Patent Publication Number: US-2006013231-A1

Title: Consolidated ethernet optical network and apparatus

Description:
BACKGROUND OF THE DISCLOSURE  
      A network may be characterized by several factors, such as who can use the network, the type of traffic the network carries, the medium carrying the traffic, the typical nature of the network&#39;s connections, and the transmission technology the network uses. For example, one network may be public and carry circuit-switched voice traffic while another may be private and carry packet-switched data traffic. Whatever the make-up, most networks facilitate the communication of information between at least two nodes, and as such act as communications networks.  
      At a physical level, a communication network may include a series of nodes interconnected by communication paths. Whether a network operates as a local area network (LAN), a metropolitan area networks (MAN), a wide are network (WAN) or some other network type, the act of designing the network becomes more difficult as the size and complexity of the network grows. When designing a given network, an operator or provider may decide where to physically locate various network nodes, may develop an interconnection strategy for those nodes, and may prepare a list of deployed and/or necessary networking components.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      It will be appreciated that for- simplicity and clarity of illustration, elements illustrated in the Figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements are exaggerated relative to other elements. Embodiments incorporating teachings of the present disclosure are shown and described with respect to the drawings presented herein, in which:  
       FIG. 1  illustrates a block diagram of a network that processes aggregate and core EON layers in accordance with the teachings of the present disclosure;  
       FIG. 2  presents a block diagram of a multiple-layer access node capable of accessing both aggregation and core layers according to one aspect of the present disclosure;  
       FIG. 3  presents a flow diagram illustrating operation of a multiple-layer access node within an EON in accordance with the teachings of the present disclosure; and  
       FIG. 4  illustrates a functional diagram of an EON in accordance with the teachings of the present disclosure.  
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS  
      Given the relative complexity of some communication networks, designers may invest substantial time and money to develop a feasible design for a given network. A feasible design may be one that satisfies design objectives like network coverage, network availability, and traffic demands, while considering that design limiters prefer defined limitations on equipment and/or interconnection topology.  
      In one form of the present disclosure, one or more core layer node and aggregator nodes are combined within the same node to reduce the number of physical nodes/locations required to employ a network. Such an embodiment displays several advantages over conventional networks that utilize separate nodes locations to access each layer. For example, the overall number of nodes or network elements required within a network may be reduced through the use of multiple-layer access nodes or elements and, as a result, the costs associated with cabling and electronics may be reduced. In other words, providing a multiple-layer node may assist in limiting the amount of hardware needed to deploy a desired network thereby reducing the overall cost of the network without sacrificing network performance.  
      Larger networks are often designed in layers. Each layer has its own roles and responsibilities. The goal of many network designers is to create a network that delivers high performance while maintaining a high degree of manageability. The following disclosure focuses on a layered design consisting of three layers, including a core layer, an aggregation layer, and an access layer.  
      From a high level, the core layer of a network may perform the backbone-like functions and may need to be both high speed and redundant. The aggregation layer may contain intermediate switches and routers, such as those used to route between subnets or VLANs. And, the access layer may be the point at which users actually plug into their local switch.  
      In practice, each layer in the model may have a primary responsibility and may be tasked with performing specific functions. As such, nodes of a given layer may need to have specific capabilities unique to that node&#39;s assigned layer. For example, the core layer may need to act as a high-speed switched backbone. A typical core layer node, therefore, does not perform routing functions. Core layer nodes may instead be expected to focus on switching traffic. Asking a core layer node to route traffic may reduce overall network performance, because each frame typically must be recreated as it passes through a router. In the core layer, the traffic tends to stay at OSI Layers  1  and  2  instead of having to be considered at Layer  3 .  
      Unlike the core layer, the aggregation layer is the layer at which the routing functions are likely to be performed. The aggregation layer may also represent the point at which various traffic policies are implemented. This may be accomplished with the assistance of access lists maintained in network repositories.  
      As mentioned above, the access layer may act as the point at which end stations connect to the network. A typical interface into the layered network may involve plugging into a Layer  2  switch or hub. As such, one of the primary responsibilities at the access layer is management of network collision domains. The access layer may also be used to define additional network security policies and filtering.  
       FIG. 1  illustrates a block diagram of a network capable of processing aggregation layer and core layer traffic at a single network node. The network described is a three layer EON. Though the following description focuses on EON design, the techniques of  FIG. 1  and this disclosure may also be used to design other types of networks. As indicated above, networks may take several forms. For example, a network implementing teachings of the present disclosure may embody a three layer, high-speed, fiber-based, Ethernet over MPLS network. By practicing the teachings disclosed herein, an operator may elect to integrate Layer  2  switching capabilities and Layer  3  routing capabilities into a single network node. In some embodiments, a network designer may make use of Multiprotocol Label Switching (MPLS) techniques to facilitate this integration.  
      In an MPLS-based network, a network operator may enjoy greater flexibility when routing traffic around link failures, congestion, and bottlenecks. From a Quality of Service (QoS) perspective, MPLS-based networks may also allow network operators to better manage different kinds of data streams based on priority and/or service plans.  
      In operation, a packet entering an MPLS network may be given a “label” by a Label Edge Router (LER). The label may contain information based on routing table entry information, Internet Protocol (IP) header information, Layer  4  socket number information, differentiated service information, etc. As such, different packets may be given different Labeled Switch Paths (LSPs), which may “allow” network operators to make better decisions when routing traffic based on data-stream type.  
      An EON like network  20 , as illustrated in  FIG. 1  manages traffic flow using a layer-based access topology designed to expedite communication of information across a fiber network. Customer Premises Equipment (CPE)  21  and  22  may serve as nodes of an access layer at a customer site and may be communicatively coupled to Provider Edge—Point of Presence (PE-POP) node  23  via multiple port communication modules  25 . PE-POP node  23  may act as a node in the aggregation layer, and may perform some routing functions for access layer traffic to and from CPE  21  and  22 . Moreover, node  23  may also work to multiplex and demultiplex traffic associated with CPE  21  and  22 . In some embodiments, node  23  may also be tasked with managing traffic from different types of media. For example, in operation, CPE  21  may be communicating with node  23  via an Ethernet link, and CPE  22  may be communicating with node  23  via a token ring link.  
      As shown, EON  20  also includes a core node  24  coupled to PE-POP  23  via communication ports  26 , which may be operable to communicate information between nodes within EON  20 . Core node  24  may serve core layer functions and may enable the high speed switching of traffic that is communicated between different aggregation layer nodes or PE-POP nodes.  
      PE-POP node  23  and core node  24  are typically provided as separate nodes having different physical locations within a network. As shown in  FIG. 1 , these nodes may be combined into a single node  10  capable of performing aggregation layer and core layer functions. As deployed, node  10  may have a housing component that at least partially defines an interior cavity. In preferred embodiments, one or more computing platforms capable of performing aggregation layer and core layer functions will be located within that interior cavity. Node  10  may also include one or more interface ports that allow for interconnection of node  10  with other nodes. In an EON network, these ports may facilitate coupling a fiber optic cable to node  10 . The ports may also be labeled as “core layer port” or “aggregation layer port.” As such, traffic arriving via the Core layer port may be directed to a node  10  mechanism capable of performing core layer switching. Similarly, traffic arriving via an aggregation layer port may be directed to the same or different node  10  mechanism capable of performing aggregation layer functions, such as routing.  
       FIG. 2  illustrates one embodiment of a multiple-layer network node operable to perform both aggregation and core layer functions according to one aspect of the disclosure. Within EON  33 , access layer sites  27  and  28  may allow users to interact with the network. Sites  27  and  28  are communicatively coupled to a multiple-layer network node  29  via communication ports  30 . In practice, some aggregation layer and core layer functionality may be performed by multiple-layer node  29 . For example, node  29  may be capable of combining network traffic for CPE  27  and  28  within a metro-based optical system. In addition, node  29  may be MPLS capable and operable to serve as the LER into the MPLS cloud.  
      In embodiments where multiple-layer node  29  also performs core layer switching, node  29  facilitates a reduction in the amount of network nodes. Depending upon the complexity of the network topology, data may be communicated upstream/downstream from multiple-layer node  29 , to another core node, to a different aggregation node, to another multiple-layer node, to access layer nodes, etc.  
      As such, EON  33  presents several advantages over typical networks that may employ discrete boxes to perform aggregation layer and core layer processing. For example, the overall number of fibers needed within EON  33  may be reduced, the overall number of routers and switches may be reduced, the amount of common equipment may be reduced, the number of repeaters between each node or network element may be reduced, a reduction in the number of remote test heads may be provided, the amount of supporting test equipment may be reduced, and a reduction in network traffic may be realized. One or more of these advantages should enable a network operator to increase a network&#39;s efficiency, reduce network latency, and lower the amount of power needed to operate the network.  
      Depending upon implementation detail, one or more elements within EON  33  may be configured with encoded logic to assist with accessing and/or processing one or more layers of the OSI stack. Such encoded logic may be provided as computer-readable mediums having computer-readable instructions capable of instructing a network node to perform aggregation layer functions, to perform core layer functions, and/or to perform access layer functions, as needed. For example, multiple-layer node  29  may include encoded logic operable to allow for switching traffic at Layer  2  and routing traffic at Layer  3 .  
      Several techniques may be used to provide for such a capability. Node  29  may employ a parallel processing schemas that make use of a multi-tasking processing engine. Node  29  may make use of discrete computing platforms—one dedicated to Layer  2  operations and another dedicated to Layer  3  operations. Node  29  may also elect to have both an internal core layer engine and an internal aggregation layer engine. Other techniques may also be utilized without departing from the teachings disclosed herein, and a choice of which technique to utilize may be determined by network design details, implementation details, and/or cost concerns.  
       FIG. 3  presents a flow diagram illustrating operation of a multiple-layer node within an EON in accordance with the teachings of the present disclosure. The method may be employed by the one or more nodes of the networks disclosed herein or other network and/or nodes operable to employ the method of  FIG. 3 . The method begins generally when data is presented to a multiple-layer node operable to act on both core layer traffic and aggregation layer traffic. Capabilities to operate on other layers may also be incorporated.  
      At step  312 , a type of processing needed is determined and access to an appropriate mechanism is provided at step  314 . If aggregation layer capability is needed, traffic from one or more sources may be routed for aggregation layer treatment at step  316  and an aggregation layer processing routine may be deployed at step  318  to properly work on the traffic. For example, an originating node or address for the data traffic may be communicatively-coupled to the multiple-layer node via an aggregation layer port, and the multiple-layer node may recognize that traffic arriving via the port needs to be internally routed to a module capable of handling aggregation layer functionality.  
      Similarly, if some core layer capability is needed, traffic from one or more sources may be routed for core layer treatment at step  320  and a core layer processing routine may be deployed at step  322  to properly work on the traffic. As indicated above, the mechanism used to distinguish between traffic needing core layer processing and aggregation layer processing may be as simple as hard-wiring specific ports to specific modules. The mechanism may also involve actually looking at and/or sniffing information contained in the packet being received by the multiple-layer node. The node may look at information contained in a packet header, for example, and make a determination based on that information. The node may also use other technologies like VLAN tagging and/or MPLS to assist in making a proper determination.  
      However accomplished, traffic received at step  312  may be properly processed and communicated to the next node in the network chain at step  324 . The method may then proceed to step  26  where the method is repeated based on access and/or required processing. As such, a single node or network element may be used to combine processing of both core layers and aggregation layers thereby increasing the efficiency of an EON system. It should be understood that  FIG. 3  illustrates one example of a method that may be used to enable multiple-layer processing in a layered network. The method of  FIG. 3  may also be applied to other types of networks and/or devices. Moreover, an entity making use of the method may add steps, delete steps, re-order steps, loop steps, and/or modify the method without departing from the teachings.  
       FIG. 4  illustrates a functional diagram of an EON in accordance with the teachings of the present disclosure. EON  70  illustrates one embodiment for employing a multiple-layer node capable of aggregation and core layer processing within a communication network. Information or data may be communicated between various access points having one or more types of configurations or topologies. For example, dual network access points  50  and  58  may include access modules that provide access to an access layer using two CPE modules. Single network access points  52  and  57  may allow for a single CPE to access an access layer. EON  70  further includes a multiple access module at site  51  that may be configured to allow for communication with multiple CPE access points using a series-based network topology. A hub access site  61  may also provided within EON  70  and may include a parallel access hub terminal coupled to multiple access modules and associated CPEs.  
      EON  70  illustrates specific layers for handling network traffic based on access privileges and functionality that is specific to each node within EON  70 . For example, each CPE element may communicate information to and from an access layer node. Aggregation processing modules  53  and  56  may be configured to manage aggregation layer functions, and core layer processing module  54  may be configured to manage core layer functions. Each node or element may be aligned with a specific layer to enable efficient management of network traffic within EON  70 . However, multiple-layer node  55  may straddle the aggregation layer and the core layer paradigms, and allow for aggregation layer and core layer processing of network traffic.  
      In one embodiment, aggregation layer processing modules  53  and  56 , core layer processing module  54 , and combined processing module  55  may be included within a single device configured to perform the functionality of two or more network layers. For example, a network designer may elect to utilize a Cisco 7609 IP/MPLS switch to perform multiple-layer functionalities.  
      Within network  70 , the communication of network traffic may be provided by fiber optic interconnects, fibers, etc.—facilitating metropolitan Ethernet services. As such, additional components, such as repeaters, may be utilized based on network complexity, size, cable distance, db loss, etc. Redundancy of communication mediums may also be provided via EoMPLS-VC 60 and backup VC 59 connections.  
      During operation, network traffic may be communicated from CPE sites  50  and  51  using aggregation node  53 . Similarly, network traffic for CPE sites  57  and  61  may be consolidated using aggregation node  56 . Core node  54  may support aggregation nodes  53  and  56  by enabling switched communication with other core layer nodes. Network traffic for each of aggregation nodes  53  and  56  may further be routed to multiple-layer node  55 , which may be operable to access both the aggregation layer and the core layer. As shown, multiple-layer node  55  is coupled to CPE sites  52  and  58 , and provides efficient processing of data by reducing the number of nodes required to access both aggregation and core layers. In this manner, processing of data associated with CPE sites  52  and  58  may be reduced thereby limiting the level of network complexity and overall network traffic within EON  70 .  
      Many of the above techniques may be provided by a computing device executing one or more software applications or engines. The software may be executing on a single system, node, more than one, etc. It will be apparent to those skilled in the art that the disclosed embodiments may be modified in numerous ways and may assume many embodiments other than the particular forms specifically set out and described herein.  
      Accordingly, the above-disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments that fall within the true spirit and scope of the present invention. Thus, to the maximum extent allowed by law, the scope of the present invention is to be determined by the broadest permissible interpretation of the following claims and their equivalents, and shall not be restricted or limited by the foregoing detailed description.