CN100407692C - A system and method for realizing IP header compression - Google Patents

Abstract

The invention discloses a system and method for realizing IP header compression. The method includes: setting a router supporting L2TP tunnel protocol and IP header compression protocol between the PDSN and the real-time service control center. The method includes: A. PDSN receiving After receiving the IP real-time service request sent by the MS under its jurisdiction, establish a point-to-point PPP connection with the MS, and complete the LCP negotiation and authentication; B. After the PDSN establishes the L2TP tunnel with the router, it establishes a session with the router; C. The router completes the IP header compression negotiation process with the MS through the PDSN; D. The PDSN converts the PPP frame with the corresponding IP header compression received from the MS into an L2TP data frame, and sends it to the Router through the established tunnel, and the Router sends the L2TP data frame The data frame is converted into corresponding signaling and sent to the service control center, or the L2TP data frame is converted into corresponding media stream and sent to the IP bearer network.

Description

A system and method for realizing IP header compression

technical field

The invention relates to the compression technology of the Internet Protocol (IP) header on the mobile packet switching network, in particular to a system and method for realizing IP header compression on the mobile packet switching network.

Background technique

Code Division Multiple Access (CDMA) system is a digital communication multiple access method using advanced wireless spread spectrum technology. The most important feature of the CDMA system is that it uses spread spectrum communication and orthogonal coding technology, enabling a large number of users to share the same frequency, and has the advantages of large capacity, high spectrum utilization, good voice quality, and low mobile phone transmission power.

At present, several CDMA 1X systems have been established all over the world. The core network of the system includes two parts: the circuit (CS) domain and the packet (PS) domain: the CS domain mainly provides voice services based on circuit switching, and the network in the CS domain Elements mainly include circuit switching center (MSC), home location register (HLR), service control node (SCP) and short message center (SMS), etc.; PS domain provides high-speed packet switching data services, and network elements of PS domain mainly include packet Control unit (PCF), packet switching node (PDSN).

A typical network structure diagram of a CDMA 1X system is shown in Figure 1. Wherein, when the mobile terminal wants to perform the packet-switched data service, the mobile terminal such as the mobile phone 100 or the notebook computer 101 sends a request for the packet-switched data service to the PDSN103 through the base station subsystem/packet control unit (BSS/PCF) 102, and the PDSN103 utilizes the authentication server ( AAA) 104 authenticates the mobile terminal, and if the authentication passes, the mobile terminal is provided with the corresponding Internet (Internet) 105 access service according to the request, and the mobile terminal performs packet-switched data services; otherwise, the authentication Right not passed, end.

With the development of packet switching services, providing IP-based real-time services on the packet switching network of the CDMA system has become a current hot topic, such as voice over IP (VoIP). When real-time IP services are to be implemented on the CDMA system packet switching network, the PDSN103 connects the mobile terminal to the IP bearer network according to the IP service request message sent by the mobile terminal, and the real-time service control center in the IP bearer network, such as VoIP packet According to the request message, the control center performs routing conversion to the functional entity providing the corresponding IP service, and the functional entity provides the corresponding IP service to the mobile terminal through the IP bearer network, PDSN103 and BSS/PCF102 to which the mobile terminal belongs.

The difficulty of implementing IP real-time services on the CDMA system packet switching network is that the transmission delay of IP is very large, and the key technology to solve the problem of long IP transmission delay is Real-time Protocol (RTP)/User Datagram Protocol (UDP)/IP Head domain compression technology, however, the PDSN in the current CDMA system packet switching network has very limited support for IP header domain compression, and only supports RFC1144 IP header compression. RFC2508, RTP/UDP/TCP/IP header compression and RFC2509, RTP/UDP/IP header compression Over Point-to-Point Protocol (PPP) and other protocols are not supported. In this case, the transmission time delay of the IP real-time service transmitted through the PDSN cannot be optimized, and the user may not be able to tolerate the IP real-time service with a large time delay.

The solution to the long delay of IP real-time services transmitted by PDSN is to upgrade all packet switching nodes PDSN within the entire network of the packet switching network of the CDMA system. After the upgrade, the entire network-wide PDSN supports RFC2507, namely UDP/TCP/IP Header compression, RFC2508, namely RTP/UDP/TCP/IP header compression and RFC2509, namely RTP/UDP/IP header compression Over PPP and other protocols. However, this upgrade method has disadvantages: equipment manufacturers that produce PDSN do not support all IP header compression protocols consistently, and the development of compression functions has a certain development cycle, so it is not possible to quickly upgrade all PDSNs in the entire network. Provide the required IP header compression function; upgrading the PDSN in the whole network will greatly increase the network construction and operation costs.

Contents of the invention

In view of this, the main purpose of the present invention is to provide a system for realizing IP header compression on the one hand. This system implements IP header compression technology without the need for existing PDSN upgrades and changes, reducing network construction and operating costs. cost;

Another aspect of the present invention provides a method for realizing IP header compression. The method is based on the system realization of IP header compression, which can reduce the delay time of IP real-time services transmitted through PDSN, so that users can receive the delay time Short IP real-time business.

According to above-mentioned purpose, technical scheme of the present invention is achieved like this:

A system for realizing IP header compression, the system includes a code division multiple access system packet switching network, an Internet Protocol (IP) bearer network and a real-time service control center, and a mobile terminal MS passes through a base station sub-network in the code division multiple access system packet switching network The system/packet control unit BSS/PCF performs information exchange with the packet switching node PDSN, which is characterized in that a router is added between the PDSN and the real-time service control center, the router is located in the IP bearer network, and is used to provide MS with IP real-time services with IP header compression.

The router supports Layer 2 L2TP tunneling protocol and IP header compression protocol.

The IP header compression protocol is RFC2507, or RFC2508, or RFC2509, or RFC3095, a revised opinion draft.

The router is connected with multiple PDSNs in the packet switching network of the code division multiple access system, and forms a virtual private network with the service control center and MSs under the jurisdiction of multiple PDSNs.

The service control center is provided by content providers or service providers.

The router is also used to uniformly and dynamically assign IP addresses to all MSs in the virtual private network.

A method for realizing IP header compression, a router supporting L2TP tunneling protocol and IP header compression protocol is set between PDSN and real-time service control center, the method includes:

A. After the PDSN receives the IP real-time service request sent by the MS under its jurisdiction, it establishes a point-to-point PPP connection with the MS, and completes the link control protocol LCP negotiation and authentication;

B. After the PDSN establishes the L2TP tunnel with the router, it establishes a session with the router;

C. The router completes the negotiation process of IP header compression with the MS through the PDSN;

D. The PDSN converts the PPP frame with the corresponding IP header compression received from the MS into an L2TP data frame, and sends it to the router through the established tunnel, and the router converts the L2TP data frame into corresponding signaling and sends it to the service control center, or The L2TP data frame is converted into a corresponding media stream and sent to the IP bearer network.

The IP header compression protocol is RFC2507, or RFC2508, or RFC2509, or RFC3095.

The one router exchanges messages with all PDSNs in the packet switching network of the CDMA system.

The method further includes:

E. The router converts the signaling flow received from the service control center into an L2TP data frame and sends it to the PDSN through the established tunnel; or converts the media flow received from the IP bearer network into an L2TP data frame and sends it to the PDSN through the established tunnel ;

F. The PDSN converts the received L2TP data frame into a PPP frame with corresponding IP header compression and sends it to the MS.

The negotiation process described in step C includes: negotiating parameters and data required for compression, and assigning a dynamic IP address to the MS.

As can be seen from the foregoing scheme, the method provided by the present invention adds a Router supporting the L2TP tunneling protocol and the IP header compression protocol between the PDSN and the real-time service control center, and the Router can establish a PPP connection between the PDSN and the MS, thereby Transmit IP real-time services to MS. Because the PDSN only plays the function of forwarding the real-time business or signaling flow of IP in the system provided by the present invention, it only needs to set up an L2TP tunnel and session between the MS and the Router, and the UDP of the IP real-time business is completed by the Router /IP header domain compression technology, so the system provided by the present invention implements the IP header compression technology without the need for existing PDSN upgrades and changes. Because the present invention has only increased a Router between PDSN and the real-time service control center, and this Router can be connected with all PDSNs in the CDMA system packet data network, so compare with changing the setting of each PDSN in the CDMA system packet data network , Reduce network construction and reduce operating costs. Since the system provided by the present invention supports UDP/IP header compression technology, the method based on the system of the present invention provided by the present invention can reduce the delay time of IP real-time services transmitted through the PDSN, so that users can receive the delay time Short IP real-time business.

Description of drawings

Figure 1 is a typical network structure diagram of a CDMA 1X system.

FIG. 2 is a network architecture diagram of the present invention.

FIG. 3 is a protocol stack model diagram of applying L2TP tunnel protocol in MS, PDSN103 and Router202 in the present invention.

Fig. 4 is a flow chart of the process of implementing IP real-time services in the present invention.

Detailed ways

In order to make the purpose, technical solution and advantages of the present invention more clear, the present invention will be further described in detail by citing the following embodiments and referring to the accompanying drawings.

The network architecture diagram of the present invention is as shown in Figure 2, between the PDSN103 and the real-time service control center 201 in the prior art CDMA system packet switching network, a support layer 2 tunneling protocol (L2TP) tunneling protocol and IP header compression is added Protocol router (Router) 202, which is located in the IP bearer network and completes the transmission of IP real-time services. The Router 202 is connected to all PDSN 103 in the CDMA system packet switching network, that is, a CDMA system packet switching network only needs to provide one Router 202 .

In Fig. 2, the BSS in BSS/PCF102 includes base station (BTS) and base station controller (BSC), BTS completes the wireless signal sending and receiving function to mobile terminal (MS), realizes the communication between CDMA network and MS; BSC completes BSS control and management, namely: call connection establishment and teardown, mobility management and soft/hard handover, etc.;

The PCF in the BSS/PCF completes the establishment, maintenance and management of the R-P connection;

PDSN103, equipment in the CDMA system packet switching network, supports L2TP tunneling protocol;

AAA104, used to authorize, authenticate and charge the MS;

Router202 supports L2TP tunnel protocol and various IP header compression protocols, and can uniformly and dynamically allocate IP addresses for MSs using IP real-time services.

The PDSNs and Routers in the CDMA network shown in Figure 2 form a distributed wide area access system. Together with the business control center, it forms a virtual private network that provides special services. The service control center may be provided by a third party, such as a content provider or a service provider.

The IP addresses of all MSs in the virtual private network established by the present invention are uniformly and dynamically assigned by the Router, and the allocation strategy of the IP addresses of the MSs can be flexibly selected according to the needs of special services, thus providing guarantee for the development of services.

The main function of the L2TP tunnel protocol is to extend the point-to-point protocol (PPP) access from the local end to the remote end, that is, to extend the PDSN103 to the Router202, and provide MS with economical remote service provider (ISP) access and enterprise network access, which is IP An extremely important protocol in a virtual private network (VPN).

The present invention adopts the L2TP tunnel protocol to extend the PPP connection between the MS and the PDSN103 from the local PDSN103 to the remote Router202 supporting the L2TP tunnel protocol. PDSN103 is used as L2TP access concentrator (LAC, L2TP Access Concentrator), and Router202 is used as L2TP network server (LNS, L2TP Network Server), running L2TP tunnel protocol between PDSN103 and Router202, between MS and Router202 Run the PPP protocol.

Fig. 3 is the protocol stack model figure that the present invention applies L2TP tunnel agreement in MS, PDSN103 and Router202, as shown in the figure: adopt PPP to communicate between MS and Router202, can implement various by PPP connection between MS and Router202 The required IP header compression protocol, such as: RFC2507/RFC2508/RFC2509/RFC3095 and other protocols. In order to transparently transmit PPP connections, PDSN103 only needs to support the L2TP tunneling protocol, and the existing PDSN in the packet data service network of the CDMA system supports the L2TP tunneling protocol, so there is no need to upgrade and modify the existing PDSN103.

Taking the VoIP service as an example, the process of implementing IP real-time service in the system provided by the present invention will be described below.

Fig. 4 is the flow chart of the process of implementing the IP real-time service in the present invention, the IP bearer network can identify the characteristic service or the common dial-up Internet service according to the user name of the MS dial-up Internet access. Assuming that the user name of the MS is VoIP.shenzhen, when the local PDSN103 receives the PPP connection establishment request sent by the user name VoIP.shenzhen, it initiates the L2TP tunnel establishment process and executes the IP header compression (IPCP) negotiation process. The specific steps for:

Step 400, the MS sends a VoIP voice service request to the local PDSN103, that is, the establishment process of the PPP connection is started between the MS and the local PDSN103, and the link control protocol (LCP) negotiation process and authentication are completed;

Step 401, the local PDSN103 recognizes that the user name of the MS is VoIP.shenzhen, and initiates the L2TP tunnel connection establishment process to the Router202, that is, the local PDSN103 acts as the LAC and the Router202 acts as the LNS to perform authentication, and assigns a tunnel identification (ID) to the L2TP tunnel , determine the bearer type and frame encapsulation format of the L2TP tunnel, and the size of the receiving window;

Step 402, after the local PDSN103 has established the L2TP tunnel, start the session establishment process, and complete the session ID allocation, data channel bearer type and frame encapsulation type, etc.;

Step 403, after the session is established at the local PDSN103, the Router202 can initiate IPCP to the MS through the PDSN103, negotiate the parameters and data required for IPCP compression, and assign an IP address to the MS. The IP address allocation strategy can be flexibly selected according to the needs of the business carried out;

Step 404, Router202 establishes the PPP connection with the MS, and adopts the required IP header compression technology according to the IPCP negotiation result;

PDSN103 will receive PPP frame from MS, encapsulate it into L2TP data frame, and send it to Router202 through L2TP tunnel;

Step 405, when the Router 202 receives the L2TP data frame, convert the content of the L2TP data frame into a signaling flow into a corresponding signaling flow and send it to the service control center, and the service control center determines to provide the function of the VoIP voice service required by the request The entity converts the content of the L2TP data frame into a media stream into a corresponding media stream and sends it to the determined functional entity through the IP bearer network and the service control center.

Similarly, Router202 can also convert media streams received from certain functional entities through the IP bearer network and service control center into L2TP data frames and send them to local PDSN103. Local PDSN103 converts the L2TP data frames into PPP frames and sends them to The MS receives; or the signaling flow received by the Router202 from the service control center is converted into an L2TP data frame and sent to the local PDSN103, and the local PDSN103 converts the L2TP data frame into a PPP frame and sent to the MS for reception.

By adopting the system and method provided by the present invention, Router 202 is added when the CDMA system packet switching service network does not support IP header compression, thereby realizing the required IP header compression technology.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the scope of the present invention. within the scope of protection.

Claims (10)

1. A system that realizes IP header compression, the system includes a CDMA system packet switching network, an Internet Protocol (IP) bearer network and a real-time service control center, and the mobile terminal MS passes through the CDMA system packet switching network The base station subsystem/packet control unit BSS/PCF performs information interaction with the packet switching node PDSN, which is characterized in that a router supporting the 2-layer L2TP tunneling protocol and IP header compression protocol is added between the PDSN and the real-time service control center, the router It is located in the IP bearer network, and is connected to the PDSN through an L2TP tunnel, and is used to provide IP real-time services with IP header compression for the MS through the PDSN. 2. The system according to claim 1, wherein the IP header compression protocol is RFC2507, or RFC2508, or RFC2509, or RFC3095, a revised opinion draft. 3. The system according to claim 1, wherein said router is connected to multiple PDSNs in the CDMA system packet switching network, and forms a virtual network with the service control center and MSs under the jurisdiction of multiple PDSNs. Private Network. 4. The system according to claim 1 or 3, said service control center is provided by a content provider or a service provider. 5. The system according to claim 4, said router is further used to uniformly and dynamically assign IP addresses to all MSs in the virtual private network. 6. A method for realizing IP header compression based on the system of claim 1, characterized in that, a router supporting L2TP tunneling protocol and IP header compression protocol is set between PDSN and the real-time service control center, the method comprising: A. After the PDSN receives the IP real-time service request sent by the MS under its jurisdiction, it establishes a point-to-point PPP connection with the MS, and completes the link control protocol LCP negotiation and authentication; B. After the PDSN establishes the L2TP tunnel with the router, it establishes a session with the router; C. The router completes the negotiation process of IP header compression with the MS through the PDSN; D. The PDSN converts the PPP frame with the corresponding IP header compression received from the MS into an L2TP data frame, and sends it to the router through the established tunnel, and the router converts the L2TP data frame into corresponding signaling and sends it to the service control center, or The L2TP data frame is converted into a corresponding media stream and sent to the IP bearer network. 7. The method according to claim 6, wherein the IP header compression protocol is RFC2507, or RFC2508, or RFC2509, or RFC3095. 8. The method according to claim 6, characterized in that said one router exchanges messages with all PDSNs in the CDMA packet switching network. 9. The method of claim 6, further comprising: E. The router converts the signaling flow received from the service control center into an L2TP data frame and sends it to the PDSN through the established tunnel; or converts the media flow received from the IP bearer network into an L2TP data frame and sends it to the PDSN through the established tunnel ; F. The PDSN converts the received L2TP data frame into a PPP frame with corresponding IP header compression and sends it to the MS. 10. The method according to claim 6, wherein the negotiation process in step C is: negotiating parameters and data required for compression, and assigning a dynamic IP address to the MS.

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