Abstract:
An adaptive module for a cable modem termination system housing having a backplane and a card cage that is attachable to the housing is provided. Active and backup first electronic modules are disposed within the card cage and are electrically connected to the backplane. The active and backup first electronic modules are respectively electrically connectable to active and backup second electronic modules disposed within the housing, where the backup first electronic module communicates with the backup second electronic module when there is a failure within the active second electronic module. A switch/relay is disposed within the card cage and is electrically connected to the backplane. The switch/relay is adapted to enable communication between the active first electronic module and the backup second electronic module when there is a failure within the active second electronic module.

Description:
TECHNICAL FIELD  
         [0001]    The present invention relates generally to the field of housings for electronics and, in particular, to an adaptive module for housings.  
         BACKGROUND  
         [0002]    A common method for improving system reliability involves redundancy. This typically involves having active system components and backup system components that duplicate the active system components. The purpose of the backup system components is to take over for the active system components in the event that the active system components fail. In many electronic systems, such as cable modem termination systems (CMTSs), this involves switching from the active system components to the backup system components when the active system components fail.  
           [0003]    In the example of cable modem termination systems, many cable modem termination systems include a number of electronic modules that are contained within housings and are plugged into backplanes within the housings. To provide redundancy, some of the electronic modules are used as backup modules. This is typically accomplished using additional components, e.g., for connecting the electronic modules to function as backups, switching to the backup modules, etc. However, this usually requires designing and manufacturing a separate line of larger housings for accommodating the additional components. Moreover, it is often desirable to upgrade non-redundant systems to redundant systems in the field. One problem with this is that the housings for many non-redundant systems are too small to accommodate the additional components. Therefore, the non-redundant system, including the housing, needs to be replaced with a redundant system in a larger housing. Some manufacturers provide for upgrades by housing the non-redundant systems in housings large enough to accommodate the additional components and include the additional components. However, many customers do not require such upgrades and end up paying for larger housings and for additional components that are not needed, as well as higher shipping costs for shipping the larger housings and additional components.  
           [0004]    For the reasons stated above, and for other reasons stated below that will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for mitigating the problems associated with adding additional components to electronic systems, such as cable modem termination systems, for making these systems redundant.  
         SUMMARY  
         [0005]    The above-mentioned problems with adding additional components to electronic systems to make these systems redundant and other problems are addressed by embodiments of the present invention and will be understood by reading and studying the following specification. Embodiments of the present invention provide an adaptive module for modifying existing housings for containing non-redundant electronic systems, such as the existing housings for non-redundant cable modem termination systems, to add redundancy to the electronic systems. This enables existing non-redundant electronic systems to be upgraded in the field to redundant systems without having to replace the existing housing. Moreover, this eliminates the need for designing and manufacturing a new line of housings for housing redundant systems. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    [0006]FIG. 1 is an exploded perspective view of a housing according to the teachings of the present invention.  
         [0007]    [0007]FIG. 2 is an exploded side view of the housing of FIG. 1. 
     
    
     DETAILED DESCRIPTION  
       [0008]    In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific illustrative embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that logical, mechanical and electrical changes may be made without departing from the spirit and scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense.  
         [0009]    [0009]FIGS. 1 and 2 illustrate an embodiment of a housing  100  for an electronic system, such as a cable modem termination system, according to the teachings of the present invention. FIG. 1 is an exploded perspective view, and FIG. 2 is an exploded side view. Housing  100  includes a base module  102  and an adaptive module  104 . In one embodiment, base module  102  is a basic housing for a non-redundant electronic system, such as a cable modem termination system, e.g., a non-redundant CUDA  12000  cable modem termination system commercially available from ADC Telecommunications of Eden Prairie, Minn. In another embodiment, adaptive module  104  is added to base module  102  to add redundancy to the electronic system.  
         [0010]    In one embodiment, adaptive module  104  is added to a basic housing of a non-redundant cable modem termination system to upgrade the non-redundant cable modem termination system without having to change the basic housing of the non-redundant system. In other embodiments, adaptive module  104  is added to the basic housing of non-redundant cable modem termination systems during manufacturing, enabling redundant cable modem termination systems to be manufactured from the existing basic housings. This eliminates the need for designing and manufacturing a new line of housings for housing redundant systems.  
         [0011]    Base module  102  is adapted to house a number of primary electronic modules adapted to transmit and receive signals, e.g., primary electronic modules  108   1  and  108   2  of the electronic system. More particularly, base module  102  includes a card cage  116  having slots  117  for receiving primary electronic modules  108   1  and  108   2 . A backplane  118  is secured within card cage  116  adjacent to an end  120  of card cage  116  using fasteners, such as screws, bolts or the like. Each of primary electronic modules  108   1  and  108   2  plugs into backplane  118 . For example, connectors  122  and  124  of primary electronic module  1081  respectively connect to connectors  126  and  128  of backplane  118 , as shown in FIG. 2. In one embodiment, base module  102  of housing  100  includes plenums  146  for providing directed airflow for cooling the electronic system.  
         [0012]    Adaptive module  104  has a backplane  110 . In one embodiment, backplane  110  is secured to card cage  116  adjacent to end  120  of card cage  116  so that backplane  110  is spaced from backplane  118  and is parallel to backplane  118 . In another embodiment, a cover  130  is disposed between backplane  110  and backplane  118 . A card cage  132  of adaptive module  104  is secured to card cage  116  adjacent to end  120  using fasteners, such as screws, bolts, or the like. A number of secondary electronic modules adapted to transmit and receive signals, e.g., secondary electronic modules  112   1  and  112   2 , are disposed in slots  134  of card cage  132 . Each of secondary electronic modules  112   1  and  112   2  respectively connects to each of primary electronic modules  108   1  and  108   2 . In various embodiments, each of secondary electronic modules  112   1  and  112   2  respectively receives signals from and/or transmits signals to each of primary electronic modules  108   1  and  108   2    
         [0013]    More specifically, connector  136  of secondary electronic module  112   1  connects to connector  138  of primary electronic module  108   1 , as illustrated in FIG. 2. Each of secondary electronic modules  112   1  and  112   2  also connect to backplane  110 , e.g., connector  140  of secondary electronic module  112   1  connects to connector  142  of backplane  110 . Circuit boards of a switch/relay  114  are disposed in slots  143  of card cage  132 . Switch/relay  114  connects to connector  144  of backplane  110 . Secondary electronic module  112   1  includes a number of connectors  148  for connecting the electronic system to remote equipment, such as modems or the like. In one embodiment, connectors  148  transmit signals to remote equipment and receive signals from the remote equipment.  
         [0014]    In one embodiment, secondary electronic modules  112   1  and  112   2  are respectively active and backup secondary electronic modules, and primary electronic modules  108   1  and  108   2  are identical. Connecting secondary electronic module  112   2  to primary electronic module  108   2  and to backplane  110  connects primary electronic module  108   2  as a backup to primary electronic module  108   1 . Switch/relay  114  switches operation from primary electronic module  108   1  to primary electronic module  108   2  in the event a failure occurs within primary electronic module  108   1 . In this way, adaptive module  104  adds redundancy to an otherwise non-redundant electronic system.  
         [0015]    During operation, secondary electronic module  112   1  receives first signals from primary electronic module  108   1 , designated as an active electronic module, and transmits a first portion of the first signals to backplane  110  and a second portion to connectors  148 . Backplane  110  transmits the first portion of the first signals to switch/relay  114 . If the first signals are okay, e.g., no failures within primary electronic module  108   1 , the first portion of the first signals are terminated at switch/relay  114  and the second portion of the first signals are transmitted to remote equipment via connectors  148 . Second signals are also received at secondary electronic module  112   1  via connectors  148  from the remote equipment. Secondary electronic module  112   1  transmits a first portion of the second signals to connector  136  and a second portion of the second signals to backplane  110 . Backplane  110  transmits the second portion to switch/relay  114 , where the second portion is terminated. Connector  136  transmits the first portion of the second signals to primary electronic module  108   1 .  
         [0016]    In the event of a failure within primary electronic module  108   1 , e.g., the first signals received at switch/relay  114  are bad, switch/relay  114  switches to a backup mode. In the backup mode, secondary electronic module  112   2  receives the first signals from primary electronic module  108   2 , designated as a backup electronic module. These first signals are the same first signals that secondary electronic module  112   1  received from primary electronic module  108   1  prior to the failure. Secondary electronic module  112   2  transmits the first signals to backplane  110 . Backplane  110  transmits the first signals to switch/relay  114 . If the first signals are okay, e.g., no failures, switch/relay  114  transmits the first signals back to backplane  110 . Backplane  110  transmits the first signals to secondary electronic module  112   1 , which outputs the first signals at connectors  148 . In switching to the backup mode, switch/relay  114  enables the first signals to be routed from secondary electronic module  112   2  to connectors  148 . In the backup mode, secondary electronic module  112   1  provides an interface between primary electronic module  1082  and remote equipment.  
         [0017]    During backup mode operation, the second signals received at connectors  148  from the remote equipment are conveyed from secondary electronic module  112   1  to backplane  110 . Backplane  110  transmits the second signals to switch/relay  114 , which sends the second signals back to backplane  110 . Backplane  110  transmits the second signals to secondary electronic module  1122 . Secondary electronic module  1122  transmits the second signals to primary electronic module  1082 . In switching to the backup mode, switch/relay  114  also enables the second signals to be routed from connectors  148  to secondary electronic module  1122 .  
         [0018]    In one embodiment, primary electronic modules  108 , secondary modules  112 , and switch/relay  114  are respectively the CMTS transceivers, interface adapters, and switch module of U.S. patent application Ser. No. ______ (Attorney Docket No. 100.361US01) filed Nov. 26, 2001, commonly assigned, which application is incorporated herein by reference.  
       CONCLUSION  
       [0019]    Embodiments of the present invention have been described. The embodiments provide an adaptive module for modifying existing housings for containing non-redundant electronic systems, such as the existing housings for non-redundant cable modem termination systems, to add redundancy to the electronic systems. This enables existing non-redundant electronic systems to be upgraded in the field to redundant systems without having to replace the existing housing. Moreover, this eliminates the need for designing and manufacturing a new line of housings for housing redundant systems.  
         [0020]    Although specific embodiments have been illustrated and described in this specification, it will be appreciated by those of ordinary skill in the art that any arrangement that is calculated to achieve the same purpose may be substituted for the specific embodiment shown. This application is intended to cover any adaptations or variations of the present invention. For example, backplane  110  can be secured within card cage  132  instead of being secured to card cage  116 .