Optical fiber ring communication system

• US 7,035,540 B2
• Filed: 01/05/2004
• Issued: 04/25/2006
• Est. Priority Date: 09/13/1999
• Status: Expired due to Term

• Current Assignee: Ciena Corporation
• Original Assignee: Ciena Corporation
• Inventors: Farley, Mark, Finan, Christopher D.
• Primary Examiner(s): PHAN, HANH
• Application Number:
  US10/750,808
• Publication Number:
  US 20040136711A1
• Time in Patent Office: 841 Days
• Field of Search: 398/3, 398/7, 398/42, 398/48, 398/59, 398/67, 398/91, 398/139, 398/5, 398/135, 398/138, 398/79, 398/98, 398/75, 398/68, 398/83, 370235-236
• US Class Current: 398/59
• CPC Class Codes: H04J 14/0226 Fixed carrier allocation, e.g. according to service
• CPC Class Codes: H04J 14/0227 Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
• CPC Class Codes: H04J 14/0241 Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths
• CPC Class Codes: H04J 14/0283 WDM ring architectures
• CPC Class Codes: H04J 14/0287 Protection in WDM systems
• CPC Class Codes: H04Q 11/0005 Switch and router aspects
• CPC Class Codes: H04Q 11/0067 Provisions for optical access or distribution networks, e.g. Gigabit Ethernet Passive Optical Network (GE-PON), ATM-based Passive Optical Network (A-PON), PON-Ring
• CPC Class Codes: H04Q 11/0071 Provisions for the electrical-optical layer interface
• CPC Class Codes: H04Q 2011/0075 Wavelength grouping or hierarchical aspects
• CPC Class Codes: H04Q 2011/0092 Ring

Abstract

An optical fiber ring network includes a plurality of interconnected nodes, each pair of neighboring nodes being interconnected by a pair of optical links. Using coarse wavelength division multiplexing, data is transmitted in both directions over each link, using a first wavelength λ1 to transmit data in a first direction over the link and a second wavelength λ2 to transmit data in a second, opposite direction over the link. The two wavelengths λ1 and λ2 differ by at least 10 nm. Each of the data streams transmitted over the optical link has a bandwidth of at least 2.5 Gbps. Further, each data stream has at least two logical streams embedded therein. A link multiplexer at each node of the network includes one or more link cards for coupling the link multiplexer to client devices, and one or more multiplexer units for coupling the link multiplexer to the optical links. Each link card includes frame buffers capable of storing numerous Fiber Channel frames that are being transmitted to and from the client device(s) coupled to that link card. The link card also includes flow control logic for pre-filling the frame buffers with frames of data before the receiving client devices send flow control messages to request their transmission. The combined effect of the frame buffers and flow control logic is that the full bandwidth of the links can be utilized even when the network nodes are very far apart and the client devices have small input data buffers.

Claims

1. A configuration for an optical fiber ring network, comprising:

two or more nodes, each node including,

a multiplexing device,

a client device, and

redundant signal connections between the multiplexing device and the client device;

redundant signal paths connecting the nodes, each of the redundant signal paths including an optical fiber link operable to transmit data bi-directionally between each pair of connected nodes,

wherein the multiplexing device is configured to selectively transmit outgoing data from the client device, and selectively receive incoming data destined for the client device, over each of the redundant signal paths, the multiplexing device being selectively linked to the client device for data communications by each of the redundant signal connections;

wherein the redundant signal connections include,

first and second link cards, each operable to communicate data between the multiplexing device and the client device, and

a switching apparatus operable to activate one of the first and second link cards, wherein

the activated link card conveys the outgoing data from the client device to the multiplexing device, and conveys the incoming data from the multiplexing device to the client device; and

wherein

the redundant data paths include a first and second data path,

the multiplexing device includes a first and a second multiplexing unit configured to transmit the outgoing data and receive the incoming data over the first and second signal path, respectively, and

the activated link card selectively links the client device to each of the first and second multiplexing units for data communications.

2. The configuration of claim 1, wherein the redundant signal connections includes a primary connection and a backup connection each being operable to convey the incoming and outgoing data between the multiplexing device and the client device, the backup connection enabling the incoming and outgoing data to be routed around a link failure occurring in the primary connection.

3. The configuration of claim 1, wherein the activated link card is a Fiber Channel (FC) link card.

4. The configuration of claim 1, wherein the first link card is configured to operate according to Fibre Channel (FC) protocol and the second link card is configured to operate according to Ethernet protocol.

5. The configuration of claim 1, wherein

the multiplexing device includes a coarse optical wavelength multiplexer and demultiplexer operable to transmit a first data stream over the optical fiber cable using a first optical wavelength and to receive a second data stream over the optical fiber cable using a second optical wavelength.

6. An apparatus for use at a node of an optical fiber ring network, comprising:

redundant data paths each including an optical fiber link operable to transmit data bi-directionally between the node and another node in the network;

a multiplexing device configured to selectively transmit outgoing data from a client device, and selectively receive incoming data destined for the client device, over each of the redundant data paths, the multiplexing device being selectively linked to the client device for data communications by redundant signal connections,

wherein the multiplexing device is operable to selectively transmit and receive the incoming and outgoing data, respectively, according to Fibre Channel (FC) protocol;

wherein the redundant data signals connections include first and second link card, each operable to communicate data between the multiplexing device and the client device; and

a switching apparatus operable to activate one of the first and second link cards, wherein the activated link card conveys the outgoing data from the client device to the multiplexing device, and conveys the incoming data from the multiplexing device to the client device; and

wherein the redundant data paths include a first and a second data path, the multiplexing device includes a first and second multiplexing unit configured to transmit the outgoing data and receive the incoming data over the first and second signal path, respectively, and the activated link card selectively links the client device to each of the first and second multiplexing units for data communications.

7. The apparatus of claim 6, wherein the first and second link cards each include an inbound FIFO frame buffer with memory capacity for storing at least 120 Fibre Channel frames sent by the client device to the link card and an outbound FIFO frame buffer with memory capacity for storing at least 120 Fibre Channel frames sent by another device to the link card for transmission to the client device.

8. The apparatus of claim 7, wherein the first and second link cards each include circuitry for exchanging buffer credit signals with another link card coupled thereto by one of the first and second optical fiber cables so as to pre-fill the outbound FIFO frame buffer with frames of data before the client device sends flow control messages to request the transmission of those data frames by another client device coupled to the other link card.

9. The apparatus of claim 7, wherein the first and second link cards each includes flow control circuitry for pre-filling the outbound FIFO frame buffer with frames of data before the client device sends flow control messages to request the transmission of those data frames.

10. The apparatus of claim 6, wherein

the first and second link cards each include an inbound FIFO frame buffer for storing frames sent by the client device to the link card and an outbound FIFO frame buffer for storing frames sent by another device to the link card for transmission to the client device;

and

the first and second link cards each store data into the inbound FIFO frame buffer and read data from the outbound FIFO frame buffer at a first clock rate associated with the client device, and read data from the inbound FIFO frame buffer for transmission to the multiplexer device and store data received from the multiplexing device into the outbound FIFO frame buffer at a second clock rate associated with the link card, whereby the data stream sent and received to and from the client device is retimed from the first clock rate to the second clock rate.

11. The apparatus of claim 10, wherein data streams sent and received to and from the client device are Fibre Channel data streams, the first clock rate is approximately 1.0625 Gbps, and the second clock rate is at least 1.25 Gbps.

12. The apparatus of claim 10, wherein the multiplexer device includes a smoothing circuit that retimes the first data stream sent from the client device from the second clock rate to a third clock rate associated with the first multiplexer device, the multiplexer device transmitting the first data stream over one of the first and second optical fiber cables at the third clock rate.

13. The apparatus of claim 6, wherein

the multiplexing device includes a coarse optical wavelength multiplexer and demultiplexer operable to transmit a first data stream over the optical fiber cable using a first optical wavelength and to receive a second data stream over the optical fiber cable using a second optical wavelength.