Arrangement for controlling learning of layer 3 network addresses in a network switch

• US 6,934,260 B1
• Filed: 02/01/2000
• Issued: 08/23/2005
• Est. Priority Date: 02/01/2000
• Status: Expired due to Term

• Current Assignee: Advanced Micro Devices, Inc.
• Original Assignee: Advanced Micro Devices, Inc.
• Inventors: Kanuri, Mrudula
• Primary Examiner(s): Patel, Ajit
• Application Number:
  US09/496,016
• Time in Patent Office: 2,030 Days
• Field of Search: 370/390, 370/392, 370/335, 370/360, 370/389, 370/395.1, 370/401, 370/469, 370/255, 370/400, 370/351, 370/254, 709/238, 709/249, 709/220, 709/221
• US Class Current: 370/255
• CPC Class Codes: H04L 49/3009 Header conversion, routing tables or routing tags
• CPC Class Codes: H04L 49/604 Hybrid IP/Ethernet switches
• CPC Class Codes: H04L 61/00 Network arrangements, protocols or services for addressing or naming
• CPC Class Codes: H04L 61/10 of different types

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 switching module for performing layer 2 and layer 3 switching operations, and a plurality of network switch ports, each configured for connecting the network switch to a corresponding subnetwork. One of the switch ports serves as a router interface port for transferring data packets between the network switch and a router. The network switch, configured for performing learning of layer 2 addresses and layer 3 addresses of the data packets, has a learning bit for each network switch port. A host network controller disables the learning bit for the router interface port in compliance with IEEE 802.1d, preventing the switching module from performing any learning of layer 2 or layer 3 addresses for the data packets transferred between the network switch and the router on the router interface port. Hence, the network switch can perform layer 3 switching operations for connected subnetworks, enabling the router to be bypassed; moreover, the disabling of the learning bit for the router interface port ensures that the router traffic does not over overwhelm the layer 2 and layer 3 address table within the network switch.

Claims

1. A method in an integrated network switch having a plurality of network ports and a switching module, the switching module configured for learning network addresses of received data packets, the method comprising:

identifying one of the network switch ports that transfer data packets between the integrated network switch and a router; and

disabling learning by the switching module of network addresses for the data packets having passed via the identified one network switch port.

2. The method of claim 1, further comprising learning layer 2 and layer 3 address information by the switching module for data packets transferred by at least two of the network switch ports between respective connected subnetworks.

3. The method of claim 2, wherein the learning step comprises:

receiving a first data packet from a second of the network switch ports configured for transferring data packets between the network switch and a first of the connected subnetworks; and

storing in an address table a table entry including a source MAC address and a source IP address from the first data packet, and an identifier of the second network switch port.

4. The method of claim 3, wherein the disabling step includes permanently setting the one network switch port into a nonlearning mode by a host controller, based on the identifying step.

5. The method of claim 3, wherein the learning step further comprises storing in the table entry a virtual local area network (VLAN) identifier and a vector that identifies at least one of the network switch ports to output the corresponding first data packet.

6. The method of claim 1, further comprising:

receiving new data packet on any one of the network switch ports;

determining if the new data packet has a layer 3 destination address stored by the switching module; and

forwarding the new data packet to the one network switch port for transfer to the router, based on a determined absence of the layer 3 destination addresses stored by the switching module.

7. The method of claim 1, wherein the disabling step includes:

receiving a data packet by a second of the network switch ports connected to a subnetwork, the data packet having a source media access control (MAC) address, a destination MAC address, a source Internet Protocol (IP) address, and a destination IP address;

learning the source MAC address and a destination MAC address of the received data packet by the switching module;

determining that the one switch port has a learning bit disabled; and

disabling learning of the destination IP address of the received data packet based on the determination that the corresponding one switch port has the corresponding learning bit disabled.

8. The method of claim 1, wherein the disabling step includes:

receiving a data packet by the identified one network switch port from the router, the data packet having a source media access control (MAC) address, a destination MAC address, a source Internet Protocol (IP) address, and a destination IP address; and

disabling learning of any of the source IP address and a destination IP address based on having received the data packet by the identified one network switch port.

9. A network switch system comprising:

an integrated network switch having a plurality of network switch ports and a switching module, the switching module configured for learning layer 2 and layer 3 network addresses of received data packets, wherein one of the network switch ports is configured for transferring data packets between the integrated network switch and a router; and

a host controller configured for disabling learning of the layer 2 and layer 3 network addresses of any of the data packets transferred by the one network switch port, based on determining that the one network switch port transfers the data packets between the integrated network switch and the router.

10. The system of claim 9, wherein the switching module includes an address table configured for storing, for each network node connected to the network switch, a media access control (MAC) address, an Internet Protocol (IP) address, a virtual local area network (VLAN) identifier, and an identifier for one of the network switch ports connected to the corresponding network node.

11. The system of claim 9, wherein the host controller resets a learning bit for the one network switch port, the switching module disabling the learning of the data packets received by the one network switch port in response to detecting the learning bit reset for the one network switch port.