Patent Publication Number: US-7724742-B2

Title: Communication bonding systems and methods

Description:
TECHNICAL FIELD 
   The present invention relates generally to communication systems and networks and, more particularly, to bonding techniques. 
   BACKGROUND 
   The increased utilization of the Internet, such as for multimedia applications, has created a growing demand for higher data rates. Consequently, Internet service providers have attempted to meet the demand by increasing the data rate available to their customers. Although new technologies are continually being developed to increase the data rate, it is generally cost prohibitive for an Internet service provider to deploy a new technology in their network or system architecture (e.g., between a customer and a central office of the Internet service provider). Thus, Internet service providers often prefer to leverage their current connection technologies to increase the available data rate to their customers. 
   Specifically, the demand for higher data rates is growing due to various factors. For example, companies may require additional capacity from their digital subscriber line for multimedia (e.g., video) applications, cable companies may require additional capacity to compete with incumbent local exchange carrier fiber deployments, and/or the central office, remote terminals, or network segments may require additional capacity due to the increased capacity between the user and the central office. 
   Several initiatives have been started to bond multiple channels of asymmetric digital subscriber line, data over cable service interface specification (DOCSIS), asynchronous transfer mode, Ethernet, and other types of access technologies and techniques to increase the effective information throughput. However, these types of bonding techniques typically require new hardware on both ends of the connection and/or a complete upgrade of existing equipment in the network. For example, a common approach for increasing capacity is to move to a new technology (e.g., fiber), but this approach, as noted above, generally is very costly. As a result, there is a need for improved communication techniques for providing greater data rates (i.e., capacity). 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a block diagram illustrating a bonding scheme in accordance with an embodiment of the present invention. 
       FIG. 2  shows a block diagram illustrating an exemplary implementation of the bonding scheme of  FIG. 1  in accordance with an embodiment of the present invention. 
   

   Embodiments of the present invention and their advantages are best understood by referring to the detailed description that follows. It should be appreciated that like reference numerals are used to identify like elements illustrated in one or more of the figures. 
   DETAILED DESCRIPTION 
   In accordance with one or more embodiments of the present invention, systems and methods are provided to implement an Internet Protocol (IP) bonding scheme. For example, in accordance with an embodiment of the present invention, Generic Routing Encapsulation (GRE) specification techniques are modified and employed to carry the additional information required to implement an IP bonding scheme. 
   An IP bonding scheme may provide certain advantages over conventional bonding schemes. For example, bonding at the IP layer allows multiple paths of access to be aggregated into one logical unit without concern for the actual access technology (e.g., physical or data layer technologies). Consequently, by implementing bonding (i.e., “channel” bonding) at a higher layer (i.e., the IP layer), the prohibitive expenses of implementing higher capacity physical layer services may be avoided. Thus, IP bonding may be more flexible for an Internet service provider implementing a bonding scheme within their current network architecture. 
   Various bonding schemes exist (e.g., Inverse Multiplexing over Asynchronous Transfer Mode (IMA), Multi-Link Point-to-Point Protocol (ML-PPP), Ethernet bonding, Time Division Inverse Multiplexing (TDIM) bonding, Multi-Link Frame Relay (ML-FR), Layer 2 Tunneling Protocol (L2TP)), however these schemes may have certain drawbacks relative to one or more embodiments of the present invention. For example, Asymmetric Digital Subscriber Line channel bonding at the Asynchronous Transfer Mode (ATM) or Ethernet layer may require new line cards for the Digital Subscriber Line Access Multiplexers (DSLAMs) or may require an entirely new DSLAM chassis. However, by bonding at the IP layer, in accordance with an embodiment of the present invention, new software code may be written for an existing DSLAM or two or more IP channels may be recombined in a router deeper within the network (e.g., within the core network). The software code may be stored in the memory of the device (e.g., provided via a network connection or provided via a machine-readable medium, such as a compact disk or other portable medium). Furthermore, by bonding at the IP layer, in accordance with an embodiment of the present invention, different technologies may be bonded, such as for example bonding one digital subscriber line connection with one data over cable service interface specification connection. 
   As an example,  FIG. 1  shows a block diagram illustrating a bonding scheme  100  in accordance with an embodiment of the present invention. Bonding scheme  100  employs a modified version of Generic Routing Encapsulation (GRE) techniques to include additional information so that information may be routed over more than one path (also referred to as channel) from a device  102  (e.g., a source device or a transmitting device) to a device  104  (e.g., a sink device or a receiving device). Thus, these techniques are applicable for transferring information (e.g., through a network) between any types of devices via any number of paths. 
   Device  102  and/or device  104  may represent, for example, any type of device (e.g., such as a gateway, a router, a computer, a server, a switch, or a hub) for communicating information. Devices  102  and  104  may include, for example, a processor and a memory for performing the techniques discussed herein, with the processor executing instructions stored in the memory. Alternatively, devices  102  and  104  may include specialized hardware for performing the techniques discussed herein as could be implemented by one skilled in the art. 
   Device  102  has an IP source address So (also referred to as the “inner” source IP address), while device  104  has an IP destination address D 0  (also referred to as the “inner” destination IP address). As shown in  FIG. 1 , the information may be transferred across any number of paths  106 , labeled Path 1  through Path n  (where n represents the number of paths, with n&gt;0) and possibly through one or more networks  108  (e.g., the Internet). Each one of paths  106  (e.g., Path 1 ) may be associated with an IP source address  110  (labeled S 1  through S n , also referred to as an “outer” source IP address) and an IP destination address  112  (labeled D 1  through D n , also referred to as an “outer” destination IP address). 
   As illustrated in  FIG. 1 , the information (or traffic) from device  102  (the source device) may be split or divided and provided through any number of paths to device  104  (the destination device), where the information is reassembled. This process may be viewed as an encapsulation of IP within IP followed by a decapsulation via a modification of Generic Routing Encapsulation techniques. The identification and/or negotiation (i.e., setup/teardown) of a bonded session (e.g., a tunnel technique) may be performed in a fashion as would be understood by one skilled in the art. 
   As an example,  FIG. 2  shows a block diagram  200  illustrating an exemplary implementation of the bonding scheme utilizing two paths (i.e., n equals two, with the paths labeled Path N  and Path N+ 1) in accordance with an embodiment of the present invention. As illustrated, encapsulation occurs at device  102  and decapsulation occurs at device  104 , with the inner source and destination IP addresses encapsulated within the outer source and destination IP addresses. The header information, as shown, may include path, session, and sequence number information as described further herein. Thus, a protocol format may include outer and inner source and destination IP addresses along with a header (e.g., S n , D n , Path n , Session M , Sequence number, S 0 , D 0 ). 
   In general, for example in reference to  FIGS. 1 and 2 , by assigning a path identification and a session identification inside the Generic Routing Encapsulation protocol, IP traffic can be split and reassembled across any number of physical or logical channels. At device  102  (i.e., the source or transmitter), the path identification specifies which channel the information (e.g., data) is assigned to or traveling through. At device  104  (i.e., the sink or receiver), the path identification specifies which channel the data arrived on or traveled through, which may be useful so that acknowledgements or requests for retransmission could, if desired, be sent back on the same path. 
   The session identification provides information to the device (e.g., device  104 ) that reassembles (or decapsulates) the information stream as to which traffic is bound together and must be kept grouped together. The sequence number (e.g., as specified in Generic Routing Encapsulation specification version 1) may be used to determine the order in which to reassemble the data in a given session identification. 
   An exemplary Generic Routing Encapsulation header, in accordance with an embodiment of the present invention, is shown in Table 1. The Generic Routing Encapsulation header (e.g., specified as version 2 or greater) may be included, for example, within a transport layer encapsulation protocol such as the following. 
   
     
       
         
             
             
             
             
             
           
             
                 
                 
             
           
          
             
                 
               MAC header 
               IP header 
               GRE header 
               Data ::: 
             
             
                 
                 
             
          
         
       
     
   
   As shown in Table 1, the Generic Routing Encapsulation is expanded from its conventional format (e.g., version 1 which includes the sequence number and acknowledgement number fields) to include a path identification field (e.g., of four bits), a path number field (e.g., a four bit “number of paths” field), and a session identification field (e.g., of eight bits). 
   
     
       
         
             
           
             
               TABLE 1 
             
           
          
             
                 
             
             
               Generic Routing Encapsulation Header 
             
          
         
         
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
          
             
               00 
               01 
               02 
               03 
               04 
               05 
               06 
               07 
               08 
               09 
               10 
               11 
               12 
               13 
               14 
               15 
               16 
               17 
               18 
               19 
               20 
               21 
               22 
               23 
               24 
               25 
               26 
               27 
               28 
               29 
               30 31 
             
             
                 
             
          
         
         
             
             
             
             
             
             
             
             
             
             
          
             
               C 
               R 
               K 
               S 
               s 
               Recur 
               A 
               Flags 
               Version 
               Protocol 
             
          
         
         
             
             
          
             
               Payload Length 
               Path ID (16-19), Path Number (20-23) Session ID (24-31) 
             
          
         
         
             
          
             
               Sequence Number 
             
             
               Acknowledgment Number  
             
             
                 
             
          
         
       
     
   
   In the exemplary Generic Routing Encapsulation header of Table 1, the “C” represents a checksum present field (e.g., one bit, which generally may be set to zero). The “R” represents a routing present field (e.g., one bit, which generally may be set to zero). The “K” represents a key present field (e.g., one bit, which generally may be set to one). The “S” represents a sequence number present field (e.g., one bit, which generally may be set to one), which is set if a payload packet is present and cleared if a payload packet is not present (the Generic Routing Encapsulation packet is an acknowledgment only). 
   The “s” represents a strict source route field (e.g., one bit, which generally may be set to zero). The “Recur” represents a recursion control field (e.g., three bits, which is an unsigned integer that generally may be set to zero). The “A” represents an acknowledgment sequence number present field (e.g., one bit) that is set to one if the packet contains an acknowledgment number to be used for acknowledging previously transmitted data. The flags field (e.g., four bits) generally must be set to zero. 
   The version field (e.g., three bits) may be set to two or more, depending upon the version number to be assigned to this form of the Generic Routing Encapsulation header. The protocol field (e.g., sixteen bits) contains the protocol type of the payload packet (e.g., 0x0800, which is the Ethernet Internet Assigned Numbers Authority (IANA) number for IPv4). The payload length field (e.g., sixteen bits) indicates the size of the payload, not including the Generic Routing Encapsulation header. 
   The path identification (path ID) field (e.g., four bits) contains the path identification for the path (e.g., tunnel or channel) to which the packet belongs. The path number field (e.g., four bits) contains the number of paths being used for the information to which this packet belongs. For example, if path number field value is set to zero (e.g., 0x00), this indicates that the session has not been split (i.e., there is only a single path for the session to which this packet belongs). The session identification (session ID) field (e.g., eight bits) indicates the session identification for the session (i.e., stream) to which this packet belongs. 
   The sequence number field (e.g., 32 bits) is an optional field that contains the sequence number of the payload. The sequence number field is present only if the “S” field (sequence number present field) bit is set (generally, this field will be used). The acknowledgement number (e.g., 32 bits) contains the sequence number of the highest numbered Generic Routing Encapsulation packet received by the sending peer for this user session. This field is present only if the “A” field (acknowledgment sequence number present) bit is set. 
   Systems and methods are disclosed herein to provide IP bonding. For example, in accordance with an embodiment of the present invention, an IP bonding scheme is disclosed that modifies Generic Routing Encapsulation techniques such that information may be divided and carried through multiple paths (e.g., to improve capacity). The exemplary implementations disclosed, in accordance with one or more embodiments of the present invention, are flexible and allow for certain types of traffic to be not split between multiple paths (e.g., such as voice over IP (VoIP) traffic). Thus, for example, the IP bonding mechanism may be applied only to those streams of data, which would benefit from (or not be harmed by) traveling down separate paths. 
   Other protocols are available, such as Real Time transport Protocol (RTP), Transmission Control Protocol (TCP over Internet Protocol (IP)), Internet Protocol Security (IPSec), and Layer 2 Tunneling Protocol (L2TP), but the techniques described herein (i.e., modified Generic Routing Encapsulation protocol techniques) may offer certain advantages in implementing higher level bonding methods. For example, the modified Generic Routing Encapsulation protocol may be encapsulated within Internet Protocol Security (IPSec). Furthermore, there is no inherent reliance on any particular protocol (e.g., point-to-point protocol (PPP), user datagram protocol (UDP), or transmission control protocol (TCP)) and a portion of the Generic Routing Encapsulation protocol may be reused (e.g., sequence numbering or acknowledgements). 
   Additional advantages may be provided by the techniques discussed herein relative to conventional approaches. For example, conventional inverse multiplexing schemes may not scale to next generation networks (e.g., as companies migrate away from ATM, IMA becomes impractical to implement, and ML-PPP relies on PPP while many broadband systems use Dynamic Host Configuration Protocol (DHCP)). It may also be difficult (or not appropriate) to modify IPv4 or IPv6 for inverse multiplexing, while a drawback of conventional Ethernet bonding schemes is their layer 2 dependence (e.g., the Ethernet). 
   In contrast, in accordance with one or more embodiments of the present invention, techniques are disclosed herein that may provide an inverse multiplexing scheme that may exist between layer 2 and layer 3 (e.g., by encapsulating IP). Consequently, the scheme may be independent of the physical layer and may be deployed to resolve “last mile” issues for broadband delivery mechanisms (e.g., wired or wireless). For example, the scheme can encapsulate IP between two physical endpoints, where the physical data rate is most likely to be constrained, without traversing an end-to-end network. As a further exemplary implementation, the scheme may prepend the IP with two bytes of information (e.g., path or channel ID of three bits, session ID of five bits, and sequence number of eight bits). Thus, for this example, up to 8 channels and 32 sessions may be bonded (or four channels with redundancy or failover) and up to 256 packets sequenced. 
   Furthermore, the techniques discussed herein may offer certain additional advantages. For example, physical links or paths may not need to be operated at the same speeds. Also, traffic that does not need to be bonded (e.g., VoIP) can still be routed over a bonded channel (e.g., a unique session ID may be provided and the traffic sent over only one channel ID or path). Load balancing may also be performed, especially for traffic that does not need to be bonded, by assigning a unique session ID and sending the traffic over a single channel such that non-bonded traffic shares the channel with bonded traffic. 
   Embodiments described above illustrate but do not limit the invention. It should also be understood that numerous modifications and variations are possible in accordance with the principles of the present invention. Accordingly, the scope of the invention is defined only by the following claims.