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SEM Configurations
The SEM v8 is available in the configurations shown in Table 2-2:
Table 2-2 SEM Configurations
SEM v8 Configurations Applicable Interfaces and Modules ASI GigE QAM/UC Module* ACP Module*
1. Full Edge, ac(part no.
507199-001) Yes Yes Yes Yes
2. Modulator/Upconverter, ac
(part no. 507199-002) Yes Yes Yes No
3. Full Edge, dc (part no.
507199-003) Yes Yes Yes Yes
SEM System Implementations
To deploy a SEM, a controller is required to perform provisioning and configuration of the SEM device. In a broadcast cable system, where the SEM is required to encrypt services, the SEM controller would be the DAC 6000. Systems that do not require encryption or prefer to use Common Tier Encryption (CTE) can rely on the SEM-EM to function as the controller if necessary.
SEM-EM Re-multiplexing Controller
As a surrogate controller, the SEM-EM is used to configure the SEM for service routings when encryption functionality is not required. When the SEM-EM is the SEM controller, the SEM can operate in Manual Routing mode, one of two UDP Mapping modes, or ASI Demultiplexing mode. Screen sets used to set up the SEM-EM for these modes are described in Section 4, “Setup and Operation.” In all of these modes, the input services to the SEM can be either clear content or
pre-encrypted content. When enabled for CTE, the SEM also can encrypt the output programs.
• In Manual Routing mode, to support re-multiplexing control, the SEM-EM provides configuration screens that allow the operator to select available input services from enabled input ports and place them into an output stream with a user assigned MPEG service number. The re-multiplexing information entered into the SEM-EM screen-sets is transmitted to the SEM as data using Simple Network Management Protocol (SNMP). The SEM internally processes the re-multiplexing data and then performs the necessary operations to implement the specified service routings. In addition to routing services, Manual Routing mode supports the ability to route an entire input stream to one or more output streams (transport stream pass through).
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• When operating in either UDP Mapping mode, the SEM receives services at one of the GigE interfaces by means of UDP/IP in the form of single program
transport streams (SPTS). Within a given GigE interface, each service is delivered to the SEM in a UDP segment stream identified by a unique UDP destination port number. The destination UDP port number of the received UDP segment stream identifies the output transport stream, physical output (for example, QAM-1, QAM-2, GigE-2, etc.), and outgoing MPEG service number to be assigned to the VOD service by the SEM. The SEM then autonomously routes incoming SPTSs to the appropriate output, and builds the appropriate output PSI based on the observed destination UDP port value.
• In ASI Demultiplexing mode, to support demultiplexing control, the SEM-EM provides configuration screens that allow the operator to select available input services from enabled ASI input ports and de-multiplex them into an output stream. The demultiplexing information entered into the SEM-EM screen-sets is transmitted to the SEM as data using Simple Network Management Protocol (SNMP). The SEM internally processes the demultiplexing data and then
performs the necessary operations to implement the specified service routings.
SEM-EM Manual Routing Mode for Broadcast Services
The SEM-EM allows an operator to provision a SEM to support broadcast services when encryption functionality is not required. To support this functionality, the SEM-EM provides GUI windows that enable the operator to configure individual service routes. To configure a service route, the SEM-EM window enables the operator to specify a specific input service, route that service to a specific SEM output transport stream, and specify the output MPEG service number.
If the SEM is receiving services on the GigE interface, there can be many input transport streams (either SPTS or MPTS), each using a different destination UDP port number. The SEM, therefore, must be configured with a list of receive UDP port numbers to open at the desired GigE input. To enter this data, the operator needs a list of the UDP ports corresponding to transport streams present at the GigE inputs to the SEM.
SEM-EM UDP Mapping Mode for VOD Systems
To support UDP Mapping mode, the SEM-EM operator must first specify the
specific SEM GigE input port that is used to receive the input services. The operator must then specify the base offset, starting program number, and a number of output services for each individual output transport stream. The combination of base offset, starting program number, and the total number of output services across all enabled output transport streams provides the SEM with a list of receive UDP port numbers to open. The SEM keeps these UDP ports open and then waits for the incoming connections (input SPTSs).
The base offset specifies the starting (lowest) receive UDP port number; all other receive UDP port numbers are in a range above the base offset. The base offset allows the SEM to be easily configured to accept receive UDP port numbers in any range that the video servers wish to use.
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The starting program number is the first output program number that is used for the output transport stream specified. For example, if the starting program number is 2, and the number of programs is 20, then the output program numbers are from 2–21.
The total number of output services across all enabled output transport streams specifies the total number of UDP ports that the SEM must open (one UDP port number per SEM output service). If the operator specifies 16 services per output transport stream and there are 8 enabled SEM output transport streams, the SEM opens 128 UDP ports starting with the base offset number.
Additionally, the operator can specify if the input content to the SEM is clear or pre-encrypted. (This is accomplished by checking the Input Program Pre-Encrypted check box on the SEM VOD Control-UDP Mapping window.) If the input content is a mix of clear and pre-encrypted, then the Pre-Encrypted check box should be
selected. When the input is pre-encrypted, the SEM determines if the individual services contain pre-encrypted content by examining the input PMT descriptors. The pre-encrypted output programs routed by the SEM contain the proper CA ECM descriptors along with additional program information messages.
SEM-EM Eight Channel UDP Mapping Mode for VOD Systems
To support Eight Channel UDP Mapping mode (eight QAM outputs only), the
SEM-EM operator must first specify the specific SEM GigE input port that is used to receive the input services. The operator must then specify the number of output services and a starting output program number for each individual QAM output transport stream. The combination of starting program number and the total number of output services across all enabled output transport streams provides the SEM with a list of receive UDP port numbers to open. The SEM keeps these UDP ports open and then waits for the incoming connections (input SPTSs).
The starting program number is the first output program number that is used for the output transport stream specified. For example, if the starting program number is 2, and the number of programs is 20, then the output program numbers are from 2–21.
The total number of output services across all enabled output transport streams specify the total number of UDP ports that the SEM must open (one UDP port number per SEM output service). If the operator specifies 16 services per output transport stream and there are eight enabled SEM output transport streams, the SEM opens 128 UDP ports.
Additionally, the operator can specify if the input content to the SEM is clear or pre-encrypted. (This is accomplished by checking the Input Program Pre-Encrypted check box on the SEM VOD Control-UDP Mapping window.) If the input content is a mix of clear and pre-encrypted, the Pre-Encrypted check box should be selected.
When the input is pre-encrypted, the SEM determines if the individual services contain pre-encrypted content by examining the input PMT descriptors. The pre-encrypted output programs routed by the SEM contain the proper CA ECM descriptors along with additional program information messages.
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SEM-EM Standardized UDP Mapping Mode for VOD Systems
To support Standardized UDP Mapping mode, the SEM-EM operator must first specify the specific SEM GigE input port that is used to receive input services. The operator must then specify the transport stream relative 0/1 setting, the number of output services, and a starting output program number for each individual QAM output transport stream. The combination of transport stream number, starting program number, and the total number of output services across all enabled output transport streams provides the SEM with a list of receive UDP port numbers to open. The SEM keeps these UDP ports open and then waits for the incoming connections (input SPTSs).
The transport stream relative 0/1 setting is used as part of the UDP port calculation.
The transport stream numbers can range from 0-15 or from 1-16, depending on the relative 0/1 setting.
The starting program number is the first output program number that is used for the output transport stream specified. For example, if the starting program number is 2, and the number of programs is 20, then the output program numbers are 2-21.
The total number of output services across all enabled output transport streams specifies the total number of UDP ports that the SEM must open (one UDP port number per SEM output service). If the operator specifies 16 services per output transport stream and there are 8 enabled SEM output transport streams, the SEM opens 128 UDP ports.
Additionally, the operator can specify if the input content to the SEM is clear or pre-encrypted. (This is accomplished by checking the Input Program Pre-Encrypted check box on the SEM VOD Control-UDP Mapping window.) If the input content is a mix of clear and pre-encrypted, the Pre-Encrypted check box should be selected.
When the input is pre-encrypted, the SEM determines if the individual services contain pre-encrypted content by examining the input PMT descriptors. The pre-encrypted output programs routed by the SEM contain the proper CA ECM descriptors along with additional program information messages.
SEM-EM ASI Demultiplexing Mode for Broadcast Systems
When the SEM receives a high-speed ASI transport stream, each individual input service can be manually routed to a SEM output transport stream (SEM in Manual Routing mode), or the automatic ASI demultiplexing feature can be used (SEM in ASI Demultiplexing mode). The purpose of the ASI demultiplexing feature is to reduce the amount of SEM configuration and provisioning necessary to support the reception and re-multiplexing of a high-speed transport stream containing a large number of services. The advantage of this mode is to allow the SEM operator to specify a range of MPEG service numbers rather than specifying each individual service route.
When automatic ASI Demultiplexing mode is selected, the SEM-EM operator essentially identifies groups of services in the input high-speed transport stream (each group specified by a sequential range of MPEG service numbers) that should be routed to the same SEM output transport stream. As illustrated in the table that follows, the range of input MPEG service numbers in the input transport stream
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from 1-10 can be routed to QAM1A (output transport stream 1), while MPEG service numbers 11-20 can be routed to QAM1B (output transport stream 2). The SEM internally generates the necessary Load SEM subcommands to configure each individual service route.
When internally configuring the service routes, the SEM uses the input MPEG Service Number as the output MPEG service number. Additionally, when configured for ASI Demultiplexing mode, the SEM-EM allows the operator to specify if all of the input services should be handled as pre-encrypted services or not. If the operator specifies that all input services should be handled as pre-encrypted, the SEM automatically generates the Load SEM Include Service subcommand for each input service with the applicable input service encryption flag set. This enables all input services to be either pre-encrypted or clear.
Figure 2-2 illustrates an example system in which multiple SEM devices under the control of the SEM-EM (using either UDP Mapping mode or Manual Routing mode) receive content from VOD servers:
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Figure 2-2 Typical example of SEM-EM Control (UDP Mapping or Manual Routing)
HFC
GbESwitch 3rdPartyservernetwork CableplantnodeACableplantnodeB
Localcontrolnetwork Cableplanthub
GbESwitch RFCombiner
Headend
Common Tier Encryption (CTE)
When the SEM is in any of the internal control modes, the SEM can be enabled to perform Common Tier Encryption. In this mode, the SEM performs all of the normal service mapping operations; however the output programs can be encrypted in either Full or Fixed Program Key encryption modes. This allows a SEM to be used in a VOD environment and encrypt the output programs without the need for an external controller, such as the DAC 6000. All programs in this mode are encrypted using the same program tier.
In order for the SEM to encrypt programs in Full encryption mode, the SEM requires a connection to an external EMM Server (EMMS). Typically, the DAC 6000 operates as an EMMS. This is necessary since the SEM needs EMMs to fully encrypt all programs. The SEM can encrypt programs using Fixed Program Key (FPK) encryption
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without the need for an EMMS. This allows a SEM to encrypt programs in FPK mode without the need for any other external devices.
Output Program Encryption Process
When CTE is enabled, the SEM can be configured to encrypt all output programs mapped from GigE inputs. Programs mapped from the Host Ethernet inputs (OAM&P or Data IP) cannot be encrypted.
The number of programs that can be encrypted for each output is limited based on the amount of ACP resources assigned to each output stream. This is set by the number of encrypted programs per output configuration parameter (Output Transport Stream configuration screen).In addition, the SEM limits the number of programs that can be mapped to the total number of programs that can be encrypted. When the SEM is enabled for CTE, the maximum number of programs that can be mapped from GigE inputs is 128.
Encrypting output programs via CTE is only allowed under the following conditions:
• SEM is configured in an internal operating mode (such as UDP Port mapping, Manual Routing).
• SEM contains an ACP Module.
• SEM CTE parameter is set to enabled.
• SEM Encryption mode parameter is set to Full or Fix Program Key (FPK).
CTE Encryption Modes
The SEM supports encrypting programs in Full encryption mode or FPK mode. The user selects the encryption mode when CTE is enabled. The SEM can always encrypt output programs in FPK mode, but requires Entitlement Management Messages (EMMs) from an EMMS in order to fully encrypt programs. The SEM can also be placed in Clear mode when CTE is enabled (programs are not encrypted).
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DAC 6000 Controlling SEMs in a Broadcast System
In a DAC 6000 broadcast system, the SEM receives either SPTS or MPTS inputs, re-multiplexes services, encrypts services, and provides MPTS outputs that contain the encrypted services in ASI, GigE, or QAM RF formats. In the example system shown in Figure 2-3, all of the SEMs are located at the headend and the QAM RF outputs of each SEM are distributed to each hub in the system. As determined by system size and the specific system topology, the SEMs can be implemented as edge devices in the hub locations. In the illustrated implementation, the SEMs are receiving eight ASI MPTSs from the satellite Integrated Receiver Decoders (IRDs), which provide decryptor functions, and input transport streams containing
clear/unencrypted services to the GigE from a DWDM distribution network.
In a broadcast system the DAC 6000 functions as the SEM controller. To provision the SEMs, the operator must route input services to output transport streams in the DAC 6000 for each SEM. The DAC 6000 configures each SEM by generating Load SEM subcommand sequences.
Figure 2-3 Typical example of DAC 6000 controlling SEMs in a broadcast system
HFC (each IRD receives a MPTS)
SEM
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Digital Video Broadcasting (DVB) SimulCrypt Operation
When operating within a SimulCrypt system, the SEM provides the functionality of the Control Word Generator (CWG), SimulCrypt Synchronizer (SCS), Multiplexer (MUX), Scrambler (SCR), and Motorola ECM Generator (ECMG). The SEM is also capable of receiving ECMs from third party ECMGs for insertion into an output multiplex.
Note: PID re-mapping must be enabled when the SEM is operating in SimulCrypt mode.
Daisy Chaining SEMs
Motorola recommends that each SEM device always be connected to its own dedicated port on the GigE switch. The loop-through configuration allows multiple SEM devices to share a common switch port, but requires extra processing in the SEM, which can reduce performance. Up to six SEMs can be configured to be daisy-chained in a single loop. SEM daisy chaining supports transmission of ARP replies, ICMP echo replies, IGMP join messages, and other upstream traffic. When SEMs are configured in loop through-configuration, Motorola requires the network to be bi-directional, so that the last SEM in the daisy chain has a physical connection back to the GigE switch. The use of loop-through mode with uni-directional
networks is not supported. Figure 2-4 illustrates two SEM daisy chains off of an L2 switch.
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Figure 2-4 Two SEM daisy chains
SEM 1
(SEM 3 passes ARP Reply from SEM 2)
In the upper daisy chain, ARP requests from the L2 switch are forwarded through the chain from SEM 1 GigE-1 down the chain, through SEM 2, to the SEM 3 GigE-1 input, which is configured as a loop through (LT) terminator. The other GigE-1 ports of SEM 1 and SEM 2 are enabled as loop through interfaces. A SEM’s GigE-1 and/or GigE-2 port is enabled from a drop-down list as a loop through or LT terminator on the SEM Input/Output Configuration–Gigabit Ethernet window, which is displayed from the SEM-EM. A SEM’s GigE-3 port cannot be used in daisy chains, as only GigE-1 and GigE-2 ports are valid.
As shown in Figure 2-5, each SEM in the chain passes data destined only for it to its network stack. It filters out that data, injects new data from the network stack, and passes all other remaining information to the next SEM in the chain.
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Figure 2-5 SEM with loop through interface
Loop Through
From Switch or previous SEM in chain Copy Frames
Pass data destined for SEM.
Pass all frames except unicast for this interface and pass frames injected by this SEM.
To next SEM in chain
To Network Stack
From Network Stack
(GigE-3 not used for chaining SEMs)
As shown in Figure 2-6, the LT terminator performs all of the functions of a pass through interface; however, it also passes ARP replies, Echo replies, IGMP join messages, etc., from the entire chain back onto the network. It terminates any traffic
As shown in Figure 2-6, the LT terminator performs all of the functions of a pass through interface; however, it also passes ARP replies, Echo replies, IGMP join messages, etc., from the entire chain back onto the network. It terminates any traffic