Packet switch and method for relaying management cells and data cells in a form of IP packet

• US 6,795,431 B2
• Filed: 03/04/2002
• Issued: 09/21/2004
• Est. Priority Date: 10/24/1997
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Endo, Noboru
• Primary Examiner(s): Chin, Wellington
• Assistant Examiner(s): PHAM, BRENDA H
• Application Number:
  US10/086,693
• Publication Number:
  US 20020101863A1
• Time in Patent Office: 932 Days
• Field of Search: 370/236.2, 370/236.1, 370/241.1, 370/395.1, 370/265, 370/395, 370/395.52, 370/359, 370/419, 370/400, 370/412
• US Class Current: 370/352
• CPC Class Codes: H04L 12/4608 LAN interconnection over ATM networks
• CPC Class Codes: H04L 12/5601 Transfer mode dependent, e.g. ATM
• CPC Class Codes: H04L 2012/5625 Operations, administration and maintenance [OAM]
• CPC Class Codes: H04L 2012/5652 Cell construction, e.g. including header, packetisation, depacketisation, assembly, reassembly
• CPC Class Codes: H04L 2012/5658 using the AAL5
• CPC Class Codes: H04L 2012/5667 IP over ATM
• CPC Class Codes: H04L 49/254 Centralised controller, i.e. arbitration or scheduling
• CPC Class Codes: H04L 49/30 Peripheral units, e.g. input or output ports
• CPC Class Codes: H04L 49/3009 Header conversion, routing tables or routing tags
• CPC Class Codes: H04L 49/602 Multilayer or multiprotocol switching, e.g. IP switching

Abstract

A packet switch comprising a plurality of line interfaces each connected to a pair of input and output ATM lines, and a routing unit for transferring packets received from each of said line interfaces to one of the other line interfaces specified by the header information of the packets, wherein each of the line interfaces is configured to convert a group of ATM cells received from the input ATM line selectively into either a first type of packet in which ATM cell headers are excluded or a second type of packet in which ATM cell headers are remained, whereby management cells received from the input ATM line are relayed to said one of the other line interface by inserting said management cell into said second type of packet together with user cells on the same connection.

Claims

1. A packet switch comprising:

a plurality of line interfaces each of which is coupled with a pair of input, and output ATM lines to communicate ATM cells with said input and output ATM lines, each of said ATM cells including an IP packet;

an IP routing unit coupled with said line interfaces and configured to receive IP packets from each of said line interfaces and to selectively transfer the IP packet to one of said line interfaces specified by IP header of said IP packets,

wherein at least two of said line interfaces are configured to selectively convert a group of ATM cells received from the input ATM line associated therewith to one of a first type of IP packet including none of management cell in its information field and a second type of IP packet including at least one management cell in its information field, and

wherein said at least two of said line interfaces are also configured to convert first and second types of IP packets received from said IP routing unit to a group of ATM cells to be transmitted to the output ATM line associated therewith.

2. A packet switch according to claim 1, wherein said second type of IP packet includes a plurality of data cells derived from one original data packet and at least one management cell belonging to the same connection as that of said data cells in the information field.

3. A packet switch, comprising:

a plurality of line interfaces each of which is coupled with a pair of input, and output ATM lines to communicate ATM cells with said input and output ATM lines, each of said ATM cells including an ATM header and a payload for carrying information to be transmitted; and

a routing unit coupled with said line interfaces and configured to receive data packets from each of said line interfaces and to selectively transfer the data packet to one of said line interfaces specified by the header information of said data packets,

wherein at least two of said line interfaces are configured to selectively convert a group of ATM cells received from the input ATM line associated therewith to one of a first type of data packet in which ATM headers of said ATM cells are removed and a second type of data packet in which ATM headers of said ATM cells are remained and to convert first and second type of data packets received from said routing unit to a group of ATM cells to be transmitted to the output ATM line associated therewith,

wherein said first type of data packet comprises a packet header including identifier for identifying the data packet as the first type and an information field in which a plurality of ATM payloads are arranged continuously, and said second type of data packet comprises a packet header including identifier for identifying the data packet as the second type and an information field in which a plurality of ATM cells with ATM headers are arranged continuously, and

wherein said first type of data packet includes a plurality of data cells derived from one original data packet and at least one management cell belonging to the same connection as that of said data cells in the information field.

4. A packet switch comprising:

a plurality of line interfaces coupled with a pair of input and output ATM lines respectively; and

an IP routing unit coupled with said line interfaces to relay an IP (Internet Protocol) packet received from one of said line interfaces to the other one of said line interfaces specified by the IP header,

wherein each of said line interfaces is configured to convert a group of ATM cells received from the input ATM line associated therewith to an IP packet to be transferred to said IP routing unit, and also configured to insert management cells received from said input ATM line into said IP packet to be transferred to said IP routing unit, and further configured to convert an IP packet received from said IP routing unit to a group of ATM cells to be transmitted to the output ATM line associated therewith.

5. A packet switch according to claim 4, a wherein each of said line interface is configured to insert said management cells into one of IP packets which includes a string of data cells belonging to the same connection as that of said management cell.

6. A packet switch according to claim 5, wherein each of said line interfaces includes a memory for storing information indicating whether a management cell should be relayed to one of the other line interfaces in corresponding to respective connections on the input ATM line associated therewith so that management cells are selectively inserted into said IP packet.

7. A packet switch, comprising:

a plurality of line interfaces connected to a pair of input and output lines respectively, each of said input and output lines transmitting IP packets in a form of fixed lengthy of data cells each having a cell header and a payload for carrying a data block composing a part of said IP data-packet; and

an IP routing unit for relaying IP packets among said line interfaces;

wherein each of said line interfaces includes;

means for determining whether to relay a management cell for each connection defined on the input line associated therewith;

memory means for storing data cells received from said input line and at least one management cell to be relayed for each connection;

means for extracting an IP packet header carried by the first cell of a group of data cells derived from of each of data-IP packets;

means for composing an IP packet comprising said extracted IP packet header and an information field in which data cells and at least one management cell read out from said memory means are arranged and for passing the IP packet to said IP routing unit;

means for decomposing an IP packet composed of data cells and at least one management cell received from said IP routing unit into a plurality of cells;

header converting means for updating the connection identifier in the cell header of each of said decomposed cells according to the header information of said IP packet received from said IP routing unit; and

means for transmitting said data cells and said management cell whose header is updated respectively to the output line associated therewith, sequentially.

8. A packet switch connected to a plurality of input and output ATM lines for switching IP packets, each of which is received in a form of ATM cells from one of said input ATM lines, to one of said output ATM lines specified by a packet header of said IP packet, comprising:

a plurality of line interfaces each connected to one of said input ATM lines and configured to convert a group of ATM cells received from said one input ATM line to an IP packet, and also configured to selectively insert management cells received from the input ATM line into an IP packet composed of ATM cells on the same connection as that of said management cells; and

an IP routing controller coupled with said line interfaces to communicate IP packets with said line interfaces.

9. In a packet switch including an IP routing unit coupled with a plurality of line interfaces each connected to a pair of input and output ATM lines, wherein IP packets are received by said line interfaces in a form of ATM cells from said input ATM lines and switched by said IP routing unit to one of the other line interfaces according to respective packet headers of said IP packets, characterized in that at least two of said line interfaces are configured to communicate with said IP routing unit an IP packet which includes at least one management cell received from one of said input ATM lines.

10. A method for relaying management cells in a packet switch provided with a plurality of line interfaces each connected to a pair of input and output ATM lines, wherein each of said line interfaces receives ATM cells from the input ATM line associated therewith and converts a series of ATM cells belonging to the same original packet to a first type of IP packet having an IP header and an information field in which respective payloads of said series of ATM cells are arranged continuously, said IP packet is transferred to one of the other line interfaces specified by said IP packet header and then converted to a series of output ATM cells and sent out to the output ATM line of said one of the other line interfaces, said method comprising the steps of:

converting a series of ATM cells including at least one management cell at first one of said line interfaces into a second type of IP packet having a an IP header and an information field in which a series of said ATM cells are arranged continuously;

transferring said second type of IP packet to second one of said line interfaces specified by said packet header; and

extracting a series of said ATM cells from the information field of said second type of IP packet at said second line interface and transmitting the extracted ATM cells to the output ATM line associated therewith after updating respective cell header of said extracted ATM cells.