Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
1999-12-30
2004-04-13
Pham, Chi (Department: 2667)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C709S216000, C709S241000
Reexamination Certificate
active
06721321
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a transmitter and method thereof for the transmission of data signals over a transmission line, and more particularly, to a protocol stack for providing data communication between communication application entities.
2. Description of the Related Art
Generally, a transmitter refers to as an apparatus for linking two transmitters or for linking a switching system to a subscriber. Such transmitter is mainly classified into two types: a radio transmitter and a cable transmitter. There are numerous types of cable transmitters such as optical transmitters used to transmit and receive the optical signals. The optical transmitters provide data link connection through optical links between two transmitters, a switching system and a transmitter, or a transmitter and a plurality of subscribers. These types of optical transmitters using the optical links communicate the data through data communication channel (DCC). Now, reference will be made as to the optical transmitter in connection with FIG.
1
.
A transmitter
10
is linked to another transmitter
20
via an optical link. Data are processed by the data channel processors
11
and
21
provided in the transmitters
10
and
20
, respectively, and communicated between the transmitters
10
and
20
. As these two transmitters have the same construction, a description will be made depicting only the transmitter
10
as an illustrative example. First, the data channel processor
11
having a plurality of slave processors
12
a
,
12
b
, . . . , and
12
n
coupled thereto in the lower application layer controls the traffic flow of the data communication to and from another data channel processor
21
as well as the slave processors
12
a
,
12
b
, . . . , and
12
n
. The type and the number of the slave processors are dependent on the processing capacity of the transmitter
10
. For example, a 2.5 Gbps transmitter would have four slave processors and the processing rate for each slave processor would be 622 Mbps. These slave processors are further linked to other information processing equipment or subscriber via optical links. The slave processors are usually linked to the data channel processor
11
through Ethernet. The data channel processor
11
of the transmitter
10
is provided with a protocol stack module that specify the physical media, the manner, and the process for conducting the data communication. Each of the slave processors
12
a
,
12
b
, . . . , and
12
n
is also provided with its own protocol stack. A description will be made below with reference to
FIG. 2
as to the protocol stacks of the data channel processor
11
and the slave processors
12
a
,
12
b
, . . . , and
12
n.
The data channel processor
11
has a protocol stack of a seven-layer model as set forth in the OSI (Open System Interconnection) Basic Reference Model. More specifically, the data channel processor
11
includes an application layer
31
as the highest layer which contains a CMIP (Common Management Interface Protocol) for exchanging data between the application entities, an ROSE (Remote Operation Service Element) for a remote operation service by providing request/reply transaction in situations where a long-term association between the application entities is required, and an ACSE (Association Control Service Element) for transporting Call Detail Records to a centralized administrative center.
The lower layers of the application layer
31
are as follows. A presentation layer
32
has an ASN.1 (Abstract Syntax Notion 1) associated with the statement of a language used. The syntax is only concerned with the representation of the data and not the meaning to the application layer. A session layer
33
employs an X.225 standard for managing the data exchange between the application entities. A transport layer
34
serves to control the transfer of data between the entities, and a network layer
35
serves to perform the routing process to establish, maintain, and terminate the network connection. A data link layer
36
is divided into one section using an LAPD (Link Access Procedure of D-channel) and another section for an LLC
1
section. The LLC
1
section is linked to the slave processors for the data processing function. The LAPD section is further divided into a first subnet for data communication in the east direction of the data channel processor
11
and a second subnet for data communication in the west direction of the data channel processor
11
. Accordingly, the data link layer
36
provides functional and procedural means to establish, maintain, and release the data link connections among network entities. Lastly, a physical layer
37
,which is the lowest layer, has a section for the east/west data processing through optical links, and 10 Base 2 Ethernet is provided therein for data communication. The physical layer
37
is mostly a hardware dependent layer in OSI which provides mechanical, electrical, functional and procedural means to activate, maintain and de-activate a physical connection for data transmission between data link entities.
The individual slave processors
12
a
to
12
n
include a network layer
41
, a data link layer
42
, and a physical layer
43
. The data link layer
42
is divided into two sections, LAPD and LLC
1
. The configuration of the data link layer
42
is similar to the data link layer
36
of the data channel processor
11
. In the case that a 2.5 Gbps optical transmitter is employed, the LAPD would have one slave DCC and four subnets, each with 622 Mbps processing capability, and coupled to different information processing units.
As illustrated in the foregoing, each of the slave processors in a transmitter includes the OSI 7-layer protocol stack. However, such implementation has disadvantages in that the software cost rises as each slave processor incorporates its own protocol stack. That is, the cost increases as more protocol stacks are added to the system. Also, as each of the data channel processor and the slave processors is provided with its own protocol stack module in a given transmitter, the transmitter with one node has to have two network service access points (NASPs). This makes an operator or the system to perform the unnecessary functions by assigning two network service access points to one node. The two network access points assigned to one node causes the system to have different addresses depending on which data channel processor and slave processor is connected to the node. As a result, the operator experienced more hardship and confusion in managing and maintaining such system. Furthermore, as two different addresses are assigned to one node and the structure is formed as if one node occupies two nodes, it leads to an increase in the number of nodes of the network, which in turn increases the load of the network. This is because the respective protocol stacks have to exchange a large amount of data mutually while communicating the different routing information, and the increase in the number of nodes requires more data to be processed, thereby increasing the load of the network.
Moreover, as more software is implemented than necessary in each of the slave processors, more man power and more time is consumed in developing new programs. Further, the manufacturing cost of the system device is increased as more memory in the system devices, such as DRAM, SRAM of FROM, for the development of the programs is needed. Furthermore, the data channel processor is linked to the slave processors via Ethernet, which is the same network as that used by a graphic user interface (GUI) for providing the interface between a network management subsystem (NMS) and an operator. As the system experience heavy load owing to the data communication between two processors, the system experience more load on the system when using GUI or NMS.
As described above, using the OSI 7-layer protocol stacks separately in both the data channel processor and the slave processors of the transmitter causes the following pro
Cha & Reiter L.L.C.
Pham Chi
Waxman Andrew M.
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