CN100566340C - Support SIP soft switchcall server and its implementation of P2P media delivery - Google Patents
Support SIP soft switchcall server and its implementation of P2P media delivery Download PDFInfo
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Abstract
The present invention relates to SIP soft switchcall server and its implementation of a kind of P2P of support media delivery, this system comprises signaling Control Server, media relays server, super relay services node, STUN service node and P2P client or normal client end, adopt the communication protocol of expansion Session Initiation Protocol, focus on forwarding by the signaling Control Server that is in the system centre position as the signaling key-course; This method comprises: system initialization; Register to the signaling Control Server; The P2P client is connected to relay services overlay network and STUN service coverage network, carries out self-assessment; Set up communication session between the client; Current transmission path lost efficacy and caused dropped calls, P2P client both sides to switch to alternative media delivery path.The present invention has excellent controllability, manageability, compatibility, reliability and autgmentability, has effectively improved communication quality, realizes the decentralized of network burden, adapts to the requirement of following terminal.
Description
Technical field
The present invention relates to the network communications technology, specifically a kind of SIP soft switchcall server and its implementation of supporting the P2P media delivery.
Background technology
SIP (session initiation protocol) is the application layer signaling control protocol that is used to create, revise and stop Multimedia session on the IP network by the definition of IETF (Internet engineering duty group) MMUSIC (Multimedia session control in many ways) working group.At present Session Initiation Protocol is constantly perfect, and its final goal is that the application for all Internet successes provides immanent access.Session Initiation Protocol with its opening more, easier expansion, progressively defeat H.323 with characteristics such as Internet combine closely, agreement such as MGCP becomes VoIP (Voice over Internet Protocol, Internet Protocol telephone or wideband telephony) popular protocol, just obtaining support more and more widely.
P2P (the abbreviation of peer-to-peer, " point-to-point " or be called equity networking) network is a kind of distributed p 2 p of breaking traditional C lient/Server (client/server) pattern, network participants is shared a part of hardware resource that they are had, such as disposal ability, storage capacity, the network concatenation ability, printer etc., these shared resources provide service and content by network, can directly be visited by other peer node and need not through intermediate entities, network participants is resource (service and content) supplier, is again that resource (service and content) obtains taker.The development of P2P technology and P2P combine with network technology, with the notion of the whole computer network of influence and the pattern that people obtain information.In the field of mass data transmission, P2P can effectively alleviate load of server, increases the extensibility and the robustness of system.But the distributed characteristics of P2P have caused its manageability and controllability relatively poor, and this has limited the long-run development of P2P to a great extent.
The performance advantage separately that at present SIP and P2P combined is a research focus, researchers have expanded resource distribution and resource location protocol in the Session Initiation Protocol based on the P2P technology, make full use of Session Initiation Protocol is simple efficient, versatility the is good characteristics and the characteristics of P2P technology enhanced scalability and high robust, these expansions are referred to as SIP P2P.The combination different with the P2P agreement according to Session Initiation Protocol among the SIP P2P, SIP P2P can be divided into two kinds of different types of P2P over SIP and SIP over P2P.So-called P2P over SIP promptly utilizes sip message to safeguard the P2P overlay network, and just SIP transmits the signaling of P2P in the mode of tunnel (tunnel), and SIP provides the function of maintenances, control, the foundation of responsible media session simultaneously for the P2P nerve of a covering.So-called SIP over P2P, SIP is placed on the P2P nerve of a covering, finish the maintenance of resource location and P2P network self by the P2P nerve of a covering, that is to say that the resource storage of the sip server in the standard Session Initiation Protocol and resource positioning function finish by distributed P2P network is alternative.
But the expansion of Session Initiation Protocol or the decentralization of Session Initiation Protocol are paid close attention in existing SIP P2P correlative study too much, overemphasize flexibility distributed and that decentralization is brought, having ignored P2P, to use intrinsic for a long time problem one controlled pipe property poor, and shortage can be gained, the operation mode of sustainable development.Good session foundation and controlling mechanism how effectively to utilize Session Initiation Protocol and provided are integrated the various resources of P2P network, improve the utilance and the service ability of the various resources of P2P network, are urgent problems.
Summary of the invention
Poor at the controlled pipe property that P2P in the prior art uses, shortage can be gained, the deficiency of the operation mode of sustainable development, the object of the present invention is to provide a kind of signaling control to handle by the signaling Control Server is unified alternately, adapt to SIP soft switchcall server and its implementation of the controlled support P2P media delivery of managing, can run in the Internet.
In order to solve the problems of the technologies described above, the present invention is achieved through the following technical solutions:
The present invention supports the SIP soft switchcall server of P2P media delivery to comprise signaling Control Server, media relays server, super relay services node, STUN service node and P2P client or normal client end, adopt the communication protocol of expansion Session Initiation Protocol, focus on forwarding by the signaling Control Server that is in the system centre position as the signaling key-course; Media delivery support media Relay Server is transmitted, the point-to-point straight-through and P2P Network Transmission mulitpath of ICE mode, wherein: the signaling Control Server, control centre for entire I P communication system, all sip messages are all transmitted through the signaling Control Server, the signaling Control Server receives the register requirement from P2P client or normal client end, and log-on message is registered in the database of signaling Control Server, be responsible for the foundation of all multimedia communication sessions, revise and remove, be responsible for communication session and select the media relays server, a kind of media delivery alternative path through the media relays server forwards is provided; The media relays server, has public network IP address, processing is from the relay request of signaling Control Server, for communication session distributes trunking port, P2P client or normal client end both sides all send to trunking port with media data packet, and the media data packet that the media relays server will come from a side P2P client or normal client end is forwarded to another P2P client or normal client end; Super relay services node is the relay services node of a long-time running, joins the P2P network, Bootstrap node as the P2P network, processing is from the relay request of P2P client, for communication session distributes trunking port, the media data packet between the relaying P2P client; The STUN service node joins the P2P network, as the Bootstrap node of P2P network, handles the STUN request from the P2P client; The P2P client after the signaling control of setting up communication is mutual, and is carried out ICE reciprocal process between another P2P client, for the point-to-point straight-through media delivery alternative path of ICE mode is sought in this communication; Be that in the P2P network this communication seeks the media delivery alternative path of transmitting through the relay services node, ownly satisfy when becoming the condition of relay services node that P2P client application adding P2P network is for other P2P client provides relay services when detecting.
Described P2P network has double-layer structure, i.e. resource overlay network and service coverage network, and wherein the resource overlay network provides unified resource storage, search function for service coverage network; Service coverage network is towards different COS, and every kind of COS all forms an independently overlay network, and all service coverage networks use unified issue of resource overlay network access interface and retrieval service information; The COS of P2P network support comprises relay services and STUN service, wherein the service coverage network of relay services is a structureless networks, each P2P client node obtains a large amount of relay services nodal informations from the resource overlay network and screens, and the available service node of buffer memory part, and interactive information periodically between P2P client and the relay services node and between relay services node and the relay services node; The service coverage network of STUN service is a structureless networks, and each P2P client node obtains STUN service node information from the resource overlay network, the STUN service node that buffer memory can be used; Described P2P client is divided into relatively independent SIP application layer, P2P service layer and P2P access layer from top to bottom, and lower floor provides service for its last layer; The abstract all P2P COS of P2P service layer, relatively independent between the COS; Described super relay services node and STUN service node are divided into P2P service layer and P2P access layer from top to bottom respectively, and lower floor provides service for its last layer; The abstract all P2P COS of P2P service layer, relatively independent between the COS.
The present invention supports the implementation method of the SIP soft switchcall server of P2P media delivery to have following steps:
System initialization: signaling Control Server, media relays server, super relay services node and STUN service node start and carry out initialization; Super relay services node joins the relay services overlay network; The STUN service node joins the STUN service coverage network; P2P client and normal client end are registered to the signaling Control Server; The P2P client is connected to relay services overlay network and STUN service coverage network; The P2P client is carried out self-assessment, if estimate by then joining the relay services overlay network, becomes the relay services node; Set up communication session by the control Signalling exchange between the client: the control signaling is handled and transmitted to the signaling Control Server, selects the media relays server for this communication, and a kind of media delivery alternative path through the media relays server forwards is provided; The P2P client judges according to the control Signalling exchange whether another client has the P2P function; If communicating pair is the P2P client, the P2P client is sought the P2P network media transmission alternative path of transmitting through the relay services node for this communication in the relay services overlay network; P2P client calling party estimates all media delivery alternative paths, selects the media delivery path of best performance, and P2P client both sides switching media transfers to optimum media delivery path; P2P client both sides still keep other alternative media delivery path; If current transmission path lost efficacy and caused dropped calls, P2P client both sides to switch to alternative media delivery path; Communication session finishes, and the P2P client discharges P2P network media transmission path, and the signaling Control Server discharges the media delivery path through the media relays server forwards.
The P2P client is carried the ICE collected address information in setting up the control Signalling exchange of communication session, and carries out the ICE detection of connectivity after the control Signalling exchange, for the point-to-point straight-through media delivery alternative path of ICE mode is sought in this communication.
Described basis is set up in the process control Signalling exchange in session, and to judge whether another client has the P2P function specific as follows:
When the P2P client makes a call, the parameter of INVITE SDP part is set, is used to show oneself to have the P2P function; During P2P client callee answering call, the parameter of 200OK message SDP part is set; P2P client calling party checks the parameter of 200OK message SDP part, can judge whether the communication callee has the P2P function; P2P client callee checks the parameter of INVTE message SDP part, can judge whether the communication calling party has the P2P function.
Described P2P client is sought the media delivery alternative path of transmitting through the relay services node for this communication in the relay services overlay network, wherein use INFO to carry out alternately between the P2P client, and step is as follows:
1) P2P client calling party according to priority selects a plurality of relay services nodes to form new tabulation from present available relay services node;
2) P2P client calling party constructs first INFO, and the relay services nodal information that obtains is filled up in this message, sends the message to P2P client callee;
3) after P2P client callee received first INFO, return response message was given P2P client calling party, and obtains relay services node listing information to be selected from first INFO;
4) P2P client callee carries out overall merit to all the relay services nodes in the tabulation of relaying service node, according to priority rearrangement;
5) P2P client callee constructs second INFO, and new relay services node listing information is filled up in this message, sends the message to P2P client calling party;
6) after P2P client calling party received second INFO, return response message was given P2P client callee, and obtained the relay services node listing information through P2P client both sides evaluation from second INFO;
7) P2P client calling party obtains first relay services node in the above-mentioned relay services node listing, to this relay services node request relay resource; If ask successfully, then construct the 3rd INFO, the relay resource information that obtains is filled up in this message, send the message to P2P client callee, go to step 8);
If request is unsuccessful, then with the deletion from the tabulation of relaying service node of this relay services node, repeating step 7); If the relay services node listing is empty, the then selection course in this P2P Network Transmission path failure after a period of time, restarts the selection course in P2P Network Transmission path;
8) after P2P client callee receives the 3rd INFO, return response message is given P2P client calling party, and from the 3rd INFO, obtain relay services nodal information to be selected, and to this relay services node request relay resource, if ask successfully, then construct the 4th INFO, the relay resource information that obtains is filled up in the 4th INFO, send the 4th INFO to P2P client calling party; If request is unsuccessful, P2P client callee does not do any operation;
9) after P2P client calling party received the 4th INFO, return response message was given P2P client callee, and obtains relay services nodal information to be selected from the 4th INFO; If do not receive P2P client callee's the 4th INFO within a certain period of time, then with relay services node to be selected deletion from the tabulation of relaying service node, repeating step 7).
Described P2P client calling party is specially all alternative path evaluations: P2P client calling party flows to the test data that alternative path sends given time, calculates packet loss, delay and the jitter parameter of test data stream.
Use disposable encryption key that the media stream data bag of communication session is encrypted between the P2P client, set up the safe transmission of finishing disposable encryption key in the process at communication session.
The present invention has following beneficial effect and advantage:
1. have excellent controllability and manageability.The signaling control section of communication session of the present invention focuses on forwarding by the signaling Control Server that is in the center, can realize perfect billing function, statistical function and monitoring function etc., so whole system has excellent controllability and manageability.
2. has good compatibility.Signaling of the present invention is controlled mutual employing standard Session Initiation Protocol processing mode, still continue to use traditional C/S model, handle by the centralized signaling Control Server that is in the center is unified, as long as the SIP client of conformance with standard Session Initiation Protocol all can be used with native system, therefore has favorable compatibility.
3. has very high reliability.P2P client of the present invention is that communication session is being kept many media delivery alternative paths simultaneously, reduces the communication disruption of bringing because of the unsteadiness of network as far as possible, therefore has very high reliability.
4. has favorable expansibility.Standard sip terminal and the loosely-coupled mode of P2P function are adopted in the realization of P2P client of the present invention, the P2P funtion part is that SIP application in upper strata provides interface with the form of dynamic link library, the standard sip terminal only needs minor modifications can support the P2P function, therefore has favorable expansibility.
5. effectively improve communication quality.The present invention sets up the back in communication many media delivery paths is estimated, and selects the media delivery path of best performance, has effectively improved communication quality.
6. realize the decentralized of network burden.The present invention is distributed to client with more function, has disperseed network burden, has adapted to the more and more functionalized requirement of following terminal.
Description of drawings
Fig. 1 is a system construction drawing of the present invention;
Fig. 2 is P2P network structure in the system of the present invention;
Fig. 3 is the protocol hierarchy structure chart of P2P client in the invention system;
Fig. 4 is the protocol hierarchy structure chart of super relay services node in the invention system;
Fig. 5 is the protocol hierarchy structure chart of STUN service node in the invention system;
Fig. 6 is the self-assessment mechanism flow chart of the inventive method P2P client;
Fig. 7 is the inventive method session interaction procedure chart;
Fig. 8 is the selection course figure in the inventive method P2P Network Transmission path;
Fig. 9 is the negotiations process figure of the disposable encryption key of the inventive method Media Stream.
Embodiment
1. system configuration is formed
As shown in Figure 1, the present invention supports the SIP soft switchcall server of P2P media delivery to comprise signaling Control Server, media relays server, super relay services node, STUN service node and P2P client or normal client end, adopt the communication protocol of expansion Session Initiation Protocol, focus on forwarding by the signaling Control Server that is in the system centre position as the signaling key-course; Media delivery support media Relay Server is transmitted, the point-to-point straight-through and P2P Network Transmission mulitpath of ICE mode; Wherein, P2P Network Transmission path is optimized according to set strategy, finally carries out the selection in media delivery path by communication terminal by set evaluation mechanism; Media flow transmission adopts cipher mode, and encryption key is set up in the process in conversation by communicating pair and consulted.The Session Initiation Protocol of the complete compatibility standard of signaling control procedure of process is set up in session, thus system compatible all follow the client of Session Initiation Protocol standard, comprise various soft phones, IP phone, mobile communication terminal etc.Wherein:
The signaling Control Server is the control centre of entire I P communication system, and all sip messages are all transmitted through the signaling Control Server; The function of the registrar and the acting server of standard is provided, accepts register requirement, and log-on message is registered in the database of signaling Control Server from P2P client or normal client end; Be responsible for foundation, modification and the dismounting of all multimedia communication sessions; Be responsible for communication session and select the media relays server, a kind of media delivery alternative path through the media relays server forwards is provided;
The media relays server, has public network IP address, processing is from the relay request of signaling Control Server, for communication session distributes trunking port, P2P client or normal client end both sides all send to trunking port with media data packet, the media data packet that the media relays server will come from a side P2P client or normal client end is forwarded to another P2P client or normal client end, real time data is not made other additional operations, reduces the forwarding time delay of real time data as far as possible;
Super relay services node is the relay services node of a long-time running, joins the P2P network, as the Bootstrap node of P2P network; Processing is from the relay request of P2P client, for communication session distributes trunking port, the media data packet between the relaying P2P client;
The STUN service node joins the P2P network, as the Bootstrap node of P2P network; Processing is from the STUN request of P2P client, the STUN server capability with standard;
The P2P client, except that following the standard Session Initiation Protocol fully, the also encryption of support media stream packets, ICE function and P2P function: in setting up the signaling control reciprocal process of communication, consult to be used for the disposable encryption key of media stream data packet encryption between the P2P client; After the signaling control of setting up communication is mutual, and carry out ICE reciprocal process between another P2P client, for the point-to-point straight-through media delivery alternative path of ICE mode is sought in this communication; In the P2P network, seek the media delivery alternative path of transmitting through the relay services node for this communication; Oneself satisfy when becoming the condition of relay services node when detecting, the application of P2P client adds the P2P network, for other P2P client provides relay services.Along with the continuous expansion of system, client is more and more, and the also corresponding increase of relay services node of relay services is provided simultaneously.
Described signaling Control Server and media relays server all do not have the P2P function, promptly do not join the P2P network or obtain resource from the P2P network; Described super relay services node, STUN service node all have the P2P function, join the P2P network, for communication terminal provides corresponding service, are deployed on the stable machine.
2.P2P network configuration
As shown in Figure 2, described P2P network has double-layer structure, i.e. resource overlay network and service coverage network, and wherein the resource overlay network provides unified resource storage, search function for service coverage network; Service coverage network is towards different COS, and every kind of COS all forms an independently overlay network, and all service coverage networks use unified issue of resource overlay network access interface and retrieval service information.
The COS of P2P network support comprises relay services and STUN service, for relay services, the P2P client need find an available relay services node in a short period of time, and the delay of this relay services node to two communication terminal all should be smaller, therefore must fully excavate the topology information of relay services overlay network, corresponding resource overlay network adopts complicated graph model, each client node obtains a large amount of service node information from the resource overlay network, according to certain strategy it is screened, and the available service node of buffer memory part, and interactive information periodically between client and the relay services node and between relay services node and the relay services node; For STUN service, less demanding because of to real-time, the resource overlay network adopts simple graph model, and each P2P client node obtains STUN service node information from the resource overlay network, the STUN service node that buffer memory can be used.
3.P2P network is formed the protocol hierarchy structure of entity
As shown in Figure 3, described P2P client is divided into SIP application layer, P2P service layer and P2P access layer from top to bottom, and the three is relatively independent, and lower floor provides service with the form of dynamic link library for its upper strata.
As shown in Figure 4 and Figure 5, described super relay services node and STUN service node are divided into P2P service layer and P2P access layer from top to bottom respectively, and both are relatively independent, and lower floor provides service with the form of dynamic link library for its upper strata.
The SIP application layer is finished the control of expansion Session Initiation Protocol, and is mutual by interface and P2P service layer, finishes visit and use to the P2P Internet resources.
The P2P access layer provides open, transparent resource overlay network access interface for P2P service layer, is shared by all service coverage networks, is included in the resource overlay network Service Source is stored and retrieved.
The abstract all P2P COS of P2P service layer, relatively independent between the COS, every kind of COS is divided into service layer's client logic and service stratum server logic according to the functional role difference;
Service layer's client logic provides the interface of access services resource for the SIP application layer, and concrete function comprises:
1) service node evaluation: service node is carried out connectedness, validity and Performance Detection;
2) service node screening: the service node of better performances is chosen according to qualifications according to set strategy;
3) service node management: service node is carried out multi-level buffer, dynamically, management service node efficiently;
4) self-assessment mechanism: the terminal many index is carried out self-assessment, comprise NAT type, the network bandwidth, CPU ability and occupancy, memory size and utilization rate etc.; When determining to provide certain service, become service node to the P2P network bootstrap;
5) Service Source request: to the specific Service Source of service node request, for the SIP application layer provides service.
Service layer's server logic provides specific Service Source for the P2P client, and concrete function comprises:
1) Service Source management: the Service Source to this locality manages and adds up, and the Service Source of improper release is reclaimed, and the assurance resource can be utilized again, and the actual bearer ability of various services is provided for service layer's client logic;
2) local resource statistics: local cpu ability and occupancy, memory size and utilization rate and bandwidth parameter are collected, added up;
3) provide resource service: the Service Source request of respond services layer client logic provides related service for it.
4. system's implementation method
4.1 implementation method summary
The present invention supports the implementation method of the SIP soft switchcall server of P2P media delivery to have following steps:
System initialization: signaling Control Server, media relays server, super relay services node and STUN service node start and carry out initialization; Super relay services node joins the relay services overlay network; The STUN service node joins the STUN service coverage network;
P2P client and normal client end are registered to the signaling Control Server; The signaling Control Server is accepted client registration and update user information database;
The P2P client is connected to relay services overlay network and STUN service coverage network;
The P2P client is carried out self-assessment, if estimate by then joining the relay services overlay network, becomes the relay services node; Become of the relay resource request of the P2P client awaits of relay services node, relay services is provided for it from other P2P client;
Set up communication session by the control Signalling exchange between the client: the control signaling is handled and transmitted to the signaling Control Server, selects the media relays server for this communication, and a kind of media delivery alternative path through the media relays server forwards is provided; The P2P client judges according to the control Signalling exchange whether another client has the P2P function;
If communicating pair is the P2P client, the P2P client is carried the ICE collected address information in above-mentioned control Signalling exchange, and after the control Signalling exchange, carry out the ICE detection of connectivity, for the point-to-point straight-through media delivery alternative path of ICE mode is sought in this communication;
If ICE detection of connectivity result is point-to-point straight-through for not realizing local area network (LAN), the P2P client is sought the media delivery alternative path of transmitting through the relay services node for this communication in the relay services overlay network;
P2P client calling party estimates all media delivery alternative paths, selects the media delivery path of best performance, and P2P client both sides switching media transfers to optimum media delivery path;
Switch to after the optimum media delivery path, P2P client both sides still keep other alternative media delivery path, and periodically carry out keep-alive;
If current transmission path lost efficacy and caused dropped calls, P2P client both sides to switch to alternative media delivery path;
Communication session finishes, and the P2P client discharges P2P network media transmission path; The signaling Control Server discharges the media delivery path through the media relays server forwards.
4.2 the job step of major function entity
4.2.1 signaling Control Server
1) initialization comprises and sets IP address, port numbers etc., initialization User Information Database;
2) registration of wait client;
3) receive client registration after, the update user information database;
4) wait for the communication request that receives client;
5) receiving the communication request of client, is that media relays server is selected in this communication, revises communication request, judges that the destination also transmits communication request;
4.2.2 media relays server
1) initialization comprises and sets IP address, port numbers etc.;
2) wait for the relay request that receives the signaling Control Server;
3) receiving the relay request of signaling Control Server, is that communication session distributes relay address and port numbers, trunking traffic both sides' media stream data bag;
4.2.3 super relay services node
1) initialization comprises and sets IP address, port numbers etc.;
2) join the relay services overlay network;
Pending relay request such as 3) from the P2P client;
4) receiving the relay request of P2P client, is that communication session distributes relay address and port numbers, trunking traffic both sides' media stream data bag;
4.2.4STUN service node
1) initialization comprises and sets IP address, port numbers etc.;
2) join the STUN service coverage network;
3) etc. pending STUN request from the P2P client
4) STUN that receives the P2P client asks, and makes corresponding response according to the type of STUN request;
4.2.5P2P client
1) initialization comprises and sets IP address, port numbers etc.;
2) registration: use the REGISTER message in the Session Initiation Protocol to register to the signaling Control Server;
3) be connected to the relay services overlay network: from the relaying service coverage network, obtain a plurality of relay services nodes, and carry out performance evaluation, be kept in the buffer memory by the performance prioritization;
4) be connected to the STUN service coverage network: from the STUN service coverage network, obtain a plurality of STUN service nodes, and carry out performance evaluation, be kept in the buffer memory by the performance prioritization;
5) self-assessment: estimate P2P client itself and whether meet the condition that becomes the relay services node,,, become the relay services node if estimate by then joining the relay services overlay network referring to 4.3 parts;
6) become the relay request of the P2P client awaits processing of relay services node, relay services is provided for it from other P2P client;
7) communicate the session interaction process with another client: use INVITE, through signaling Control Server processing forward, referring to 4.4 parts;
4.3P2P client self-assessment mechanism
The relay services layer client logic of P2P client carried out the self-assessment process, as Fig. 6 and shown in Figure 1, comprises following process:
Many index to P2P client itself detects; Comprise the network bandwidth, CPU ability and occupancy, memory size and utilization rate etc.;
If satisfy preset threshold, use STUN service detection P2P client itself whether to be in after the NAT;
If be in after the NAT, then use the STUN service to judge the type of NAT;
If the type of NAT is all-pass NAT (Full Cone NAT), then the P2P client becomes the relay services node, and joins the relay services overlay network;
If whether perhaps above-mentioned use STUN service detection P2P client itself is in NAT result afterwards for not after NAT, then the P2P client becomes the relay services node, and joins the relay services overlay network.
4.4 communication session reciprocal process
As shown in Figure 7, be that example is illustrated with the communication session reciprocal process between P2P client UA-1 and the P2P client UA-2, step is as follows:
1) P2P client calling party UA-1 and P2P client callee UA-2 set up process by the session of finishing alternately of control signaling INVITE/200OK/ACK message:
The signaling Control Server receives behind the INVITE session for this reason and has selected a media relays server, after receiving INVITE and 200OK message, sends relay request to selected media relays server; The media relays server distributes trunking port for it, and relay address and port information are put into relaying response loopback to the signaling Control Server; The signaling Control Server is responded Media Stream address and the port information of revising INVITE and 200OK message SDP part according to relaying, and transmits INVITE and 200OK message;
" i=" parameter of P2P client calling party UA-1 INVITE SDP part is set to " sipp2p "; " i=" parameter of P2P client callee UA-2 200OK message SDP part is set to " sipp2p "; Whether P2P client calling party UA-1 and P2P client callee UA-2 are that " sipp2p " learns that Correspondent Node has the P2P function by " i=" parameter of checking INVITE/200OK message SDP part.
2) P2P client calling party UA-1 and P2P client callee UA-2 partly carry the address information that ICE collects at INVITE and 200OK message SDP respectively, and carry out the ICE detection of connectivity after the control Signalling exchange; Wherein the address information collected of ICE according to priority comprises from high to low:
The local address and the port of transmission and receiving media stream;
If the local address of transmission and receiving media stream is a private net address, also comprise the address, NAT mapping back that obtains by Simple Traversal of UDP Through Network Address Translators.
3) through after the ICE detection of connectivity, do not realize between P2P client calling party UA-1 and the P2P client callee UA-2 that local area network (LAN) is straight-through, in the relay services overlay network, seek the media delivery alternative path of transmitting through the relay services node for this communication
4) P2P client calling party UA-1 estimates all alternative paths, send the test data stream of given time to alternative path, calculate the parameters such as packet loss, delay and shake of test data stream, finally selected P2P Network Transmission path, P2P client calling party UA-1 and P2P client callee UA-2 switching media are transferred to the relay services node;
5) after the media delivery path is selected, P2P client calling party UA-1 and P2P client callee UA-2 are still keeping other alternative transmission path, and periodically carry out keep-alive, in case current transmission path lost efficacy and caused dropped calls, can switch to alternative media delivery path in time;
6) P2P client calling party UA-1 finishes this communication session, sends BYE message to the signaling Control Server, and the transmission of the relay services node in P2P Network Transmission path relay resource recovery request, and request relay services node reclaims relay resource; After the signaling Control Server receives BYE message, to the selected media relays server transmission dismounting request of session for this reason, request media relays server reclaims relay resource, and transmits BYE message to P2P client callee UA-2, and P2P client callee UA-2 gives a response BYE message.
4.5P2P the selection course in Network Transmission path
As shown in Figure 8, described P2P client is sought the media delivery alternative path of transmitting through the relay services node for this communication in the relay services overlay network, wherein uses INFO to carry out alternately between the P2P client, and step is as follows:
1) the SIP application layer of P2P client calling party UA-1 is to the present available relay services node of P2P service layer request, P2P service layer according to priority selects a plurality of relay services nodes to form new tabulation from relaying service node cache list, and carry out ascending sort by comprehensive evaluation value, turn back to the SIP application layer;
2) the SIP application layer of P2P client calling party UA-1 is constructed first INFO INFO-1, and the relay services nodal information that obtains is filled up in the message body of this message, sends the message to P2P client callee UA-2;
3) after the SIP application layer of P2P client callee UA-2 receives first INFO INFO-1, return response message 200OK gives P2P client calling party, and partly obtains relay services node listing information to be selected from the message body of first INFO INFO-1;
4) the SIP application-level request P2P service layer of P2P client callee UA-2 carries out overall merit to all the relay services nodes in the tabulation of relaying service node, with the length of delay obtained and P2P client calling party's length of delay addition as the new length of delay of service node, length of delay rearrangement according to priority;
5) second INFO INFO-2 of the SIP application layer of P2P client callee UA-2 structure is filled up to new relay services node listing information in the message body of this message, sends the message to P2P client calling party UA-1;
6) after the SIP application layer of P2P client calling party UA-1 receives INFO-2 message, return response message 200OK gives P2P client callee, and partly obtains the relay services node listing information that process P2P client both sides estimate from the message body of second INFO INFO-2;
7) the SIP application layer of P2P client calling party UA-1 obtains first relay services node in the above-mentioned relay services node listing, and request P2P service layer is to this relay services node request relay resource; If ask successfully, then construct the 3rd INFO INFO-3, the relay resource information (comprising relay services IP addresses of nodes, service control port, media relays port etc.) that obtains is filled up in the message body of this message, send the message to P2P client callee UA-2, go to step 8);
If request is unsuccessful, then with the deletion from the tabulation of relaying service node of this relay services node, repeating step 7); If the relay services node listing is empty, the then selection course in this P2P Network Transmission path failure after a period of time, restarts the selection course in P2P Network Transmission path;
8) after the SIP application layer of P2P client callee UA-2 receives the 3rd INFO INFO-3, return response message 200OK gives P2P client calling party, and partly obtain relay services nodal information to be selected from the message body of the 3rd INFO INFO-3, and to this relay services node request relay resource, if ask successfully, then construct the 4th INFO INFO-4, the relay resource information that obtains (is comprised the relay services IP addresses of nodes, the service control port, media relays port etc.) be filled up in the message body of the 4th INFO INFO-4, send the 4th INFO INFO-4 to P2P client calling party; If request is unsuccessful, P2P client callee UA-2 does not do any operation;
9) after the SIP application layer of P2P client calling party UA-1 receives the 4th INFO INFO-4, return response message 200OK gives P2P client callee, and partly obtains relay services nodal information to be selected from the message body of the 4th INFO INFO-4; If do not receive P2P client callee's the 4th INFO INFO-4 within a certain period of time, then with relay services node to be selected deletion from the tabulation of relaying service node, repeating step 7).
4.6 the safe transmission of Media Stream
Use disposable encryption key that the media stream data bag of communication session is encrypted between the P2P client.As shown in Figure 9, set up in the process, finish the safe transmission of disposable encryption key between the P2P client at communication session, specific as follows:
1) P2P client calling party is produced as the disposable encryption key (p) of this communication encryption media stream data bag, the user cipher (sa) of caller SIP URI is encrypted disposable encryption key as symmetric key, and the privately owned header field of expansion carries disposable encryption key ((p) sa) and integrity verification information (MD5 (p)) after the encryption in INVITE;
2) the signaling Control Server is obtained the disposable encryption key after the encryption from INVITE, user cipher (sa) with caller SIP URI is decrypted (((p) sa) sa) to it, the disposable encryption key that the user cipher (sb) of using called SIP URI again comes out to deciphering is encrypted, and the disposable encryption key after will newly encrypting ((p) sb) is reentered into and is forwarded to P2P client callee in the INVITE;
3) P2P client callee obtains disposable encryption key and the integrity verification information after the encryption from INVITE, user cipher (sb) with called SIP URI is decrypted (((p) sb) sb) to the disposable encryption key after encrypting, obtain disposable encryption key, and carry out integrity verification.
Claims (10)
1. SIP soft switchcall server of supporting the P2P media delivery is characterized in that:
Comprise signaling Control Server, media relays server, super relay services node, STUN service node and P2P client or normal client end, adopt the communication protocol of expansion Session Initiation Protocol, focus on forwarding by the signaling Control Server that is in the system centre position as the signaling key-course; Media delivery support media Relay Server is transmitted, the point-to-point straight-through and P2P Network Transmission mulitpath of ICE mode, wherein:
The signaling Control Server is the control centre of entire I P communication system, and all sip messages are all transmitted through the signaling Control Server; Acceptance is from the register requirement of P2P client or normal client end, and log-on message is registered in the database of signaling Control Server; Be responsible for foundation, modification and the dismounting of all multimedia communication sessions; Be responsible for communication session and select the media relays server, a kind of media delivery alternative path through the media relays server forwards is provided;
The media relays server, has public network IP address, processing is from the relay request of signaling Control Server, for communication session distributes trunking port, P2P client or normal client end both sides all send to trunking port with media data packet, and the media data packet that the media relays server will come from a side P2P client or normal client end is forwarded to another P2P client or normal client end;
Super relay services node is the relay services node of a long-time running, joins the P2P network, as the Bootstrap node of P2P network; Processing is from the relay request of P2P client, for communication session distributes trunking port, the media data packet between the relaying P2P client;
The STUN service node joins the P2P network, as the Bootstrap node of P2P network; Processing is from the STUN request of P2P client;
The P2P client after the signaling control of setting up communication is mutual, and is carried out ICE reciprocal process between another P2P client, for the point-to-point straight-through media delivery alternative path of ICE mode is sought in this communication; In the P2P network, seek the media delivery alternative path of transmitting through the relay services node for this communication; Oneself satisfy when becoming the condition of relay services node when detecting, the application of P2P client adds the P2P network, for other P2P client provides relay services.
2. by the described SIP soft switchcall server of supporting the P2P media delivery of claim 1, it is characterized in that: described P2P network has double-layer structure, be resource overlay network and service coverage network, wherein the resource overlay network provides unified resource storage, search function for service coverage network; Service coverage network is towards different COS, and every kind of COS all forms an independently overlay network, and all service coverage networks use unified issue of resource overlay network access interface and retrieval service information.
3. by the described SIP soft switchcall server of supporting the P2P media delivery of claim 2, it is characterized in that: the COS of P2P network support comprises relay services and STUN service, wherein the service coverage network of relay services is a structureless networks, each P2P client node obtains a large amount of relay services nodal informations from the resource overlay network and screens, and the available relay services node of buffer memory part, and interactive information periodically between P2P client and the relay services node and between relay services node and the relay services node; The service coverage network of STUN service is a structureless networks, and each P2P client node obtains STUN service node information from the resource overlay network, the STUN service node that buffer memory can be used.
4. by the described SIP soft switchcall server of supporting the P2P media delivery of claim 1, it is characterized in that: described P2P client is divided into relatively independent SIP application layer, P2P service layer and P2P access layer from top to bottom, lower floor provides service for its last layer, the abstract all P2P COS of P2P service layer, relatively independent between the COS;
Described super relay services node and STUN service node are divided into P2P service layer and P2P access layer from top to bottom respectively, and lower floor provides service for its last layer; The abstract all P2P COS of P2P service layer, relatively independent between the COS.
5. implementation method of supporting the SIP soft switchcall server of P2P media delivery is characterized in that having following steps:
System initialization: signaling Control Server, media relays server, super relay services node and STUN service node start and carry out initialization; Super relay services node joins the relay services overlay network; The STUN service node joins the STUN service coverage network;
P2P client and normal client end are registered to the signaling Control Server;
The P2P client is connected to relay services overlay network and STUN service coverage network;
The P2P client is carried out self-assessment, if estimate by then joining the relay services overlay network, becomes the relay services node;
Set up communication session by the control Signalling exchange between the client; The control signaling is handled and transmitted to the signaling Control Server, selects the media relays server for this communication, and a kind of media delivery alternative path through the media relays server forwards is provided; The P2P client judges according to the control Signalling exchange whether another client has the P2P function;
If communicating pair is the P2P client, the P2P client is sought the P2P network media transmission alternative path of transmitting through the relay services node for this communication in the relay services overlay network;
P2P client calling party estimates all media delivery alternative paths, selects the media delivery path of best performance, and P2P client both sides switching media transfers to optimum media delivery path;
P2P client both sides still keep other alternative media path;
If current transmission path lost efficacy and caused dropped calls, P2P client both sides to switch to alternative media delivery path;
Communication session finishes, and the P2P client discharges P2P network media transmission path; The signaling Control Server discharges the media delivery path through the media relays server forwards;
Described P2P client is carried out self-assessment and is comprised following process:
Many index to P2P client itself detects, and comprises the network bandwidth, CPU ability and occupancy, memory size and utilization rate;
If satisfy preset threshold, use STUN service detection P2P client itself whether to be in after the NAT;
If be in after the NAT, then use the STUN service to judge the type of NAT;
If the type of NAT is an all-pass, then the P2P client becomes the relay services node, and joins the relay services overlay network.
6. by the described implementation method of supporting the SIP soft switchcall server of P2P media delivery of claim 5, it is characterized in that: the P2P client is in setting up the control Signalling exchange of communication session, carry the ICE collected address information, and after the control Signalling exchange, carry out the ICE detection of connectivity, for the point-to-point straight-through media delivery alternative path of ICE mode is sought in this communication.
7. by the implementation method of the SIP soft switchcall server of the described support of claim 5 P2P media delivery, it is characterized in that: described basis is set up in the process control Signalling exchange in session, and to judge whether another client has the P2P function specific as follows:
When the P2P client makes a call, the parameter of INVITE SDP part is set, is used to show oneself to have the P2P function; During P2P client callee answering call, the parameter of 200OK message SDP part is set; P2P client calling party checks the parameter of 200OK message SDP part, can judge whether the communication callee has the P2P function; P2P client callee checks the parameter of INVTE message SDP part, can judge whether the communication calling party has the P2P function.
8. by the described implementation method of supporting the SIP soft switchcall server of P2P media delivery of claim 5, it is characterized in that: described P2P client is sought the media delivery alternative path of transmitting through the relay services node for this communication in the relay services overlay network, wherein use INFO to carry out alternately between the P2P client, step is as follows:
1) P2P client calling party according to priority selects a plurality of relay services nodes to form new tabulation from present available relay services node;
2) P2P client calling party constructs first INFO, and the relay services nodal information that obtains is filled up in this message, sends the message to P2P client callee;
3) after P2P client callee received first INFO, return response message was given P2P client calling party, and obtains relay services node listing information to be selected from first INFO;
4) P2P client callee carries out overall merit to all the relay services nodes in the tabulation of relaying service node, according to priority rearrangement;
5) P2P client callee constructs second INFO, and new relay services node listing information is filled up in this message, sends the message to P2P client calling party;
6) after P2P client calling party received second INFO, return response message was given P2P client callee, and obtained the relay services node listing information through P2P client both sides evaluation from second INFO;
7) P2P client calling party obtains first relay services node in the above-mentioned relay services node listing, to this relay services node request relay resource; If ask successfully, then construct the 3rd INFO, the relay resource information that obtains is filled up in this message, send the message to P2P client callee, go to step 8);
If request is unsuccessful, then with the deletion from the tabulation of relaying service node of this relay services node, repeating step 7); If the relay services node listing is empty, the then selection course in this P2P Network Transmission path failure after a period of time, restarts the selection course of P2P Network Transmission alternative path;
8) after P2P client callee receives the 3rd INFO, return response message is given P2P client calling party, and from the 3rd INFO, obtain relay services nodal information to be selected, and to this relay services node request relay resource, if ask successfully, then construct the 4th INFO, the relay resource information that obtains is filled up in the 4th INFO, send the 4th INFO to P2P client calling party; If request is unsuccessful, P2P client callee does not do any operation;
9) after P2P client calling party received the 4th INFO, return response message was given P2P client callee, and obtains relay services nodal information to be selected from the 4th INFO; If do not receive P2P client callee's the 4th INFO within a certain period of time, then with relay services node to be selected deletion from the tabulation of relaying service node, repeating step 7).
9. by the described implementation method of supporting the SIP soft switchcall server of P2P media delivery of claim 5, it is characterized in that: described P2P client calling party is specially all alternative path evaluations: P2P client calling party flows to the test data that alternative path sends given time, calculates packet loss, delay and the jitter parameter of test data stream.
10. by the described implementation method of supporting the SIP soft switchcall server of P2P media delivery of claim 5, it is characterized in that: use disposable encryption key that the media stream data bag of communication session is encrypted between the P2P client, set up the safe transmission of finishing disposable encryption key in the process at communication session.
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