HK1050779A - Method of and system for providing quality of service in ip telephony - Google Patents

Description

Method and system for providing IP telephone service quality

Field of the invention

The present invention relates generally to the field of internet telephony, and more particularly to a method and system for providing quality of service for internet telephone conversations.

Background of the invention

Two trends are currently emerging in the telecommunications market. First, telephony services are added to internet protocol based devices. Second, Asynchronous Transfer Mode (ATM) networks are being established, as part of the capabilities of ATM switched virtual circuit services, with the ability to support user-specified quality of service (QoS) on a per-connection basis.

Each of these trends is somewhat problematic. The main problem with introducing telephony services into IP networks is the problem of providing predictable QoS on a per call/connection basis. Although these techniques are being studied in the internet community that addresses this problem, there is currently no way to guarantee QoS over an IP network on a per connection basis. The main problem of the second trend is not the problem of basic service capabilities, but access to the service. Virtually all desktop devices today have access to the IP network through some local area network technology, such as through ethernet. The problem is that these desktop devices typically do not have access to an ATM network that provides per call/connection guaranteed QoS.

The primary approach to addressing QoS in current IP-based networks is to over-provision the amount of bandwidth available in the network. This approach will be feasible as long as the use of the network stays within the bounds of the available bandwidth. If the use of the network is unpredictable, it is difficult, for example, to prevent the transmission of low priority files from interfering with the connection established for the transmission of real-time voice or video data.

The main approach to providing ATM switched virtual circuit services to devices that do not have native ATM support is to install routers between the IP network and the ATM network that have the ability to generate ATM switched virtual circuits on a per IP flow basis. The problems with this approach are: (1) the need to provide possible destination IP addresses in the router in advance, and (2) the impossibility of specifying on an IP flow basis which IP flow should get the ATM switched virtual circuit service and which should get the IP best effort service. If a destination address is provided in an ATM interworking router, all connections to the destination address will require an ATM switch virtual circuit.

Summary of The Invention

The present invention provides a method and system for providing quality of service in an IP telephone conversation between a calling party client and a called party client. The system of the present invention establishes a high quality of service ATM virtual circuit for a session between first and second devices, each device having ATM capability and IP capability. The first and second devices provide bi-directional conversion between Internet Protocol (IP) media and ATM media. The system delivers IP media for the conversation between the caller client and the first device, and the conversation between the callee client and the second device. The virtual circuit transports ATM media for a session between the first and second devices. An intelligent control layer provides IP and ATM signaling to establish the session.

In one embodiment of the invention, the first and second devices include access control managers that are bridges between the IP network and the ATM network. The intelligent control layer assigns an IP proxy address of a temporary session to the called party on the first access control manager and assigns an IP proxy address of a temporary session to the calling party on the second access control manager. The system establishes a switched virtual circuit through the ATM network for a session between a first access control manager and a second access control manager by assigning a temporary session calling party number on the first access control manager and a temporary session called party number on the second access control manager.

During the session, the system transfers IP media from the calling party to the temporary IP proxy address of the called party at the first access control manager. The first access control manager groups the IP media into ATM cells for delivery to the second access control manager via the virtual circuit. The system then transfers the IP media from the second access control manager to the called party. Also, the system transfers IP media from the called party to the temporary IP proxy address of the calling party at the second access control manager. The second access control manager groups the IP media into ATM cells for delivery to the first access manager over the virtual circuit. The system then transfers the IP media from the first access control manager to the calling party.

In another embodiment, the first and second devices comprise both IP and ATM capable routers. The calling party client obtains the authentication credentials and then initiates an IP telephony session with a quality of service request. When the called client accesses this session, the calling client initiates an IP media session that establishes a resource reservation protocol using an ingress router. The ingress router then establishes an IP media session through an egress router to the called party client. When the IP media session is established, the ingress router establishes an ATM switched virtual connection with the egress router.

Brief Description of Drawings

FIG. 1 is a block diagram of a preferred embodiment of a system of the present invention.

Fig. 2 is a call flow diagram illustrating signaling and call setup in the embodiment according to fig. 1.

Fig. 3 is a block diagram of another embodiment of the system of the present invention.

Fig. 4 is a call flow diagram illustrating signaling and call setup in the embodiment according to fig. 3.

Detailed Description

Referring now to the drawings, and initially to FIG. 1, a system in accordance with a preferred embodiment of the present invention is designated generally by the numeral 11. The system 11 includes a Media Service Control Point (MSCP) 13. The MSCP13 includes IP telephony session establishment servers, in the preferred embodiment a Session Initiation Protocol (SIP) server 15, ingress Asynchronous Transfer Mode (ATM) MSCP17, and egress ATM MSCP 19. As will be explained in detail later, MSCP13 provides an intelligent control layer for establishing an Internet Protocol (IP) telephony session between a first IP telephony user client 21 and a second IP telephony user client 23.

The system 11 includes an ingress access control manager 25 and an egress access control manager 27. The access control managers 25 and 27 provide a media gateway between the IP telephony user clients 21 and 23 and the ATM network 27. The ingress access control manager 25 provides an ATM media and signal interface to an ingress ATM switch 29 in the ATM network 27. Similarly, the egress access control manager 27 provides an ATM media and signal interface to an egress ATM switch 31 in the ATM network 27.

In fig. 1, IP signal paths are indicated by dotted lines and ATM signal paths are indicated by segment lines. The IP media path is shown by a solid line and the ATM media path is shown by a bold solid line.

In the embodiment of fig. 1, the quality of service (QoS) connections are provided by transporting communication traffic over QoS-capable trunks provided by the ATM network 27. According to the invention, an ATM connection is established for an IP telephone conversation between user clients 21 and 23. The QoS extension to the Data Network Application Part (DNAP) protocol enables signaling between MSCP13 and access control managers 25 and 27. Access control managers 25 and 27 establish connections with ATM QoS capabilities. Although in the preferred embodiment of the present invention, the QoS capable connections are provided by ATM switched virtual circuits, the present invention may be implemented using a wide variety of other technologies, such as SONET, and waveform division multiplexing.

As will be explained in detail later, the data path for the conversation is protected from unauthorized communication traffic by using proxy addressing. Proxy addressing requires translation by the access control managers 25 and 27 in order to deliver the media to its designated destination. During session setup, addresses of media stream endpoints are exchanged between the user client 21 and the user client 23. The signaling message containing the media address of the user client 21 is changed to reflect a proxy address, which is an interface on the egress access control manager 27. The access control manager interface is allocated on a per session basis. The uniqueness of each session interface is achieved by the assignment and withdrawal of short ports on the access control manager. The addresses used to establish and transfer ATM connections are associated with ephemeral ports. Also, the signaling message containing the media address for the user client 23 is changed to reflect a proxy address on the ingress access control manager 25.

The system of the present invention dynamically configures QoS connections and guarantees their security in two ways. First, the QoS connection is dynamically configured by using ATM switched virtual connections. The switched virtual connection is established on a per session basis during call setup. MSCP13 invokes the IP to ATM interface mechanism of access control managers 25 and 27 using DNAP QoS messages. As will be explained in detail later, the access control manager 25 enables a User Network Interface (UNI) protocol to be established. ATM traffic sent to and received by access control managers 25 and 27 is cross-intercepted by ATM switches 29 and 31, respectively, and delivered to their associated ATM MSCPs 17 and 19. The access control managers 25 and 27 map the media streams of the sessions to its switched virtual circuits, and the session traffic transfers their respective switched virtual circuits.

A second aspect of the real-time configuration solution is to dynamically guarantee the security of access to the connection. This is done by dynamically assigning the proxy address from a pre-provisioned proxy address library during session establishment. The proxy address is returned to the user clients 21 and 23 in an information message. The mapping of the session proxy address is established on MSCP and communicated to the access control managers 25 and 27 via the DNAP protocol. The proxy address and the actual session address are retained in the SIP server 15 and the access control managers 25 and 27 during the session. When the session terminates, the proxy address is revoked.

Reference is now made to fig. 2. There is shown a call flow diagram for session initiation according to the embodiment of figure 1. The user client 12 initiates the conversation by sending SIP INVITE a message 33 to the user client 23. For purposes of illustration, the user client's IP address is a @ xyz.com.sip invite addressing the user client 23 at a proxy address to the MSCP SIP server 15, which for purposes of illustration is B @ XYZ-sip.com. SIP INVITE specifying the source as the actual IP address of the user client 21 and specifying a required QoS. Upon receiving the INVITE 33, the SIP server 15 sends the INVITE 35 to the actual IP address of the user client 23, and the B @ xyz2000. com. INVITE 35 specifies that the sound source is a temporary IP proxy address assigned to the user client 21 at the egress access control manager 27, which for the sake of illustration is a @ ACM-y.com. If the user client 23 accepts the dialog, the user client 23 sends a 200OK SIP response 37 back to the SIP server 15 specifying that the voice destination is its actual IP address. Although in the preferred embodiment SIP IP telephony signals are used, other IP signaling protocols, such as h.323, may be used.

Upon receiving the response 37, the SIP server 15 assigns a call label and sends a reserve bandwidth message 39 to the ingress ATM MSCP 17. Message 39 specifies the voice destination for the conversation as a temporary IP proxy address assigned to the user client 23 at the ingress access control manager 25. For the sake of illustration, the temporary IP proxy address assigned to the user client 23 is B @ ACM-x.com. The bandwidth reservation message also identifies the call label and specifies the called number for the ATM connection at the egress access control manager 27.

Upon receiving the bandwidth reservation message 39, the ingress ATM MSCP17 sends a QoS setup request 41 to the ingress access control manager 25. The setup request 41 identifies the actual source address and the proxy source address for the user client 21. The setup request 41 also identifies the calling tag and the called party number. Ingress ATM MSCP17 also sends QoS setup indication messages 43 to egress access control manager 27. The setup indication 43 identifies the actual destination address and the proxy destination address for the user-client 23, as well as the calling tag and called party number for the ATM session. The egress access control manager 27 responds to the setup indication 23 by returning a setup indication acknowledgement 45 to the ingress ATM MSCP 17. Upon receiving the QoS setup request 41, the ingress access control manager 25 sends a User Network Interface (UNI) protocol setup message 47 to the ingress ATM switch 29. Upon receiving the UNI set-up message 47, the ingress ATM switch 29 sends a DNAP set-up 49 to the ingress ATM MSCP 17. When the ingress ATM MSCP17 responds, the ingress ATM switch 29 sends a set up message 53 to the egress ATM switch 31 as indicated at 51, and upon receipt of the set up message 53 the egress ATM switch 31 sends a DNAP set up message 55 to the egress ATM scp 19. When the egress ATM MSCP19 responds, the egress ATM switch 31 sends a UNI setup message 59 to the egress access control manager 27 as indicated at 57.

Upon receiving the setup message 59, the egress access control manager 27 sends a CONNECT message 61 to the ingress access control manager 25. Upon receipt of the CONNECT message 61, the ingress access control manager 25 responds to the QoS setup request with a QoS setup request acknowledgement 63 back to the ingress ATM MSCP 17. Upon receipt of the setup request acknowledgement 63, the ingress ATM MSCP17 responds to the reserved bandwidth message 39 with a reserved bandwidth acknowledgement message 65 back to the MSCP SIP server 15. Upon receiving the reserve bandwidth acknowledgement 65, the SIP server 15 drops the call label and sends a SIP 200OK response back to the user client 21. The OK response identifies the voice destination as a temporary IP proxy address assigned to the user client 23 at the ingress access control manager 25. The user client 21 then sends the addressed IP media packets to the user client 23 at the temporary proxy address on the access control manager 25. Likewise, the user client 23 sends the addressed IP media packets to the user client 21 at the temporary proxy address on the egress access control manager 27.

From the foregoing, it can be seen that the embodiment of fig. 1 provides QoS for IP telephony conversations between IP user clients. By using a temporary proxy, the user clients 21 and 23 do not know that their session is implemented on an ATM switched virtual circuit. The user clients 21 and 23 use standard SIP messages and standard proxy approaches for call setup without special knowledge on the part of the user clients 21 and 23. An intelligent network layer makes the system of the present invention transparent to the user clients 21 and 23.

Referring now to FIG. 3, another embodiment of the system of the present invention is designated generally by the numeral 71. The system 71 includes a MSCP, generally indicated at 73. MSCP73 includes MSCP SIP server 75, ingress ATM MSCP77, egress ATM MSCP 79. In addition, MSCP73 includes a policy server 81. MSCP73 is adapted to establish a QoS IP telephony session between calling user client 83 and called user client 85.

The ingress router 87 provides an interface between the IP user client 83 and the ATM network 89. The egress router 91 provides an interface between the user customer 85 and the ATM network 89. The ingress router 87 provides an interface to an ingress ATM switch 93 in the ATM network 89. Likewise, the egress router 91 provides an interface to an egress ATM switch 95 in the ATM network 89.

Referring now to fig. 4, shown therein is a call flow diagram of a session initiation according to the embodiment of fig. 3. User client 83 initiates a dialog with a Diameter protocol dialog authentication request 97 addressed to MSCP SIP server 75. Server 75 responds with a Diameter dialog authentication response (label), as shown at 99. The user client 83 then sends SIP INVITE a message 101 to the user client 85. For purposes of illustration, the IP address of the user client 85 is the address of the user client 85 of the proxy address on MSCP SIP addressed by a @ xyz.com.sip INVITE 101, which for purposes of illustration specifies that the source is the actual IP address of the user client 83, and specifies that the qos.sip INVITE 101 also includes an authentication tag received in response to the Diameter dialog authentication request 97. Upon receipt SIP INVITE 101, the SIP server 75 sends the INVITE103 to the actual IP address of the user client 85, B @ XYZ2000. com. INVITE103 specifying that the sound source is the IP address of the user client 83. If user client 85 accepts the dialog, user client 85 sends a 200OK SIP response 105 back to SIP server 75 specifying that the voice destination is its actual IP address.

Upon receiving the 200OK SIP response 105, the SIP server 75 sends a reserve bandwidth message 107 to the MSCP policy server 81. Message 107 specifies that the sound source for the conversation is the actual IP address of user client 83 and the sound destination for the conversation is the actual IP address of user client 85. Message 107 also includes an authentication tag. Upon receiving message 107, MSCP policy server 81 sends a response 109 back to MSCP SIP server 81. The SIP server 75 then sends a SIP 200OK response 111 to the user client 83.

After receiving the 200OK response 111. The user client 83 sends a resource reservation protocol (RSVP) path message 113 to the ingress router 87. Ingress router 87 then sends COPS request handling message 115 to MSCP policy server 81. When MSCP policy server 81 responds, ingress router 87 sends RSVP path message 119 to egress router 91 as shown at 117. The egress router 91 then sends an RSVP path message 121 to the user client 85. The user client 85 responds with an RSVP reservation response 123 back to the egress router 91. The egress router 91 then responds back to the ingress router 87 with an RSVP reservation response 125.

Upon receiving the response 125, the ingress router 87 sends a UNI, set up message 127 to the ingress ATM switch 93. Upon receiving the UNI set up message 127, the ingress ATM switch 93 sends a DNAP set up 129 to the ingress ATM MSCP 77. When the ingress ATM MSCP77 responds, the ingress ATM switch 93 sends a setup message 133 to the egress ATM switch 95 as shown at 131. Upon receiving the setup message 133, the egress ATM switch 95 sends a DNAP setup message 135 to the egress ATM MSCP 79. When egress ATM MSCP79 responds, egress ATM switch 95 sends UNI setup message 139 to egress router 91 as shown at 137.

Upon receiving the setup message 139, the egress router 91 sends a CONNECT message 141 to the ingress router 87. Upon receipt of the CONNECT message 141, the ingress router 87 responds to the RSVP path message 113 by returning to the user client 83 a RSVP reservation response 143. Then, an IP telephone conversation is established between the user client 83 and the user client 85.

The embodiment of fig. 3 and 4 allocates a certain amount of system intelligence to user clients 83 and 85. The user clients 83 and 85 are responsible for a larger part of the call set-up work than the user clients 21 and 23 in the embodiments of fig. 1 and 2. User clients 83 and 85 process signals in the Diameter and RSVP protocols in addition to signals in the SIP protocol.

From the foregoing it can be seen that the present invention overcomes the disadvantages of the prior art. The present invention dynamically establishes and secures QoS IP telephony sessions by carrying traffic over a high QoS backbone, preferably an ATM backbone. Those skilled in the art will recognize that various alternative embodiments will provide the benefit of this disclosure. Accordingly, the foregoing disclosure is intended to be illustrative rather than limiting.

Claims (24)

1. A method of providing quality of service in an Internet Protocol (IP) telephony session between a calling party and a called party, comprising the steps of:

transmitting IP media for said session between said IP-capable and ATM-capable calling party and the first device;

communicating IP media for said session between said IP capable and ATM capable called party and a second device; and

establishing an ATM virtual circuit for a session between said first device and said second device.

2. The method of claim 1, wherein said first and second devices are routers.

3. The method of claim 1, wherein:

said first device is identified by an IP proxy address of a temporary session of said called party; and

the second device is identified by the IP proxy address of a temporary session of the calling party

4. The method of claim 1, wherein said step of establishing an ATM virtual circuit between said first and second devices comprises the steps of:

assigning a caller number for the conversation on the first device; and

assigning a called party number for the conversation on the second device.

5. A method of providing quality of service in an IP telephony session between a calling party and a called party, comprising the steps of:

assigning a temporary IP proxy address for said called party to said session at a first access control manager;

assigning a temporary IP proxy address for said calling party to said session at a second access control manager; and

a switched virtual circuit is established for the session between the first access control manager and the second access control manager.

6. The method of claim 5, wherein said step of establishing said virtual circuit comprises the steps of:

assigning a temporary calling party address to said session at said first access control manager; and

assigning a temporary called party address to said session at said second access control manager.

7. The method of claim 6, wherein said step of assigning a temporary calling party address comprises the step of selecting a calling party address from a pool of calling party addresses assigned to said first access manager.

8. The method of claim 6, wherein said step of assigning a temporary called party address comprises the step of selecting a called party address from a pool of called party addresses assigned to said second access manager.

9. The method of claim 5, further comprising the step of:

communicating IP media traffic from said calling party to said called party IP agent address at said first access control manager; and

transmitting IP media traffic from said called party to said calling party IP proxy address at said second access control manager.

10. The method of claim 9, further comprising the step of:

converting IP media traffic received at said called party IP agent address to ATM traffic for transmission from said first access control manager to said second access control manager over said virtual circuit; and

converting IP media traffic received at said calling party IP agent address to ATM traffic for transmission from said second access control manager to said first access control manager over said virtual circuit.

11. The method of claim 10, further comprising the step of:

converting ATM traffic received at said temporary called party address into IP media traffic for delivery to said called party, and

converting ATM traffic received at said temporary calling party address to IP media traffic for delivery to said calling party.

12. A method of providing quality of service in an IP telephony session between a calling party and a called party, comprising the steps of:

assigning a temporary IP proxy address for said called party to said session at a first access control manager;

assigning a temporary IP proxy address for said calling party to said session at a second access control manager;

assigning a temporary second network calling party address to said session at said first access control manager; and

and allocating a temporary second network called party address to the conversation on the second access control manager.

13. The method of claim 12, wherein said step of assigning a temporary second network calling party address comprises the step of selecting a calling party address from a pool of second network calling party addresses assigned to said first access manager.

14. The method of claim 12 wherein said step of assigning a temporary second network called party address comprises the step of selecting a called party address from a pool of second network called party addresses assigned to said second access manager.

15. The method of claim 12, further comprising the step of:

communicating IP media traffic from said calling party to said called party IP agent address at said first access control manager; and

transmitting IP media traffic from said called party to said calling party IP proxy address at said second access control manager.

16. The method of claim 15, wherein:

said second network comprises an ATM network;

the temporary second network calling party address comprises a temporary calling party number; and

the temporary second network called party address includes a temporary called party number.

17. The method of claim 16 further comprising the step of establishing a switched virtual connection between said temporary called party number and said temporary calling party number through said ATM network.

18. The method of claim 17, further comprising the step of:

converting IP media traffic received at said called party IP agent address to ATM traffic for transmission from said first access control manager to said second access control manager over said virtual circuit; and

converting IP media traffic received at said calling party IP agent address to ATM traffic for transmission from said second access control manager to said first access control manager over said virtual circuit.

19. The method of claim 17, further comprising the step of:

converting ATM traffic received at said temporary called party number to IP media traffic for delivery to said called party; and

converting ATM traffic received at said temporary calling party number to IP media traffic for delivery to said calling party.

20. A system for providing quality of service in an IP telephony conversation between a calling party and a called party, comprising:

an IP network providing IP access to a calling party and a called party;

an ATM network;

a first device connected between said IP network and said ATM network, said first device providing bidirectional conversion between IP media traffic and ATM traffic;

a second device connected between said IP network and said ATM network, said second device providing bidirectional conversion between ATM traffic and IP media traffic; and

and the intelligent control layer is used for establishing a virtual circuit for the IP telephone conversation between the calling party and the called party through the ATM network.

21. The system of claim 20, wherein:

an ingress switch for connecting said first device to said ATM network; and

said second device is connectable to an egress switch of said ATM network.

22. The system of claim 20, wherein said intelligent control layer comprises:

an ATM intelligent controller, said ATM intelligent controller providing session establishment signaling to said first and second devices; and

an IP intelligent controller providing call setup signaling to said ATM intelligent controller.

23. The system of claim 20, wherein each of said first and second devices comprises a router.

24. The system of claim 20, wherein said intelligent control means comprises:

means for assigning a temporary IP session proxy address to said called party on said first device; and

means for assigning a temporary IP session proxy address to said calling party on said second device.