Abstract:
A communication method comprises: processing a first message from the user CPE to select a circuit switch from a plurality of circuit switches, and selecting an identifier and a DS0 to route user communications from the user CPE to the circuit switch; transferring a second message indicating the identifier and the DS0 and transferring an SS7 IAM to the circuit switch; receiving the user communications from the user CPE in a packet format having the identifier in headers, and routing the user communications in the packet format based on the identifier in the headers; and receiving the second message and the user communications in the packet format, and in response, converting the user communications from the packet format into a DS0 format and transferring the user communications in the DS0 format over the DS0 to the one circuit switch.

Description:
RELATED APPLICATIONS  
       [0001]     This patent application is a continuation of U.S. patent application Ser. No. 10/261,530; filed Oct. 1, 2002; entitled “BROADBAND TELECOMMUNICATIONS SYSTEM;” which is a continuation of U.S. Pat. No. 6,501,759; filed Feb. 4, 2000; entitled “BROADBAND TELECOMMUNICATIONS SYSTEM;” which is a continuation of U.S. Pat. No. 6,115,380; filed on Nov. 22, 1996; entitled “BROADBAND TELECOMMUNICATIONS SYSTEM;” and which is hereby incorporated by reference into this patent application. 
     
    
     FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       [0002]     Not applicable  
       MICROFICHE APPENDIX  
       [0003]     Not applicable  
       BACKGROUND OF THE INVENTION  
       [0004]     1. Field of the Invention  
         [0005]     The invention relates to broadband systems, and in particular, to broadband systems that utilize narrowband systems for various capabilities.  
         [0006]     2. Background of the Prior Art  
         [0007]     Conventional circuit switches provide the backbone for many current telecommunications networks. These switches process call signaling and extend the call connection towards the destination. They have also been developed to include sophisticated capabilities. Examples include caller validation, number screening, routing, connection control, and billing. These switches are also used to deploy various services. Examples include calling cards, “800” calling, voice messaging, and class services.  
         [0008]     At present, Asynchronous Transfer Mode (ATM) technology is being developed to provide broadband switching capability for telecommunications calls, which are requests for telecommunications services. Some ATM systems have used ATM cross-connects to provide virtual connections, but cross-connect devices do not have the capacity to process signaling used by telecommunications networks to set-up and tear down calls. Thus, ATM cross-connects cannot make connections on a call-by-call basis. As a result, connections through cross-connect systems must be pre-provisioned which creates a relatively rigid switching fabric. Due to this limitation, ATM cross-connect systems have been used primarily to provide dedicated connections, such as permanent virtual circuits (PVCs) and permanent virtual paths (PVPs). But, they do not provide ATM switching on a call by call basis as required to provide switched virtual circuits (SVCs) or switched virtual paths (SVPs). Those skilled in the art are well aware of the efficiencies created by using SVPs and SVCs as opposed to PVCs and PVPs because SVCs and SVPs utilize bandwidth more efficiently.  
         [0009]     ATM switches have also been used to provide PVCs and PVPs. Because PVCs and PVPs are not established on a call-by-call basis, the ATM switch does not need to use its call processing or signaling capacity. ATM switches require both signaling capability and call processing capability to provide SVCs and SVPs. In order to achieve virtual connection switching on a call by call basis, ATM switches are being developed that can process calls in response to signaling to provide virtual connections for each call. These systems cause problems, however, because they must be very sophisticated to support current networks. These ATM switches must process high volumes of calls and transition legacy services from existing networks. An example would be an ATM switch that can handle large numbers of POTS, 800, and VPN calls.  
         [0010]     Currently, ATM multiplexers are capable of interworking traffic of other formats into the ATM format. These are known as ATM interworking multiplexers (muxes). ATM multiplexers are being developed that can interwork traffic into ATM cells and multiplex the cells for transport over an ATM network. These ATM mux are not used to implement virtual connections selected on a call-by-call basis.  
         [0011]     Unfortunately, there is a need for efficient systems that can integrate the capabilities of broadband components with the capabilities of conventional circuit switches. Such a system would provide ATM virtual connections on a call-by-call basis, but support the numerous services currently provided by circuit switches.  
       SUMMARY  
       [0012]     Examples of the invention include a method of operating a communication system to transfer user communications from user Customer Premises Equipment (CPE) to one of a plurality of circuit switches. The method comprises receiving and processing a first message from the user CPE to select the one circuit switch from the plurality of circuit switches, and selecting an identifier and a DS0 to route user communications from the user CPE to the one circuit switch. The method comprises transferring a second message indicating the identifier and the DS0 and transferring a Signaling System Seven (SS7) Initial Address Message (IAM) to the one circuit switch indicating the DS0. The method comprises receiving the user communications from the user CPE in a packet format having the identifier in headers, and routing the user communications in the packet format based on the identifier in the headers. The method comprises receiving the second message and the user communications in the packet format, and in response, converting the user communications from the packet format into a DS0 format and transferring the user communications in the DS0 format over the DS0 to the one circuit switch. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  is a block diagram for a version of the invention.  
         [0014]      FIG. 2  is a logic diagram for a version of the invention.  
         [0015]      FIG. 3  is a block diagram for a version of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0016]      FIG. 1  depicts a version of the invention. The term “connection” refers to the transmission media used to carry user traffic and the term “link” refers to the transmission media used to carry signaling or control messages. On  FIG. 1 , connections are shown by solid lines and links are shown by dashed lines. Users  100  and  102  are connected to broadband system  104  by connections  150  and  151  respectively. Users  100  and  102  are linked to broadband system  104  by links  160  and  161  respectively. Users  100  and  102  could be any entity that supplies telecommunications traffic to broadband system  104  or that receives traffic from broadband system  104 . Some examples would be a telecommunications switch or customer premises equipment (CPE). Connections  150  and  151  represent any connection that might be used by users  100  and  102  to access broadband system  104 . Examples include: DS3, DS1, DS0, ISDN, E3, E1, E0, SDH, SONET, cellular, and PCS connections. Links  160  and  161  represent any signaling link that might be used between users  100  and  102  and broadband system  104 . Examples include signaling system #7 (SS7), C7, ISDN, TCP/IP, and UDP/IP.  
         [0017]     Broadband system  104  includes ATM interworking multiplexer (mux)  110 , mux  112 , mux  114 , ATM cross-connect  120 , narrowband switches  130  and  132 , and signaling processor  140 . Broadband system  104  also includes connections  152 - 156  and links  162 - 166 . Cross-connect  120  is connected to mux  110 ,  112 , and  114  by connections  152 ,  153 , and  154  respectively. Mux  112  is connected to switch  132  by connection  155 , and mux  114  is connected to switch  130  by connection  156 . Mux  112  is connected to user  100  by connection  150 , and mux  112  is connected to user  102  by connection  151 . Connections  152 - 154  are ATM connections—preferably carried by SONET. Connections  155  and  156  are narrowband connections similar to connections  150  and  151 . Preferably, connections  155  and  156  are DS3 or DS1 connections with embedded DSOs.  
         [0018]     Signaling processor  140  is linked to mux  110  by link  162 , to mux  112  by link  163 , to switch  132  by link  164 , to mux  114  by link  165 , and to switch  130  by link  166 . Signaling processor is linked to users  100  and  102  by links  160  and  161  respectively. One skilled in the art is aware that an STP might be used to exchange signaling instead of direct links. Links  160 ,  161 ,  164  and  166  are conventional signaling links with examples being SS7, ISDN, or C7. Links  162 ,  163 , and  165  are any links that carry control messages, with examples being SS7 links, UDP/IP over-ethemet, or a bus arrangement using a conventional bus protocol. Typically the switches and muxes are connected to a network management system that is not shown for purposes of clarity.  
         [0019]     ATM cross-connect  120  is a conventional device that provides a plurality of ATM virtual connections between the muxes. Typically, the virtual connection would use DS 1, DS3, or SONET for transport. The virtual connections are typically designated by the Virtual Path Identifier/Virtual Channel Identifier (VPI/VCI) in the cell headers. These VPI/VCIs are provisioned from mux to mux, but the cross-connect does not need to be controlled on a call-by-call basis. An example of the cross-connect is the NEC model  20 . Those skilled in the art are aware that a multiple cross-connects could be used in this fashion, but for purposes of clarity, only a single cross-connect is shown. Either a single cross-connect or multiple cross-connects are referred to as a cross-connect system.  
         [0020]     Muxes  110 ,  112 , and  114  are operational to interwork (convert) traffic between ATM and non-ATM formats in response to control messages from signaling processor  140 . Typically, this interworking entails interworking individual DS0s with individual VPI/VCIs in accord with messages from by signaling processor  140 . A detailed description of the muxes is provided further below.  
         [0021]     Narrowband switches  130  and  132  are conventional circuit switches. These switches process and interconnect calls. Typically, they connect an incoming DS0 to an outgoing DS0. Often, they perform numerous tasks including, validation, screening, routing, billing, and echo control. These switches can also be configured to provide special services. Examples of special services are: calling cards, class services, voice activated calling, and voice messaging, virtual private networking, hearing impaired assistance/enhancement, operator services and intelligent network call routing (local number portability, personal/terminal mobility, toll free calling).  
         [0022]     Signaling processor  140  is operational to receive and process signaling to select a narrowband switch and connections to the selected switch. This switch selection can be based on various criteria. A few examples are: available access to the switch, current loading on the switch, the service capabilities of the switch, or the area served by the switch. Typically, the connections would be a VPI/VCI and a DS0. Signaling processor  140  is capable of providing control messages to the muxes to implement the connections. Signaling processor  140  is also capable of exchanging signaling with the switches to facilitate call processing. If required signaling processor  140  can also exchange signaling with the users to facilitate the call. A detailed description of signaling processor  140  follows further below.  
         [0023]     In one embodiment, the invention operates as follows for a call from user  100  to user  102 . In this embodiment, signaling processor  140  is transparent to the users and to the narrowband switches. The users and narrowband switches attempt to interact as they would in a typical network scenario. In the context of the invention, signaling is “intercepted” and processed by signaling processor  140 . Connections are “intercepted” and extended by the muxes.  
         [0024]     User  100  will seize a call connection on connection  150  to mux  110 . Typically, this is a DS0 embedded within a DS3. User  100  will also forward a call set-up message to signaling processor  140 . Typically, this is an SS7 Initial Address Message (IAM). Signaling processor  140  will process the IAM in order to select a switch to process the call, it will select the connections to that switch. For example, if switch  130  is selected, an ATM connection pre-provisioned through cross-connect  154  from mux  110  to mux  114  over connections  152  and  154  would be selected. In addition, a connection to switch  130  would be selected within connection  156 . For a standard call, a VPI/VCI and a DS0 would be selected by signaling processor  140 .  
         [0025]     Signaling processor  140  would send an IAM to switch  130  over link  166 . The IAM would contain information used to process the call, such as the dialed number and the incoming DS0. Signaling processor would send a control message to mux  110  over link  162 . The control message would instruct mux  110  to interwork the DS0 on connection  150  with the selected VPI/VCI on connection  152 . Signaling processor would send a control message to mux  114  over link  165 . The control message would instruct mux  114  to interwork the selected VPI/VCI on connection  154  with the selected DS0 on connection  156 . As a result, a call path from user  100  to switch  130  would be established through mux  110 , cross-connect  120 , and mux  114 .  
         [0026]     Switch  130  would process the call and select a route for the call. The switch would interconnect the incoming DS0 on connection  156  with another DS0 on connection  156 . Switch  130  would also send an IAM indicating the destination for the call. In this example, the destination selected by switch  130  would be user  102 . The IAM from switch  130  would be routed to signaling processor  140 . Signaling processor  140  could read the destination point code in this LAM to determine the destination (user  102 ) selected by the switch for the call. Signaling processor  140  would select a VPI/VCI from mux  114  to the mux serving the destination—mux  112 . Signaling processor  140  would also select a DS0 within connection  151  between mux  112  and user  102 .  
         [0027]     Signaling processor  140  would send a control message to mux  114  over link  165 . The control message would instruct mux  114  to interwork the DS0 on connection  156  with the selected VPI/VCI on connection  154 . Signaling processor  140  would send a control message to mux  112  over link  163 . The control message would instruct mux  112  to interwork the selected VPI/VCI on connection  153  with the selected DS0 on connection  151 . Signaling processor  140  might send a signaling message to user  102  to facilitate call completion.  
         [0028]     As a result, a call path from switch  130  to user  102  would be established through mux  114 , cross-connect  120 , and mux  112 . Combining the two call paths, a connection from user  100  to user  102  is established through broadband system  104 . Advantageously, this is accomplished over broadband ATM connections, but without the need for an ATM switch or the call-by-call control of the ATM cross-connect. The muxes and the cross-connect provide ATM connections selected by the signaling processor on a call-by-call basis. The signaling processor makes these selections based on the call processing of the narrowband switch. The narrowband switch is also able to provide special features to the call.  
         [0029]     Advantageously, only one narrowband switch was required within system  104 . Because ATM broadband transport is available, the location of this switch is relatively independent. Any switch in system  104  could be used to process call. The ATM system provides the connection from the origination point to the switch, and from the switch to the destination point. This means narrowband switches can be selected based on load and availability. A narrowband switch could also be taken out of service simply by instructing the signaling processor to quit selecting it.  
         [0000]     The Signaling Processor  
         [0030]     The signaling processor would typically be separate from the muxes, but those skilled in the art appreciate that they could be housed together and coupled in a bus arrangement instead of being coupled by a data or signaling link. The signaling processor may support a single mux or a plurality of muxes. The signaling processor is comprised of hardware and software. Those skilled in the art are aware of various hardware components which can support the requirements of the invention. One example of such hardware is the FT-Sparc provided by Integrated Micro Products PLC. The FT-Sparc could use the Solaris operating system. Any data storage requirements could be met with conventional database software systems.  
         [0031]      FIG. 2  illustrates an example of the signaling processor, but any processor which supports the requirements stated for the invention would suffice. As shown in  FIG. 2 , signaling processor  240  includes functional blocks composed of SS7 interface  242 , mux interface  244 , and connection processor  246 . These functional blocks have interrelations that are indicated and that are discussed below. SS7 interface  242  receives and transmits SS7 signaling over link  261 . Mux interface  244  exchanges control messages with the muxes over link  263 . Connection processor  246  exchanges network management information with network management systems over link  263 .  
         [0032]     SS7 interface  242  is operational to receive and transmit SS7 messages. SS7 interface  242  includes Message Transfer Part (MTP) functionality for MTP levels 1, 2 and 3. MTP 1 defines the physical and electrical requirements for a signaling link. MTP 2 sits on top of MTP 1 and maintains reliable transport over a signaling link by monitoring status and performing error checks. Together, MTP 1-2 provide reliable transport over an individual link. A device would need MTP 1-2 functionality for each link it uses. MTP 3 sits on top of MTP 2 and provides messages to the proper signaling link (actually to the MTP 2 for that link). MTP 3 directs messages to applications using MTP 1-2 for access to the signaling system. MTP 3 also has a management function which monitors the status of the signaling system and can take appropriate measures to restore service through the system. MTP levels 1-3 correspond to layers 1-3 of the open systems interconnection basic reference model (OSIBRF).  
         [0033]     SS7 interface  242  also includes Integrated Services Digital Network User Part (ISUP) functionality. This might include ISUP timers that generate release message or re-transmit message where appropriate. If B-ISUP signaling is being used, SS7 interface  242  could also be equipped with B-ISUP capability. All of these elements are known in the art. SS7 interface  242  could be constructed using commercially available SS7 software interface tools. An example of such tools would be SS7 interface software provided by either Trillium, Inc., or by Dale, Gesek, McWilliams, and Sheridan, Inc.  
         [0034]     SS7 interface  242  forwards IAM messages from link  261  to connection processor  246 . SS7 interface  242  also receives IAMs from connection processor  246  and transmits them over link  261 . SS7 interface  242  will receive subsequent SS7 call-related messages from link  261 . SS7 interface  242  will alter the routing labels of these subsequent messages and re-transmit them over link  261 . Examples of these subsequent messages include Address Complete Messages (ACM), Answer Messages (ANM), Release Messages (REL), and Release Complete Messages (RLC).  
         [0035]     The routing label contains a Destination Point Code (DPC), an Originating Point Code (OPC), a Circuit Identification Code (CIC), and a Signaling Link Selection (SLS) code. The OPC and DPC identify the origin and intended destination for the signaling message. For example, a message sent from point A to point B would have an OPC of A and a DPC of B. A return message would reverse the two and have an OPC of B and DPC of A. The CIC identifies the originating circuit used on the call. The SLS is used to allow load sharing among the signaling links.  
         [0036]     The following discussion refers to  FIG. 1  and its associated embodiment. When subsequent call related messages are received by the SS7 interface of signaling processor  140 , the OPC, DPC, and/or CIC may need to be altered. A message from originating user  100  to selected switch  130  would have its DPC and CIC altered to reflect the new DPC and CIC selected for the call by signaling processor  140 . This is because switch  130  expects its own DPC and switch  130  also needs to know the actual DS0 used by mux  114  on connection  156 . A message to originating user  100  from switch  130  would have its OPC altered to reflect the DPC in the original IAM from user  100 . This is because user  100  expects response messages for the call from the point where the original IAM was sent. This point code is the DPC of the original IAM. The CIC is also altered to reflect the CIC in the original LAM from user  100 . This is because user  100  expects the DS0 in the message to be the DS0 used in connection  150 . Messages between terminating user  102  and selected switch  130  would need the CICs altered to reflect the actual DS0s used by the recipient of the message. The CIC in messages from user  102  to switch  130  would reflect the DS0 in connection  156 . The CIC in messages from switch  130  to user  102  would reflect the DS0 in connection  151 .  
         [0037]     Referring back to  FIG. 2 , connection processor  246  is operational to process incoming LAMs and select connections. On calls into the network, connection processor  246  selects a narrowband switch to process the call and also selects the connections to this narrowband switch. These connections are typically VPI/VCI—DS0 combinations. If the call is extended beyond the selected narrowband switch, connection processor  246  identifies the required call destination in the IAM from the narrowband switch. Connection processor  246  also selects the connections to this destination. These connections are typically VPI/VCI—DS0 combinations.  
         [0038]     As discussed above, the signaling processor can be transparent to the users. As a result, the users will send signaling to the narrowband switch selected by the user. The destination of this SS7 signaling message is identified by the Destination Point Code (DPC). Thus, on calls entering the network, the DPC indicates a narrowband switch selected by the user. Connection processor  246  typically uses this DPC to select a narrowband switch. This may be the same narrowband switch selected by the user or another narrowband switch. Connection processor  246  may then check the current usage of the selected switch. This might include the available trunk access to the switch and/or the processing load of the switch. If the access to the switch is congested or if the switch CPU is heavily loaded, then an alternate switch may be selected. In addition, special network operations may require the use of an alternate switch—for example, if a switch is inactive for maintenance or testing.  
         [0039]     Once the switch is selected, connections to the switch are selected. The DS0 in the inbound connection is identified by the Circuit Identification Code (CIC) in the IAM. A VPI/VCI is selected that has been previously provisioned through the cross-connect from the mux connected to the incoming DS0 to the mux serving the selected switch. A DS0 is selected from the latter mux to the selected switch. Based on the selections, IAM information is provided to SS7 interface  242 , and control message information is provided to mux interface  244 .  
         [0040]     As discussed above, once the narrowband switch processes the call, it will send an IAM to the destination. Connection processor  246  will receive this IAM and use the DPC to identify the destination and select the appropriate connections to this destination. The CIC in the IAM identifies the DS0 from the selected switch to the mux. A VPINCI from that mux to a destination mux and a DS0 from the destination mux to the destination are selected. The selections are then implemented by the muxes in response to control messages from signaling processor  240 . Connection processor  246  also tracks the usage and status of connections and connection groups for the connections under its span of control. It also receives network management information.  
         [0041]     In some embodiments, connection processor  246  uses at least portions of the dialed number to select the narrowband switch. For example, narrowband switch “A” might be assigned to area code “X.” On calls to area code “X,” switch “A” is selected. If switch “A” is unavailable, alternate switch “B” could be used. This could also be carried out using the area code and exchange (NPA-NXX). In some embodiments, the dialed number may correspond to a special service offered by a select group of switches. For example, the number “1-800-NXX-XXXX” might correspond to a calling card service offered from only two switches. “888” and “900” numbers are also used in this fashion. Connection processor  246  could select one of these switches based on the dialed number. In some embodiments, the caller&#39;s number (commonly referred to as ANI), may be used in a similar fashion in order to select the switch to provide services to a caller. In some embodiments, the call could be routed to a switch based on the carrier identified in the signaling. This information is found in the carrier identification parameter in the IAM.  
         [0042]     Mux interface  244  accepts information from connection processor  246  indicating the connections that are to be made or disconnected. Mux interface  244  accepts this information and provides corresponding control messages to the appropriate muxes. Mux interface  244  may also receive acknowledgments from the muxes. As a result, signaling processor  240  can provide ATM header information to the muxes for use in configuring the headers of ATM cells so that the cells are routed to the desired destination.  
         [0000]     ATM Interworking Multiplexers  
         [0043]      FIG. 3  shows one embodiment of the mux that is suitable for the present invention, but other muxes that support the requirements of the invention are also applicable. Shown are control interface  300 , 0C-3 interface  305 , DS3 interface  310 , DS1 interface  315 , DS0 interface  320 , ATM adaption Layer (AAL)  330 , and 0C-3 interface  335 . Control interface  300  exchanges control messages with the signaling processor. Typically, these messages include DS0—VPI/VCI interworking assignments that are to be implemented by AAL  330 . As such, this information is provided to AAL  330 .  
         [0044]     OC-3 interface  305  accepts the 0C-3 format and makes the conversion to DS3. DS3 interface  310  accepts the DS3 format and makes the conversion to DS1. DS3 interface  310  can accept DS3s from 0C-3 interface  305  or from an external connection. DS1 interface  315  accepts the DS1 format and makes the conversion to DS0. DS 1 interface  315  can accept DS Is from DS3 interface  310  or from an external connection. DS0 interface  320  accepts the DS0 format and provides an interface to AAL  330 . 0C-3 interface  335  is operational to accept ATM cells from AAL  330  and transmit them to the cross-connect.  
         [0045]     AAL  330  comprises both a convergence sublayer and a segmentation and reassembly (SAR) layer. AAL  330  is operational to accept the user information in DS0 format from DS0 interface  320  and convert the information into ATM cells. AALs are known in the art and information about AALs is provided by International Telecommunications Union (ITU) document 1.363. An AAL for voice is also described in patent application Ser. No. 08/395,745, filed on Feb. 28, 1995, entitled “Cell Processing for Voice Transmission,” and hereby incorporated by reference into this application. AAL  330  obtains the virtual path identifier (VPI) and virtual channel identifier (VCI) for each call from control interface  300 . AAL  330  also obtains the identity of the DS0 for each call (or the DS0s for an N×64 call). AAL  330  then converts user information between the identified DS0 and the identified ATM virtual connection. Acknowledgments that the assignments have been implemented may be sent back to the signaling processor if desired. Calls with a bit rate that are a multiple of 64 kbit/second are known as N×64 calls. If desired, AAL  330  can be capable of accepting control messages through control interface  300  for N×64 calls.  
         [0046]     As discussed above, the mux also handles calls in the opposite direction—from OC-3 interface  335  to DS0 interface  320 . This traffic would have been converted to ATM by another mux and routed to 0C-3  335  by the cross-connect over the selected VPI/VCI. Control interface  300  will provide AAL  330  with the assignment of the selected VPI/VCI to the selected outbound DS0. The mux will convert the ATM cells with the selected VPI/VCI in the cell headers into the DS0 format and provide it to the selected outbound DS0 connection. A technique for processing VPINCIs is disclosed in patent application Ser. No. 08/653,852, filed on May 28, 1996, entitled “Telecommunications System with a Connection Processing System,” and hereby incorporated by reference into this application.  
         [0047]     DS0 connections are bi-directional and ATM connections are typically uni-directional. As a result, two virtual connections in opposing directions will typically be required for each DS0. As discussed, this can be accomplished provisioning the cross-connect with companion VPI/VCIs in the opposite direction as the original VPI/VCIs. On each call, the muxes would be configured to automatically invoke the particular companion VPI/VCI to provide a bi-directional virtual connection to match the bi-directional DS0 on the call.  
         [0048]     With an understanding of the preferred embodiment, those skilled in the art will appreciate that the present invention allows the integration of high speed broadband transport with systems configured for narrowband process and control. By performing call handling functions in narrowband switches, the broadband transport capability is transparent to the users and to other existing network components configured to interact with narrowband switches. Moreover, the broadband transport is accomplished economically and efficiently without the need for broadband switches.  
         [0049]     Those skilled in the art will appreciate that variations from the specific embodiments disclosed above are contemplated by the invention. The invention should not be restricted to the above embodiments, but should be measured by the following claims.