Patent Publication Number: US-7911937-B1

Title: Communication network architecture with diverse-distributed trunking and controlled protection schemes

Description:
RELATED APPLICATIONS 
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     FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
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     MICROFICHE APPENDIX 
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     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention is related to the field of communications, and in particular, to communication network architectures that have diverse-distributed trunking and controlled protection schemes. 
     2. Description of the Prior Art 
     Communication networks are becoming increasingly complex and costly. Part of the complexity and cost is due to the various protection schemes that are implemented. A protection scheme specifies how the network ensures that user communications reach their destination. This protection can be implemented at different layers of the well-known Open Systems Interconnection (OSI) Reference Model. 
     OSI layer one is the physical layer, and layer one protection entails using a back-up physical path when the primary physical path fails. For example, if the layer one interface detects a failure of the primary physical path, then the layer one interface automatically re-routes the traffic over the back-up physical path. An example of layer one protection is SONET 4-fiber, bi-directional, line-switched ring protection. SONET systems re-route traffic from a failed work path to a protect path. SONET systems also use rings, where if both work and protect physical paths fail around one side of the ring, then traffic is re-routed to the protect path around the opposite side of the ring. Another example of layer one protection is digital cross-connect systems that make connections/disconnections to physically replace a failed trunk with a back-up trunk between switches. 
     OSI layer two is the data link layer, and layer two protection entails re-sending traffic that is not properly received by the switch on the receiving end of the trunk. Thus, layer two protection ensures that packets are correctly transferred from one switch to another over their connecting trunk. Examples of layer two protection include the Proprietary Network-to-Network Interface (PNNI) for ATM and Dynamic Packet Routing Service (DPRS) for FR. In cases where a trunk fails or becomes congested, layer two protection will divert the traffic to another trunk. 
     OSI layer three is the network layer, and layer three protection entails re-sending traffic that is not properly received by the destination. Thus, layer three protection ensures that packets are correctly transferred from source to destination over the connecting network. Examples of layer three protection include the Transmission Control Protocol (TCP) that is used with IP. 
     Current communication networks typically implement protection schemes at layer one, layer two, and layer three. Unfortunately, layer one protection requires significant excess bandwidth to provide the back-up physical paths—especially when SONET rings are used. The increased bandwidth leads to increased cost. The multiple protection schemes are also complex to manage as communication networks migrate closer to a mesh configuration. 
     SUMMARY OF THE INVENTION 
     Some examples of the invention include a communication network architecture comprising an access tier including access packet switches coupled to users, a backbone tier including hub packet switches coupled to one another, and a transit tier including transit packet switches coupling the access tier to the backbone tier. The access packet switches are coupled to the transit tier by physically diverse access communication trunks. The transit packet switches are coupled to the backbone tier by physically diverse transit communication trunks. OSI layer one protection is disabled between the access tier and the transit tier and is disabled between the transit tier and the backbone tier. OSI layer two protection is enabled between the access tier and the transit tier and is enabled between the transit tier and the backbone tier. 
     Some examples of the invention include a communication network architecture comprising a plurality of access packet switches, a plurality of transit packet switches, a plurality of hub packet switches, a plurality of backbone communication trunks coupling the hub packet switches together, a plurality of transit communication trunks coupling the hub packet switches to the transit packet switches, and a plurality of access communication trunks coupling the transit packet switches to the access packet switches. Each one of the transit packet switches is coupled to two of the hub packet switches by physically diverse ones of the transit communication trunks. Each one of the access packet switches is coupled to two of the transit packet switches by physically diverse ones of the access communication trunks. The access packet switches and the transit packet switches are configured to exchange user communication packets over the access communication trunks. The transit packet switches and the hub packet switches are configured to exchange the user communication packets over the transit communication trunks. The hub packet switches are configured to exchange the user communication packets with one another over the backbone communication trunks. The access packet switches, the transit packet switches, and the hub packet switches are configured to implement layer two protection for the user communication packets. Layer one protection is disabled on the access communication trunks and the transit communication trunks. 
     Some examples of the invention include a communication network architecture comprising a plurality of communication trunks, a plurality of communication nodes, and a control system. The communication nodes are configured to exchange user communications over the communication trunks. The communication nodes are configured to enable or disable layer one protection and enable or disable layer two protection for a selected one of the communication trunks in response to a control message. The control system is configured to select the selected one of the communication trunks and a protection scheme for the selected one of the communication trunks. The selected protection scheme indicates if layer one protection is enabled or disabled and whether layer two protection is enabled or disabled. In response, the control system is configured to generate and transfer the control message indicating the selected one of the communication trunks and the selected protection scheme for the selected one of the communication trunks. 
     Some examples of the invention include a communication network architecture comprising a plurality of communication trunks, a plurality of communication nodes, and a control system. The communication nodes are configured to exchange user communications over the communication trunks. The communication nodes are configured to enable or disable layer one protection and enable or disable layer three protection for a selected one of the communication trunks in response to a control message. The control system is configured to select the selected one of the communication trunks and a protection scheme for the selected one of the communication trunks. The selected protection scheme indicates if layer one protection is enabled or disabled and whether layer three protection is enabled or disabled. In response, the control system is configured to generate and transfer the control message indicating the selected one of the communication trunks and the selected protection scheme for the selected one of the communication trunks. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The same reference number represents the same element on all drawings. 
         FIG. 1  illustrates a communication network architecture in an example of the invention. 
         FIG. 2  illustrates a communication network architecture in an example of the invention. 
         FIG. 3  illustrates a protection control system in an example of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIGS. 1-3  and the following description depict specific examples to teach those skilled in the art how to make and use the best mode of the invention. For the purpose of teaching inventive principles, some conventional aspects have been simplified or omitted. Those skilled in the art will appreciate variations from these examples that fall within the scope of the invention. Those skilled in the art will appreciate that the features described below can be combined in various ways to form multiple variations of the invention. As a result, the invention is not limited to the specific examples described below, but only by the claims and their equivalents. 
     Example #1 
       FIG. 1  illustrates communication network architecture  100  in an example of the invention. Communication network architecture  100  includes access packet switches  101 - 103 , transit packet switches  111 - 113 , hub packet switches  121 - 123 , access communication trunks  141 - 146 , transit communication trunks  151 - 156 , and backbone communication trunks  161 - 163 . The number of switches and trunks has been restricted for clarity, but there could be more switches and trunks if needed. Typically there are more access packet switches than transit packet switches, and there are more transit packet switches than hub packet switches. 
     Packet switches  101 - 103 ,  111 - 113 , and  121 - 123  could be Frame Relay (FR) switches, Asynchronous Transfer Mode (ATM) switches, Internet Protocol (IP) switches, or some other type of packet switches. In addition, the switches may integrate packet switching for multiple formats. For example, a packet switch may handle both FR traffic and ATM traffic—possibly by encapsulating the FR traffic in ATM cells. The packet switches also have internal or external physical layer interfaces, such as Synchronous Optical Network (SONET) interfaces or DS1/DS3 electrical interfaces. 
     User communication trunks  131 - 139  couple the users to access packet switches  101 - 103 . Access communication trunks  141 - 146  couple access packet switches  101 - 103  to transit packet switches  111 - 113 . Transit communication trunks  151 - 156  couple transit packet switches  151 - 156  to hub packet switches  121 - 123 . Backbone communication trunks  161 - 163  couple hub packet switches  121 - 123  together. 
     Each of trunks  141 - 146 ,  151 - 156 , and  161 - 163  comprises a communication link between two switches. The communication link is typically bi-directional and resides in an optical fiber, although metallic, wireless, or some other form of media may be used for the communication link. Multiple communication links may occupy the same physical media. 
     Note that a trunk may be physically diverse with another trunk. Physical diversity means that the two trunks follow substantially different physical paths. Substantially different physical paths may overlap when they are proximate to the switch that both trunks are coupled to, but otherwise, the different physical paths do no overlap. 
     The following table indicates the specific switch/trunk/user interconnections. 
     
       
         
           
               
               
               
               
             
               
                   
               
               
                   
                 COUPLED 
                 COUPLED 
                 DIVERSE 
               
               
                 TRUNK 
                 TO 
                 TO 
                 WITH 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                 131 
                 USERS 
                 ACCESS SWITCH 101 
                 — 
               
               
                 132 
                 USERS 
                 ACCESS SWITCH 101 
                 — 
               
               
                 133 
                 USERS 
                 ACCESS SWITCH 101 
                 — 
               
               
                 134 
                 USERS 
                 ACCESS SWITCH 102 
                 — 
               
               
                 135 
                 USERS 
                 ACCESS SWITCH 102 
                 — 
               
               
                 136 
                 USERS 
                 ACCESS SWITCH 102 
                 — 
               
               
                 137 
                 USERS 
                 ACCESS SWITCH 103 
                 — 
               
               
                 138 
                 USERS 
                 ACCESS SWITCH 103 
                 — 
               
               
                 139 
                 USERS 
                 ACCESS SWITCH 103 
                 — 
               
               
                 141 
                 ACCESS SWITCH  
                 TRANSIT SWITCH  
                 TRUNK 142 
               
               
                   
                 101 
                 111 
                   
               
               
                 142 
                 ACCESS SWITCH  
                 TRANSIT SWITCH  
                 TRUNK 141 
               
               
                   
                 101 
                 112 
                   
               
               
                 143 
                 ACCESS SWITCH  
                 TRANSIT SWITCH  
                 TRUNK 144 
               
               
                   
                 102 
                 112 
                   
               
               
                 144 
                 ACCESS SWITCH  
                 TRANSIT SWITCH  
                 TRUNK 143 
               
               
                   
                 102 
                 113 
                   
               
               
                 145 
                 ACCESS SWITCH  
                 TRANSIT SWITCH  
                 TRUNK 146 
               
               
                   
                 103 
                 111 
                   
               
               
                 146 
                 ACCESS SWITCH  
                 TRANSIT SWITCH  
                 TRUNK 145 
               
               
                   
                 103 
                 113 
                   
               
               
                 151 
                 TRANSIT SWITCH  
                 HUB SWITCH 121 
                 TRUNK 152 
               
               
                   
                 111 
                   
                   
               
               
                 152 
                 TRANSIT SWITCH  
                 HUB SWITCH 122  
                 TRUNK 151 
               
               
                   
                 111 
                   
                   
               
               
                 153 
                 TRANSIT SWITCH  
                 HUB SWITCH 122  
                 TRUNK 154 
               
               
                   
                 112 
                   
                   
               
               
                 154 
                 TRANSIT SWITCH  
                 HUB SWITCH 123  
                 TRUNK 153 
               
               
                   
                 112 
                   
                   
               
               
                 155 
                 TRANSIT SWITCH  
                 HUB SWITCH 122  
                 TRUNK 156 
               
               
                   
                 113 
                   
                   
               
               
                 156 
                 TRANSIT SWITCH  
                 HUB SWITCH 123  
                 TRUNK 155 
               
               
                   
                 113 
                   
                   
               
               
                 161 
                 HUB SWITCH 121 
                 HUB SWITCH 122 
                 — 
               
               
                 162 
                 HUB SWITCH 121 
                 HUB SWITCH 123 
                 — 
               
               
                 163 
                 HUB SWITCH 122 
                 HUB SWITCH 123 
                 — 
               
               
                   
               
            
           
         
       
     
     Note that each one of access packet switches  101 - 103  is coupled to two of transit packet switches  111 - 113  by physically diverse access communication trunks  141 - 146 . For example, access packet switch  101  is coupled to transit packet switch  111  by trunk  141  and to transit packet switch  112  by trunk  142 —where trunk  141  is physically diverse from trunk  142 . Also note that each one of transit packet switches  111 - 113  is coupled to two of hub packet switches  121 - 123  by physically diverse ones of access communication trunks  151 - 156 . For example, transit packet switch  111  is coupled to hub packet switch  121  by trunk  151  and to hub packet switch  122  by trunk  152 —where trunk  151  is physically diverse from trunk  152 . 
     In operation, the users and access packet switches  101 - 103  exchange user communication packets over user trunks  131 - 139 . Access packet switches  101 - 103  and transit packet switches  111 - 113  exchange user communication packets over access communication trunks  141 - 146 . Transit packet switches  111 - 113  and hub packet switches  121 - 123  exchange the user communication packets over transit communication trunks  151 - 156 . Hub packet switches  121 - 123  exchange the user communication packets with one another over backbone communication trunks  161 - 163 . Thus, the users may exchange user communication packets with one another over communication network architecture  100 . 
     Each of access packet switches  101 - 103  distributes its traffic to coupled ones of access communication trunks  141 - 146 . For example, for traffic sent to the transit switches, access packet switch  101  sends some of its traffic over trunk  141  and sends the rest of its traffic over trunk  142 . Likewise, transit packet switches  111 - 113  distribute their traffic over transit communication trunks  151 - 156 . For example, for traffic sent to the hub switches, transit packet switch  111  sends some of its traffic over trunk  151  and sends the rest of its traffic over trunk  152 . Thus, the packet switches distribute traffic over diverse trunks to create the diverse-distributed aspects of the network architecture. 
     The load on each of trunks  141 - 146  and  151 - 156  is limited to a percentage of trunk capacity to maintain some excess capacity on each trunk. The excess capacity is used to handle increased traffic loading if another trunk fails. For example, trunks  141 - 146  and  151 - 156  could be limited to 50% of their capacity during normal operation. 
     Communication network architecture  100  is comprised of three tiers—access tier  191 , transit tier  192 , and backbone tier  193 . Access tier  191  includes access packet switches  101 - 103  that are coupled to the users. Thus, access tier  191  provides network access to users. Backbone tier  193  includes hub packet switches  121 - 123  that are interconnected with one another. Thus, backbone tier  193  represents the top of the switching hierarchy where each hub packet switch can route traffic to any of the other hub packet switches. Transit tier  192  includes transit packet switches  111 - 113  and provides an interface between access tier  191  and backbone tier  193 . Note that each packet switch in access tier  191  has two physically diverse trunks to transit tier  192 , and each packet switch in transit tier  192  has two physically diverse trunks to backbone tier  193 . In some variations, access tier  191  may not use physically diverse trunks to access transit tier  192 . 
     A protection scheme specifies how the switches ensure that user communication packets reach their correct destination. This protection can be implemented at different layers of the well-known Open Systems Interconnection (OSI) Reference Model. 
     OSI layer one is the physical layer, and layer one protection entails using a back-up physical path when the primary physical path fails. For example, if the layer one interface detects a failure of the primary physical path, then the layer one interface automatically re-routes the traffic over the back-up physical path. An example of layer one protection is SONET protection. SONET systems re-route traffic from a failed work path to a protect path. SONET systems also use rings, where if both work and protect physical paths fail around one side of the ring, then traffic is re-routed to the protect path around the opposite side of the ring. Another example of layer one protection is digital cross-connect systems that make connections/disconnections to physically replace a failed trunk with a back-up trunk between switches. 
     OSI layer two is the data link layer, and layer two protection entails re-sending traffic that is not properly received by the switch on the receiving end of the trunk. Layer two protection can also be accomplished through the use, by layer two logic, of alternative paths in the event of failure or congestion on the primary path. Thus, layer two protection ensures that packets are correctly transferred from one switch to another over their connecting trunk. Examples of layer two protection include the Proprietary Network-to-Network Interface (PNNI) for ATM and Dynamic Packet Routing Service (DPRS) for FR. In cases where a trunk fails or becomes congested, layer two protection will divert the traffic to another trunk. For example, if trunk  151  fails or becomes congested, then transit packet switch can divert the traffic over trunk  152 . 
     OSI layer one protection is disabled for access communication trunks  141 - 146  between access packet switches  101 - 103  and transit packet switches  111 - 103 . OSI layer two protection is enabled for access communication trunks  141 - 146  between access packet switches  101 - 103  and transit packet switches  111 - 103 . OSI layer one protection is disabled for transit communication trunks  151 - 156  between transit packet switches  111 - 113  and hub packet switches  121 - 123 . OSI layer two protection is enabled for transit communication trunks  151 - 156  between transit packet switches  111 - 113  and hub packet switches  121 - 123 . Thus, layer one protection is disabled between access tier  191  and transit tier  192 , and disabled between transit tier  192  and backbone tier  193 ; and layer two protection is enabled between access tier  191  and transit tier  192 , and enabled between transit tier  192  and backbone tier  193 . 
     Example #2 
       FIG. 2  illustrates communication network architecture  200  in an example of the invention. Communication network architecture  200  includes communication nodes  201 - 205 , communication trunks  211 - 220 , protection control system  270 , and control links  271 - 275 . Control links  271 - 275  connect protection control system  270  to respective communication nodes  201 - 205 . The following table indicates how communication nodes  201 - 205  are connected by communication trunks  211 - 220 . 
     
       
         
           
               
               
               
             
               
                   
               
               
                 TRUNK 
                 NODE 
                 NODE 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 211 
                 201 
                 202 
               
               
                 212 
                 201 
                 203 
               
               
                 213 
                 201 
                 204 
               
               
                 214 
                 201 
                 205 
               
               
                 215 
                 202 
                 203 
               
               
                 216 
                 202 
                 204 
               
               
                 217 
                 202 
                 205 
               
               
                 218 
                 203 
                 204 
               
               
                 219 
                 203 
                 205 
               
               
                 220 
                 204 
                 205 
               
               
                   
               
            
           
         
       
     
     Communication nodes  201 - 205  include a layer one interface, such as SONET. Communication nodes also include a layer two interface, such as ATM or FR, and/or a layer three interface, such as and TCP/IP. Communication nodes  201 - 205  exchange user communications over communication trunks  211 - 220   
     Communication nodes  201 - 205  can enable or disable protection at layers one, two, and three for selected communication trunks in response to control messages. For example, communication nodes  201  and  202  can disable layer one protection and enable layer two protection on communication trunk  211  in response to control messages. Likewise, communication nodes  204  and  205  can enable layer one protection and disable layer two protection on communication trunk  220  in response to control messages. 
     Protection control system  270  selects communication trunks and protection schemes for the selected communication trunks. In response, protection control system  270  generates and transfers control messages indicating the selected communication trunks and their selected protection schemes. The selected protection scheme indicates which protection layers are enabled and which protection layers are disabled. 
     For example, protection control system  270  may select communication link  215  between communication nodes  202 - 203 . Protection control system  270  may then select a protection scheme with layer  1  protection disabled and layer  2  protection enabled. In response, protection control system  270  generates and transfers control messages to communication nodes  202 - 203  over respective control links  272 - 273  indicating the selected communication trunk  215  and the selected protection scheme. In response to the control messages, communication nodes  202 - 203  disable layer one protection and enable layer two protection on communication trunk  215 . 
     In another example, protection control system  270  may select communication link  218  between communication nodes  203 - 204 . Protection control system  270  may then select a protection scheme with layer  1  protection enabled and layer  2  protection disabled. In response, protection control system  270  generates and transfers control messages to communication nodes  203 - 204  over respective control links  273 - 274  indicating the selected communication trunk  218  and the selected protection scheme. In response to the control messages, communication nodes  203 - 204  enable layer one protection and disable layer two protection on communication trunk  218   
     In some variations, protection control system  270  has a user interface that allows an operator to select trunks and protection schemes, and protection control system  270  makes its selections based on operator inputs. For example, protection control system  270  could provide a graphic display of the network to allow operator trunk selection on the display. Once the trunk is selected, the display may show a dialog box indicating the current protection scheme to allow the operator to change the protection scheme on the display. A control button on the display would allow the operator to implement new protection schemes for selected trunks by issuing the appropriate control messages to the appropriate communication nodes. 
     In some variations, protection control system  270  may automatically select trunks and protection schemes in response to user communication history data and service level agreement data. For example, a user may have a service level agreement that requires a certain level of quality from the communication network. If the user communication history data indicates that recent outages are threatening to drop actual network performance below the level of quality required by the service level agreement, then protection control system can improve the protection scheme on trunks that carry user communications. In response to these changes, protection control system  270  issues the appropriate control messages to communication nodes  201 - 205 . 
       FIG. 3  illustrates protection control system  270  in an example of the invention. Protection control system  270  includes communication interface  301 , processing system  302 , and user interface  303 . Processing system  302  includes storage system  304 . Storage system  304  stores software  305 . Processing system  302  is linked to communication interface  301  and user interface  303 . Protection control system  270  could be comprised of a programmed general-purpose computer, although those skilled in the art will appreciate that programmable or special purpose circuitry and equipment may be used. Protection control system  270  may use a client server architecture where operations are distributed among a server system and client devices that together comprise elements  301 - 305 . 
     Communication interface  301  could comprise a network interface card, modem, port, or some other communication device. Communication interface  301  may be distributed among multiple communication devices. Processing system  302  could comprise a computer microprocessor, logic circuit, or some other processing device. Processing system  302  may be distributed among multiple processing devices. User interface  303  could comprise a keyboard, mouse, voice recognition interface, microphone and speakers, graphical display, touch screen, or some other type of user device. Storage system  304  could comprise a disk, tape, integrated circuit, server, or some other memory device. Storage system  304  may be distributed among multiple memory devices. 
     Processing system  302  retrieves and executes software  305  from storage system  304 . Software  305  may comprise an operating system, utilities, drivers, networking software, and other software typically loaded onto a general-purpose computer. Software  305  could comprise an application program, firmware, or some other form of machine-readable processing instructions. When executed by processing system  302 , software  305  directs processing system  302  to control protection control system  270  operation as described herein. 
     Those skilled in the art will appreciate that aspects of Example #1 and Example #2 could be implemented together to form variations of the invention. 
     ADVANTAGES 
     If desired, the invention may be implemented to provide some of the following advantages, although other implementations of the invention may provide different advantages. 
     In some examples, the invention disables layer one protection to save bandwidth and its resulting cost. These examples use layer two or three protection and diverse-distributed trunking to provide cost-effective protection for the user communications. The diverse-distributed trunking architecture is also less complex to manage than current architectures having layer one protection. 
     In some examples, the invention allows the selection of a protection scheme on a per trunk basis. This provides an effective way to manage protection across the network. These examples allow the network to set protection levels that meet the cost and quality requirements of the user.