KR101231732B1 - A system and method for selecting a multicast ｉｐ address - Google Patents

Abstract

The disclosed embodiment is directed to a system and method for inserting sync bytes into a video transport stream. More specifically, determining a parsing procedure to be supported by the first set-top box 22a, adding a first transport packet to follow the parsing procedure of the first set-top box 22a, and A method is provided that includes sending a transport packet to a first set top box 22a.

Description

A SYSTEM AND METHOD FOR SELECTING A MULTICAST IP ADDRESS

The present invention is generally directed to transmitting video or other digital data over a network. More particularly, the present invention is directed to a system for selecting a multicast group for multicasting video or other data over an Internet Protocol (“IP”) network.

This section is intended to introduce the reader to various aspects of the prior art, which may relate to various aspects of the present invention described below and / or claimed. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Therefore, it should be understood that such sentences should be read in this respect and not as admissions of the prior art.

As most people know, satellite television systems like DirectTV have become much more widespread in the past few years. In fact, since the introduction of DirectTV in 1994, more than 12 million US homes have become satellite TV subscribers. Most of these subscribers live in single-family homes, which are relatively easy to install and connect with satellite dish antennas. For example, a satellite dish antenna may be installed on the roof of the house.

However, many potential subscribers live or temporarily live in multi-dwelling units (“MDUs”), such as hotels or high-rise apartment buildings. Unfortunately, there are additional challenges involved in providing satellite TV service to individual generation units within the MDU. Providing and connecting one satellite dish antenna per generation can be unrealistic and / or very expensive. For example, in a high-rise apartment building with 1,000 furniture, it may be impractical to mount 1,000 satellite dish antennas on the roof of the building. Some of the prior art systems have avoided this problem by converting digital satellite television signals into analog signals that can be transmitted to multiple generations over a single coaxial cable. However, these systems offer limited channels, degrade quality compared to all-digital systems, and cannot provide a familiar satellite TV experience for users living in single-family homes.

Improved systems and / or methods for providing satellite TV to multigenerational units are desirable.

Certain aspects that fall within the scope of the originally claimed invention are described below. It is to be understood that this aspect has been presented solely to provide the reader with a brief summary of the specific forms the invention may take, and that such aspects are not intended to limit the scope of the invention. Indeed, the invention may encompass a variety of aspects that may not be described below.

The disclosed embodiments are directed to a system and method for selecting a multicast IP address. More specifically, selecting a first IP address from a plurality of IP addresses, hashing the first IP address to generate a first hash value corresponding to the first IP address, wherein the first hash value is Determining whether it corresponds to a second IP address in use, and if the first hash value does not correspond to a second IP address in use, allocating the first IP address.

Advantages of the present invention may become more apparent upon reading the following detailed description and referring to the drawings below.

1 is a block diagram of an exemplary satellite television on an IP system in accordance with an embodiment of the present invention.

2 is another embodiment of an exemplary satellite television on the IP system illustrated in FIG. 1 of the present invention.

3 is a block diagram of an exemplary satellite gateway of the present invention.

4 is a flow diagram illustrating an exemplary method for selecting a multicast IP address in accordance with an embodiment of the invention.

One or more specific embodiments of the invention will be described below. In an effort to provide a brief description of these embodiments, not all features of an actual implementation are described herein. In the development of any such actual implementation, as in any engineering or design project, the developer achieves specific goals, such as compliance with systems-related and business-related constraints, which may vary from implementation to implementation. A number of implementation-specific decisions must be made to accomplish this. In addition, while such development efforts may be complex and time consuming, it should nevertheless be appreciated that it is an ever-presenter of design, fabrication, and manufacturing to those skilled in the art having the benefit of this disclosure.

1, a block diagram of an exemplary satellite television on an IP system is described and generally designated by reference numeral 10, according to one embodiment. As described, in one embodiment, system 10 includes one or more satellite dish antennas 12a through 12m, a head-end unit such as satellite gateway 14, IP distribution network 20, and one or more set top boxes. ("STBs") (22a through 22n). However, those skilled in the art will recognize that the embodiment of the system 10 described in FIG. 1 is only one potential embodiment of the system 10. As such, in alternative embodiments, the described components of system 10 may be rearranged or omitted, or additional components may be added to system 10. For example, via mirror modification, system 10 may be configured to distribute distributed non-satellite video and audio services.

Satellite dish antennas 12a-12m may be configured to receive video, audio, or other types of television-related data transmitted from satellites orbiting the earth. As described further below, in one embodiment, satellite dish antennas 12a-12m are configured to receive DirecTV programming on the KU band from 10.7 to 12.75 gigahertz (“GHz”). However, in alternative embodiments, the satellite dish antennas 12a-12m may be other types of direct broadcast satellites ("DBSs") or television receive-only: dish antenna network signals, ExpressVu signals, StarChoice signals, or the like. "TVRO") signal. In another non-satellite based system, satellite dish antennas 12a-12m may be omitted from system 10.

In one embodiment, the low noise-block ("LNB") within the satellite dish antennas 12a-12m receives input signals from satellites orbiting the earth and transmits these input signals to 950 and 2150 MHz ("MHz"). Convert to a frequency in the L band between). As described in more detail below with respect to FIG. 2, each of the satellites 12a-12m receives one or more input satellite TV signals with special polarizations on a particular frequency (referred to as transponders) to L-band the satellite signals. Configured to convert to a signal, each of which may comprise a plurality of video or audio signals.

As illustrated in FIG. 1, satellite dish antennas 12a-12m may be configured to transmit L band signals to a head-end unit or gateway server, such as satellite gateway 14. In alternative non-satellite embodiments, the head-end unit may be a cable television receiver, a high definition television receiver or other video distribution system.

The satellite gateway 14 includes a satellite tuning, demodulation and demultiplexing module 16 and an IP wrapper module 18. Module 16 may include a plurality of tuners, demodulators and demultiplexers for converting the modulated and multiplexed L band signals transmitted from satellites 12a-12m into a plurality of single program transport streams ("SPTS"). Each of the plurality of single program transport streams carries a service (eg, television channel video, television channel audio, program guide, etc.). In one embodiment module 16 is configured to generate a single program transport stream for all services received by satellite dish antennas 12a-12m. However, in an alternative embodiment, module 16 may only generate a transport stream for a subset of services received by satellite dish antennas 12a-12m.

The satellite tuning, demodulation and demultiplexing module 16 may send the SPTS to the IP wrapper module 18. In one embodiment, IP wrapper module 18 repackets data in SPTS into a plurality of Internet Protocol ("IP") packets suitable for transmission on IP distribution network 20. For example, IP wrapper module 18 may convert DirecTV protocol packets in the SPTS into IP packets. IP wrapper module 18 also receives server requests from STBs 22a-22n and multicasts IP SPTS to the STBs 22a-22n that requested this particular service (i.e., on one IP address). It may be configured to broadcast to one or more STBs 22a-22n.

In alternative embodiments, IP wrapper module 18 may also be configured to multicast IP protocol SPTS for services not requested by one of STBs 22a-22n. It should be noted that modules 16 and 18 are just one exemplary embodiment of satellite gateway 14. In alternative embodiments as described below with respect to FIGS. 2 and 3, the functionality of modules 16 and 18 may be redistributed or integrated between various suitable components or modules.

IP distribution network 20 may include one or more routers, switches, modems, splitters, bridges. For example, in one embodiment, satellite gateway 14 is a master distribution frame coupled to an intermediate distribution frame (" IDF ") coupled to a coaxial cable to an Ethernet bridge coupled to a router coupled to one or more STBs 22a-22n. ("MDF"). In another embodiment, IP distribution network 20 may be an MDF coupled to a digital subscriber line access multiplexer (“DSLAM”) coupled to a DSL modem coupled to a router. In another embodiment, the IP distribution network may comprise a wireless network, such as an 802.11 or WiMax network. In this type of embodiment, the STBs 22a-22n may include a wireless receiver configured to receive multicasted IP packets. Those skilled in the art will recognize that the embodiments described above are merely illustrative. As in alternative embodiments, many suitable forms of IP distribution networks may be used in the system 10.

The IP distribution network 20 may be connected to one or more STBs 22a-22n. The STBs 22a-22n may be any suitable type of video, audio, and / or other data receiver capable of receiving IP packets such as IP SPTS on the IP distribution network 20. It will be appreciated that the term set top box ("STB") used herein does not include only devices that can be placed on a television. Rather, the STBs 22a-22n may be any device or device, internal or external to a television, display, or computer, which may be configured to function as described herein, such device or device being, without limitation. , Video components, computers, cordless phones, or other types of video recorders. In one embodiment, the STBs 22a-22n may be DirecTV receivers configured to receive services, such as video and audio, over Ethernet ports (among other inputs). In alternative embodiments, the STBs 22a-22n may be coaxial cable, twisted pair, copper conductors, or I.E.E.E. It may be designed and / or configured to receive wirelessly multicasted transmissions over a wireless standard such as the 802.11 standard.

As discussed above, system 10 may receive video, audio and / or other data sent to satellites in space and process / transform such data for distribution on IP distribution network 20. have. Thus, FIG. 2 is another embodiment of an exemplary satellite television on IP system 10 according to one embodiment. 2 illustrates three exemplary satellite dish antennas 12a-12c. Each of the satellite dish antennas 12a-12c may be configured to receive signals from one or more satellites that orbit. Those skilled in the art will often refer to satellites and satellites and signals transmitted from the satellites by the orbital slot in which the satellites are located. For example, satellite dish antenna 12a is configured to receive signals from DirecTV satellites arranged in 101 degree orbit slots. Similarly, satellite dish antenna 12b receives signals from satellites arranged at 119 degrees, and satellite dish antenna 12c receives signals from satellites arranged in orbit slots of 110 degrees. In alternative embodiments, satellite dish antennas 12a-12c may receive signals from a plurality of other satellites initiated in various orbital slots, such as 95 degree orbital slots. In addition, satellite dish antennas 12a-12c may be configured to receive polarized satellite signals. For example, in FIG. 2, the satellite dish antenna 12a is configured to receive a signal polarized to the left (indicated by " 101L " in FIG. 2) and also polarized to the right (indicated by " 101R ").

As described above with respect to FIG. 1, satellite dish antennas 12a-12c may receive satellite signals in the KU band and convert them into L band signals transmitted to the satellite gateway 14. However, in some embodiments, the L band signal generated by the satellite dish antennas 12a-12c may be merged into fewer signals or split into more signals before reaching the satellite gateway 14. . For example, as illustrated in FIG. 2, the L band signal from satellite dish antennas 12b and 12c may be a single L band signal that includes L band signals from both a satellite at 110 degrees and a satellite at 119 degrees. It can be incorporated by the switch 24.

As described, system 10 includes a plurality of 1: 2 dividers 26a, 26b, 26c and 26d to split the L band signal transmitted from satellite dish antennas 12a-12c into two L band signals. And each of the two L band signals includes half of the services of the pre-divided L band signal. In alternative embodiments, the 1: 2 dividers 26a-26b may be omitted or integrated into the satellite gateways 14a and 14b.

The newly divided L band signal may be transmitted from the 1: 2 dividers 26a-26d to the satellite gateways 14a and 14b. The embodiment of the system 10 described in FIG. 2 includes two satellite gateways 14a and 14b. However, in alternative embodiments, system 10 may include any suitable number of satellite gateways 14. For example, in one embodiment, the system may include three satellite gateways 14.

The satellite gateways 14a and 14b then subdivide the L band signal, one on the L band signal to generate one or more SPTS that can be repackaged into IP packets and multicast on the IP distribution network 20. We can synchronize with the above service. In addition, one or more satellite gateways 14a, 14b may also be connected to a public switched telephone network (“PSTN”) 28. The satellite gateways 14a and 14b are connected to the PSTN 28, and the STBs 22a-22n can communicate with the satellite service provider via the IP distribution network 20 and the satellite gateways 14a and 14b. This function can advantageously eliminate the need to have each individual STB 22a-22n connected directly to the PSTN 28.

IP distribution network 20 may also be connected to an Internet service provider (“ISP”) 30. In one embodiment, IP distribution network 20 is used to provide Internet services, such as high speed data access, to STBs 22a-22n and / or other suitable devices (not shown) connected to IP distribution network 20. Can be.

As described above, the satellite gateways 14a and 14b may be configured to receive L band signals, generate a plurality of SPTSs, and multicast the requested SPTS on the IP distribution network 20. Referring now to FIG. 3, shown is a block diagram of an example satellite gateway 14. As described, the satellite gateways 14a and 14b include a power supply 40, two front ends 41a and 41b and a rear end 52. The power source 40 may be any one of a number of industry-standard AC or DC power sources in which the front end portions 41a and 41b and the rear end 52 may be configured to perform the functions described below.

The satellite gateways 41a and 41b may also include two front ends 41a and 41b. In one embodiment, each front end 41a, 41b may be configured to receive two L band signal inputs from the 1: 2 dividers 26a-26d described above with respect to FIG. 2. For example, the front end 41a may receive two L-band signals from the 1: 2 divider 26a, and the front end 41b may receive two L-band signals from the 1: 2 divider 26b. can do. In one embodiment, each of the L band inputs to the front ends 41a, 41b includes up to eight services.

The front end portions 41a and 41b can then further subdivide the L band input using 1: 4 L band dividers 42a, 42b, 42c and 42d. Once subdivided, the L band signal can be delivered to four banks 44a, 44b, 44c and 44d of the dual tuner link. Each of the dual tuner links in banks 44a-44d may be configured to tune to two services in the L band signal received by the respective dual tuner link to produce an SPTS. Each of the dual tuner links may then send the SPTS to one of the low voltage differential signal (“LVDS”) drivers 48a, 48b, 48c, and 48d. LVDS drivers 48a-48d may be configured to amplify a transport signal for transmission to the rear end 52. In alternative embodiments, other types of differential drivers and / or amplifiers may be used in place of the LVDS drivers 48a-48d. Other embodiments may use the serialization of all transport signals together to route to the back end 52.

As described, the front end portions 41a and 41b may include microprocessors 46a and 46b. In one embodiment, the microprocessors 46a and 46b may control the banks 44a-44d and the 1: 4 L band dividers 42a-42d and / or relay the commands of the dual tuning links. Microprocessors 46a and 46b may include ST10 microprocessors produced by ST Microelectronics. Microprocessors 46a and 46b may be connected to the LVDS receiver and transmitter modules 50a and 50b. The LVDS receiver / transmitter modules 50a and 50b may assist in communication between the components of the microprocessor 46a and 46b and the rear end 52, as described further below.

Turning next to the back end 52, the back end 52 includes LVDS receivers 54a, 54b, 54c and 54d configured to receive transport stream signals transmitted by the LVDS drivers 48a-48d. do. The rear end 52 also includes LVDS receiver / transmitter modules 56a and 56b that are configured to communicate with the LVDS receiver / transmitter modules 50a and 50b.

As described, LVDS receivers 54a-54d and LVDS receivers / transmitters 56a, 56b are configured to communicate with transport processors 58a and 58b. In one embodiment, the transport processors 58a, 58b are configured to receive the SPTS generated by the dual tuning links in the front ends 41a, 41b. For example, in one embodiment, the transport processors 58a, 58b may be configured to generate 16 SPTSs. Transport processors 58a and 58b may be configured to repacket the SPTS into IP packets that may be multicast on IP distribution network 20. For example, transport processors 58a and 58b may repacket DirecTV protocol packets into IP protocol packets, thereby multicasting IP packets on one IP address to one or more STBs 22a-22n.

Transport processors 58a and 58b may also be connected to a bus 62, such as a 32-bit, 66 MHz peripheral component interconnect (“PCI”) bus. Via bus 62, transport processors 58a and 58b may communicate with network processor 70, Ethernet interface 84, and / or expansion slot 66. The network processor 70 may be configured to receive a request for a service from the STBs 22a-22n and direct the request to the transport processor 58a, 58b for multicasting the requested service. In one embodiment, the network processor is an IXP425 network processor produced by Intel. Although not described, the network processor 70 may also be configured to transmit status data to the front panel of the satellite gateways 14a and 14b, or to support debugging or monitoring of the satellite gateways 14a and 14b through debug ports. Can be.

As described, transport processors 58a and 58b may also be connected to Ethernet interface 68 via bus 62. In one embodiment, Ethernet interface 68 is a gigabit Ethernet interface that provides copper wire or fiber optic interface to IP distribution network 20. In addition, the bus 62 may also be connected to an expansion slot such as a PCI expansion slot to enable upgrade or expansion of the satellite gateways 14a and 14b.

Transport processors 58a and 58b may also be coupled to host bus 64. In one embodiment, host bus 64 is a 16-bit data bus that connects transport processors 58a and 58b to modem 72, which may be configured for communication on PSTN 28, as described above. to be. In alternative embodiments, modem 72 may also be connected to bus 62.

As described above, the satellite gateway 14 is configured to receive services such as television, video, audio or other data and to multicast these services to the STBs 22a-22n via the IP distribution network 20. Can be. In one embodiment, STBs 22a-22n use Ethernet integrated circuits (“ICs”) to monitor the IP distribution network for critical multicast of STBs 22a-22n to each particular STB. In other words, the Ethernet IC in each STB 22a-22n can monitor the IP distribution network for transmission on the IP address being used to transmit such services, used by each STB 22a-22n. have. For example, satellite gateway 14 may multicast services to a first group of STBs on one IP address and multicast a second service to a second set of groups of STBs on second IP address. have. In this example, the Ethernet ICs in the STB of the first group will monitor the IP distribution network 20 for activity on the first IP address, and the Ethernet ICs in the STB of the second group will monitor the activity on the second IP address. Will be monitored. The Ethernet IC can monitor the activity on a particular IP address by comparing the IP address of the incoming packet with the IP address being monitored.

However, in general, to reduce computational complexity for Ethernet ICs, IP addresses can be hashed to simpler numbers to simplify this comparison. For example, a 32-bit IP address can be reduced to a 6-bit value through hashing. Those skilled in the art will appreciate that a 32-bit IP address can provide millions of non-duplicate identification values, while a 6-bit value can provide only 64 unique values that can be referred to as hash buckets. . Thus, while hashing an IP address reduces the complexity for Ethernet ICs, this hashing can cause additional problems within system 10. For example, if two unrelated multicast groups use IP addresses hashed to the same 6-bit value, the STB monitoring for one of these IP addresses will be suspended for both. Such unnecessary interruption may cause choppy or distorted reproduction of video and / or audio on the STBs 22a-22n. Accordingly, it is desirable to reduce hash mismatches in multicast groups.

Accordingly, FIG. 4 is a flow diagram illustrating an example method 80 for selecting a multicast IP address, according to one embodiment. The method 80 may be performed by the satellite gateway 14. As further described below, the method 80 may facilitate the selection of multicast IP addresses by the satellite gateway 14 uniformly distributed among the available number of hash buckets. For example, the method 80 selects one multicast IP address per hash bucket until each hash bucket has one IP address, and then there are two IP addresses corresponding to each hash bucket. Until you can choose up to two IP addresses per hash bucket, different numbers of IP addresses are selected in this way.

As described, the method 80 begins by setting the counter variable MaxBucketCount to 1, clearing the array HashBucketCount, and resetting the remaining multicast address pool. MaxBucketCount may indicate the maximum number of IP addresses that satellite gateway 14 can allow to hash to the same hash bucket. HashBucketCount may contain a location (eg, 64 spaces with 6-bit hash values) for each HashBucket. The HashBucketCount array can store the number of currently allocated multicast IP addresses corresponding to each hash bucket. For example, if satellite gateway 14 assigned IP addresses corresponding to hash buckets 1 and 6, array locations 1 and 6 would each contain the number 1. The remaining multicast address pool may be a list of IP addresses that (1) are not currently being used to multicast satellite services and (2) have not been temporarily removed from the multicast IP address pool as described below.

Next, the satellite gateway 14 may wait for a service request from one of the STBs 22a-22n indicated at block 84. Once the service request is received, the satellite gateway 14 may determine whether there are any multicast addresses remaining in the multicast address pool, as indicated at block 86. If there is a multicast IP address remaining in the multicast address pool, the satellite gateway 14 selects one of the remaining IP addresses as indicated by block 88 and sets the variable as indicated in block 90. You can set n equal to the selected hash bucket number. The satellite gateway 14 may then examine the HashBucketCount array to determine if the value stored at location n in the HashBucketCount array exceeds MaxBucketCount as indicated in block 92. For example, if MaxBucketCount is 1, the satellite gateway 14 will determine if the HashBucketCount array location corresponding to the selected IP address is less than 1 (ie equal to 0).

If the location in the HashBucketCount array that corresponds to the hash bucket associated with the remaining multicast address is not less than MaxBucketCount, then as indicated in block 94, the satellite gateway 14 sends the selected multicast address from the remaining multicast address pool. Can be removed After removing the selected multicast IP address from the remaining multicast address pool, the method 80 may cycle back to block 86 as described in FIG. In this way, the satellite gateway 14 either determines that a multicast IP address corresponding to a location in the HashBucketCount array with a value less than the maximum bucket count is found or that all remaining multicast IP addresses are from the multicast address pool. Until removed, it can continue to check multicast IP addresses from the remaining multicast address pool.

Returning to block 92, if the value of the HashBucketCount array corresponding to the hash value of the selected IP address is less than MaxBucketCount, the satellite gateway 14 may assign the selected multicast address, and by block 96 As indicated, you can increment the HashBucketCount array at the location corresponding to the HashBucket for the selected multicast address. After incrementing the HashBucketCount array, the method 80 may cycle back to block 84, waiting for another service request from one of the STBs of the STBs 22a-22n.

As described above, the satellite gateway loops back to block 86 until the satellite gateway 14 assigns one of the multicast IP addresses, or until all IP addresses have been removed from the remaining multicast address pool. can do. Once all the multicast addresses have been removed from the multicast address pool, the method 80 can increment the MaxBucketCount variable (which causes one more IP address to be assigned to each hash bucket), as indicated in block 98, and The remaining multicast address pool may be reset to include all multicast addresses that are not currently being used by satellite gateway 14. After resetting the remaining multicast address pool, the method 80 may return to block 86, as described above. In this way, the method 80 assigns one IP address per bucket until all hash buckets have one IP address or there are no more available IP addresses in the remaining multicast address pool. Promote even allocation of IP addresses to hash buckets.

While the invention is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in greater detail herein. However, it should be understood that the invention is not intended to be limited to the particular form disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims.

The present invention is generally available for transmitting video or other digital data over a network, and more particularly, the present invention is available in a system for inserting sync bytes into a video transport stream.

Claims (20)

As a method, Selecting a first IP address from the plurality of IP addresses; Hashing the first IP address to generate a first hash value corresponding to the first IP address; Determining whether the first hash value corresponds to a second IP address in use; And If the first hash value does not correspond to the second IP address being used, assigning the first IP address, Hashing the first IP address includes hashing the first IP address from a 32-bit value to a 6-bit value. delete As a method, Selecting a first IP address from the plurality of IP addresses; Hashing the first IP address to generate a first hash value corresponding to the first IP address; Determining whether the first hash value corresponds to a second IP address in use; If the first hash value does not correspond to a second IP address being used, assigning a first IP address; And If the first hash value does not correspond to the second IP address being used, multicasting the satellite service to the set top box (22) using the first IP address. 4. The method of claim 3, wherein determining if the first hash value corresponds to a second IP address in use comprises determining whether a satellite service is multicasting using the second IP address. 4. The method according to claim 3, comprising receiving a request from a set top box (22) for satellite service. 4. The method of claim 3, wherein multicasting the satellite service comprises multicasting the DirecTV service. As a method, Selecting a first IP address from the plurality of IP addresses; Hashing the first IP address to generate a first hash value corresponding to the first IP address; Determining whether the first hash value corresponds to a second IP address in use; If the first hash value does not correspond to a second IP address being used, assigning a first IP address; If the first hash value corresponds to a second IP address in use, selecting a third IP address; And Hashing the third IP address to generate a second hash value. As the head-end unit 14, Select a first IP address from the plurality of IP addresses; Hash the first IP address to generate a first hash value corresponding to the first IP address; Determine whether the first hash value corresponds to a second IP address in use; And If the first hash value does not correspond to the second IP address being used, it is configured to assign the first IP address, The head-end unit (14) is configured to hash the first IP address from a 32-bit value to a 6-bit value. delete As the head-end unit 14, Select a first IP address from the plurality of IP addresses; Hash the first IP address to generate a first hash value corresponding to the first IP address; Determine whether the first hash value corresponds to a second IP address in use; If the first hash value does not correspond to the second IP address being used, assign the first IP address; And If the first hash value does not correspond to the second IP address being used, the head-end unit is configured to multicast satellite services to the set-top box (22) using the first IP address. 11. The head-end unit of claim 10, wherein the head-end unit (14) is configured to determine if satellite services are being multicasted using the second IP address. 11. The head-end unit of claim 10, wherein the head-end unit (14) is configured to receive a request from the set top box (22) for satellite service. 11. The head-end unit of claim 10, wherein the head-end unit (14) is configured to multicast DirecTV service. As the head-end unit 14, Select a first IP address from the plurality of IP addresses; Hash the first IP address to generate a first hash value corresponding to the first IP address; Determine whether the first hash value corresponds to a second IP address in use; If the first hash value does not correspond to the second IP address being used, assign the first IP address; If the first hash value corresponds to the second IP address being used, select the third IP address; And The head-end unit, configured to hash the third IP address to generate a second hash value. As the head-end unit 14, Means for selecting a first IP address from the plurality of IP addresses; Means for hashing the first IP address to generate a first hash value corresponding to the first IP address; Means for determining if the first hash value corresponds to a second IP address in use; And Means for assigning a first IP address if the first hash value does not correspond to a second IP address in use; Means for hashing the first IP address comprises means for hashing the first IP address from a 32-bit value to a 6-bit value, Head-end unit. delete As the head-end unit 14, Means for selecting a first IP address from the plurality of IP addresses; Means for hashing the first IP address to generate a first hash value corresponding to the first IP address; Means for determining if the first hash value corresponds to a second IP address in use; Means for assigning a first IP address if the first hash value does not correspond to a second IP address in use; And And if the first hash value does not correspond to a second IP address in use, means for multicasting satellite services to the set-top box (22) using the first IP address. 18. The head of claim 17, wherein the means for determining whether the first hash value corresponds to a second IP address in use comprises means for determining if a satellite service is being multicasted using the second IP address. End unit. 18. The head-end unit of claim 17, comprising means for receiving a request from a set top box (22) for satellite service. 18. The method of claim 17, Means for selecting a third IP address if the first hash value corresponds to a second IP address in use; Means for hashing a third IP address to generate a second hash value.

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