DE10153833A1 - Method for carrying out communication between two terminal points as network devices allows communication/interventions by correlating first and second connections. - Google Patents

Abstract

Two terminal points (UA-A,UA-B) interconnect as network devices via a first connection (Session-AB) in a network based on a terminal-to-terminal connection that does not allow any direct interventions or data transmissions by further network devices (P1-P5) via parts of the first connection between the two terminal points. In order to allow a communication or interventions by the network devices with regard to the first connection, a second connection (Session-P34) between two (P3-P4) of the network devices is correlated with the first connection. An Independent claim is also included for a network device for carrying out communication between two terminal points as network devices.

Description

The invention relates to a method for Communication of two network devices based on an end-to-end Connection with the generic features of Claim 1 or network devices therefor.

For packet-oriented networks with one Connection protocols are known to the subscriber-oriented structure special end-to-end connections between two enable communicating stations or endpoints at which only the endpoints - in contrast to the Network elements - generate signaling messages can.

An example of such a protocol is the so-called Session Initiation Protocol (SIP (Session Initialization Protocol)) found in the RFC2543bis-05 draft of the IETF Internet Engineering Task Force). The SIP only allows that Establishing end-to-end connections in which in the Header sections of data packets to be transmitted a fixed call Identification code or call ID as well as fixed to and from Header section information or To and From Header are registered. A connection or to be transmitted via it Data packets are thus made up of the combination To / From / Call-ID- Head sections clearly defined.

In addition, with SIP every message that is on a such connection is sent in one direction, one consecutive, increasing number assigned, the so-called CSeq. Because of this, network elements can exist between the endpoints do not send messages on an existing call ID because the increasing number otherwise from the synchronization would run.

SIP therefore only allows the endpoints of one Connection to send new messages. One between endpoints lying network element ("proxy") can therefore not via the same connection with one of the endpoints or another Communicate network element in between. Between these Network elements located at endpoints, i.e. no endpoints of the connection, therefore have none or only conditional permission to manipulate the connection or the on messages sent to her.

With SIP it is assumed that the network is special offered services are provided at application servers, which is then an end point of a special connection between must represent the service user and the application server.

In tele communication networks according to e.g. B. the IMS specified by the 3GPP (3GPP IMS: 3rd Generation Partnership Project Internet Multimedia Subsystem), on the other hand, services based on these ideas are planned. In the 3 GPP IMS there is a home proxy for each subscriber, which takes over the basic control for the calls, registration, authentication etc. of the subscriber. At this home proxy, which is also called the serving connection state and / or service state control function S-CSCF (Serving Call State Control Function), all application servers that this subscriber can or may use are connected via SIP.

Critical are z. B. Pre-paid application servers that Manage prepaid, so-called prepaid cards and accounts. All Calls from a subscriber are pre-paid via the home proxy Server and from there back to the home proxy, so that the connection to other servers if necessary can forward. There are solutions in which the pre- Paid servers themselves do not manage the budget for each call of the participant only controls the account balance announces and allows the home proxy to pay a partial amount debited from this account. This money can then be used by the user be consumed. If the partial amount runs low, the Home proxy new amounts from the prepaid server. Is there too no more money, it tells the home proxy trigger the call. However, this is problematic with pure End point-to-end point connections, because for the triggering or A corresponding intervention terminates the main connection from a proxy between or away from the endpoints would have to be made, however, from the foregoing Reasons is not possible. In particular, no so-called BYE message sent to initiate a connection become. Beyond that there is already communication between the home proxy and the pre-paid server via the call ID the end point-to-end point connection is not possible.

In many cases there is therefore a generation of messages desirable through network elements. An example is one such charging of calls, which usually of several network elements is performed, which is necessary with each other based on an existing end-to-end Connection need to communicate without it generated messages must be forwarded to the endpoints become.

It would also be beneficial in some networks if Network elements existing connections between two endpoints can trigger.

A possible solution to the problem would be a so-called back to-back user agent (B2BUA), but who in his Implementation is very complex and the construction and handling of Call slowed down unnecessarily.

Another alternative solution would be to use the so-called REFER message. You can use this message Network element in a special connection to a terminal request a specific SIP defined by the network element Message for a clearly identified connection send. A network element can be used via this mechanism Request terminal to send a BYE message. Out Security reasons, e.g. B. to avoid Manipulation possibilities of end devices by the user, it is in some network environments, e.g. B. 3GPP IMS necessary that the Connection trigger message (BYE) in these cases not from Terminal is expected.

The object of the invention is a method propose communications between network devices enables a pure end-to-end connection, where at least one of these network facilities is not one of the endpoints is.

This task is accomplished through the process of communicating Network devices based on an end-to-end connection with the features of claim 1 or a network device therefore solved with the features of claim 11.

Advantageous configurations are the subject of dependent Claims.

There are various types of network equipment Understand facilities and network elements, in particular independent data terminals, servers, telephones, computers, Network interfaces and the like. The connections can be wired or radio-based connections.

The method enables the correlation of two end-to-end Connections in a packet-based network. The used Connection protocol is an end-to-end protocol, d. H. Network elements that are not endpoints of the connection usually only have limited authorization to Manipulation of the actual connection or on it sent messages.

The correlation of two end-to-end connections is included possible regardless of the purpose of the correlation. A independent communication of network elements is based on a main connection already existing in parallel or on the basis new connections can be established. In particular is for the communication of network elements also the use of a own, especially new connection type possible.

Particularly advantageous and of independent inventive Salary is also the possibility of triggering. H. ending an end-to-end connection between two endpoints a network element between these.

When requesting the correlation of the further connection with to transmit an instruction to the first connection, which the receiving network device instructs the connection not to accept or not to build if the functionality of the Connection correlation from the received network device is not supported is particularly advantageous because of this incorrect interpretations or evaluations can be avoided. In SIP, mechanisms known per se can be used for this be used.

A network device for performing such a method preferably has at least one interface for building of at least two mutually independent connections and a control device for processing and / or providing of those transmitted or to be transmitted via the connections Information and / or instructions and to control the Functions of the network device, the control device the information and / or instructions on one of the Connections processed or referenced to the other connection provides.

In particular, these methods and network devices the establishment of charging systems possible, in which the actual charging facilities not directly with or must be available in the network facilities.

Exemplary embodiments are described below with reference to the drawing explained in more detail. Show it:

Fig. 1 shows two end points and a plurality of network elements arranged between them according to a first embodiment of a communication between such network elements via a correlated to the main connection link;

Fig. 2 shows an alternative embodiment and

Fig. 3 shows such an arrangement with a network element that can terminate a connection between the end points.

As can be seen from FIG. 1, communication takes place in a network between two end points UA-A and UA-B in accordance with an end-to-end protocol, with a connection, also referred to below as session AB, via a large number in between lying network elements P1-P5 leads. The network elements P1-P5 cannot act directly on the session-AB connection or send their own data packets on this session-AB connection. The end points UA-A, UA-B and the network elements P1-P5 can be various devices depending on the network type, e.g. B. cellular radio stations, data servers, networked computers, proxies and / or network nodes for the management and control of network resources. The following distinction between endpoints and network elements is only used for easier differentiation.

As an example of such an end-to-end protocol the SIP listed, in the head sections of transmitting data packets the fixed call Identification code or call ID as well as fixed to and from Header section information or To and From Header be entered. In addition, with each message or each Data packet a consecutive, increasing number in the Head section entered, the so-called CSeq.

According to the first embodiment, from the end point UA-A starting a connection session-AB between the two End points UA-A and UA-B are built. The first calls End point UA-A the second end point UA-B, whereupon the desired connection session-AB via network elements P1, P2, P3, P4 and P5 is built. The network elements P1-P5, so-called proxies, force all messages or Data packets of the Session-AB connection are forwarded via them become. To do this, they wear the first one Connection request, with SIP a so-called INVITE message or a INVITE protocol element, in the data record guidance information Record header or record route header. The Connection session AB is used with the methods of Signaling protocol built, in the case of SIP dem Send INVITE, wait for a so-called 200 OK Message and sending a confirmation message to the so-called ACK message.

Instead of entering the individual network element addresses in the record guidance information header can also corresponding information, e.g. B. the connection Identification information Call ID with sender and Destination address in a corresponding memory of the network elements P1-P5 entered and when data packets arrive later be used to forward them.

The connection session-AB is clearly identified in SIP by the following exemplary data in the header section of data packets:
From: ua-a@home1.net; tag = 123
To: ua-b@home2.net; tag = 456
Call ID: session-ab@home1.net
UA --- A ---- ---- P1 P2 P3 ---- ---- ---- P5 P4 ---- UA-B.

The from and from information contains the address the first end point UA-A from which the data packet originates, here in the format of an Internet address, and a so-called Tag, i.e. an identification in the form of a flag or a Label. The To or To information includes the Destination address, i.e. the address of the second end point UA-B. The day the To address is generated by the destination node and added. This is done in order to fork different Connections that came out of a connection to be able to clearly differentiate from one another. The reputation Identification information Call-ID is used to assign the Data packets for a specific connection, here the Connection session AB. In addition, in the head section shown example information about each Stations and network elements P1-P5 on the connection Session AB carried.

In the present embodiment, between the Network elements P3 and P4 exchange messages take place, with the news directly related to the Have connection session AB, but due to the SIP Restrictions do not apply directly via the Session-AB connection can be transferred.

The first builds to enable the exchange of messages (the third from the left in the figure) of these network elements P3 a new connection to the second (in the figure the fourth of left) of these network elements P4. When establishing a connection will be together with the usual information, in particular Header information, additional information transmitted, which has a correlation with the session AB connection produce. This is, for example, an implementation SIP with new protocol extensions compared to the current protocol.

In addition, the head section can be used when establishing a connection by means of z. B. the INVITE message according to SIP advantageously contain a field (Require: Header), which is the second Network element P4 instructs not to accept the connection if the functionality of the connection correlation is not is supported. The correlation connection between the two Network elements P3 and P4 are also referred to as session P34 designated.

The session P34 connection is then clearly identified, for example, by the following data in the header section of data packets:
INVITE p4.home1.net
From: p3.home1.net; tag = 789
To: p4.home1.net
Call ID: session-p34@p3.home1.net
Require: correlate
Correlate-From: ua-a@home1.net; tag = 123
Correlate-To: ua-b@home2.net; tag = 456
Correlate Call ID: session-ab@home1.net

The INVITE message is followed by the address or the name of the called network element P4. The From, To and Call fields ID are according to the header section example above with the data of the two network elements P3 and P4.

This is followed by a block of additional information related to Correlate the new session-P34 connection serve the existing session-AB connection. This Information is preferably a "Require" of the Correlation "correlate" with another connection, data, in particular addresses of the end points UA-A and UA-B of the correlating connection session AB and a correlation call Identification information Correlate call ID for assignment of the data packet to the specific correlation connection Session P34.

Of course, there are other types of information can be used, provided that this clearly assigns the data packets on the one hand the parallel connection Session-P34 and on the other hand, enable the main connection Session-AB. in the In the simplest case, a single field is sufficient, e.g. B. the Correlation Call Identification Information Correlate Call ID, if corresponding connection and / or assignment data in the individual network elements P1-P5 and / or the end points UA-A, UA-B are ready.

After receiving the connection request "INVITE P4.home1.net", the second network element P4 now completes the connection setup and sends a positive response back to the first network element P3. The answer, with SIP z. For example, a "200 OK" message can then be uniquely identified, for example, by the following data in the header section, the contents being occupied in accordance with the above header sections:
200 OK
From: p3.home1.net; tag = 789
To: p4.home1.net; tag = 098
Call ID: session-p34@p3.home1.net
Correlate-From: ua-a@home1.net; tag = 123
Correlate-To: ua-b@home2.net; tag = 456
Correlate Call ID: session-ab@home1.net.

As a result, the two connections Session-AB and Session- P34 connected together.

Messages now on session P34 between the two Network elements P3 and P4 are replaced by everyone network elements involved as additional components of Session AB to see.

In particular, both connections are session-AB and Session P34 independently of one another with corresponding messages, for SIP BYE messages, triggered or ended.

In addition to the possibility of establishing a new connection to an existing Session-AB connection in parallel over at least part of the route, it is e.g. It is also possible, for example, to correlate two existing connections afterwards, as will be explained using the second exemplary embodiment with reference to FIG. 2.

If two independent connections already exist, one can new message that also corresponds to SIP Protocol extension required on one of the two Connections are sent.

With SIP this procedure or a corresponding message could e.g. B. be called CORRELATE. In order to correlate two independent connections Session-AB and Session-P34 with one another, a message would then be transmitted on one of the two connections Session-AB or Session-P34. B. contains the following information, which is backed up according to the examples described above:
CORRELATE p2.home2.net
From: p1.home1.net; tag = 898
To: p2.home2.net; tag = 767
Call ID: session-p12@home1.net
Correlate-From: ua-a@home1.net; tag = 123
Correlate-To: ua-b@home2.net; tag = 456
Correlate Call ID: session-ab@home1.net

Also in this example, the two connections preferably triggered again independently of one another.

Alternatively or additionally, connections can also be made different types are correlated with each other. So one can Connection established via INVITE with a Connection established with SUBSCRIBE correlated become. The SIP SUBSCRIBE message allows that a User at an application server for delivery certain event-related information (events) (Subscribed). An event occurs for which the user the application server has registered the user via a NOTIFY message that additional May contain event information.

Also in this example, the two connections preferably triggered or run again independently of one another independently.

According to a further embodiment, the in The first alternative described CORRELATE method for subsequent correlation of two or more existing connections also be used to create your own connection type initiate. This would be analogous to others known per se SIP requests or SIP requests, such as B. INVITE (Establishing a connection for parallel media streams), SUBSCRIBE (registration for event information), REGISTER (announcement of the current location of the user, d. H. the address of the Terminal to which he has registered), MESSAGE (Short messages via instant messaging) or REFER (call forwarding and requesting individual SIP messages). possible. This type of connection would be particularly useful preferred if the additional connection is purely at the signaling level can be dealt with and does not require SIP methods that a transfer only within others Allow connection types, such as B. the INFO known from SIP Method used to signal additional information during serves an already established connection.

For this alternative, three exemplary trigger mechanisms for terminating the connections and / or correlations are presented below:
For example, the CORRELATE connection can be triggered automatically if the main connection Session-AB, to which the CORRELATE connection Session-P34 refers, is also triggered. This is preferred. If the main connection according to SIP z. B. established with INVITE, the SIP instruction BYE / 200 OK transmitted on the main connection Session-AB also triggers the correlated CORRELATE connection Session-P34.

Does the CORRELATE connection refer to a SUBSCRIBE Connection, the CORRELATE connection is preferred automatically when the timer for the valid one expires Connection duration or the so-called SUBSCRIBE Expires timer triggered.

If the correlated connection Session-P34 with the CORRELATE statement associated with history headers or so-called Expires Header is built, so it will independent of the main connection when the Timer for the valid connection duration or the expires Timer triggered.

According to a particularly preferred exemplary embodiment, which is illustrated with reference to FIG. 3, a connection initiation of the main connection Session-AB initiated by the network or its network elements P1-P5 is also possible.

About the additional header section entry, for example or header section "Correlate Method" can be the parallel or correlated connection session-P31 or session-P35 used messages instead of the main link too transport. This news on the correlated Connection session P31 or session P35 must then be from the receiving facility like a message on the Main connection session-AB are treated. This mechanism is similar to that of the so-called REFER method in SIP.

In particular, this also initiates one initiated by the network Connection triggering of the main connection Session-AB by a Network element P3 enables, as shown.

The session-AB connection between the end points UA-A and UA-B is established as in the first exemplary embodiment according to FIG. 1.

If a network element P3 lying between these end points UA-A and UA-B later recognizes that the connection session-AB is to be triggered, the network element P3 sends two CORRELATE messages, one to the first end point UA-A and one to the second end point UA-B. In principle, two short-term parallel connections Session-P3A or Session-P3B are set up for this purpose, which in the simplest case only serve for the one-off transmission of the trigger information or trigger message without a confirmation of the setup. The messages can e.g. B. be constructed as follows:
CORRELATE et al
From: p3; day = 999
To: ua-a
Call-ID session-P3A
Expires: 0
Correlate-To: ua-a@home1.net; tag = 123
Correlate-From: ua-b@home2.net; tag = 456
Correlate Call ID: session-ab@home1.net
Correlate method: BYE
CORRELATE ua-b
From: p3; day = 777
To: ua-b
Call-ID session-P3B
Expires: 0
Correlate-From: ua-a@home1.net; tag = 123
Correlate-To: ua-b@home2.net; tag = 456
Correlate Call ID: session-ab@home1.net
Correlate method: BYE

The CORRELATE statement gives basic connection information indicates that the field with the validity period EXPIRES specifies one remaining period of validity from 0 in this case, d. H. an instruction to immediately end the correlated Connection, and as the correlation method Correlate-Method is triggering or ending the main connection with the command "BYE" specified.

An end point UA-A or UA-B or a network element P1-P5, especially the proxy that receives this message should treat it as if it were a BYE message directly for the Main connection session AB were received or via the Main connection session-AB was transmitted. The CORRELATE Instruction is preferably from the two endpoints UA-A and UA-B with a final response answered. This then becomes the correlated connection ended because the valid header or Expires header was set to the value 0 insofar as this correlated Connection does not end automatically.

A practical application can be found, for example, in Area of charging for claimed services. With the The above procedure is one with networks Protocol for end-to-end connections through the extension no longer mandatory that all functions must be able to act directly on the main connection at or at the end points UA-A or UA-B.

It is possible, for. B. the use of an application server that Manages pre-paid cards and accounts. All calls one Participants are via the home or home proxy, e.g. B. a first network element P1, to the pre-paid server, for example another network element P3, directed and from there again back to the home proxy so that the connection forward to other servers if necessary. It is possible also that the pre-paid server itself is not the Budget management for each call of the subscriber only controls announces the account balance and allows the home proxy, To withdraw money from this account. This money can then from Participants or their station are consumed. Is this When the home proxy is used up, it requests a new amount from the pre-paid server. Is the money or credit there too? consumed, it notifies the home proxy, the call trigger. In this example, the advanced features the establishment of parallel, correlated connections to both Manage the credit as well as trigger the Main connection used.

Claims (12)

1. Method for performing communication between two endpoints as network devices (UA-A or UA-B) via a first connection (Session-AB) in a network based on an end-to-end connection (SIP), which are not direct Interventions or data transmissions made possible by at least one further network device (P1-P5) via at least parts of the first connection (Session-AB) between these end points (UA-A and UA-B), characterized in that
at least one further connection (session P34; session P12; session P3A, session P3B) between two of the network devices (P3-P4; P1-P2; P3-UA-A, P3-UA-B) with the first connection (Session-AB) is correlated,
wherein at least one of the network devices (P3-P4; P1-P2; P3-UA-A, P3-UA-B) of the further connection (Session-P34; Session-P12; Session-P3A, Session-P3B) as a network device on the first connection (session AB) between the end points (UA-A or UA-B) of the first connection (session AB) is arranged. 2. The method according to claim 1, wherein on the further connection (session P34; session P12; Session-P3A, Session-P3B) transmitted messages and Information from the receiving network device (P4; P2; UA-A, UA-B) with direct reference to the first connection (session AB) be evaluated. 3. The method according to claim 1 or 2, wherein on the further connection (session P34; session P12; Session-P3A, Session-P3B) data packets with direct reference to the first connection (session AB) are transmitted. 4. The method according to any preceding claim, in which when establishing the further connection (session P34; session P3A, Session-P3B) information to request a Transfer correlation with the first connection (session AB) becomes. 5. The method according to any one of claims 1-3, in which after establishing the further connection (session P12) one Information when requesting correlation of these others Transfer connection with the first connection (session AB) becomes. 6. The method according to any preceding claim, in which a request to correlate the further connection (Session-P34; Session-P12; Session-P3A, Session-P3B) with the first connection (session AB) as an extended one Header data (Correlate-From; Correlate-To; Correlate-Call-ID) or transmitted with a separate head section (Correlate) becomes. 7. The method according to any preceding claim, in which as another connection a connection of another Connection type correlated with the first connection (session AB) or is generated and correlated. 8. The method according to any preceding claim, in which on the further connection (session P3A, session P3B) transmitted messages and information (correlate method) from the receiving network device (UA-A, UA-B) as one of the the first connection (session AB) associated instruction become. 9. The method according to any preceding claim, in which on the further connection (session P3A, session P3B) transmitted messages and information (Correlate-Method: BYE) from the receiving network device (UA-A, UA-B) as Instruction to end the first connection (session AB) dealt with become. 10. The method according to any preceding claim, in which the further connection for the transmission of Billing-related data and / or instructions related to the first Connection is used as the connection to be charged. 11. Network device (UA-A, UA-B, P1-P5) for performing a method according to any preceding claim
at least one interface for establishing at least two mutually independent connections (session AB; session P34) and
a control device for processing and / or providing information and / or instructions transmitted or to be transmitted via the connections (Session-AB; Session-P34) and for controlling the functions of the network device, wherein
the control device processes or provides the information and / or instructions on one of the connections (session P34) with reference to the other connection (session AB). 12. Network device according to claim 11, wherein the network device as a pre-charging server and / or Home proxy is trained.