Apparatus and method for implementing distributed layer 3 learning in a network switch

• US 6,574,240 B1
• Filed: 01/19/2000
• Issued: 06/03/2003
• Est. Priority Date: 01/19/2000
• Status: Active Grant

• Current Assignee: Advanced Micro Devices, Inc.
• Original Assignee: Advanced Micro Devices, Inc.
• Inventors: Tzeng, Shr-jie
• Primary Examiner(s): Olms, Douglas
• Assistant Examiner(s): Sam, Phirin
• Application Number:
  US09/487,289
• Time in Patent Office: 1,231 Days
• Field of Search: 370/389, 370/252, 370/255, 370/352, 370/355, 370/356, 370/391, 370/392, 370/394, 370/398, 370/395.32, 370/400, 370/401, 370/402, 370/415, 370/414, 370/413, 370/417, 370/418, 370/455, 370/469, 370/471
• US Class Current: 370/469
• CPC Class Codes: H04L 49/355 Application aware switches, e.g. for HTTP
• CPC Class Codes: H04L 49/602 Multilayer or multiprotocol switching, e.g. IP switching

Abstract

A network switch, configured for performing layer 2 and layer 3 switching in an Ethernet (IEEE 802.3) network without blocking of incoming data packets, includes a network switch port having a port filter configured for evaluating an incoming data packet on an instantaneous basis. The filter is configured for determining the presence of prescribed layer 3 information in a received data packet. The port filter also signals a switch fabric of the network switch to learn the IP-MAC association of the data packet. The port filter determines whether or not the data packet is part of the data traffic between connected subnetworks of the network switch. With the port filter in the above configuration, the network is enabled to perform layer 3 and layer 2 switching for 100 Mbps and gigabit networks without blocking in the network switch.

Claims

1. A network switch for switching a data packet, comprising:

at least one port for receiving said data packet, said at least one port including a port filter configured for determining a presence of layer 3 switching information within said data packet;

a layer 3 switch logic for switching said data packet according to a layer 3 protocol in response to the determined presence of the layer 3 switching information; and

a layer 2 switch logic for switching said data packet according to a layer 2 protocol in response to a determined absence of the layer 3 switching information;

wherein the port filter outputs a learn signal to the layer 3 switch logic in response to determining an absence of the prescribed layer 3 switching information.

2. The network switch according to claim 1, wherein said layer 3 switching logic further comprising:

an internet-protocol rules queue to receive a header data from the data packet in response to said learn signal outputted from the port filter.

3. The network switch for switching a data packet according to claim 2, wherein said layer 3 switching logic further comprising:

a destination IP address module for retrieving from said address table a destination MAC address for said data, packet by searching for a corresponding associated layer 3 address matching a destination IP address in the data packet; and

a modify module for replacing an existing MAC address in said header data with said retrieved destination MAC address, and forwarding the header data having the retrieved destination MAC address to the layer 2 switching logic in response to said subnet signal and the layer 3 switching logic has learned said destination MAC address.

4. The network switch according to claim 3, wherein:

said modify module signals to the layer 2 switching logic not to write a source MAC address of said data packet.

5. The network switch according to claim 4, further comprising:

at least another port for transmitting the data packet according to said destination MAC address, the data packet received from the layer 2 switching logic.

6. The network switch according to claim 1, wherein said layer 3 switching logic further comprising:

an address table for storing a plurality of address entries, each including a layer 2 media access control address (MAC) and an associated layer 3 internet protocol (IP) address; and

a source IP address module for writing the layer 2 MAC address and said associated layer 3 IP address of said data packet into the address table in response to said learn signal.

7. The network switch according to claim 6, further comprising:

at least another port for transmitting the data packet according to said destination MAC address, the data packet received from the layer 2 switching logic.

8. A network switch for switching a data packet, comprising:

at least one port for receiving said data packet, said at least one port including a port filter configured for determining a presence of layer 3 switching information within said data packet;

a layer 3 switch logic for switching said data packet according to a layer 3 protocol in response to the determined presence of the layer 3 switching information; and

a layer 2 switch logic for switching said data packet according to a layer 2 protocol in response to a determined absence of the layer 3 switching information;

said port filter outputting a subnet signal to the layer 3 switch logic in response to determining the layer 3 switching information relates to at least one network station directly connected to said network switch.

9. The network switch according to claim 8, wherein said layer 3 switching logic further comprising:

an internet-protocol rules queue for receiving a header data and a portion of data from the data packet in response to said subnet signal outputted from the port filter.

10. A method for switching a data packet within an integrated network switch, comprising:

receiving said data packet by one of a plurality of ports;

determining a presence of prescribed layer 3 switching information in said data packet by a port filter within the one port;

switching said data packet according to one of a layer 3 protocol by a layer 3 switch logic and a layer 2 protocol by a layer 2 switch logic in response to said port filter determining the presence and an absence of the prescribed layer 3 switching information, respectively; and

outputting a learn signal by the one port to said layer 3 switch logic in response to the port filter having determined an absence of said prescribed layer 3 switching information within a memory configured for storing existing layer 3 switching information having been learned by said layer 3 switch logic.

11. The method according to claim 10, further comprising:

receiving header data from said data packet into an internet-protocol rules queue in response to said learn signal outputted from said port filter.

12. The method according to claim 11, said layer 3 switching logic further comprising:

retrieving, by a destination IP address module with said layer 3 switching logic, a destination MAC address from said address table for said data packet by searching for a corresponding associated layer 3 address matching a destination IP address in the data packet; and

replacing, by a modify module, an existing MAC address in said header data with said retrieved destination MAC address, and forwarding the header data having the retrieved destination MAC address to the layer 2 switching logic in response to said subnet signal and the layer 3 switching logic has learned said destination MAC address.

13. The method according to claim 10, wherein said layer 3 switching logic further comprising:

writing, by a source internet-protocol (IP) address module, a layer 2 MAC address and an associated layer 3 IP address of said data packet into an address table for storing a plurality of address entries, each entry including the layer 2 MAC address and the associated layer 3 IP address.

14. A method for switching a data packet within an integrated network switch, comprising:

receiving said data packet by one of a plurality of ports;

determining a presence of prescribed layer 3 switching information in said data packet by a port filter within the one port;

switching said data packet according to one of a layer 3 protocol by a layer 3 switch logic and a layer 2 protocol by a layer 2 switch logic in response to said port filter determining the presence and an absence of the prescribed layer 3 switching information, respectively; and

outputting a subnet signal to said layer 3 switch logic in response to the port filter determining said prescribed layer 3 switching information relates to at least one network station directly connected to said network switch.

15. The method according to claim 14, further comprising:

receiving header data and a portion of data from said data packet into an internet-protocol rules queue in response to said subnet signal outputted from said port filter.