避免承载媒体迂回的方法应用于 IMS架构中的一个实施例 信令流程图；
图 5为本发明避免承载媒体迂回的方法应用于 IMS架构中的另一个实施 例的信令流程图；
图 6为本发明避免承载媒体迂回的方法应用于 IMS架构中的另一个实施 例的信令流程图；
图 7为本发明避免承载媒体迂回的方法应用于 IMS架构中的第四较佳实 施例的信令流程图；
图 8为本发明避免承载媒体迂回的方法应用于 IMS架构中的第五较佳实 施例的信令流程图；
图 9为本发明避免承载媒体迂回的方法应用于 IMS架构中的第六较佳实 施例的信令流程图；
图 10为本发明避免承载媒体迂回的方法应用于 IMS架构中的第七较佳实 施例的信令流程图。
具体实施方式
在 NGN组网中， 当处于同一 IP可直接路由的 IP地址域的不同网络实体 间互通时存在多次网络地址和 /或端口转换时， 由于一对 NAPT转换信令处理 实体和 NAPT媒体转换执行实体仅负责相邻的两互通 IP域的网络地址和 /或端 口转换， 并不了解最终两个互通网络实体实际处于同一 IP可直接路由的 IP地 址域， 这样通过多次的网络地址和 /或端口转换后， 媒体流也需要经过多个 NAPT媒体转换执行实体进行媒体中继， 导致本来媒体流可以进行直接 IP寻 址互通的情况下却进行了不必要的媒体迂回问题。解决这个问题的关键是让两 个互通网络实体之间的多个 NAPT转换信令处理实体和 NAPT媒体转换执行 实体得知两个互通网络实体实际处于同一 IP可直接路由的 IP地址域， 不进行 承载层媒体流的网络地址和 /或端口的转换， 从而实现媒体面的直接 IP寻址互 通。
本发明提供了一种避免承载媒体迂回的方法及其系统。为使本发明更加清 楚明了， 以下结合附图对本发明进行详细描述。
请参照图 2, 为本发明避免承载媒体迂回系统较佳实施例的结构示意图。 本发明避免承载媒体迂回系统包括两个通信网络实体 20和 21 , 与所述通信网 络实体 20和 21分别相连的两个信令中继 22和 23 , 位于所述信令中继 22和 23之间的多个 NAPT转换信令处理实体 24、 26和 28 , 以及分别与所述 NAPT 转换信令处理实体 24、 26和 28相连的多个 NAPT媒体转换执行实体 25、 27 和 29。 所述通信网络实体 20或信令中继 22向所述通信网络实体 21或信令中 继 23发出 IP域协商请求， 并提供所述所述通信网络实体 20的 IP域信息， 所 述通信网络实体 21或信令中继 23向所述通信网络实体 20或信令中继 22发送 IP域相同的响应， 所述 NAPT转换信令处理实体 24、 26和 28不对承载媒体 的网络地址和 /或端口进行转换， 以便通信网络实体 20和 21可以直接进行通 信。 所述通信网络实体 20和 21、 信令中继 22和 23以及 NAPT转换信令处理 实体 24、 26和 28均需要进行相应功能扩展， 具体扩展的功能如后所述。
在 3GPP所定义的 IMS架构中，所述信令中继为代理呼叫会话控制功能实 体 (P-CSCF) , 所述 NAPT 转换信令处理实体为 IMS 应用网关功能实体 (IMS-ALG) , 所述 NAPT执行功能实体为转换网关功能实体 (TrGW)。
请参阅图 3 , 为本发明避免承载媒体迂回的方法较佳实施例的流程图， 具 体过程包括以下步骤：
步骤 301 : IP域协商发起实体向 IP域协商接收实体发送携带所述 IP域协 商发起实体 IP域信息的 IP域协商请求， IP域协商发起实体为通信发起端网络 实体或信令中继实体等， IP域协商接收实体为通信接收端网络实体或信令中 继实体等；
步骤 302: IP域协商接收实体接收从 IP域协商发起实体发出的 IP域协商 请求， 并向通信发起端发送携带通信发起端 IP域信息的 IP域协商请求响应； 步骤 303: 如果 IP域协商请求响应表示通信发起端的 IP域与通信接收端 的 IP域相同， 所述通信发起端和所述通信接收端协商获得对端的媒体连接 IP 地址和 /或端口信息。 之后通信双方之间通过直接路由进行通信。
上述 IP域协商发起实体和 IP域协商接收实体之间存在 NAPT转换信令处 理实体。
上述方法中的 NAPT转换信令处理实体可以是 ITU-T、 3GPP、 ETSI各标 准组织标准规范中定义的网络地址和 /或端口转换流程中的 NAPT代理功能实 体、 IMS-ALG功能实体或 AF功能实体等实体。 下面以 3GPP所定义的 IMS 网络架构中各种情况下， 如何解决媒体迂回问题对上述方法进行进一步的说 明。
下面举例说明在 IMS网络组网中， 当处于同一个可直接 IP寻址的地址域 的两个用户端互通时， 怎样利用本发明避免承载媒体进行不必要的 IP地址转 换的过程。
请参阅图 4,本发明避免承载媒体迂回的方法应用于 IMS架构中的第一较 佳实施例的信令流程图， 其中 UE1和 UE2为所要进行通信的两个用户终端； P-CSCF1和 P-CSCF2分别为将用户终端 UE1和 UE2接入 IMS核心网络的代 理呼叫会话控制功能实体； IMS-ALG i实体和 TrGW i实体表示两通信终端互 通路径上实现多次网络地址和 /或端口转换功能的多对 IMS-ALG和 TrGW实 体； 信令层面各网络实体之间使用 SIP协议； 各 IMS-ALG和相应的 TrGW之 间通过 Ix接口实现网络地址和 /或端口转换控制。 其具体过程包括：
步骤 401 : UE1向 P-CSCF1发送 SDP offer报文中携带 UE1的媒体连接 IP 地址 IP-0；
步骤 402: P-CSCF1对 SDP offer报文进行扩展， 增加 IP域协商信息， 例 如增加媒体连接 IP地址 IP-o所处的 IP地址域信息 D-abc ,并转发扩展后的 SDP offer报文到信令路径中的 IMS-ALG— I；
IP地址域信息 D-abc中 c行所包括的 IP域协商信息示例如下：
c=<network type> <address type> <connection address> <domain identify> , 上述网络类型 (network type)、地址类型 (address type)、连接地址 (connection address为现有 SDP协议已有的定义， 而 IP域标识 （domain identify)为新增的 定义，用于表示通信端所属于的 IP域标识，这个参数域是 SDP标准中可选的， 能够全球唯一识别每个处于同一 IP可直接路由的 IP域， 以便通信双方能够根 据这个标识判断通信双方是否处于同一 IP可直接路由的 IP地址域。 IP域标识 取值规则示例如下： 当通信端所处的 IP地址域为 IPv4公网 IP地址域， 则取 值为 IP4PUB; 当通信端所处的 IP地址域为 IPv6公网 IP地址域， 则取值为 IP6PUB； 当通信端所处的 IP地址域为私网地址或公网私用地址域则可以用一 个合法域名形式加以表示，其中主机名部分表示主机名之后所在的域中处于同 一 IP可直接路由的 IP地址域， 如 abc.sz.gd.cn表示 sz.gd.cn域下处于同一 IP 可直接路由的 IP地址域 abc。 IP域的协商过程可以使用 SDP的提供 (offer)/应 答（answer)模式进行， 例如 SDP offer中 c行所携带的 IP域标识为提供方所处 的 IP域， 而 SDP answer中 c行所携带的 IP域标识为应答方所处的 IP域， 当 这两个 IP域标识相同时则说明提供方和应答方处于同一 IP可直接路由的 IP 地址域。
在 IMS架构中用户终端所处的 IP域是由运营商在网络规划时确定的， 因 此 UE—般没有 IP域信息， 因此可以对由用户终端接入 IMS网络的第一个网 络侧信令实体例如 P-CSCF的功能进行扩展， 例如接收到发自终端的 SDP报 文时往 SDP ^艮文中添加 IP域协商信息， 同时为了保证安全性， P-CSCF在转 发 SDP报文给用户终端时可以删除 SDP报文中的 IP域协商信息， P-CSCF可 以通过静态配置或从 IP接入网中查询等方式获得每个终端所对应的 IP域信 息。
步骤 403: IMS-ALG i向 TrGW i发送携带有 IP-o的 IP地址绑定请求； 步骤 404: TrGW i从地址池中选择一个空闲地址 IP-i,把 IP-i和 IP-o进行 绑定， 并向 IMS-ALG i返回携带有 IP-i的 IP地址绑定响应；
步骤 405: IMS-ALG-i把 SDP offer报文中的 IP-o地址替换为返回的 IP-i 地址， 转发 SDP offer报文到接收方的 P-CSCF2;
步骤 406: P-CSCF2删除 SDP offer 4艮文中的 IP地址域信息 D-abc, 转发 SDP offer报文到 UE2;
步骤 407: UE2向 P-CSCF2发送 SDP answer报文中携带 UE2的媒体连接 IP地址 IP-d;
步骤 408: P-CSCF2在 SDP answer报文中增加媒体连接 IP地址 IP-d所处 的 IP地址域信息 D-abc, 转发 SDP answer 4艮文到信令路径中的 IMS-ALG— i; 步骤 409: IMS-ALG— i发现 SDP offer和 SDP answer中的 IP地址域信息 D-abc相同，知道通信双方处于同一 IP可直接路由的 IP地址域，因此向 TrGW— i 发送解除 IP-o和 IP-i地址绑定申请；
步骤 410: TrGW— i向 IMS-ALG— i发送解除 IP地址绑定成功响应； 步骤 411 : IMS-ALG— i在解除 IP地址绑定操作同时， 转发 SDP answer报 文给 P-CSCF1 ;
步骤 412: P-CSCF1删除 SDP answer报文中的 IP地址域信息 D-abc, 转 发 SDP answer报文到 UE1；
步骤 413： P-CSCF1再次发起携带 UE1的媒体连接 IP地址 IP-o的 SDP offer 报文；
由于 UE1发送的第一个 SDP offer报文中的 UE1的媒体连接 IP地址信息 IP-o可能被中间的 IMS-ALG— i实体所改动， 导致 UE2最后得到的 IP地址信 息不是 UE1的实际媒体连接 IP地址， 如前面流程中 UE2通过 SDP offer报文 得到的 UE1的媒体连接 IP地址为 IMS-ALG— i实体改动后的 IP地址 IP-i; 为 了保证 UE2能够得到 UE1的实际媒体连接 IP地址 ΙΡ-ο, Ρ-CSCFl再次发起携 带 UE1的媒体连接 IP地址 IP-o的 SDP offer报文。
步骤 414: IMS-ALG— i根据前面的 IP地址域协商结果， 知道通信双方处 于同一 IP可直接路由的 IP地址域， 而且此 SDP offer报文中的 IP域并没有发 生变化， 直接转发 SDP offer报文到 P-CSCF2;
步骤 415: P-CSCF2转发 SDP offer报文到 UE2, UE2把 UE1的媒体连 接地址从以前协商的 IP-i更改为 IP-o;
步骤 416: UE2向 P-CSCF2返回 SDP answer;
步骤 417: P-CSCF2向 TrGW i返回 SDP answer;
步骤 418: TrGW I向 P-CSCF1返回 SDP answer;
通过上述方法， UE1得知与 UE2处于可直接路由的地址域， UE1和 UE2 可以通过对端的地址信息直接进行通信。 由于路径中的各个 IMS-ALG根据前面的 IP地址域协商结果，知道通信双 方处于同一 IP可直接路由的 IP地址域， 而且当前 SDP answer并没有改变 IP 域，因此不对 SDP answer报文进行特别处理，只是直接进行转发，当 SDP offer 报文到达 P-CSCF1时， P-CSCF1知道是对前面 P-CSCF1发起的 SDP offer报 文的响应， 不再转发 SDP answer给 UE1。
上述实施例中， 对 3GPP定义的 IMS架构中的 P-CSCF、 IMS-ALG功能 实体都进行了功能扩展。 例如对 P-CSCF而言， 在转发来自终端的 SDP offer 报文时，在 SDP offer中增加媒体端点所处的 IP地址域信息；在转发 SDP offer 才艮文给终端时，先删除相应的 IP地址域信息；当接收到通信对端的 SDP answer ^艮文时， 如果所协商的媒体连接 IP地址域信息一致则发送与前一次 SDP offer 报文完全相同的 SDP offer报文； 当接收到 SDP answer报文时， 不再转发给 UE。 对 IMS-ALG而言， 当接收到 SDP answer报文时， 如果报文中的媒体连 接 IP地址域信息和相应的 SDP offer报文一致则直接转发 SDP answer报文， 如果相应的 SDP offer报文已经申请了 IP地址的资源绑定， 则释放相应的 IP 地址资源绑定； 当接收到 SDP报文时， 如果此会话已经进行过 IP地址域信息 协商并且两端 IP地址域一致，如果当前 SDP ^艮文的 IP地址域信息和之前协商 时的 IP地址域信息相同则直接转发相应的 SDP报文。
由于 UE1发送的第一个 SDP offer报文中的 UE1的媒体连接 IP地址信息 IP-o可能被中间的 IMS-ALG i实体所改动，导致 UE2最后得到的 IP地址信息 不是 UE1的实际媒体连接 IP地址。 为了保证 UE2能够得到 UE1的实际媒体 连接 IP地址 IP-o, P-CSCF1只好再次发起一次 SDP协商过程， 这样将导致会 话建立时间增长， 而且 P-CSCF1需要代理 UE1发起第二次 SDP协商。 为了解 决这个问题， P-CSCF1在 SDP中插入 IP域协商信息的同时， 为避免由于中 间的 IMS-ALG实体对 SDP中媒体连接地址信息的改动而丟失 UE1所发出的 SDP offer报文中原始的媒体连接地址信息， P-CSCF 1可以扩展 SDP协议把报 文中的媒体连接地址信息拷贝到新的扩展域中。
下面举例说明在 IMS网络组网中， 当处于同一个可直接 IP寻址的地址域 的两个用户端互通时， 怎样利用本发明避免承载媒体进行不必要的 IP地址转 换且缩短会话建立时间的具体过程。 请参阅图 5 ,为本发明避免承载媒体迂回的方法应用于 IMS架构中的第二 较佳实施例的信令流程图， 其具体过程包括：
步骤 501 : UE1向 P-CSCF1发送 SDP offer报文中携带 UE1的媒体连接 IP 地址 IP-0；
步骤 502: P-CSCF1对 SDP offer报文进行扩展， 增加 IP域协商信息， 例 如增加媒体连接 IP地址 IP-o所处的 IP地址域信息 D-abc, 并复制 SDP offer 才艮文中的原始媒体连接地址信息 IP-o 至原地址和端口（Original Address and Port)参数域， 并转发扩展后的 SDP offer报文到信令路径中的 IMS-ALG— I； 所述扩展后 SDP中 c行包含 IP域协商信息和原始的媒体连接地址信息的 示例如下：
c=<network type> <address type> connection address> <domain identify> <original address and ports>
其中原地址和端口参数域是为了保留用户终端所发出的 SDP报文中原始 的媒体连接地址信息所新扩展的， 这个参数中除了原 IP地址信息外还可以表 示 SDP中每个 m行媒体流的原始端口信息。 一个原地址和端口参数域的取值 示例为： IPv4— l/portl/port2,其中 IPv4— 1为原 IPv4地址， ortl为此会话中第一 个 m行中给出的媒体连接端口， port2为此会话中第二个 m行中给出的媒体连 接端口。
步骤 503: IMS-ALG i向 TrGW i发送携带有 IP-o的 IP地址绑定请求； 步骤 504： TrGW i从地址池中选择一个空闲地址 IP-i ,把 IP-i和 IP-o进行 绑定， 并向 IMS-ALG i返回携带有 IP-i的 IP地址绑定响应；
步骤 505: IMS-ALG-i把 SDP offer报文中的媒体连接地址 IP-o地址替换 为返回的 IP-i地址， 转发携带有 IP地址域信息 D-abc和原媒体连接地址信息 IP-o的 SDP offer报文到接收方的 P-CSCF2;
步骤 506: P-CSCF2根据 IP地址域信息 D-abc知道通信双方处于同一 IP 可直接路由的 IP地址域，把 SDP offer报文中的媒体连接地址 IP-i地址替换为 原媒体连接地址 IP-o, 删除 SDP offer报文中的 IP地址域信息 D-abc和原媒体 连接地址信息 IP-o, 转发 SDP offer报文到 UE2;
步骤 507: UE2向 P-CSCF2发送 SDP answer报文中携带 UE2的媒体连接 IP地址 IP-d;
步骤 508: P-CSCF2在 SDP answer报文中增加媒体连接 IP地址 IP-d所处 的 IP地址域信息 D-abc, 转发 SDP answer 4艮文到信令路径中的 IMS-ALG— i; 步骤 509: IMS-ALG— i发现 SDP offer和 SDP answer中的 IP地址域信息 D-abc相同，知道通信双方处于同一 IP可直接路由的 IP地址域，因此向 TrGW— i 发送解除 IP-o和 IP-i地址绑定申请；
步骤 510: TrGW— i向 IMS-ALG— i发送解除 IP地址绑定成功响应； 步骤 511 : IMS-ALG— i在解除 IP地址绑定操作同时， 转发 SDP answer报 文给 P-CSCF1 ;
步骤 512: P-CSCF1删除 SDP answer报文中的 IP地址域信息 D-abc, 转 发 SDP answer报文到 UE1。
通过上述方法， UE1得知与 UE2处于可直接路由的地址域， UE1和 UE2 可以通过对端的地址信息直接进行通信。
上述实施例中， 同样对 3GPP定义的 IMS架构中的 P-CSCF、 IMS-ALG 功能实体都进行了功能扩展， 具体扩展的功能这里不再赘述。
当两用户端不处于同一 IP地址域 ,但 IP地址转换之后两端接入网的 TrGW 在核心网侧处于同一 IP地址域时， 假如两端接入网的 TrGW之间还存在多对 IMS-ALG实体和 TrGW实体， 为避免两端接入网的 TrGW之间的媒体迂回 , 通信双方的 P-CSCF之间还需要进行接入网 TrGW所在核心网的 IP地址域信 息协商。 这样需扩展 SDP同时携带终端地址域协商信息和接入网 TrGW所在 核心网的地址域协商信息， 其扩展方法和前面图 4和图 5方法类似， 这里不在 赘述。
下面举例说明在 IMS网络组网中， 当两个用户端不处于同一 IP地址域， 但 IP地址转换之后两端接入网的 TrGW在 IMS核心网侧处于同一 IP地址域 时， 怎样利用本发明避免两端接入网的 TrGW之间的媒体迂回。
请参阅图 6,为本发明避免承载媒体迂回的方法应用于 IMS架构下的第三 较佳实施例的信令流程图， 其具体过程包括：
步骤 601 : UE1向 P-CSCF/IMS-ALG1发送 SDP offer报文中携带 UE1的 媒体连接 IP地址 IP-o; 步骤 602: P-CSCF/IMS-ALG1向 TrGWl发送携带有 IP-o的 IP地址绑定 请求；
步骤 603: TrGWl从地址池中选择一个空闲地址 IP-11 , 把 IP-11和 IP-o 进行绑定， 并向 P-CSCF/IMS-ALG1返回携带有 IP-11的 IP地址绑定响应； 步骤 604： P-CSCF/IMS-ALG1把 SDP offer报文中的 IP-o地址替换为返回 的 IP- 11地址，在 SDP offer 4艮文中增加 IP-o和 IP- 11所处的 IP地址域信息 D1 和 D2, 以及拷贝 IP-o和 IP-11到新扩展的 SDP参数域进行备份， 转发 SDP 报文， 最终到达 IMS-ALG— i;
步骤 605: IMS-ALG-i向 TrGW-i发送携带有 IP-11的 IP地址绑定请求； 步骤 606: TrGW-i从地址池中选择一个空闲地址 IP-i, 把 IP-i和 IP-11进 行绑定， 并向 IMS-ALG-i返回携带有 IP-i的 IP地址绑定响应；
步骤 607: IMS-ALG-i把 SDP offer报文中的 IP-o地址替换为返回的 IP-i 地址， 转发 SDP offer报文， 最终到达接收方的 P-CSCF/IMS-ALG2；
步骤 608: P-CSCF/IMS-ALG2根据 SDP报文中的 IP地址域信息 D2, 知 道通信双方虽然 IP接入网不处于同一 IP地址域，但接入网 TrGW所在核心网 处于同一 IP地址域 D2, 接入网还是需要进行 IP地址转换， 向 TrGW2发送携 带有 IP-11的 IP地址绑定请求；
步骤 609： TrGW2从地址池中选择一个空闲地址 IP- 12 , 把 IP- 12和 IP- 11 进行绑定， 并向 P-CSCF/IMS-ALG2返回携带有 IP-12的 IP地址绑定响应； 步骤 610: P-CSCF/IMS-ALG2把 SDP offer报文中的 IP连接地址替换为
IP- 12,删除 IP地址域信息 D1和 D2以及备份地址信息 IP-o和 IP-11 ,转发 SDP 才艮文到 UE2;
步骤 611 : UE2向 P-CSCF/IMS-ALG2发送 SDP answer报文中携带 UE2 的媒体连接 IP地址 IP-d;
步骤 612: P-CSCF/IMS-ALG2向 TrGW2发送携带有 IP-d的 IP地址绑定 请求；
步骤 613: TrGW2从地址池中选择一个空闲地址 IP-22, 把 IP-d和 IP-22 进行绑定， 并向 P-CSCF/IMS-ALG2返回携带有 IP-22的 IP地址绑定响应； 步骤 614: P-CSCF/IMS-ALG2把 SDP answer报文中的 IP连接地址替换为 IP-22,并在报文中增加 IP-d和 IP-22所处的 IP地址域信息 D3和 D2,转发 SDP 报文， 最终到达 IMS-ALG— i;
步骤 615: IMS-ALG— i发现 SDP offer和 SDP answer中的 IP地址域信息 有一个 D2相同， 知道通信双方处于同一 IP可直接路由的 IP地址域， 因此向 TrGW— i发送解除 IP- 11和 IP-i地址绑定申请；
步骤 616: TrGW— i向 IMS-ALG— i发送解除 IP地址绑定成功响应； 步骤 617: IMS-ALG— i在解除 IP地址绑定操作同时， 转发 SDP answer报 文， 最终到达 P-CSCF/IMS-ALG1 ;
步骤 618: P-CSCF/IMS-ALG1根据 SDP answer报文中的 IP地址域信息 D3和 D2,知道通信双方虽然 IP接入网不处于同一 IP地址域，但接入网 TrGW 所在核心网处于同一 IP地址域 D2, 接入网还是需要进行 IP地址转换， 向 TrGW2发送携带有 IP-22的 IP地址绑定请求；
步骤 619: TrGWl从地址池中选择一个空闲地址 IP-21 , 把 IP-21和 IP-22 进行绑定， 并向 P-CSCF/IMS-ALG1返回携带有 IP-21的 IP地址绑定响应； 步骤 620： P-CSCF/IMS-ALG1把 SDP answer报文中的 IP连接地址替换为
IP-21 , 并删除 IP地址域信息 D3和 D2 , 转发 SDP 4艮文到 UE1。
通过上述方法， UE1得知与 UE2处于可直接路由的地址域， UE1和 UE2 可以通过对端的地址信息直接进行通信。
上述实施例中， 需要对 3GPP定义的 IMS架构中的 P-CSCF/IMS-ALG功 能合一实体、 IMS-ALG 独立功能实体进行功能扩展。 其中 ， 对 P-CSCF/IMS-ALG功能合一实体的功能扩展如下：
在转发来自终端的 SDP报文时，如果 SDP中给出了媒体连接 IP地址，则 在 SDP中增加终端媒体连接 IP地址所处的 IP地址域信息和 IP地址转换绑定 之后核心网侧的 IP地址域信息；
在转发来自终端的 SDP offer报文时， 如果 SDP中给出了媒体连接的 IP 地址和或端口信息， 则拷贝媒体连接的 IP地址和或端口信息以及转换之后的 IP地址和或端口信息到本专利所扩展的 SDP原地址和端口参数域中进行备份； 在转发 SDP offer报文给终端时， 如果 SDP报文中的核心网 IP地址域信 息和本端核心网 IP地址域信息一致， 则使用备份的对端核心网侧的 IP地址和 或端口先进行 IP地址绑定请求，把报文中的媒体连接地址和或端口替换 IP地 址绑定响应返回的地址和或端口； 如果 SDP ^艮文中的终端 IP地址域信息和本 端终端的 IP地址域信息一致， 则把报文中的媒体连接地址和或端口替换为原 地址和端口参数域中所携带的对端终端的媒体连接地址和或端口；
在转发 SDP报文给终端时， 如果 SDP报文中包含 IP地址域信息和 /或原 地址和 /或端口信息 ,则转发之前先删除相应的 IP地址域信息和 /或原地址和或 端口信息；
当接收到 SDP answer报文时，如果通信双方终端地址域一致则不替换 SDP 中的媒体连接地址和或端口信息，如果相应的 SDP offer报文已经申请了 IP地 址资源绑定则释放相应的 IP地址资源绑定；
当接收到 SDP报文时， 如果此会话已经进行过 IP地址域信息协商并且两 端终端 IP地址域一致，如果当前 SDP ^艮文的终端 IP地址域信息和之前协商时 的 IP地址域信息相同则不替换 SDP中的媒体连接地址和或端口信息；
当接收到 SDP报文时， 如果此会话尚未进行终端 IP地址域信息协商或者 终端 IP地址域协商结果为两端终端 IP地址域不一致则执行 3GPP 29.162、 23.228等标准规范所规定的 IMS-ALG的功能过程。
对 IMS- ALG独立功能实体的功能扩展如下：
当接收到 SDP answer报文时， 如果报文中的媒体连接 IP地址域信息和相 应的 SDP offer报文一致则直接转发 SDP answer报文， 如果相应的 SDP offer 文已经申请了 IP地址资源绑定则释放相应的 IP地址资源绑定；
当接收到 SDP报文时， 如果此会话已经进行过 IP地址域信息协商并且两 端 IP地址域一致， 如果当前 SDP ^艮文的 IP地址域信息和之前协商时的 IP地 址域信息相同则直接转发相应的 SDP报文；
当接收到 SDP报文时， 如果此会话尚未进行 IP地址域信息协商或者 IP 地址域协商结果为两端 IP地址域不一致则执行 3GPP 29.162、 23.228等标准规 范所规定的 IMS-ALG的功能过程。
图 4和图 5和图 6给出了与 IMS核心网同一 IP版本的两个用户端避免承 载媒体迂回的两个具体实施例， 下面举例说明在 IMS 网络组网中， 当两个用 户端与 IMS核心网釆用的 IP版本不一样时， 怎样利用本发明避免承载媒体进 行不必要的 IP版本转换的过程。
请参阅图 7 ,为本发明避免承载媒体迂回的方法应用于 IMS架构下的第四 较佳实施例的信令流程图，其中， IMS核心网釆用 IPv6, UE1和 UE2处于 IPv4 地址域， 其具体过程包括：
步骤 701 : UE1向 P-CSCF1发送 SDP offer报文中携带 UE1的媒体连接 IP 地址 IPv4-l和端口 P1;
步骤 702: P-CSCF1对 SDP offer 4艮文进行扩展， 增加 IPv4-l所处的 IP地 址域信息 D-1 , 并复制 SDP offer报文中的原始媒体连接地址 IPv4-l和端口 P1 到本专利方法中新扩展的原地址和端口（original address and ports)参数域，转发 扩展后的 SDP offer报文至 IMS-ALG1；
步骤 703: IMS-ALG1向 TrGWl发送携带有地址 IPv4-l和端口 P1地址绑 定申请；
步骤 704: TrGWl从地址池中选择一个空闲地址 IPv6-l和端口 P61 , 把 IPv4-l/Pl和 IPv6-l/P61进行绑定， 并向 IMS-ALG1返回携带有 IPv6-l/P61的 IP地址绑定响应；
步骤 705: IMS-ALG1把 SDP offer报文中的媒体连接地址 IPv4-l和端口 P1替换为返回的地址 IPv6-l和端口 P61 , 转发携带有 IP地址域信息 D-1和原 媒体连接地址 IPv4-l 和端口 P1 的 SDP offer 报文， 最终到达接收方的 IMS-ALG2;
步骤 706: IMS-ALG2向 TrGW2发送携带有地址 IPv6-l和端口 P61地址 绑定申请；
步骤 707: TrGW2从地址池中选择一个空闲地址 IPv4-12和端口 P12, 把 IPv4-12/P12和 IPv6-l/P61进行绑定， 并向 IMS-ALG2返回携带有 IPv4-12/P12 的 IP地址绑定响应；
步骤 708: IMS-ALG2把 SDP offer报文中的媒体连接地址 IPv6-l和端口
P61替换为返回的地址 IPv4-12和端口 P12, 转发携带有 IP地址域信息 D-1和 原媒体连接地址 IPv4-l 和端口 P1 的 SDP offer报文， 最终到达到接收方的 P-CSCF2;
步骤 709: P-CSCF2才艮据 IP地址域信息 D-1知道通信双方处于同一 IP可 直接路由的 IP地址域，把 SDP offer报文中的媒体连接地址 IPv4-12和端口 P12 替换为原媒体连接地址 IPv4-l和端口 P1 , 删除 SDP offer报文中的 IP地址域 信息 D-1和原媒体连接地址 IPv4-l和端口 P1 , 转发 SDP offer 艮文到 UE2; 步骤 710: UE2向 P-CSCF2发送 SDP answer报文中携带 UE2的媒体连接 地址 IPv4-2和端口 P2;
步骤 711 : P-CSCF2在 SDP answer报文中增加媒体连接 IP地址 IPv4-2所 处的 IP地址域信息 D- 1 , 转发 SDP answer报文， 最终到达 IMS-ALG2；
步骤 712: IMS-ALG2发现 SDP offer和 SDP answer中的 IP地址域信息 D-1相同， 知道通信双方处于同一 IP可直接路由的 IP地址域， 因此向 TrGW2 发送解除 IPv4-12/P12和 IPv6-l/P61地址绑定申请；
步骤 713: TrGW2向 IMS-ALG2发送解除 IP地址绑定成功响应； 步骤 714: IMS-ALG2在解除 IP地址绑定操作同时， 转发 SDP answer报 文， 最终到达 IMS-ALG1 ;
步骤 715: IMS-ALG1发现 SDP offer和 SDP answer中的 IP地址域信息 D-1相同， 知道通信双方处于同一 IP可直接路由的 IP地址域， 因此向 TrGWl 发送解除 IPv4-l/Pl和 IPv6-l/P61地址绑定申请；
步骤 716: TrGWl向 IMS-ALG1发送解除 IP地址绑定成功响应； 步骤 717: IMS-ALG1在解除 IP地址绑定操作同时， 转发 SDP answer报 文， 最终到达 P-CSCF1 ;
步骤 718: P-CSCF 1删除 SDP answer 4艮文中的 IP地址域信息 D- 1 , 转发 携带有 UE2的媒体连接地址 IPv4-2和端口 P2的 SDP answer报文到 UE1。
通过上述方法， UE1得知与 UE2处于同一 IPv4地址域的 IP接入网， UE1 和 UE2通过对端的地址信息直接进行通信。
下面举例说明在 IMS网络组网中， 当两个用户端处于同一个可以直接 IP 寻址私网时，怎样利用本发明避免承载媒体进行不必要的 IP地址转换的过程。
请参阅图 8,为本发明避免承载媒体迂回的方法应用于 IMS架构下的第五 较佳实施例的信令流程图， 其中， UE1和 UE2处于同一私网， 其具体过程包 括：
步骤 801 : UE1向 P-CSCF/IMS-ALG1发送 SDP offer报文中携带 UE1的 媒体连接 IP地址 IP-1 ;
步骤 802: P-CSCF/IMS-ALG1向 TrGWl发送携带有地址 IP-1的地址绑定 申请；
步骤 803: TrGWl从地址池中选择一个空闲地址 IP-lr, 把 IP-1和 IP-lr 进行绑定， 并向 P-CSCF/IMS-ALG1返回携带有 IP-lr的 IP地址绑定响应； 步骤 804: P-CSCF/IMS-ALG1对 SDP offer报文进行扩展， 增加 IP-1所处 的 IP地址域信息 D-1 , 并复制 SDP报文中的原始媒体连接地址 IP-1到新扩展 的原地址和端口（original address and ports)参数域， 把 SDP offer报文中的媒体 连接地址 IP-1替换为返回的地址 IP-lr, 转发扩展后的 SDP offer报文， 最终到 达 UE2侧的 P-CSCF/IMS-ALG2；
步骤 805: P-CSCF/IMS-ALG2根据 IP地址域信息 D-1知道通信双方处于 同一 IP可直接路由的 IP地址域，把 SDP offer报文中的媒体连接地址 IP-lr替 换为原媒体连接地址 IP-1 ,删除 SDP offer报文中的 IP地址域信息 D-1和原媒 体连接地址 IP-1 , 转发 SDP offer报文到 UE2;
步骤 806: UE2向 P-CSCF/IMS-ALG2发送 SDP answer报文中携带 UE2 的媒体连接地址 IP-2;
步骤 807: P-CSCF/IMS-ALG2在 SDP answer报文中增加媒体连接 IP地址 IP-2 所处的 IP 地址域信息 D-1 , 转发 SDP answer 文， 最终到达 P-CSCF/IMS-ALG1 ;
步骤 808: P-CSCF/IMS-ALG1发现 SDP offer和 SDP answer中的 IP地址 域信息 D-1相同， 知道通信双方处于同一 IP可直接路由的 IP地址域， 因此向 TrGWl发送解除 IP-1和 IP-lr的地址绑定申请；
步骤 809: TrGWl向 P-CSCF/IMS-ALG1发送解除 IP地址绑定成功响应； 步骤 810: P-CSCF/IMS-ALG1删除 SDP answer 文中的 IP地址域信息 D-1 , 转发携带有 UE2的媒体连接地址 IP-2的 SDP answer报文到 UE1。
通过上述方法， UE1得知与 UE2处于同一可直接寻址的私网， UE1和 UE2通过对端的地址信息直接进行通信。
下面举例说明在 IMS网络组网中， 当处于同一个可直接 IP寻址的地址域 的同一个运营商的两个漫游终端互通时 ,怎样利用本发明避免承载媒体进行不 必要的 IP地址和端口转换的过程。
请参阅图 9,为本发明避免承载媒体迂回的方法应用于 IMS架构下的第六 较佳实施例的信令流程图， 其中， P-CSCF1处于拜访地 1 , 拜访地 1网络和归 属域网络互通时需要通过集成 IMS-ALG1功能的 IBCF1和 TrGWl进行互通， 其中 P-CSCF2处于拜访地 2,拜访地 2网络和归属域网络互通时需要通过集成 IMS-ALG2功能的 IBCF2和 TrGW2进行互通， 两漫游用户 UE1和 UE2处于 同一个可直接 IP寻址的地址域， 其具体过程包括：
步骤 901 : UE1向 P-CSCF1发送 SDP offer报文中携带 UE1的媒体连接 IP 地址 IP-1和端口 P1 ;
步骤 902: P-CSCF1对 SDP offer 文进行扩展， 增加 IP-1所处的 IP地址 域信息 D-1并复制 SDP报文中的原始媒体连接地址 IP-1和端口 P1到新扩展 的原地址和端口参数域， 转发扩展后的 SDP offer报文， 最终到达 IMS-ALG1； 步骤 903: IMS-ALG1向 TrGWl发送携带有地址 IP-1和端口 P1地址绑定 申请；
步骤 904: TrGWl 从地址池中选择一个空闲地址 IP-11 和端口 P11 , 对
IP-1/P1和 IP-11/P11进行绑定， 并向 IMS-ALG1返回携带有 IP-11/P11的 IP地 址绑定响应；
步骤 905: IMS-ALG1把 SDP offer报文中的媒体连接地址 IP-1和端口 P1 替换为返回的地址 IP-11和端口 P11 ,转发携带有 IP地址域信息 D-1和原媒体 连接地址 IP-1和端口 P1的 SDP offer报文， 最终到达接收方的 IMS-ALG2; 步骤 906: IMS-ALG2向 TrGW2发送携带有地址 IP-11和端口 P11地址绑 定申请；
步骤 907: TrGW2从地址池中选择一个空闲地址 IP-22和端口 P22, 将 IP-11/P11和 IP-22/P22进行绑定， 并向 IMS-ALG2返回携带有 IP-22/P22的 IP 地址绑定响应；
步骤 908: IMS-ALG2将 SDP offer报文中的媒体连接地址 IP-11和端口 P11替换为返回的地址 IP-22和端口 P22 , 转发携带有 IP地址域信息 D-1和原 媒体连接地址 IP-1和端口 P1的 SDP offer 4艮文，最终到达接收方的 P-CSCF2; 步骤 909: P-CSCF2才艮据 IP地址域信息 D-1知道通信双方处于同一 IP可 直接路由的 IP地址域， 把 SDP offer报文中的媒体连接地址 IP-22和端口 P22 替换为原媒体连接地址 IP-1和端口 P1 , 删除 SDP offer 4艮文中的 IP地址域信 息 D-1和原媒体连接地址 IP-1和端口 P1 , 转发 SDP offer才艮文到 UE2。
步骤 910: UE2向 P-CSCF2发送 SDP answer报文中携带 UE2的媒体连接 地址 IP-2和端口 P2;
步骤 911： P-CSCF2扩展 SDP answer报文， 增加媒体连接 IP地址 IP-2所 处的 IP 地址域信息 D-1 , 转发 SDP answer报文， 最终到达信令路径中的 IMS-ALG2;
步骤 912: IMS-ALG2发现 SDP offer和 SDP answer中的 IP地址域信息 D-1相同， 知道通信双方处于同一 IP可直接路由的 IP地址域， 因此向 TrGW2 发送解除 IP-11/P11和 IP-22/P22地址绑定申请；
步骤 913: TrGW2向 IMS-ALG2发送解除 IP地址绑定成功响应； 步骤 914: IMS-ALG2在解除 IP地址绑定操作同时， 转发 SDP answer报 文， 最终到达 IMS-ALG1 ;
步骤 915: IMS-ALG1发现 SDP offer和 SDP answer中的 IP地址域信息
D-1相同， 知道通信双方处于同一 IP可直接路由的 IP地址域， 因此向 TrGWl 发送解除 IP-1/P1和 IP-11/P11地址绑定申请；
步骤 916: TrGWl向 IMS-ALG1发送解除 IP地址绑定成功响应； 步骤 917: IMS-ALG1在解除 IP地址绑定操作同时， 转发 SDP answer报 文， 最终到达 P-CSCF1 ;
步骤 918: P-CSCF1删除 SDP answer报文中的 IP地址域信息 D-1 , 转发 携带有 UE2的媒体连接地址 IP-2和端口 P2的 SDP answer报文到 UE1。
通过上述方法， 漫游终端 UE1得知与漫游终端 UE2处于同一可直接寻址 的地址域， UE1和 UE2通过对端的地址信息直接进行通信。
上述几个实施例中， IP域协商发起端发起 IP域协商请求时同时携带了 IP 地址和 /或端口协商信息， IP域协商发起端与 IP域协商接收端互通路径中的 IMS-ALG实体由于不知道通信两端是否处于同一 IP域， 因此向 TrGW发送了 IP地址绑定请求。 为了进一步缩短会话建立时间， IP域协商发起端与 IP域协 商接收端之间也可以先进行 IP域协商，协商完成之后再发送 IP地址和 /或端口 信息， 这样当 IP域协商结果为通信两端 IP域一致时， 可以不进行 IP地址绑 定操作。
请参阅图 10, 为本发明避免承载媒体迂回的方法应用于 IMS架构下的第 七较佳实施例的信令流程图， 其具体过程包括：
步骤 1001： UE1向 P-CSCF/IMS-ALG1发送 SDP offer报文中携带 UE1的 媒体连接 IP地址 IP- 1 ;
步骤 1002: P-CSCF/IMS-ALG1发送携带有 IP-1所处的 IP地址域信息 D-1 的 SDP offer报文， 最终到达 UE2侧的 P-CSCF/IMS-ALG2；
步骤 1003: P-CSCF/IMS-ALG2返回 UE2所处的 IP地址域信息 D-1的 SDP answer报文 , 最终到达 UE1侧的 P-CSCF/IMS-ALG1；
步骤 1004: P-CSCF/IMS-ALG1根据 IP地址域信息 D-1知道通信双方处 于同一 IP 可直接路由的 IP 地址域， 不进行 IP 地址绑定操作， P-CSCF/IMS-ALG1发送 SDP offer报文中携带 UE1的媒体连接 IP地址 IP-1 , 如果通信路径中还有其它的 IMS-ALG,他们将根据前面 IP域协商结果知道通 信双方处于同一 IP可直接路由的 IP地址域， 也不进行 IP地址绑定操作， SDP offer ^艮文最终到达 UE2侧的 P-CSCF/IMS-ALG2;
步骤 1005: P-CSCF/IMS-ALG2根据前面 IP域协商结果知道通信双方处 于同一 IP可直接路由的 IP地址域，也不进行 IP地址绑定操作，直接转发 SDP offer报文给 UE2;
步骤 1006: UE2返回携带有 UE2的媒体连接 IP地址 IP-2的 SDP answer 报文；
步骤 1007: P-CSCF/IMS-ALG2根据前面 IP域协商结果知道通信双方处 于同一 IP可直接路由的 IP地址域，直接转发 SDP answer报文，最终到达 UE1 侧的 P-CSCF/IMS-ALG1；
步骤 1008: P-CSCF/IMS-ALG1根据前面 IP域协商结果知道通信双方处 于同一 IP可直接路由的 IP地址域， 直接转发 SDP answer报文给 UE1。
通过上述方法， UE1 通过 SDP协商报文获得了 UE2 的媒体连接地址为 IP-2, 同时 UE2也通过 SDP协商 ^艮文获得了 UE1的媒体连接地址为 IP-1 , 由 于两终端处于同一个可直接 IP寻址的私网， 后续通信双方终端就可以使用对 端的媒体连接地址信息直接进行媒体通信， 避免了双方通信媒体流经过 TrGWl和 TrGW2进行多次不必要的 IP地址转换和媒体中继， 缩短了媒体通 信时延， 节省了 TrGW等网络处理资源。
上述几个实施例中， 当 IP域协商发起实体与 IP域协商接收实体已进行过 IP域协商后且通信发起端和通信接收端的 IP域相同， 由于通信发起端和通信 接收端之间协商除 IP地址和 /或端口外的其它媒体连接属性时， 例如编解码协 商时， 也需携带媒体连接 IP地址和 /或端口信息， 此时， 所述网络地址和 /或端 口转换信令处理功能实体直接转发所述媒体连接 IP地址和 /或端口信息至对 端。
通过本发明实施例提供的避免承载媒体迂回的方法及其系统，处于可直接 路由的 IP地址域的不同网络实体之间的媒体互通可以直接进行通信， 避免了 不必要的承载媒体路径迂回， 缩短了通信时间和节省了网络处理资源。
进一步地， 通过本发明实施例提供的避免承载媒体迂回的方法及其系统， 对于虽然 IP地址域的不同，但接入网的转换网关的 IP域相同的不同网络实体 之间的通信， 可以减少承载媒体转换网关之间的路径迂回， 缩短了通信时间和 节省了网络处理资源。
以上对本发明所提供的避免承载媒体迂回的方法及其系统进行了详细介 例的说明只是用于帮助理解本发明的方法及其核心思想； 同时，对于本领域的 一般技术人员，依据本发明的思想，在具体实施方式及应用范围上均会有改变 之处， 综上所述， 本说明书内容不应理解为对本发明的限制。

Claims

权 利 要 求
1. 一种避免承载媒体迂回的方法， 其特征在于， 所述方法包括：
IP域协商发起实体向 IP域协商接收实体发送携带通信发起端 IP域信息的 IP域协商请求；
IP域协商接收实体向 IP域协商发起实体发送 IP域协商请求响应； 确定 IP域协商请求响应表示通信发起端的 IP域与通信接收端的 IP域相 同； 之后，
所述通信发起端和所述通信接收端协商获得对端的媒体连接 IP地址和 /或 端口信息， 通信双方之间通过直接路由进行通信。
2. 根据权利要求 1 所述的避免承载媒体迂回的方法， 其特征在于， 所述 通信发起端和所述通信接收端协商获得对方的媒体连接 IP地址和 /或端口信息 的具体方式为： 所述 IP域协商发起实体和所述 IP域协商接收实体之间的网络 地址和 /或端口转换信令处理实体直接转发双方的媒体连接 IP地址和 /或端口 信息至对端。
3. 根据权利要求 1 所述的避免承载媒体迂回的方法， 其特征在于， 所述 通信发起端和所述通信接收端协商获得对方的媒体连接 IP地址和 /或端口信息 的具体方式为：
所述 IP域协商发起实体向 IP域协商接收实体发送 IP域协商请求时还携 带通信发起端的媒体连接 IP地址和 /或端口信息，
所述 IP域协商发起实体和所述 IP域协商接收实体之间的网络地址和 /或端 口转换信令处理实体对通信发起端的媒体连接 IP 地址和 /或端口信息进行绑 定， 如果 IP域协商请求响应为通信发起端的 IP域与通信接收端的 IP域相同， 则解除所述 IP地址绑定，
所述 IP域协商发起实体发送所述通信发起端的媒体连接 IP地址和 /或端口 信息至通信接收端， 所述网络地址和 /或端口转换信令处理实体直接转发通信 接收端的媒体连接 IP地址和 /或端口信息至通信发送端。
4. 根据权利要求 1 所述的避免承载媒体迂回的方法， 其特征在于， 所述 通信发起端和所述通信接收端协商获得对方的媒体连接 IP地址和 /或端口信息 的具体方式为： 所述 IP域协商发起实体向 IP域协商接收实体发送 IP域协商请求时还携 带通信发起端的媒体连接 IP地址和 /或端口信息， 并携带通信发起端的媒体连 接 IP地址和 /或端口的备份信息，
所述 IP域协商发起实体和所述 IP域协商接收实体之间的网络地址和 /或端 口转换信令处理功能实体对通信发起端的媒体连接 IP地址和 /或端口信息进行 绑定，并直接转发通信发起端的媒体连接 IP地址和 /或端口备份信息至 IP域协 商接收实体，如果 IP域协商请求响应为通信发起端的 IP域与通信接收端的 IP 域相同， 则解除所述 IP地址绑定，
所述 IP域协商接收实体发送所述通信发起端的媒体连接 IP地址和 /或端口 备份信息至通信接收端， 所述网络地址和 /或端口转换信令处理实体直接转发 通信接收端的媒体连接 IP地址和 /或端口信息至通信发送端。
5. 根据权利要求 1 所述的避免承载媒体迂回的方法， 其特征在于， 如果 IP域协商请求响应为通信发起端的 IP域与通信接收端的 IP域不同，但通信发 起端的接入网的转换网关 IP域与通信接收端的接入网的转换网关 IP域相同， 则所述通信发起端的接入网的转换网关和所述通信接收端的接入网的转换网 关协商获得对方的媒体连接 IP地址和 /或端口信息。
6. 根据权利要求 1至 4中任一权利要求所述的避免承载媒体迂回的方法， 其特征在于， 当 IP域协商发起实体与 IP域协商接收实体已进行过 IP域协商 后且通信发起端和通信接收端的 IP域相同， 由于通信发起端和通信接收端之 间协商除 IP地址和 /或端口外的其它媒体连接属性时携带媒体连接 IP地址和 / 或端口信息， 所述网络地址和 /或端口转换信令处理功能实体直接转发所述媒 体连接 IP地址和 /或端口信息至对端。
7. 根据权利要求 1至 5中任一权利要求所述的避免承载媒体迂回的方法， 其特征在于， 所述 IP域协商发起实体为通信发起端或通信发起端网络侧信令 中继， 所述 IP域协商接收实体为通信接收端或通信接收端网络侧信令中继。
8. 根据权利要求 7 所述的避免承载媒体迂回的方法， 其特征在于， 所述 IP域协商发起实体向 IP域协商接收实体发送携带通信发起端 IP域信息的 IP 域协商请求以及所述 IP域协商接收实体向 IP域协商发起实体发送携带通信接 收端 IP域信息的 IP域协商请求响应的具体方式均为通过会话描述协议携带 IP 域协商信息。
9. 根据权利要求 1至 5中任一权利要求所述的避免承载媒体迂回的方法， 其特征在于， 所述会话描述协议中携带的通信发起端 IP域协商信息由通信发 起端接入网的网络侧信令实体将所述通信发起端 IP域协商信息添加至所述会 话描述协议， 所述会话描述协议中携带的通信接收端 IP域协商响应信息由通 信接收端接入网的网络侧信令实体将所述通信接收端 IP域协商响应信息添加 至所述会话描述协议。
10.根据权利要求 1至 5中任一权利要求所述的避免承载媒体迂回的方法， 其特征在于， 所述 IP域协商发起实体向 IP域协商接收实体发送的 IP域协商信 息包括通信发起端 IP域标识， 所述 IP域标识用于表示通信发起端所属的 IP域。
11. 根据权利要求 1 至 5 中任一权利要求所述的避免承载媒体迂回的方 法， 其特征在于， 所述 IP域协商接收实体向 IP域协商发起实体发送的 IP域 协商响应信息包括通信接收端 IP域标识， 所述 IP域标识用于表示通信接收端 所属的 IP域。
12. 一种避免承载媒体迂回的系统， 其特征在于， 所述避免承载媒体迂回 的系统包括：
IP域协商发起实体， 发送携带通信发起端 IP域信息的 IP域协商请求； IP域协商接收实体， 接收从 IP域协商发起实体发送的 IP域协商请求， 并 根据所述 IP域协商请求， 向 IP域协商发送实体发送 IP域协商请求响应； 网络地址和 /或端口转换信令处理实体， 如果 IP域协商请求响应为通信发 起端的 IP域与通信接收端的 IP域相同， 则转发所述通信发起端和接收端的媒 体连接 IP地址和 /或端口信息至对端。
13. 根据权利要求 12所述的避免承载媒体迂回的系统， 其特征在于， 所 述 IP域协商发起实体为通信发起端或通信发起端网络侧信令中继， 所述 IP域 协商接收实体为通信接收端或通信接收端网络侧信令中继。
14、 一种 IP域协商发起 /接收实体， 其特征在于， 包括：
IP域信息增删模块， 用于转发来自终端的 SDP offer报文时， 在 SDP offer 中增加媒体端点所处的 IP域信息； 在转发 SDP offer报文给终端时， 删除相应 的 IP域信息。
15、 根据权利要求 14所述的 IP域协商发起 /接收实体， 其特征在于， 还 包括：
第一报文处理模块， 用于接收到通信对端的 SDP answer报文， 如果所协 商的媒体连接 IP地址域信息一致时，发送与前一次 SDP offer报文完全相同的 SDP offer报文； 当接收到 SDP answer报文时， 不再转发给终端。
16、 根据权利要求 14所述的 IP域协商发起 /接收实体， 其特征在于， 还 包括：
^分模块， 用于转发来自终端的 SDP offer报文时， 如果 SDP中给出了媒体 连接的 IP地址和或端口信息， 则拷贝媒体连接的 IP地址和或端口信息以及转换 之后的 IP地址和或端口信息到扩展的 SDP原地址和端口参数域中进行备份。
17、 根据权利要求 16所述的 IP域协商发起 /接收实体， 其特征在于， 还 包括：
第二报文处理模块， 用于转发 SDP offer报文给终端时， 如果 SDP报文中 的核心网 IP地址域信息和本端核心网 IP地址域信息一致， 则使用备份的对端 核心网侧的 IP地址和或端口先进行 IP地址绑定请求，把报文中的媒体连接地 址和或端口替换 IP地址绑定响应返回的地址和或端口； 如果 SDP ^艮文中的终 端 IP地址域信息和本端终端的 IP地址域信息一致， 则把报文中的媒体连接地 址和或端口替换为原地址和端口参数域中所携带的对端终端的媒体连接地址 和或端口。
18、 一种网络地址和 /或端口转换信令处理实体， 其特征在于， 包括： 第三报文处理模块， 用于接收到 SDP answer报文时， 如果报文中的媒体 连接 IP地址域信息和相应的 SDP offer报文一致则直接转发 SDP answer报文， 如果相应的 SDP offer报文已经申请了 IP地址的资源绑定， 则释放相应的 IP 地址资源绑定。
19、 根据权利要求 18所述的网络地址和 /或端口转换信令处理实体， 其特 征在于， 还包括：
第四报文处理模块， 用于接收到 SDP报文时， 如果此会话已经进行过 IP 域信息协商并且两端 IP地址域一致，如果当前 SDP ^艮文的 IP地址域信息和之 前协商时的 IP地址域信息相同则直接转发相应的 SDP报文。
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