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Satellite Networking Principles and Protocols p5

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Mỗi hai mã có thể được bất kỳ của các lập trình hiện có. Không đi vào chi tiết của mã Turbo, chúng tôi sẽ chỉ minh họa cho khái niệm của coder Turbo và bộ giải mã bằng cách sử dụng hình 2,19 và 2,20, tương ứng. Bộ mã hóa đơn giản và đơn giản. Bộ giải mã là phức tạp hơn, nơi mà các thông tin bên ngoài được sử dụng đệ quy. | 118 Satellite Networking Principles and Protocols ISO Data Country Code 39 DCC Routing Fields End system ID SEL International Code Designator 47 ICD ị j j Routing Fields Ị Ị Ị End system ID Ị Ị Ị SEL E164 Private Address 45 E164 Nụmber Roụting Fields End system. ID SEL Figure 3.22 ATM address format The three address formats are 1. Data country code DCC . DCC numbers are administered by various authorities in each country. For instance ANSI has this responsibility in the USA. The DCC identifies the authority that is responsible for the remainder of the routing fields. 2. International code designator ICD . ICDs are administered on an international basis by the British Standards Institute BSI . 3. E.164 private addresses. E.164 addresses are essentially telephone numbers that are administered by telephone carriers with the administering authority identity code as a part of the E.164 number. Regardless of the numbering plan used it is very important that an ATM network imple-menter obtains official globally unique numbers to prevent confusion later on when ATM network islands are connected together. Following the DCC or ICD fields - or immediately following the E.164 in the case of the E.164 format - is the routing field. For DCC and IDC this is the information that contains the address that is being called or is placing the call . This routing field can be thought of as an address space. The term routing field implies that there is more to the field than a simple address. In particular the addressing mechanism will very probably be hierarchical to assist in the routing. In the E.164 option the use of the routing field is not defined at this time. Each address in the routing field may refer to a particular switch or it may even refer to a particular UNI on a switch. If it refers only to a switch then more information will be needed to find the exact UNI that is specified. On the other hand if it specifies a UNI then this is sufficient to serve as a unique globally .