Abstract:
The present invention provides systems and methods to effectively combine layer one and layer two cross-connects in a hierarchical fashion. The present invention combines layer one and layer two cross-connects between a layer one (L1) line card and a layer two (L2) line card in a transport and aggregation platform. Advantageously, the present invention provides network operators increased flexibility and capability in transport and aggregation networks. Particularly, transport networks tend to contain only layer one capabilities. The present invention makes the introduction of layer two functionality into transport networks practical because an entire physical connection need not be dedicated to all layer one cross-connects or all layer two cross-connects.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to communications networks, such as transport and aggregation networks. More specifically, the present invention relates to systems and methods for a hierarchical layer one (L1) and layer two (L2) cross-connect in a transport and aggregation platform. 
       BACKGROUND OF THE INVENTION 
       [0002]    Multi-service transport and aggregation platforms are capable of supporting any transport protocol, such as Time Division Multiplexing (TDM), Ethernet, storage, video, and the like, on any available port on a line card. Such platforms can include user-programmable line ports, allowing services of up to 10 Gbps to be provisioned, upgraded, or changed through software. 
         [0003]    For example, a transport and aggregation platform can be configured to utilize ITU G.709 standards-based technology (also known as Digital Wrapper). The platform can groom multiple optical services running on any port onto higher-speed wavelengths. These higher-speed wavelengths, such as an Optical Transmission Unit of level 1 (OTU1) (2.7 Gbps) or an Optical Transmission Unit of level 2 (OTU2) (10.7 Gbps) signals, carry any mix of individual services up to 10 Gbps. Standards-based protocols supported can include: 10/100/1000 Ethernet, 10 Gbps Ethernet, OC-3/12/48/192, or STM1/4/16/64, FC/FICON, ESCON, OTU1, OTU2, etc. 
         [0004]    In communications networks, such as transport and aggregation networks, current systems and methods include L1 cross-connects typically in transport-oriented devices like Digital Cross-connect Systems (DCSs) and Add-Drop Multiplexers (ADMs), and L2 cross-connects (i.e., Virtual Local Area Network (VLAN) cross-connects) in multi-service switches (MSSs) and SONET Multi Service Provisioning Platforms (MSPPs). With current techniques, a physical connection must terminate on an L1 switching card or on an L2 switching card. This reduces flexibility and makes network planning more difficult. 
         [0005]    A traditional transport and aggregation platform has a fixed relationship between client port bandwidth and transport network port bandwidth. For example, a Gigabit Ethernet (GbE) client port consumes exactly 1 Gb of transport or Optical Transport Network (OTN) bandwidth. Given a limit of 10 Gbps of bandwidth per wavelength and the mapping of GbEs into Virtual Concatenation Groups (VCGs), where a VCG is a collection of one to sixteen 155 Mbps timeslots contained in an OTU1, a single-wavelength transport and aggregation network can only carry eight GbE clients. To carry more than eight GbE clients, one must stack on additional transport and aggregation platforms and add a wavelength to the network for every eight additional GbE clients. The lack of scale in this solution can cause the cost and complexity of the total network solution to be unacceptable for a service provider. Especially when those GbEs are underutilized. 
         [0006]    Further, traditional transport and aggregation platforms cannot deliver service to Ethernet ports of different speeds. In other words, one cannot connect a Fast Ethernet (FE) client to a GbE client, nor a GbE client to a 10 GbE client, etc. Systems and methods are thus needed to effectively combine L1 and L2 cross-connects in a transport and aggregation platform. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    In various exemplary embodiments, the present invention provides systems and methods that effectively combine layer one and layer two cross-connects in a hierarchical fashion. The present invention combines layer one and layer two cross-connects between a layer one (L1) line card and a layer two (L2) line card in a transport and aggregation platform. For example, a physical connection can still terminate on the L1 line card, but portions of that connection may be internally routed (e.g., through a backplane) to the L2 line card for additional processing. An example of a physical connection includes a channelized OTU2 carrying 64 time slots of 155 Mbps each, for an aggregate of approximately 10 Gbps. By terminating the physical OTU2 to a line card capable of performing L1 cross-connects at each of the 64 time slots, flexibility is greatly increased by allowing any particular time slot to be cross-connected to another port at L1, or to an L2 card for further processing. The L2 card, in turn, can cross-connect a portion of the time slot (i.e., a particular VLAN) to a different L1 time slot terminated anywhere within the node, to a physical port on itself, or to a physical port on another L2 card. 
         [0008]    Advantageously, the present invention provides network operators with increased flexibility and capability in transport and aggregation networks. Particularly, transport networks tend to contain only L1 capabilities. The present invention makes the introduction of. L2 functionality into transport networks practical because an entire physical connection need not be dedicated to all L1 cross-connects or all L2 cross-connects. 
         [0009]    The present invention, with the ability to switch at L2 and even oversubscribe, allows flexible mappings between Ethernet Clients (10/100/1000/10G) and the transport network, such that an unlimited number of Ethernet clients can share a single wavelength. This allows attachment for a virtually unlimited number of Ethernet clients to a transport and aggregation network without the need to increase the number of wavelengths or stack platforms. 
         [0010]    In an exemplary embodiment of the present invention, a hierarchical layer one and layer two cross-connect in a transport and aggregation platform includes a layer one line card including a plurality of ports and a layer one cross-connect configured to cross-connect a plurality of time slots, a layer two line card including a plurality of ports and a layer two cross-connect configured to cross-connect a portion of one or more of the plurality of time slots to another of the plurality of time slots or to one of the plurality of ports on the layer two line card, and a connection between the layer one line card and the layer two line card. Optionally, the hierarchical layer one and layer two cross-connect also includes a second layer two line card including a second plurality of ports and a second layer two cross-connect configured to cross-connect a portion of one or more of the plurality of time slots to another of the plurality of time slots, to one of the second plurality of ports on the second layer two line card, or to one of the plurality of ports on the layer two line card, wherein the second layer two line card connects to the layer one line card and the layer two line card through the connection. The layer two line card further includes an OTU1 or OUT2 port for transporting aggregated, shaped Ethernet traffic. The plurality of ports are configured to transmit and receive any of Ethernet signals including 10/100/1000Base-TX, 100Base-FX, 1000Base-SX/LX/EX/CWDM, 10GBase-SX/LX/EX/CWDM (including LAN or WAN PHY) with the same hardware. The layer one line card is configured to send and receive a portion of the plurality of time slots to the layer two line card. The layer two line card encapsulates Ethernet frames into a Generic Framing Procedure-Frame. The layer one line card maps a plurality of time slots and one or more Generic Framing Procedure-Frames into an Optical Transport Network payload. The Optical Transport Network payload includes one of an Optical Transmission Unit of level 1 or an Optical Transmission Unit of level 2. Alternatively, the layer two line card is configured to send and receive traffic to and from a Virtual Concatenation Group residing in one of the plurality of ports on the layer one line card. The Virtual Concatenation Group includes one to sixteen timeslots. 
         [0011]    In another exemplary embodiment of the present invention, a method of performing hierarchical layer one and layer two cross-connects in a transport and aggregation platform includes terminating a physical connection comprising a plurality of time slots, cross-connecting the plurality of time slots at layer one, routing a portion of one or more of the plurality of time slots to a layer two card, and cross-connecting the portion of one or more of the plurality of time slots at layer two. The method also includes encapsulating the portion of one or more of the plurality of time slots into a Generic Framing Procedure-Frame. Optionally, the method further includes aggregating the Generic Framing Procedure-Frame into a channelized Optical Transmission Unit of level 1 or of level 2. The physical connection includes a Virtual Concatenation Group comprising one to sixteen of the plurality of timeslots. 
         [0012]    In a further exemplary embodiment of the present invention, a transport and aggregation platform utilizing a hierarchical layer one and layer two cross-connect includes a backplane for connecting line cards together; a layer two line card including a connection to the backplane, a plurality of client ports, a layer two cross-connect, and a layer one interface; and a layer one card including a connection to the backplane, a plurality of flexible protocol and rate client ports, and a layer one cross-connect. The layer one card is configured to transmit and receive a plurality of times slots on the plurality of flexible protocol and rate client ports, and perform switching of the time slots and layer two, and further the layer one cross-connect is configured to route portions of one or more of the plurality of time slots through the backplane to the layer one interface. The layer two card is configured to switch layer two signals from the plurality of client ports on the layer two card and layer two signals from the portions of one or more of the plurality of time slots to another portion of one or more of the plurality of time slots or to another of the plurality of client ports on the layer two card. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The present invention is illustrated and described herein with reference to the various drawings, in which like reference numbers denote like system components and/or method steps, respectively, and in which: 
           [0014]      FIGS. 1   a - 1   b  illustrate transport and aggregation network elements (NEs) including layer two hierarchical cross-connects according to an exemplary embodiment of the present invention. 
           [0015]      FIGS. 2   a - 2   b  illustrate a transport and aggregation network for providing aggregation, transport, and bridging of multiple NEs at layer one and layer two, and a head-end NE configured to aggregate, transport, and bridge multiple NEs and clients together and to other NEs, according to an exemplary embodiment of the present invention. 
           [0016]      FIG. 3  illustrates a transport and aggregation NE configured with the hierarchical layer one/layer two cross-connect of the present invention to provide the ability to manage layer one wavelength services port-to-port and layer two services end-to-end. 
           [0017]      FIG. 4  illustrates line modules in an exemplary embodiment of the present invention configured with flexible ports and the hierarchical layer one/layer two cross-connect connected to switches for aggregation and transport of multiple customer local area networks (LANs). 
           [0018]      FIG. 5  illustrates line modules configured to support high-end business Ethernet services between customer premises through a metropolitan or wide area network (MAN/WAN) to aggregate multiple LANs. 
           [0019]      FIG. 6  illustrates exemplary embodiments of lines cards with the hierarchical L1/L2 cross-connect of the present invention in various example chassis deployments. 
           [0020]      FIG. 7  illustrates an exemplary embodiment of the hierarchical L1/L2 cross-connect of the present invention. 
           [0021]      FIG. 8  illustrates an exemplary block diagram of a line card configured to provide hierarchical L1/L2 cross-connects according to the present invention. 
           [0022]      FIG. 9  illustrates exemplary block diagrams of line cards configured to provide hierarchical L1 /L2 cross-connects according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0023]    In various exemplary embodiments, the present invention provides systems and methods that effectively combine layer one and layer two cross-connects in a hierarchical fashion. The present invention combines layer one and layer two cross-connects between a layer one (L1) line card and a layer two (L2) line card in a transport and aggregation platform. For example, a physical connection can still terminate on the L1 line card, but portions of that connection may be internally routed (e.g., through a backplane) to the L2 line card for additional processing. An example of a physical connection includes a channelized OTU2 carrying 64 time slots of 155 Mbps each, for an aggregate of approximately 10 Gbps. By terminating the physical OTU2 to a card capable of performing L1 cross-connects at each of the 64 time slots, flexibility is greatly increased by allowing any particular time slot to be cross-connected to another port at layer one or to a L2 card for further processing. The L2 card, in turn, can cross-connect a portion of the time slot (i.e., a particular VLAN) to a different layer one time slot terminated anywhere within the node, to a physical port on itself, or to a physical port on another L2 card. 
         [0024]    The hierarchical L1/L2 cross-connect of the present invention utilizes Ethernet-centric port cards in a transport and aggregation platform which are capable of L2 packet switching. These port cards can communicate to L1 port cards which are capable of L1 cross-connecting. In a hierarchical fashion, the Ethernet-centric port cards and the L1 port cards form a L1/L2 cross-connect within a transport and aggregation platform that allows network operators to efficiently transport L1 and L2 traffic without requiring expensive aggregation devices or the like. The present invention supports Ethernet multiplexing allowing service delivery between Ethernet clients of many speeds and types (10BaseT, 100BaseT, 1000BaseT, 100FX, GbE Optical, 10GbE, and the like). 
         [0025]    Generic Framing Procedure-Frame (GFP-F), as defined by ITU-T G.7041, encapsulates complete Ethernet, r other types of, frames with a GFP header. GFP-F is key to the hierarchical L1/L2 approach, with the Ethernet-centric port card sending and receiving traffic to/from a VCG that resides in a port on the L1 port card. When this is done, the Ethernet frames are first encapsulated in GFP-F and then mapped into an OTN (e.g., OTU1/OTU2) payload, as appropriate. The GFP-F is primarily responsible for frame delineation. In this regard, it is very similar to a 10 GbE WAN-PHY approach, where Ethernet is encapsulated into GFP-F and then mapped into a SONET OC-192c payload. However, the 10 GbE WAN-PHY approach is single rate (OC-192c payload), whereas the present invention supports any VCG size from 1-16 timeslots and can be extended to support a clear-channel OTU2. 
         [0026]    The present invention provides the ability to switch at L2 and even oversubscribe, to allow flexible mappings between Ethernet Clients (10/100/1000/10G) and the transport network, such that an unlimited number of Ethernet clients can share a single wavelength. This allows attachment for a virtually unlimited number of Ethernet clients to the transport and aggregation network without the need to increase the number of wavelengths or stack platforms. 
         [0027]    Additionally, the present invention allows multiple point-to-point connections to be created from the same physical port. Existing transport and aggregation platforms today only connect a single client port to exactly one other client port in the network. The present invention allows multiple connections originating at a single port. This is important in “client-server” type networks typical of a service provider environment (i.e., Internet access). 
         [0028]    Referring to  FIGS. 1   a - 1   b,  in an exemplary embodiment of the present invention, transport and aggregation network elements (NE)  10 , 30  include layer two hierarchical cross-connects  12 .  FIG. 1  a illustrates a client aggregation network element  10  configured to provide an “on-ramp” to multiple clients  20 , 22 . The NE  10  connects to clients  20 , a router/switch  22 , and the like through port cards, such as multiple port small-form factor pluggables (SFP). The NE  10  is configured to aggregate the clients  20 , router/switch  22 , and the like into the OTN/transmission domain, i.e. layer one cross-connect. The present invention provides the ability to route the layer one traffic to the layer two cross-connect  12  in a hierarchical fashion as described further herein. The layer two cross-connect  12  is configured to forward shaped traffic from the attached devices  20 , 22  to VCGs/timeslots. Additionally, the cross-connect  12  can be configured to provide policing on the ingress and shaping into right-sized VCGs. The result allows the NE  10  to transmit OTN timeslots and VCGs with aggregated, shaped Ethernet traffic. Advantageously, this removes the need to include Ethernet switches and the like as a front-end to the NE  10  for Ethernet cross-connects. 
         [0029]      FIG. 1   b  illustrates a high-capacity head-end transport and aggregation NE  30  configured to provide an “off-ramp” to devices such as a local application server  24 , switch  26 , and broadband remote access switch (B-RAS)  28 . The NE  30  includes two L1/L2 hierarchical cross-connects  12 , and is configured to cross-connect the incoming OTN timeslots and VCGs carrying Ethernet traffic through connections, such as GbE, 10 GbE, or the like, to the devices  24 , 26 , 28 . 
         [0030]    Referring to  FIGS. 2   a - 2   b,  in an exemplary embodiment of the present invention, a transport and aggregation network  40  provides aggregation, transport, and bridging of multiple network elements at layer one and layer two, and a head-end NE  30  can also aggregate, transport, and bridge multiple network elements and clients together and to other NEs  10 , 30 .  FIG. 2   a  illustrates the network  40  which includes a first network  42  including multiple NEs  10 , and a second network  44  including an NE  10 , a switch  26 , and a head-end NE  30 , with the two networks  42 , 44  sharing a head-end NE  30  configured to bridge the networks  42 , 44  together. The NEs  10  in network  42  are configured to aggregate layer one and layer two traffic with the hierarchical cross-connect of the present invention into VCGs from remote terminals and end-office equipment, and to forward upstream into aggregate VCGs. The NE  30  includes the hierarchical cross-connect of the present invention, and is configured to bridge OTN timeslots/VCGs with aggregated Ethernet traffic to the devices  10 , 26 , 30  in network  44 . 
         [0031]      FIG. 2   b  illustrates another head-end NE  30  configured to aggregate, transport, and bridge multiple devices together at layer one and layer two. The NE  30  is connected to local devices, such as the local application server  24 , switch/router  26 , an multiple local clients  20 , for layer one and layer two aggregation and transport. Further, the NE  30  is configured to transport remotely to other NEs  10 , 30 , forwarding OTN timeslots/VCGs with aggregated Ethernet. 
         [0032]    Referring to  FIG. 3 , the hierarchical L1/L2 cross-connect of the present invention provides the ability to manage layer one wavelength services port-to-port and layer two services end-to-end with a single transport and aggregation network element  30 . As described herein, the NE  30  includes client ports, such as multiple port small-form factor pluggables (SFP). Further, the client ports can include flexible rate ports which are capable of a plurality of protocols and bit rates solely with software provisioning. The client ports on the NE  30  can connect to multiple devices, such as a network element  52  providing a wavelength service not at layer two (e.g. OTN interface to the client port), Ethernet over ATM from a digital subscriber loop access multiplexer (DSLAM) (e.g. OC-3 interface to the client port), Ethernet over fiber to the node (FTTN)  56  (e.g., GbE interface to the client port), Ethernet over T1/DS3s/E1s  58  (e.g., GbE interface to the client port), and the like. 
         [0033]    The NE  30  can be part of a network  50  including other NEs  30  as well as other devices, such as switches, routers, BRAS, and the like. Advantageously, the NE  30  provides a single platform for transport and aggregation to combine layer one and layer two services, allowing OTN and 10 GbE aggregation. Further, the network elements can include control through session management, such as Session Initiation Protocol (SIP). 
         [0034]    Referring to  FIG. 4 , in an exemplary embodiment of the present invention, a line module  60  configured with flexible ports and including a hierarchical layer one/layer two cross-connection can be configured to interface to switches  70  to aggregate and transport multiple customer local area network (LAN)  72  connections. For example, the line modules  60  can connect to a remote terminal, end-office, or on-premises  64 , or to an end office or central office  66 . The line module  60  is configured to operate in a transport and aggregation platform. The line module  60  can include an uplink port, such as an OTU1 port. Additionally, an uplink module  62  can provide additional uplink ports, such as an OTU2 port, and can communicate to the line module  60  through a backplane. 
         [0035]    The line modules  60  can connect to the switch  70  through a GbE connection or the like. The line modules  60  are configured to provide both layer one and layer two cross-connects in a hierarchical fashion. The line modules  60  can be configured to support IEEE 802.3ah Ethernet in the First Mile (EFM) management to the final demarcation device, and IEEE 802.1ag per flow Operations, Administration &amp; Maintenance (OAM) for robust layer two Fault, Configuration, Accounting, Performance, Security (FCAPs). 
         [0036]    Referring to  FIG. 5 , the line modules  60  can be configured to support high-end business Ethernet services between customer premises  82 , 84  through a metropolitan or wide area network (MAN/WAN)  80  to aggregate multiple LANs  72 . The line modules  60  can support comprehensive performance monitoring and service level agreement (SLA) enforcement. Further, the line modules  60  can support media access control in media access control (MAC-in-MAC) for scalability and separation of customer traffic. 
         [0037]    Referring to  FIG. 6 , exemplary embodiments of lines cards  60 , 66  including the hierarchical L1/L2 cross-connect of the present invention are depicted in various example chassis deployments. The line cards  60 , 66  can include multiple client ports, such as flexible, reconfigurable ports capable of a plurality of protocols and bit rates based on software configuration. In an exemplary embodiment, the line card  60  is a L2 line card including multiple ports, such as SFP, XFP, X2, XENPAK or the like, operable to transmit and receive a variety of Ethernet types with the same hardware, such as 10/100/1000Base-TX, 100Base-FX, 1000Base-SX/LX/EX/CWDM, 10GBase-SX/LX/EX/CWDM (including LAN or WAN PHY). Additionally, the line card  60  can include uplink ports configured to transmit and receive aggregated Ethernet at a higher rate, such as OTU1. 
         [0038]    The line card  66  is a L1 line card including multiple ports, such as SFP, XFP, or the like, operable to transmit and receive any signal up to 10 Gbps including a variety of protocols. The line card  66  can be a flexible rate and protocol card, meaning that each port can support a variety of protocols and bit rates up to 10 Gbps solely through software configuration. The line card  66  includes a Time Slot Interchange (TSI) layer one cross-connect. For example, the TSI cross-connect can be configured to perform layer one cross-connects across VCGs. 
         [0039]    Node  90  includes two line cards  60  connected to a backplane. In this deployment, a since OTU1 wavelength is shared among multiple nodes  90  through VCG multiplexing. In node  90 , the line cards  60  are configured to cross-connect a portion of a time slot (i.e., a particular VLAN) to a different L1 time slot terminated anywhere in the node  90 , to a physical port on the same card  60 , or to a physical port on another card  60 . Node  92  illustrates the use of wavelength division multiplexing (WDM) or coarse-wavelength division multiplexing (CWDM) through the use of filters  98  included in the node  92  to increase the line bandwidth. 
         [0040]    Node  94  includes two L1 line cards  66  and two L2 line card  60  connected in a single chassis through a backplane, such as an electrical or optical plane. Here, the L1 card  66  is configured to transmit and receive an OTU2, and to transmit and receive client signals at rates below OTU2 carrying L1 and L2 traffic. The L2 line cards  60  are configured to receive Ethernet signals. Node  96  includes the same components  60 , 66  as node  90  with the addition of filters  98  to allow for CWDM and WDM transmission. 
         [0041]    In nodes  94 , 96 , the L1 cards  66  and L2 cards  60  communicate to each other through both a packet bus and a TSI bus on the backplane. Each of the L1 cards  66  include a L1 cross-connect configured to switch VCGs, such as 155 Mbps timeslots, to any other timeslot within the card or within other L1 cards  66  in the node  94 , 96 . Additionally, the L1 cards  66  can switch VCGs to L2 card  60  in the node  94 , 96  where additional L2 processing can occur. 
         [0042]    Referring to  FIG. 7 , an exemplary embodiment of the hierarchical L1/L2 cross-connect of the present invention is illustrated between line cards  100 , 150  connected by a packet bus  164  and a TSI bus  162 . The line cards  100 , 150  can be configured in a chassis with a backplane through which the packet bus  164  and TSI bus  162  operate.  FIG. 7  depicts an example of L2 cross-connects between a pair of L2 cards  100  and a L1 card  150 . The L2 card  100  includes a network processing unit (NPU)  110 , a TSI field programmable gate array (FPGA)  120 , connections to the backplane including the packet bus  164  and TSI bus  162 , and front panel ports for Ethernet inputs. 
         [0043]    The L1 card  150  includes a L1 cross-connect  160  configured to cross-connect VCGs between any port on the L1 card  150 , ports on any other L1 card  150  through the TSI bus  162  on the backplane, and ports on any L2 card  100  through the TSI bus  162  on the backplane. The TSI FPGA  120  on the L2 card  100  is configured to transmit and receive L1 timeslots carrying L2 traffic from one or more L1 card  150 . 
         [0044]    The NPU  110  is cross-connects Ethernet Channels/Logical Ports (Leth/Lport) between physical ports. A first Leth/Lport  130  is available as a logical port representing remote L2 cards  100  on the packet bus  162 . This Leth/Lport  130  can provide statistics and status monitoring of the remote card  100 . Another Leth/Lport  132  represents the collection of timeslots from the L1 card  150 . Here, all of the front ports on the L1 card  150  are available through this Leth/Lport  132  for L2 cross-connects through the NPU  110 . For each physical port on the L2 card  100 , there is a corresponding Leth/Lport  134 , 136 , 138  available for L2 cross-connects through the NPU  110 . 
         [0045]      FIG. 7  illustrates three example L2 cross-connects. First, a L2 cross-connect  102  connects a port on the second L2 card  100  with a port on the first L2 card  100  through the packet bus  164 . Another L2 cross-connect  104  connects a port on the L2 card  100  with on a collection of timeslots on the L1 card  150 . Finally, a L2 cross-connect  106  connects the port  134  with port  136  on the same L2 card  100 . 
         [0046]    Referring to  FIG. 8 , an exemplary block diagram of a line card  200  configured to provide hierarchical L1/L2 cross-connects according to the present invention is depicted. The line card  200  can include 1 to n SFP modules  240  to receive client signals. The SFP modules  240  connect to a network processor  210 . The network processor  210  includes a full-duplex L2 switching/forwarding engine between the SFPs  240  and the backplane VCGs. In an exemplary embodiment, the network processor  210  is capable of 10 Gbps full-duplex (20 Gbps simplex) L2 switching and forwarding. 
         [0047]    The TSI fabric FPGA  220  interfaces to and from a backplane. The backplane can include electrical or optical connections through which the line card  200  communicates with other line cards  200  and L1 line cards. The TSI fabric FPGA  220  includes a protection switch  222  to provide signal protection to/from the backplane. The TSI fabric FPGA  220  is configured to route signals to/from the network processor  210  to other devices through the backplane. 
         [0048]    As described herein, the line card  200  is configured to perform L2 cross-connecting in a hierarchical fashion with attached L1 line cards configured to perform L1 cross-connecting. In an exemplary embodiment, the TSI fabric FPGA  220  is capable of terminating up to twenty VCGs in total among up to three other line cards to which the FPGA  220  can connect through the backplane. Each VCG can scale from a single 155 Mbps timeslot to a concatenation of up to sixteen, mapped into a channelized OTU2. Multi-timeslot concatenated VCGs can be from any collection of contiguous or non-contiguous timeslots. Each line card  200  can be capable of terminating up to 10 Gbps from the VCGs on the backplane to each L1 line card. 
         [0049]    Multiple line cards  200  can be connected together through the backplane and the TSI fabric FPGA  220  to form a single L2 switch. For example, each line card  200  can support 12.5 Gbps to the backplane through a 4×3.125 interface. In an exemplary configuration, two line cards  200  can be connected through the backplane for a total of n×GbE ports (one GbE per SFP module  240 ) and n Gbps of OTN VCGs. 
         [0050]    Additionally, the line card  200  includes a network SFP  250  configured to provide an aggregate output, such as an OTU1 with aggregated Ethernet traffic from the SFPs  240 . An OTU1 FPGA  230  communicates to the network SFP  250  and to the TSI fabric FPGA  220  to transmit and receive the aggregated Ethernet traffic. The OTU1 FPGA  230  performs OTN framing to create an OTU1. 
         [0051]    The line card  200  also includes random access memory (RAM)  212  attached to the network processor  210  for storage of the network processor  210  instructions and data. A central processor unit (CPU)  260  provides control of all the functions on the line card  200  including monitoring, control, and alarms. The CPU  260  can include a 100Base-T interface for external operations, administration, maintenance, and provisioning (OAM&amp;P), and it can communicate to RAM  266 , flash memory  264 , and control light emitting diodes (LEDs) for a visual representation of the line card  200  status. 
         [0052]    Referring to  FIG. 9 , exemplary block diagrams of a line card  300  with different input modules  350 , 360  configured to provide hierarchical L1/L2 cross-connects according to the present invention are depicted. The same line card  300  can be front-ended with different input modules  350 , 360  for GbE or 10 GbE/OTU2 connections. The line card  300  provides higher aggregate L2 switching capacity over the line card  200  depicted in  FIG. 8 . The line card  300  includes a 24 Gbps Packet Engine  310  configured to support a single 10 GbE plus 14 GbE or 24 GbE worth of capacity for switching/forwarding between input modules  350 , 260  and a backplane. 
         [0053]    A TSI FPGA with Frame Engine  320  interfaces to the backplane and the packet engine  310  to allow the line card  300  to operate with other line cards  300  in a single L2 switch or other L1 line cards. As described herein, the TSI FPGA  320  transmits and receives multiple VCGs from other cards and interfaces them to the packet engine  310  for processing. Multiple line cards  300  can be connected together through the backplane and the TSI fabric FPGA  320  to form a single L2 switch. The line card  300  includes additional functions, such as power  340  and a control complex  330  to manage the card  300  functions and OAM&amp;P. 
         [0054]    The input module  350  can support GbE inputs (e.g., ten SFP modules  352 ), and includes a 10 Ports PHY controller  354  and an ECC FPGA  356  to interface to the line card  300 . Note, the input module  350  and the line card  300  can be include in a single line card, as can the input module  360  and the line card  300 . The input module  360  can support a single 10 GbE input  362  and 2 OTU2 inputs  370 . An Optical Ethernet Module  368  is configured to process Ethernet streams in the OTU2 inputs  370  and provided the to the packet engine  310 . A 10G PHY controller  364  interfaces to the 10 GbE input  362 , and a Rubicon module  366  provides the 10 GbE to the packet engine  310 . 
         [0055]    Although the present invention has been illustrated and described herein with reference to preferred embodiments and specific examples thereof, it will be readily apparent to those of ordinary skill in the art that other embodiments and examples may perform similar functions and/or achieve like results. All such equivalent embodiments and examples are within the spirit and scope of the present invention and are intended to be covered by the following claims.