Abstract:
A method and system for providing quality of service in an IP telephony session between a calling party and a called party establishes a high quality of service ATM virtual circuit for the session between first and second devices, each of the devices having ATM capability and IP capability. The first and second devices provide bidirectional translation between IP media and ATM media. The system transports IP media for the session between the calling party and the first device, and between said called party and a second device. The virtual circuit transports ATM media for the session between the first and second devices. An intelligent control layer provides IP and ATM signaling to set up the session.

Description:
RELATED APPLICATIONS  
       [0001]     This application is a continuation of U.S. patent application Ser. No. 09/370,504 filed Aug. 9, 1999, which is hereby incorporated by reference. 
     
    
     BACKGROUND  
       [0002]     The present invention relates generally to the field of Internet telephony, and more particularly, to a method of and system for providing quality of service in an Internet telephony session.  
         [0003]     Two trends are currently occurring in the telecommunications marketplace First, telephony services are being added to Internet protocol-based devices. Second, Asynchronous Transfer Mode (ATM) networks are being built with the ability to support user specified quality of service (QoS) on a per connection basis, as part of the ATM switched virtual circuit service capability. Each of these trends have problems. The primary problem with the introduction of telephony services to the IP network is one providing predictable QoS on a per call/connection basis. Although technologies are being developed in the Internet community to address this problem, there is currently no way to guarantee QoS on a per connection basis through an IP network. The primary problem with the second trend is not one of basic service capability, but is rather one of access to the service. Today virtually all desktop devices have access to an IP network through some sort of local area network technology, for example through Ethernet. The problem is that these desktop devices generally do not have access to ATM networks that provide the per call/connection guarantee QoS.  
         [0004]     The primary method of addressing QoS in the current IP-BASED networks is to over-provision the amount of bandwidth available in the network. This approach will work as long as the usage of the network stays within the bounds of the available bandwidth. If the usage of the network is not predictable, then it is difficult, for example, to prevent a low priority file transfer from interfering with a connection established to carry real-time voice or video data.  
         [0005]     The primary method of 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) possible destination IP addresses need to be provisioned in the router ahead of time, and (2) it is not possible to define, on an IP flow basis, which IP flow should get the ATM switched virtual circuit service and which should get IP best efforts service. If a destination address is  30  provisioned in the ATM interworking router, then all connections to that destination address will require an ATM switched virtual circuit.  
       SUMMARY  
       [0006]     The present invention provides a method of and a system for providing quality of service in an IP telephony session 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 the session between first and second devices, each of the devices having ATM capability and IP capability. The first and second devices provide bidirectional translation between Internet Protocol (IP) media and ATM media. The system transports IP media for the session between the calling party client and the first device, and between the called party client and the second device. The virtual circuit transports ATM media for the session between the first and second devices. An intelligent control layer provides IP and ATM signaling to set up the session  
         [0007]     In one embodiment of the present invention, the first and second devices include access control managers that are bridges between an IP network and an ATM network. The intelligent control layer assigns a temporary session IP proxy address for the called party at the first access control manager and a temporary session IP proxy address for the calling party at the second access control manager. The system establishes a switched virtual circuit through the ATM network for the session between the first access control manager and the second access control manager by assigning a temporary session calling party number at the first access control manager and a temporary session called party number at the second access control manager.  
         [0008]     During the session, the system routes 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 packages the IP media in ATM cells for transport through the virtual circuit to the second access control manager. The system then routes IP media from the second access control manager to the called party. Similarly, the system routes 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 packages the IP media in ATM cells for transport through the virtual circuit to the first access control manager. The system then routes IP media from the first access control manager to the calling party.  
         [0009]     In an alternative embodiment, the first and second devices include routers that have both IP and ATM capability. The calling party client obtains an authentication ticket and then initiates an IP telephony session with a quality of service request. When the called party client accepts the session, the calling party client initiates setup of a resource reservation protocol IP media session with an ingress router. The ingress router then sets up the IP media session through an egress router to the called party client. When the IP media session is setup, the ingress router sets up an ATM switched virtual connection with the egress router. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is a block diagram of a preferred embodiment of the system of the present invention.  
         [0011]      FIG. 2  is a call flow diagram illustrating the signaling and call setup according to the embodiment of  FIG. 1 .  
         [0012]      FIG. 3  is a block diagram of an alternative embodiment of the system of the present invention.  
         [0013]      FIG. 4  is a call flow diagram illustrating the signaling and call setup according to the embodiment of  FIG. 3 .  
     
    
     DETAILED DESCRIPTION  
       [0014]     Referring now to the drawings, and first to  FIG. 1 , a system according to a preferred embodiment of the present invention is designated generally by the numeral  11 . System  11  includes a media service control point (MSCP)  13 . MSCP  13  includes an IP telephony session establishment server, which in the preferred embodiment is a session initiation protocol (SIP) server  15 , an ingress Asynchronous Transfer Mode (ATM) MSCP  17 , and an egress ATM MSCP  19 . As will be explained in detail hereinafter, MSCP  13  provides an intelligent control layer for the establishment of an Internet Protocol (IP) telephony session between a first IP telephony user client  21  and a second IP telephony user client  23 .  
         [0015]     System  11  includes an ingress access control manager  25  and an egress access control manager  27 . Access control managers  25  and  27  provide a media gateway between IP telephony user clients  21  and  23  and an ATM network  27 . Ingress access control manager  25  provides an ATM media and signaling interface to an ingress ATM switch  29  of ATM network  27 . Similarly, egress access control  25  manager  27  provides an ATM media and signaling interface to an egress ATM switch  31  of ATM network  27 .  
         [0016]     In  FIG. 1 , IP signaling paths are indicated with dotted lines and ATM of signaling paths are indicated with dashed lines. IP media paths are indicated with solid lines and ATM media paths are indicated with bold solid lines.  
         [0017]     In the embodiment of  FIG. 1 , a Quality of Service (QoS) connection is provided by routing traffic on the QoS capable backbone provided by ATM network  27 . According to the present invention, an ATM connection is created for the IP telephony session between user clients  21  and  23 . QoS extensions to the data network applications part @NAP) protocol perform the signaling between MSCP  13  and access control managers  25  and  27 . The access control managers  25  and  27  establish the ATM QoS capable connection. While in the preferred embodiment of present invention, the QoS capable connection is provided by ATM switched virtual circuits, the present invention can also be implemented in a variety of other technologies, such as SONET, and wave division multiplexing.  
         [0018]     As will be explained in detail hereinafter, the data path for the session is secured against unauthorized traffic by the use of proxy addressing. The proxy addressing requires translation by the access control managers  25  and  27  to route the media to its intended destination. During session establishment, the addresses of the media stream endpoints are exchanged between user client  21  and user client  23 . The signaling message containing the media address of user client  21  is changed to reflect a proxy address, which is an interface at egress excess control manager  27 . The excess control manager interface is assigned on a per session basis. The per session interface uniqueness is accomplished by the allocation and deallocation of ephemeral ports at the access control managers. Associated with the ephemeral ports are the addresses used to create and transit the ATM connection. Likewise, the signaling message containing the media address for user client  23  is changed to reflect a proxy address at ingress access control manager  25 .  
         [0019]     The system of the present invention dynamically configures QoS connections and ensures their security in two ways. First, the QoS connection is dynamically configured by the use of ATM switched virtual connections. The switched virtual connections are created on a per session basis during call establishment. MSCP  13  invokes the IP to ATM interface mechanisms of access control managers  25  and  27  with DNAP QoS messages. As will be explained in detail hereinafter, access control manager  25  launches a user network interface protocol setup. The ATM traffic sent to and received by access control managers  25  and  27  is intercepted by ATM switches  29  and  31 , respectively, and forwarded to their associated ATM MSCPs  17  and  19 . The ATM MSCPs create the switched virtual circuit between ATM switches  29  and  3   1 . Access control managers  25  and  27  map the media stream of the session to its switched virtual circuit and the session traffic transits their respective switch virtual circuit.  
         [0020]     The second aspect of the real-time configuration solution is the dynamic securing of the access to the connections. This is done by dynamically allocating the proxy addresses during session establishment from a pre-provisioned proxy address pool. The proxy addresses are returned to the user clients  21  and  23  in the signaling messages. The session proxy address mapping is created at the MSCP and communicated to access control managers  25  and  27  by the DNAP protocol. The proxy addresses and the actual session addresses are held at the SIP server  15  and the access control managers  25  and  27  for the duration of the session. When the session is terminated, proxy addresses are deallocated.  
         [0021]     Referring now to  FIG. 2 , there is shown a call flow diagram of session initiation according to the embodiment of  FIG. 1 . User client  21  initiates the session by sending a SIP INVITE message  33  to user client  23 . For purposes of illustration, the IP address of user client  21  is A@XYZ.COM. The SIP INVITE is addressed to user client  23  at a proxy address at MSCP SIP server  15 , which for purposes to illustration is B@XYZ-SIP.COM. The SIP INVITE specifies the audio source as the real IP address of user client  21 , and specifies that QoS is requested. Upon receipt of invite  33 , SIP server  15  sends an invite  35  to the real IP address of user client  23 , at B@XYZ2000.COM. Invite  35  specifies the audio source as a temporary IP proxy address allocated to user client  21  at egress access control manager  27 , which for purposes of illustration is A@ACM-Y.COM. If user client  23  accepts the session, user client  23  sends a 2000 K SIP response  37  back to SIP SERVER  15 , specifying an audio destination as its real IP address While in the preferred embodiment, SIP IP telephony signaling is used, other IP signaling protocols, such as H.323 may be used.  
         [0022]     Upon receipt of response  37 , SIP server  15  allocates a call tag, and sends a reserve bandwidth message  39  to ingress ATh4 MSCP  17 . Message  39  specifies the audio destination for the session of as a temporary IP proxy address allocated to user client  23  at ingress access control manager  25 . For purposes of illustration, the temporary IP proxy address allocated user client  23  is B@ACM-X.COM. The bandwidth reservation message also identifies the call tag and specifies the called number for the ATM connection as egress access control manager  27 .  
         [0023]     Upon receipt of bandwidth reservation message  39 , ingress ATM MSCP  17  sends a QoS setup request  41  to ingress access control manager  25 . Setup request  41  identifies the real source address and proxy source address for user client  21 . Setup request  41  also identifies the call tag and the called party number. Ingress ATM MSCP  17  also sends a QoS setup indication message  43  to egress access control manager  27 . Setup indication  43  identities the real destination address and proxy destination address for user client  23 , as well as the call tag and the called party number for The ATM session. Egress access control manager  27  responds to setup indication  23  with a setup indication acknowledgment  45  back to ingress ATMMSCP  17 . Upon receipt of the QoS setup request  41 , ingress access control manager  25  sends a user network interface  0  protocol setup message  47  to ingress ATM switch  29 . Upon receipt of UNI setup message  47 , ingress ATM switch  29  sends a DNAP setup  49  to ingress ATM MSCP  17 . When ingress ATM MSCP  17  responds, as indicated at  5   1 , ingress ATM switch  29  sends a setup message  53  to egress ATM switch  3  I. Upon receipt of setup message  53 , egress ATM switch  31  sends a DNAP setup message  55  to egress ATM MSCP  19 . When egress ATM MSCP  19  responds, as indicated at  57 , egress ATM switch  3   1  sends a UNI setup message  59  to egress access control manager  27 .  
         [0024]     Upon receipt of setup message  59 , egress access control manager  27  sends a CONNECT message  61  to ingress access control manager  25 . Upon receipt of CONNECT message  61 , ingress access control manager  25  responds to QoS setup request  41  with a QoS setup request acknowledgment  63  back to ingress ATM MSCP  17 . Upon receipt of setup request acknowledgment  61 , ingress ATM MSCP  17  responds to the reserve bandwidth message  39  with a reserve bandwidth acknowledgment message  65  back to MSCP SIP server  15 . Upon receipt of reserve bandwidth acknowledgment  65 , SIP server  15  deallocates the call tag and sends a SIP 200 OK response  67  back to user client  21 . The OK response identifies the audio destination as the temporary IP proxy address allocated to user client  23  at ingress access control manager  25 . Then, user client  21  sends IP media packets addressed to user client  23  at the temporary proxy address at access control manager  25 . Similarly, user client  23  sends IP media packet addressed to user client  21  at the temporary proxy address at egress access control manager  27 .  
         [0025]     From the foregoing, it may be seen that the embodiment of  FIG. 1  provides QoS for IP telephony sessions between IP user clients. Through the use of temporary proxies, user clients  21  and  23  are unaware that their session is carried on an ATM switched virtual circuit. User clients  21  and  23  use standard SIP messaging and standard proxying for call setup and no special intelligence is required on the part of the user clients  21  and  23 . An intelligent network layer makes the system of the present invention transparent to user clients  21  and  23 .  
         [0026]     Referring now to  FIG. 3 , an alternative embodiment of the system of the present invention is designated generally by the numeral  71 . System  71  includes MSCP indicated generally at  73 . MSCP  73  includes an MSCP SIP server  75 , an ingress ATM MSCP  77 , and an egress ATM MSCP  79 . Additionally, MSCP  73  includes a policy server  81 . MSCP  73  is adapted to establish a QoS IP telephony session between a calling user client  83  and a called user client  85 .  
         [0027]     An ingress router  87  provides an interface between IP user client  83  and an ATM network  89 . An egress router  91  provides interface between user client  85  and ATM network  89 . Ingress router  87  provides an interface to an ingress ATM switch  93  of ATM network  89 . Similarly, egress router  91  provides an interface to an egress ATM switch  95  of ATM network  89 .  
         [0028]     Referring now to  FIG. 4 , there is shown a call flow diagram of session initiation according to the embodiment of  FIG. 3 . User client  83  initiates the session with a Diameter protocol session authentication request  97  addressed to MSCP SIP server  75 . Server  75  responds with a Diameter session authentication response (ticket), as indicated at  99 . Then, user client  83  sends a SIP INVITE message  101  to user client  85 . For purposes of illustration, the IP address of user client  85  is A@XYZ.COM. The SIP INVITE  101  is addressed to user client  85  at a proxy address at MSCP SIP server  75 , which for purposes to illustration is B@XYZ-SIP.COM. The SIP INVITE  101  specifies the audio source as the real IP address of user client  83 , and specifies that QoS is requested. The SIP INVITE  101  also includes the authentication ticket received in response to Diameter session authentication request  97 . Upon receipt of the SIP INVITE  101 , SIP server  75  sends an INVITE  103  to the real IP address of user client  85 , at B@XYZ2000.COM. INVITE  103  specifies the audio source as the IP address of user client  83 . If user client  85  accepts the session, user client  85  sends a 2000 K SIP response  105  back to SIP Server  75 , specifying an audio destination as its real IP address.  
         [0029]     Upon receipt of 2000 K SIP response  105 , SIP server  75  sends a reserve bandwidth message  107  to MSCP policy server  81 . Message  107  specifies the audio source for the session of as the real IP address of user client  83 , and the audio destination for the session as the real IP address of user client  85 . The message  107  also includes the authentication ticket. Upon receipt of the message  107 , MSCP policy server  81  sends a response  109  back to MSCP S P server  81 . Then, SIP server  75  sends a SIP 2000 K response  11   1  to user client  83 .  
         [0030]     Upon receipt of 2000 K response  11   1 , user client  83  sends a resource reservation protocol (RSVP) path message  113  to ingress router  87 ; Then, ingress router  87  sends a COPS request handle message  115  to MSCP policy server  81 . when MSCP policy sewer  81  responds, as indicated at  117 , ingress router  87  sends an RSVP path message  119  to egress router  91 . Then, egress router  91  sends an RSVP path message  121  to user client  85 . User client  85  responds with an RSVP reservation response  123  back to egress router  91 . Egress router  91  then responds with an RSVP reservation response  125  back to ingress router  87 .  
         [0031]     Upon receipt of response  125 , ingress router  87  sends a UNI setup message  127  to ingress ATM switch  93 , Upon receipt of UNI setup message  127 , ingress ATM switch  93  sends a DNAP setup  129  to ingress ATM MSCP  77 . When ingress ATM MSCP  77  responds, as indicated at  131 , ingress ATM switch  93  sends a setup message  133  to egress ATM switch  95 . Upon receipt of setup message  133 , egress ATM switch  95  sends a DNAP setup message  135  to egress ATM MSCP  79 . When egress ATM MSCP  79  responds, as indicated at  137 , egress ATM switch  95  sends a UNI setup message  139  to egress router  91 .  
         [0032]     Upon receipt of setup message  139 , egress router  91  sends a CONNECT message  141  to ingress router  87 . Upon receipt of CONNECT message  141 , ingress router  87  responds to RSVP path message  113  with an RSVP reserve response  143  back to user client  83 . Then, the IP telephony session is established between user client  83  and user client  85 .  
         [0033]     The embodiment of  FIGS. 3 and 4 , distributes a certain amount of system intelligence to user clients  83  and  85 . User clients  83  and  85  are responsible for a greater part of call setup than are user clients  21  and  23  of the embodiment of  FIGS. 1 and 2 . User clients  83  and  85  process signaling in Diameter and RSVP protocols in addition to signaling in SIP protocol.  
         [0034]     From the foregoing it may be seen that the present invention overcomes the shortcomings of the prior art. The present invention dynamically establishes and secures QoS I′ telephony sessions by routing traffic on a high QoS backbone, which is preferably an ATM backbone. Those skilled in the art will recognize alternative embodiments, given the benefit of this disclosure. Accordingly, the foregoing disclosure is intended for purposes of illustration and not limitation.