Packet transfer device

• US 8,687,644 B2
• Filed: 11/27/2008
• Issued: 04/01/2014
• Est. Priority Date: 04/25/2008
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Nonaka, Naomichi
• Primary Examiner(s): Jaroenchonwanit, Bunjob
• Application Number:
  US12/989,014
• Publication Number:
  US 20110091212A1
• Time in Patent Office: 1,951 Days
• Field of Search: None
• US Class Current: 370/424
• CPC Class Codes: H04J 14/0201 Add-and-drop multiplexing
• CPC Class Codes: H04J 14/0212 using optical switches or wavelength selective switches [WSS]
• CPC Class Codes: H04J 14/022 For interconnection of WDM optical networks
• CPC Class Codes: H04J 14/0254 Optical medium access
• CPC Class Codes: H04J 14/0275 using an optical service channel
• CPC Class Codes: H04J 14/0282 WDM tree architectures
• CPC Class Codes: H04J 14/0283 WDM ring architectures
• CPC Class Codes: H04J 14/0286 WDM hierarchical architectures
• CPC Class Codes: H04J 14/0295 Shared protection at the optical channel (1:1, n:m)
• CPC Class Codes: H04L 12/413 with random access, e.g. carrier-sense multiple-access with collision detection [CSMA-CD]
• CPC Class Codes: H04Q 11/0062 Network aspects
• CPC Class Codes: H04Q 11/0066 Provisions for optical burst or packet networks
• 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 2011/0039 Electrical control
• CPC Class Codes: H04Q 2011/0073 Provisions for forwarding or routing, e.g. lookup tables
• CPC Class Codes: H04Q 2011/0079 Operation or maintenance aspects

Abstract

An optical multi-drop path is set to a downstream direction, an optical path between adjacent nodes is set to a upstream direction, a packet sorting unit is provided for appropriately controlling packet streams in the downstream direction and upstream direction, and one-to-one or one-to-N communication can be performed not only between servers and clients but also between the clients even when a multi-drop transmission is used in the downstream direction.

Claims

1. A packet transfer system, comprising:

a plurality of optical nodes which constitute a ring optical network, the ring optical network including a first transmission path which is configured to transmit signals in one direction and a second transmission path which is configured to transmit signals in the other direction; and

a plurality of packet transfer devices, each of which is connected to one of the optical nodes and is configured to transfer a packet between the connected optical node and a packet node which transmits and receives a packet,

wherein each optical node located in the middle of the first and second transmission paths

is configured to drop a signal received from the first transmission path to the packet transfer device while passing the signal to other downstream optical node, and

to drop a signal received form the second transmission path to the packet transfer device,

wherein each packet transfer device connected to each of the optical nodes located in the middle of the first and second transmission paths

is configured to transfer the signal received and dropped by the optical node from the first transmission path to the packet node, and

when the signal received and dropped by the optical node from the second transmission path is a unicast packet and a destination of the packet is the packet node is configured to transfer the received unicast packet to the packet node, and

when the signal received and dropped by the optical node from the second transmission path is a unicast packet and a destination of the packet is not the packet node, is configured to transfer the received unicast packet to the optical node,

wherein the optical node located at a starting point of the first transmission path and an end point of the second transmission path

is configured to drop a signal received from the second transmission path to the packet transfer device, and

is configured to add a signal received form the packet transfer device to the first transmission path,

wherein the packet transfer device connected to the optical node located at a starting point of the first transmission path and an end point of the second transmission path,

when the signal received and dropped from the second transmission path by the optical node is a unicast packet and a destination of the packet is the packet node, is configured to transfer the received unicast packet to the packet node, and

when the signal received and dropped from the second transmission path is a unicast packet and a destination of the packet is not the packet node, to transfer the received unicast packet to the optical node, and

when the packet received and dropped from the second transmission path is not a unicast packet, to transfer the received packet to the packet node and the optical node.

2. The packet transfer system according to claim 1,

wherein, when the packet received and dropped from the second transmission path is not a unicast packet, the packet transfer device is configured to transfer the packet to the optical node.

3. The packet transfer system according to claim 1,

wherein the packet transfer system is configured to transfer the packet received from the packet node to the optical node, and

the optical node is configured to add the packet received from the packet transfer device to the second transmission path.

4. The packet transfer system according to claim 1,

wherein the optical node located at an end point of the first transmission path and a starting point of the second transmission path

is configured to drop a signal received from the first transmission path to the packet transfer device and to not pass the signal to other optical node in the first transmission path, and

is configured to add a signal received from the packet transfer device to the second transmission path.