 Managing connection requests in a dialup computer network |
| It is thus a primary goal of the present invention to manage service requests in a dialup computer ... |
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| Access-method-independent exchange 3 |
| The present invention provides a virtual network, sitting "above" the physical connectivity and ... |
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| Semiconductor processing systems |
| OF THE PREFERRED EMBODIMENTS This disclosure of the invention is submitted in furtherance of the ... |
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| Read crossbar elimination in a VLIW processor |
| OF THE PREFERRED EMBODIMENTS FIG. 2 shows a VLIW processor according to the invention. The ... |
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| Method and system for maintaining strong ordering in a coherent memory system |
| The above and other needs are met by a method and system of strong ordering that uses timestamp ... |
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| Network data flow control technique |
| We claim: 1. A system for controlling the flow of data in a communication network of the kind in ... |
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| Optical fiber cable service system provided with video on demand service |
| The object of the present invention is to provide an optical fiber cable service system capable of ... |
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BLSR node extension
| Details |
Inventors: Bisson, Patrick R.; Elliott, Paul M.; Amon, Kate B.; Nigam, Anurag; Le, Phu S.;
Assignee: Cisco Systems, Inc. (San Jose, CA)
Primary Examiner: Yao; Kwang B.
Assistant Examiner:
Attorney, Agent or Firm: Skjerven Morrill MacPherson LLP, Chen; Tom
The present invention provides a method and structure for allowing more than 16 nodes to be configured in a single SONET BLSR network by utilizing unused portions of the transport overhead of an STS-N frame to expand the node identification field from 4 bits to 8 bits, thereby allowing up to 256 nodes to be present on a single ring. |
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DETAILED DESCRIPTION The present invention provides a method to allow more than sixteen traffic terminating nodes to be configured in a SONET bi-directional line-switched ring (BLSR) network by utilizing unused bytes in the SONET overhead to designate additional nodes in the ring.
Synchronous Optical Network (SONET) defines a transmission hierarchy of optical carrier (OC) levels and electrically equivalent synchronous transport signals (STSs) for transmission over optical fiber.
SONET uses a base transmission signal designated STS-1 with a line rate of 51.
84 Mbps.
The frame format of the base STS-1 signal is shown in FIG.
1.
An STS-1 frame has 90 columns and 9 rows, with the column size being one byte, resulting in a frame size of 810 bytes.
The STS-1 signal is transmitted byte-by-byte from column one to column 90 of row one then from column one to column 90 of row two, and proceeding in this manner to the last byte at row nine, column 90.
An entire STS-1 frame is transmitted every 125 .
mu.
sec for a frame rate of 8000 frames/sec, resulting in the basic STS-1 line rate of 51.
84 Mbps.
The first three columns of the STS-1 frame consist of transport overhead, and the remaining 87 columns consist of the synchronous payload envelope (SPE).
As shown in FIG.
1, the transport overhead, which carries signaling and protocol data, is composed of section overhead and line overhead.
Section overhead is used for communications between adjacent network elements, and line overhead is used for higher level STS-N signals between the STS-N multiplexers.
The first three rows or nine bytes of transport overhead are for the section overhead, and the remaining six rows or 18 bytes are for the line overhead.
The SPE, whose capacity is 50.
115 Mbps (9 rows*87 columns*8000 frames/sec*8 bits/byte), carries the information portion of the signal.
The first column of the SPE contains the path overhead.
In SONET, each STS-1 frame is transmitted every 125 .
mu.
sec, regardless of whether data exits in the frame.
Since the data from an STS-1 signal arrives asynchronously, data carried in the SPE can start anywhere in the SPE and is not fixed relative to the SONET frame
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Processing Data 
