Abstract:
The present invention describes a standard way of defining network service classes, which provide default quality of service levels required for corresponding communication applications. The network service classes provide end-to-end quality of service policies that extend across multiple, disparate communication networks, and the network elements therein. In effect, the network elements within these communication networks are provisioned and network performance is engineered for the various network service classes. The various communication applications will be placed into the most appropriate network service class, which will provide at least the minimum quality of service performance requirements for the communication application. As such, communication applications having similar quality of service requirements will be grouped together, instead of having unique quality of service support in the communication networks.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to packet-based communications, and in particular to defining network services classes to which communications for corresponding communication applications are assigned to provide efficient and effective quality of service control.  
       BACKGROUND OF THE INVENTION  
       [0002]     Quality of service (QoS) is a broad term used to describe the overall experience a user application will receive during communications over a network. QoS involves a broad range of technologies, architectures, and protocols. Network operators achieve end-to-end quality of service by ensuring that network elements apply consistent treatment to traffic flows as packets traverse the network.  
         [0003]     Today, network traffic is highly diverse and each traffic type has unique requirements in terms of bandwidth, delay, loss, and availability. With the explosive growth of the Internet, most network traffic currently is Internet Protocol (IP) based. Having a single end-to-end transport protocol is beneficial, because networking equipment becomes less complex to maintain, which results in a lower operating cost. This benefit, however, is countered by the fact that IP is a connectionless protocol, wherein IP packets do not take a specific path as they traverse the network. This results in unpredictable quality of service and a best effort network.  
         [0004]     The Internet Protocol was originally designed to reliably get a packet to its destination with less consideration to the amount of time it takes to get there. IP networks must now support many types of applications. Many of these applications require low latency; otherwise, the end user quality may be significantly affected, or in some cases, the application simply does not function at all.  
         [0005]     Voice applications originate on public telephone networks using Time Division Multiplexing (TDM) technology, which has a very deterministic behavior. On TDM networks, the voice traffic experiences a low and fixed amount of delay with essentially no loss. Voice applications require this type of behavior to function properly, while also requiring the same level of “TDM voice” quality to meet user expectations.  
         [0006]     When voice is transported over a best effort IP network, the IP network introduces a variable and unpredictable amount of delay to the voice packets, and also drops voice packets when the network is congested. Thus, the best effort IP network does not provide the behavior that the voice application requires. Quality of service technologies can be applied to the best effort IP network to make it capable of supporting voice over IP with acceptable, consistent, and predictable voice quality.  
         [0007]     Notably, there are numerous types of applications requiring communications over various types of networks. These applications may support communications between people or between a person and a network device application, such as a personal computer or web server. Other applications may support communications between networking devices, such as from server to server or from router to router. Unfortunately, these applications may have very different quality of service performance requirements. The table below illustrates the various quality of service performance requirements for select communication applications.  
                                                         TABLE 1                           Quality of Service Performance Requirements                QoS Performance Requirements                Sensitivity to            Application   Bandwidth   Delay   Jitter   Loss               VoIP   Low   High   High   High       Video Conferencing   High   High   High   Med-High       Streaming Video on Demand   High   Med   Low   Med-High       Streaming Audio   Low   Med   Low   Med       Client/Server Transactions   Med   Med   Low   Med       Email   Low   Low   Low   Med       File Transfer   Med   Low   Low   Med                  
 
         [0008]     Notably, the communications network can introduce a moderate amount of loss and still provide good quality of service for client/server transactions, email, and file transfer applications, since these applications use the Transmission Control Protocol (TCP), which will detect lost packets and retransmit them. This is why some applications, including Client/Server, Email and File Transfer applications, can tolerate a moderate amount of loss as indicated in Table 1. In addition to the numerous communication applications having very different quality of service requirements, an end-to-end communication session may span multiple and disparate types of communication networks, which use different techniques to control quality of service. The quality of service control generally depends on the type of information being transported, subscriber service level agreements, or network policy agreements, and are applied within the layer 2 or layer 3 protocols. Unfortunately, any given network is generally only concerned with quality of service control within that network, and does not take into consideration the quality of service requirements or actions taken in adjacent yet disparate communication networks. Thus, there is significant difficulty associated with applying consistent quality of service standards for communications spanning disparate types of communication networks.  
       SUMMARY OF THE INVENTION  
       [0009]     The present invention describes a standard way of defining end-to-end network service classes, which provide default quality of service levels required for corresponding communication applications. The network service classes provide end-to-end quality of service policies that extend across multiple, disparate communication networks and the network elements therein. In effect, the network elements within these communication networks are provisioned and network performance is engineered for the various network service classes. The various communication applications are placed into the most appropriate network service class, which will provide at least the minimum quality of service performance requirements for the communication application. As such, communication applications having similar quality of service requirements will be grouped together, instead of having unique quality of service support in the communication networks.  
         [0010]     In operation, an edge device will analyze incoming packets, and monitor aspects of these packets to select a network service class based on packet parameters, which may include the type of content being carried or other information indicative of the relative quality of service needed. Headers of the packets are marked to reflect the quality of service parameters for the selected network service class, and the packets are routed toward their destination. Routing nodes within the communication networks receiving the marked packets will analyze the markings and process the packets according to the markings. In one embodiment, these markings are simply standardized protocol markings, which are readily recognized and processed by the routing nodes within the communication networks. As such, the routing nodes within disparate types of communication networks do not need to recognize specialized or proprietary quality of service markings, but will simply route the packets using standard quality of service markings associated with the protocol, because the edge device has determined the appropriate quality of service for the identified network service class. Multiple markings may be applied to a single packet, wherein different protocols at different layers may be used for routing packets across different communication networks.  
         [0011]     Those skilled in the art will appreciate the scope of the present invention and realize additional aspects thereof after reading the following detailed description of the preferred embodiments in association with the accompanying drawing figures. 
     
    
     BRIEF DESCRIPTION OF THE DRAWING FIGURES  
       [0012]     The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the invention, and together with the description serve to explain the principles of the invention.  
         [0013]      FIG. 1  is a block representation of a communication environment configured according to one embodiment of the present invention.  
         [0014]      FIG. 2  illustrates an exemplary process for handling packet traffic according to one embodiment of the present invention.  
         [0015]      FIG. 3  is a table illustrating exemplary network service classes.  
         [0016]      FIG. 4  is a table illustrating exemplary marking techniques by protocol associated with network service classes.  
         [0017]      FIG. 5  is a block representation of a communication client according to one embodiment of the present invention.  
         [0018]      FIG. 6  is a block representation of an edge device according to one embodiment of the present invention.  
         [0019]      FIG. 7  is a block representation of a routing node according to one embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0020]     The embodiments set forth below represent the necessary information to enable those skilled in the art to practice the invention and illustrate the best mode of practicing the invention. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the invention and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure and the accompanying claims.  
         [0021]     The present invention defines network service classes that are associated with default quality of service parameters. Each network service class is associated with different quality of service parameters, and communication applications are associated with the network service classes depending on the required quality of service for associated communication sessions. Thus, traffic for communication sessions will be classified and placed into an appropriate network service class and routed through the various communication networks based on the network service class quality of service parameters and associated network engineering. Details regarding the network services classes, classifying network traffic, and routing the traffic according to the selected network service class follow.  
         [0022]     Turning now to  FIG. 1 , a communication environment according to one embodiment of the present invention is illustrated. The communication environment  10  supports Internet Protocol (IP) services and allows unidirectional or bidirectional communication sessions to be established between communication clients  12  through one or more communication networks, such as an access network  14  providing traffic access or aggregation, Asynchronous Transfer Mode (ATM) network  16 , metro-Ethernet network  18 , and Multi-Protocol Label Switching (MPLS) network  20 . As illustrated, edge devices (EDs)  22  provide access to the access networks  14 , which are coupled together through the ATM, metro-Ethernet or MPLS networks  16 ,  18 , and  20 . Those skilled in the art will recognize that the edge devices  22  may be coupled to any type of communication network that supports wired or wireless communications, and may be coupled to the communication clients  12  through any type of communication network, including various types of access networks, such as cable, digital subscriber line (DSL), integrated services digital network (ISDN), cellular, wireless local area network (WLAN), broadband fixed wireless (WiMax) or other wired or wireless network. Further, the communication clients  12  may represent a subscriber endpoint, such as a telephony device, personal digital assistant (PDA), personal computer, or other communication device, as well as a content or service provider server, which is capable of delivering and receiving various types of content. The communication sessions themselves may be data, audio, video, or voice based sessions.  
         [0023]     The edge devices  22  may take the form of any type of router, switch, or gateway that facilitates the interworking between disparate types of networks. The edge devices  22  may also represent aggregation points, wherein media flows from multiple communication clients  12  are channeled into an appropriate communication format for transfer over the adjacent communication network. Further, the various communication networks will include various routing nodes (RNs)  24 , which may represent routers, switches, or other routing entity through which packet traffic is routed when routed through the various communication networks and between the various communication clients  12  or edge devices  22 . Network policy servers (NPSs)  26  may be used to implement service policies and control access to the networks and allocation of network resources based on subscriber, network, or service provider policies.  
         [0024]     For the present invention, various levels of quality of service are defined and associated with different network service classes, which are essentially different quality of service categories. Various communication applications require different levels of quality of service, and as such, the applications will be assigned to the most appropriate network service class, which will fulfill the quality of service requirements for that particular communication application. When communication sessions are established in association with a particular communication application, the traffic for the communication session will be classified and placed into the appropriate network service class and routed through the one or more communication networks. The traffic will be marked to identify the network service class, such that the routing nodes  24  and the various communication networks can quickly determine the relative level of quality of service required by the traffic, and process the traffic accordingly.  
         [0025]     In general, the edge devices  22  will monitor incoming traffic, determine a network service class, and mark the packets making up the traffic in a manner such that the various communication networks can process the traffic according to the desired quality of service levels. Since the traffic passes through different types of communication networks, the packets may be marked according to different protocols and in a different protocol layer so that the markings may be easily detected by the communication networks during processing and routing. Thus, the edge devices  22  will classify the traffic and mark it in a way in which the routing nodes  24  can readily detect the appropriate quality of service level to apply for the traffic. As such, there is no need to reclassify the traffic once the edge device  22  has classified and marked the packets associated with the traffic. Since the packets are marked for the various protocols and protocol layers, the routing nodes  24  in the different communication networks can readily determine the quality of service levels required for the traffic.  
         [0026]     Turning now to  FIG. 2 , a detailed flow diagram is provided for classifying and marking packets in the edge device  22 . Initially, the edge device  22  will monitor packets from a communication client  12 , which may be a customer endpoint, service provider server, or other communication entity (step  100 ), and analyze packet parameters bearing on an appropriate network service class (step  102 ). The analysis may take into consideration the type of content, the communication application associated with the packets, and the subscriber&#39;s service level agreement (SLA) to determine the requisite quality of service required for the packets. Based on the packet parameters, and inherently upon the required quality of service level for the packets, the edge device  22  will select an appropriate network service class (step  104 ). At this point, the edge device  22  will mark the packets in a manner reflecting the required quality of service for the selected network service class in light of the potential communication networks through which the packets will travel (step  106 ). As such, the packets may be marked in multiple and different ways according to the protocols or protocol layers that are used in the various communication networks for routing the packets. However, the different protocol or protocol layer markings are applied consistently across each communications network. For example, if the packets were routed through access networks  14  and the MPLS network  20 , the packets would be marked such that the access networks  14  and the MPLS network  20  can readily recognize the markings without special configuration to determine the relative quality of service level for the packets. Once marked, the packets are routed towards their destination (step  108 ). At this point, the routing nodes  24  will use their native protocol processing capabilities to analyze the markings provided by the edge devices  22  and process the packets according to the markings in the corresponding protocols and protocol layers (step  110 ).  
         [0027]     For defining quality of service parameters for multiple types of communication networks, there are different technologies, standards, and network architectures to consider. There is no single quality of service technology or standard that can be used to cross disparate types of networks. With reference to  FIG. 3 , exemplary network services classes are defined to provide appropriate quality of service for different types of applications. Service providers or network managers will determine the services to be offered or the applications supported. Based on this information, the edge devices  22  are configured to essentially place the traffic into the network service class that provides the closest quality of service required by the application or service being offered. Once the network service classes are defined, services can be quickly added using the predefined network service classes without having to specifically address the underlying quality of service technologies used in the particular communications network, since the edge devices  22  and the other routing nodes  24  throughout the various communication networks are preconfigured to provide the requisite quality of service defined by the network service classes.  
         [0028]     The network service class architecture illustrated in  FIG. 3  provides for eight different types of network service classes: critical, network, premium, platinum, gold, silver, bronze, and standard. These eight names are used for illustrative purposes only and can be described using alternative nomenclature. These network service classes generally correspond to four types of traffic categories, which include network control, interactive, responsive, and timely. The network control category may relate to critical network alarms, routing, billing, and operations, administration, and maintenance (OAM) applications within the confines of a provider&#39;s communications network or between communications network providers. The remaining three categories are for traffic initiated or terminated by the subscriber. The interactive category may include IP telephony, video conferencing, and interactive gaming applications and services. The responsive category may include streaming audio and video, television, video on demand (VOD), pay-per-view (PPV), and client/server transactions. The timely category may include email, non-critical OAM, and other best effort applications with minimal or no quality of service requirements.  
         [0029]     The network control category applications require a relatively low amount of delay, and loss needs to be minimized. Interactive category applications expect a network to provide packets with the lowest possible delay, jitter, and loss. Responsive category applications expect the network to provide packets with a relatively low amount of delay, jitter, and loss. Timely category applications expect a network to provide packet with a bounded amount of delay and loss. Jitter has a negligible effect on the timely category associated applications, and loss is essentially reduced to zero because of available retransmission and recovery mechanisms used by most applications in the timely category. The various applications may be split into different network service classes as defined. For example, IP telephony may be assigned to the premium network service class, wherein streaming audio, video, and television services may be assigned to the gold network service class.  
         [0030]     As described above, the edge devices  22  will analyze the traffic for a given quality of service session, and analyze parameters associated therewith to determine the network service class to which the traffic should be assigned. Once the network service class is selected, the packets are marked so that the routing nodes  24  or other devices can readily determine the quality of service parameters required for the individual packets, which will correspond to the assigned network service class. In essence, marking may take place by changing or adding header information in each packet corresponding to the appropriate protocol and protocol layer, which may be analyzed by various routing nodes  24  over the different communication networks. The Internet Engineering Task Force (IETF) differentiated services (DiffServ) architecture is typically used in the access networks  14 , wherein the edge devices  22  will modify the packet headers to include a DiffServ code point (DSCP), which best corresponds to the appropriate network service class as shown in  FIG. 4 . DiffServ provides quality of service in layer 3 of the protocol stack. For the ATM network  16 , the packets (or cells) will include an ATM service category that will correspond to the most appropriate network service class. ATM service categories generally control quality of service in layer 2 of the protocol stack. Similarly, point to point protocol (PPP) class numbers are used to identify the quality of service over digital subscriber line (DSL), Frame Relay or time division multiplex (TDM) networks. Routing nodes in the metro-Ethernet network  18  may use the IEEE&#39;s 802.1p user priority to identify the quality of service, wherein select values are assigned to the most appropriate network service classes. The IEEE 802.1p user priority markings are used in layer 2 of the protocol stack. The MPLS network  20  may use EXP bits, which have values corresponding to an appropriate network service class. In general, it is thought that the MPLS quality of service is controlled at layer 2.5, which is effectively a hybrid between layers 2 and 3.  
         [0031]     Accordingly, applications are assigned to the most appropriate network service class. The edge device  22  will classify the packet, and mark it such that the quality of service provided by the routing nodes  24  and any of the communication networks will provide a quality of service corresponding to the network service class. Notably, the routing nodes  24  do not need to know what the network service class is. The routing nodes  24  only need to know how to recognize the marking indicia in the packets and determine the appropriate quality of service required for the packet based thereon. The routing nodes  24  will essentially operate in traditional fashion using the traditional protocols. As such, the use of network service classes pulls together various quality of service standards and technologies in a meaningful way, allowing network service providers to provide standardized quality of service over different types of networks.  
         [0032]     Turning now to  FIG. 5 , a block representation of a communication client  12  is illustrated. The communication client  12  will include a control system  28  having memory  30  with the requisite software  32  and data  34  to operate as described above. The control system  28  will also be associated with one or more communication interfaces  36  to facilitate either wired or wireless communications, depending on the particular embodiment. Again, the communication client  12  may represent a subscriber communication device, service provider server, or any other device at which packets are sent or received in association with a communication session.  
         [0033]     An edge device  22  is illustrated in  FIG. 6  as including a control system  38  with memory  40  having the requisite software  42  and data  44  to operate as described above. The control system  38  may be associated with one or more network communication interfaces  46  for facilitating communications over a communication network, as well as one or more access communication interfaces  48  for facilitating communications with the communication clients  12  over various types of access networks.  
         [0034]     An exemplary routing node  24  is illustrated in  FIG. 7  as including a control system  50  having sufficient memory  52  for the requisite software  54  and data  56  to facilitate routing of packets as described above. The control system  50  will be associated with one or more packet communication interfaces  58  to enable routing or switching of packets through the appropriate communication network, which may include the access networks  14 , ATM network  16 , metro-Ethernet network  18 , and MPLS network  20 .  
         [0035]     Those skilled in the art will recognize improvements and modifications to the preferred embodiments of the present invention. All such improvements and modifications are considered within the scope of the concepts disclosed herein and the claims that follow.