Ethernet® communication system relaying control signals

Abstract

An Ethernet® communication system wherein control signals are relayed by ADM/WDM apparatuses and are directly transferred between L2/L3 switches apparatuses to enable application for new control protocols, improvement of the maintenance ability, etc., that is, an Ethernet® communication system provided with at least two transmission apparatuses arranged opposing each other across a transmission line at which an Ethernet® path is set and terminating units connected to the transmission apparatuses and communicating between terminating units through said transmission apparatuses, wherein each of the transmission apparatuses is provided with a relaying means for relaying communications by insertion of control signals transferred by interfaces of the terminating units, without termination at the transmission apparatus, into Ethernet® frames between the transmission apparatuses, and the control signals are passed through the relaying means to the opposing side terminating unit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention may be more fully understood from the description of the preferred embodiments of the invention set forth below together with the accompanying drawings, in which

FIG. 1 is a block diagram showing the general configuration of a conventional Gigabit Ethernet® communication system in the case of use of transmission apparatuses of only WDM apparatuses;

FIG. 2 is a block diagram showing the general configuration of a conventional Gigabit Ethernet® communication system in the case of use of transmission apparatuses of only SONET/SDH ADM apparatuses;

FIG. 3 is a block diagram showing the general configuration of a communication system mixing the systems of FIG. 1 and FIG. 2;

FIG. 4 is a block diagram showing the general configuration of a conventional Gigabit Ethernet® communication system in the case of use of only the WDM apparatuses shown in FIG. 1;

FIG. 5 is a block diagram showing the general configuration of a conventional Gigabit Ethernet® communication system in the case of use of only the SONET/SDH ADM apparatuses shown in FIG. 2;

FIG. 6 is a block diagram showing in detail the configuration of a Gigabit Ethernet® communication system in the case of use of only WDM apparatuses shown in FIG. 1 according to a first embodiment of the present invention;

FIG. 7 is a block diagram showing in detail the configuration of a Gigabit Ethernet® communication system in the case of use of only SONET/SDH ADM apparatuses shown in FIG. 2 according to a second embodiment of the present invention;

FIG. 8A is a view of an example of an auto negotiation 8B signal;

FIG. 8B is a view of the signal format of an Ethernet® MAC frame; and

FIG. 9 is a block diagram showing the general configuration of a communication system mixing the systems of FIG. 6 and FIG. 7 according to a third embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 6 is a block diagram showing in detail the configuration of a Gigabit Ethernet® communication system in the case of use of only the WDM apparatuses shown in FIG. 1 according to a first embodiment of the present invention. In the figure, the WDM apparatus 60 is, for example, a GbE (Gigabit Ethernet®) multiplex transponder board provided with processors 600 to 607 for performing PHY (Physical Layer) processing and MAC (Media Access Control) processing, a GFP framer 608 for performing GFP (Generic Framing Protocol) processing, an OC192 framer 409 for performing OC192 processing, a digital wrapper LSI 610 for mapping on the OC192 frames, and a PMD (Physical Media Dependent) 611 serving as the WDM port. The opposing WDM apparatus 61 is configured the same as the WDM apparatus 60, and the same components are assigned the same reference numerals. The configuration up to here is the same as the conventional WDM Gigabit Ethernet® communication system shown in FIG. 4.

According to this embodiment of the present invention, the processors 600 to 607 are provided with circuits (A) 620 to 627 for identifying auto negotiation signals sent from the terminating units 100 to 107 and 110 to 117 based on the K28.5 and the control code (0xB5/0x42, that is, hexadecimal B5 or 42). The processors 600 to 607 and the GFP framer 608 are connected by the circuit (B) 613. The circuit (B) 613 matches the port number of the terminating units (0≦port ID≦N-1) (N is 8 in this embodiment) with the VLAN ID of the Ethernet® frame and inserts this as an Ethernet® signal in the header of the Ethernet® frame or, if detecting an Ethernet® frame showing an auto negotiation signal, judges the destination port identification number from the VLAN ID, generates an auto negotiation signal, and inserts the auto negotiation signal at the inserted port shown by the reserved area. The opposing WDM apparatus 61 is also provided with the same circuits (A) 620′ to 627′ and circuits (B) 613′. The circuits (A) 620′ to 627′, circuits (B) 613′, circuits (A) 620′ to 627′, and circuit (B) 613′ form the relaying means for relaying the control signals.

The WDM port is for example a 10.7 Gbps (Gigabit per second) OTN (Optical Transport Network). Each of the processors 600 to 607 is provided with physical layers PMD (Physical Medium Depending), PMA (Physical Medium Attachment), and PCS (Physical Coding Sub-layer). The specifications of these PMD, PMA, and PCS are determined by the ITU (International Telecommunications Union).

Between the GFP framer 608 and the processors 600 to 607, 8 B (byte) data is transmitted at for example a 1 Gbps transmission rate. The GFP framer 608 and OC192 framer 609 and the digital wrapper transfer data at a 10 Gbps transmission rate. The WDM transmission line between the WDM apparatuses 60 and 61 carries the multiplexed wavelength λ₁ to λ_N optical signals at 10.7 Gbps.

Next, the operation of the system shown in FIG. 6 will be explained. The WDM apparatus 60 receives Gigabit Ether (GbE) signals from the terminating units constituted by the L2/L3 switches 100 to 107 at the processors 600 to 607 in the WDM apparatus 60 and processes the GbE signals at the processors 600 to 607 by PHY processing and MAC processing. Next, when any of the circuit units (A) 620 to 627 in the process of 8 B/10 B code conversion at the PHY processing (PCS unit) receives the auto negotiation signal based on the special code K28.5 and control code (0xB5/0x42), the received port identification number of the port (PortID) is transferred to the circuit unit (B) 613. The “port identification number” shows a value set in common with the GbE port of the WDM apparatus when setting the GbE path between WDM nodes (0≦PortID≦N-1). The circuit unit (B) 613 generates Ethernet® frames including the auto negotiation signal in the payload and including the port identification number showing the destination in the header and inserts it in the GFP frame. The Ethernet® frames are identified by the ether type value locally determined in the apparatus. This ether type value is preferably structured to be able to be set and changed by external operation. After this, the Ethernet® frames are generally processed to be inserted into the GFP frame and mapped by the OC-192 framer 609 onto the OC-192 frame. Further, for FEC (error correction) processing, they are sometimes also mapped onto the OTN (Optical Transport Network) frames (digital wrapper processing), converted to WDM optical signals, and sent over the transmission line.

The WDM optical signal received by the opposing side WDM apparatus 61 is broken down into Ethernet® frames by the processing up to the GFP framer 608′. When the circuit unit (B) 613′ detects an Ethernet® frame suggesting an auto negotiation signal, it judges the destination port identification number from the VLAN ID included in its header and inserts the auto negotiation signal (8 B) into the port. The auto negotiation signal (8 B) is converted to a 10 B code by usual PHY processing and reaches the destination terminating units constituted by the L2/L3 switches 110 to 117.

FIG. 7 is a block diagram showing in detail the configuration of a Gigabit Ethernet® communication system in the case of use of only the SONET/SDH ADM apparatuses shown in FIG. 2 according to the second embodiment of the present invention. In the figure, the ADM apparatus 70 is, for example, a node provided with a low speed IF (interface) board 701, cross connect board 702, and high speed IF (interface) board 703. The opposing ADM apparatus 71 is configured the same as the ADM 701, and the same components are assigned the same reference numerals.

Between the high speed IF boards 703 and 703′ is a TDM (time division multiplexing) transmission line such as a 2.4 Gb SONET OC-48 or 10 Gb SONET OC-192. The low speed IF board 501 is provided with processors 510 to 517, each of which is provided with the physical layers PHY (Physical Layer), MAC (Media Access Control), PHY (Physical Layer), and VC (Virtual Container). The specifications of these PHY, MAC, PHY, and VC are defined by the ITU (International Telecommunications Union).

According to this embodiment of the present invention, the processors 710 to 717 are provided with circuits (C) 720 to 727 for identifying auto negotiation signals sent from the terminating units 100 to 107 from the K28.5 and control code (0xB5/0x42) and circuits (D) 730 to 737 for inserting Ethernet® frames showing the auto negotiation signals into the transmission signals. The opposing ADM apparatus 71 is also provided with circuits (D) 730′ to 737′ for detecting Ethernet® frames showing auto negotiation signals from the received signals and generating an auto negotiation signal with 1 byte consisting of 8 B (bits) and circuits (C) 720′ to 727′ for converting the 8B signal into auto negotiation signals with 1 byte consisting of 10 B (bits). The circuits (C) 720 to 727, circuits (D) 730 to 737, circuits (D) 730′ to 737′, and circuits (C) 720′ to 727′ form the relaying means for relaying the control signals.

Next, the operation of the system shown in FIG. 7 will be explained. The ADM apparatus 70 receives the Gigabit Ether (GbE) signals from the terminating units constituted by the L2/L3 switches 100 to 107 at the low speed IF board 701. At the low speed IF board 701, first the GbE signals are processed by PHY processing and MAC processing. In the process of 8 B/10 B code conversion at the PHY processing (PCS unit), when the circuits (C) 720 to 727 receive the auto negotiation signals based on the judgment by the special code K28.5 and control code (0xB5/0x42), they generate Ethernet® frames incorporating the auto negotiation signals in the payloads and port identification numbers showing the destination in the headers, then perform VC processing to convert them to TDM signals. The Ethernet® frames, in the same way as the case of the WDM apparatus 60 shown in FIG. 6, are identified by the ether type value locally determined in the apparatus. This ether type value is preferably structured to be able to be set and changed by external operation. After this, the VC processed Ethernet® frames are multiplexed on the high speed TDM signals (for example, OC-48 or OC-192) by the cross connect board and sent through the high speed IF board 703 to a transmission line. The TDM signal received at the opposing side ADM apparatus 71 is broken down into @Ethernet® frames up to the VC processing. When the circuits (D) 730′ to 737′ detect an Ethernet® frame suggesting an auto negotiation signal, the auto negotiation signal (8 B) is inserted into the ports. The auto negotiation signal (8 B) is converted to a 10 B code by the usual PHY processing and reaches the destination terminating units constituted by the L2/L3 switches 110 to 117.

FIG. 8A is a view showing an example of an auto negotiation signal, and FIG. 8B is a view showing the signal format of an Ethernet® MAC frame. As shown in FIG. 8A, the auto negotiation signal includes a special code K28.5 and its following control code 0xB5/0x42. These are identified and detected by the circuits (A) 620 to 627 in the system of FIG. 6 or the circuits (C) 720 to 727 of the system of FIG. 7. Further, as shown in FIG. 8B, a port identification number is mapped in the VLAN ID inside the header at a part other than the payload of the Ethernet® MAC frame and the destination port information is sent to the opposing WDM apparatus.

When as a result of the negotiations for connection between opposing terminating units constituted by the L2/L3 switches 110 to 117, the flow control function is made valid, pause signals (DA:0x0180c2000001) have to be passed through the WDM/ADM apparatuses. In conventional MAC processing of the IEEE, the rule is that the pause signals not be relayed, but in the first and second embodiments of the present invention, relaying of the pause signal is allowed in the MAC processing of the WDM/ADM apparatuses so as to enable direct flow control between opposing L2/L3 switches.

By defining a new value for the data code following the special code (K28.5) (in the auto negotiation, 0xB5/0x42) and, after the link between the opposing terminating units (L2/L3 switches) is established, notifying the quality information of the transmission line (line disconnection etc.) by the “disconnection notification control signal” to the opposing terminating unit (L2/L3 switch), application for redundancy protocol for switching routes between terminating units (L2/L3 switches) becomes possible.

FIG. 9 is a block diagram showing the general configuration of a communication system mixing the systems of FIG. 6 and FIG. 7 according to a third embodiment of the present invention. In the figure, 90 indicates a terminating unit (L2/L3 switch #A) provided with a selector SEL, 91 an ADM apparatus provided with a low speed IF board for interfacing with the terminating unit, 92 an ADM apparatus provided with a low speed IF board for interfacing with an WDM apparatus 93, 93 a WDM apparatus provided with a transponder board (TRPN) for communicating with the low speed IF board of the ADM apparatus, 94 an opposing side WDM apparatus, 95 an ADM apparatus connected to the WDM apparatus 94, 96 an ADM connected to the ADM 95, and 97 an opposing side terminating unit (L2/L3 switch #B).

Next, the operation of the system shown in FIG. 9 will be explained. Consider the case when opposing L2/L3 switches communicate over a WDM/ADM apparatus section by a preliminarily open path and the L2/L3 switches #A and #B at the two ends select data of the route I side.

First, when a fault occurs in the section of the transmission line between the ADM apparatuses 95 and 96, the loss of the optical signal (LOS) is detected by the input of the terminating unit (L2/L3 switch #B) 97.

This being the case, the terminating unit (L2/L3 switch #B) 97 switches the selection system at the SEL unit in the terminating unit (L2/L3 switch #B) from the route I to the route II due to the loss of the optical signal.

Next, the terminating unit (L2/L3 switch #B) 97 transmits a disconnection notification control signal toward the opposing side terminating unit (L2/L3 switch #A) 90, and the opposing side terminating unit (L2/L3 switch #A) 90 receives this disconnection notification control signal.

Next, the selection system of the SEL unit of the terminating unit (L2/L3 switch #A) 90 is switched from the route I to the route II.

In the above way, a redundancy protocol enable switching control by transferring disconnection notification control signals even if a fault occurs in a section of the transmission line is loaded in the terminating units (L2/L3 switches). The disconnection notification control signals are differentiated from other control signals by defining a new value in the area (1 byte) after K28.5.

Further, by newly defining a separate control signal (MTU notification control signal), it becomes possible to notify the L3 switches of each other's MTU (maximum transfer frame length). Applications may be considered in which the smaller of the values as a result of this negotiation is set as the MTU value for both terminating units (L3 switches). The MTU information is embedded in the Config register area for transferring of information. This MTU notification control signal is differentiated from other control signals by defining a new value in the area (byte) following K28.5.

In the above embodiments, eight terminating units were illustrated, but the present invention is not limited to this. Any number is possible. Further, the communication system was illustrated as a Gigabit Ethernet®, but the present invention is not limited to this and can be applied to any communication rate Ethernet®.

According to the present invention, opposing terminating units (L2/L3 switches) can transfer control signals and therefore the following applications can be realized. That is, when the WDM/ADM apparatuses relay auto negotiation signals and the opposing terminating units (L2/L3 switches) directly negotiate for connection with each other, the maintenance personnel can determine the state of the link up to the opposing apparatus a long distance away without modifying the fundamental parts of the WDM/ADM apparatuses, so the maintenance ability is greatly improved. Further, when as a result of the negotiation for connecting between opposing terminating units (L2/L3 switches), the flow control function is made valid, pause signals have to be passed through the MAC processing of the WDM/ADM apparatuses. In terms of this application, by allowing the pause signals to be relayed, direct flow control between the L2/L3 switches becomes possible.

Further, by defining a new value in the data code following a special code (K28.5) and notifying the quality and state of the transmission line (disconnection of optical signal line etc.) to the opposing terminating unit (L2/L3 switch), it is possible to realize redundancy protocol for switching routes between terminating units (L2/L3 switches).

Further, by using the control signals to notify the Layer 3 terminating units (L3 switches) of each other's MTU (maximum transfer frame length), it is possible to realize applications where the smaller of the values as a result of negotiations is set as the MTU value of both terminating units (L3 switches).

While the invention has been described by reference to specific embodiments chosen for the purposes of illustration, it should be apparent that numerous modifications could be made thereto by those skilled in the art without departing from the basic concept and scope of the invention.

Claims

1. An Ethernet® communication system comprising: at least two transmission apparatuses arranged opposing each other across a transmission line at which an Ethernet® path is set; and terminating units connected to said transmission apparatuses respectively and communicating between said terminating units through said transmission apparatuses, wherein each of said transmission apparatuses comprises a relaying means relaying communications by insertion of control signals transferred by interfaces of said terminating units, without termination at said transmission apparatuses, into Ethernet® frames between said transmission apparatuses, said control signals being passed through said relaying means to the opposing side terminating unit.

2. An Ethernet® communication system as set forth in claim 1, wherein said relaying means enables flow control by allowing the relaying of pause signals.

3. An Ethernet® communication system as set forth in claim 1, wherein said relaying means relays only the signals necessary for auto negotiation among the terminating units among the control signals.

4. An Ethernet® communication system as set forth in claim 1, wherein each transmission apparatus is a multiplex transponder board having a plurality of low speed side interfaces with said terminating units and a single high speed side network interface with the opposing transmission apparatus and multiplexing and demultiplexing data between said transmission apparatuses, maps port numbers of said terminating units at undefined areas of an order set in said control signal, and, during transferring of said control signals with the opposing transmission apparatus, converts undefined areas of the order set to VLAN ID so as to set paths between one of said terminating units and any one of said terminating units of the opposing transmission apparatus using Ethernet® frames.

5. An Ethernet® communication system as set forth in claim 1, wherein the control signals are signals defined by said terminating units notifying the opposing terminating unit of the quality and state of a link between the terminating units after being established.

6. An Ethernet® communication system as set forth in claim 5, wherein the terminating units are Layer 3 switches, the defined control signals include the maximum transfer frame lengths, and the smaller of the maximum transfer frame lengths as a result of negotiation between the Layer 3 switches is set as the maximum transfer frame length between the Layer 3 switches.

7. An Ethernet® communication system as set forth in claim 1, wherein port identification numbers are inserted into VLAN tags of said Ethernet® frame.