Multiport network switch supporting multiple VLANs per port

• US 6,775,290 B1
• Filed: 05/24/1999
• Issued: 08/10/2004
• Est. Priority Date: 05/24/1999
• Status: Expired due to Term

• Current Assignee: Advanced Micro Devices, Inc.
• Original Assignee: Advanced Micro Devices, Inc.
• Inventors: Williams, Robert, Merchant, Shashank
• Primary Examiner(s): Chin, Wellington
• Assistant Examiner(s): SCHULTZ, WILLIAM C
• Application Number:
  US09/317,148
• Time in Patent Office: 1,905 Days
• Field of Search: 370/392, 370/393, 370/395, 370/396, 370/395.53, 370/395.52, 370/395.54, 370/395.31
• US Class Current: 370/395.53
• CPC Class Codes: H04L 12/4645 Details on frame tagging routing of packets H04L45/00; support for virtual LAN H04L49/354
• CPC Class Codes: H04L 12/467 Arrangements for supporting untagged frames, e.g. port-based VLANs
• CPC Class Codes: H04L 49/3027 Output queuing
• CPC Class Codes: H04L 49/351 for local area network [LAN], e.g. Ethernet switches
• CPC Class Codes: H04L 49/352 Gigabit ethernet switching [GBPS]
• CPC Class Codes: H04L 49/354 for supporting virtual local area networks [VLAN]

Abstract

A novel method of enabling a port of a network switch to support connections with multiple VLANs. The method comprises storing VLAN data indicating a plurality of VLAN identifiers corresponding to the multiple VLANs supported by the port. A VLAN identifier of a data packet received via the port is compared with the plurality of VLAN identifiers determined using the stored VLAN data. The data packet is forwarded for further processing if the VLAN identifier matches one of the plurality of VLAN identifiers. However, the data packet is discarded if the VLAN identifier does not match one of the plurality of VLAN identifiers. Moreover, VLAN information corresponding to a VLAN identifier of a data packet to be transmitted from the port is compared with the stored VLAN data to determine whether the VLAN identifier matches one of the plurality of VLAN identifiers supported by the port. The data packet is prevented from being transmitted from the port if the VLAN identifier does not match one of the plurality of VLAN identifiers.

Claims

1. A network switching system comprising:

a first port for receiving data packets from members of a first plurality of virtual local area networks (VLANs),

a second port for transmitting the data packets, the second port being configured for transmitting the data packets to a second plurality of VLANs, and

a decision making engine responsive to the data packets received by the first port for controlling forwarding of the received data packets to the second port,

the decision making engine including;

a first logic circuit responsive to the received data packets to prevent the switching system from forwarding to the second port a received data packet that does not belong to the first plurality of VLANs, and

a second logic circuit responsive to the received data packets to prevent the second port from transmitting a data packet that does not belong to the second plurality of VLANs.

2. The system of claim 1, wherein the decision making engine further comprises a first storage for storing a VLAN member set table having a first VLAN member set indicating information on the first plurality of VLANs supported by the first port.

3. The system of claim 2, wherein the first VLAN member set comprises VLAN indices pointing to VLAN identifiers corresponding to the first plurality of VLANs.

4. The system of claim 3, wherein the decision making engine further comprises a second storage for storing a VLAN index to VLAN identifier table indicating correlation between the VLAN indices and the VLAN identifiers.

5. The system of claim 2, wherein the first logic circuit is configured to access the VLAN member set table to check whether the received data packets belong to the first plurality of VLANs.

6. The system of claim 1, wherein the VLAN member set table has a second VLAN member set indicating information on the second plurality of VLANs supported by the second port.

7. A data communication system for switching data between multiple ports, comprising:

an input logic circuit responsive to received data packets for discarding incoming data packets that do not belong to VLANs supported by receiving ports,

an output logic circuit responsive to data packets passed through the input logic circuit for preventing the ports from transmitting data packets that do not belong to VLANs supported by transmitting ports, and

a VLAN membership system coupled to the input and output logic circuits for enabling each of the multiple ports to support connections with multiple VLANs.

8. The system of claim 7, wherein the VLAN membership system comprises a VLAN member set storage for storing a VLAN member set table having multiple entries corresponding to each of the multiple ports.

9. The system of claim 8, wherein an entry in the VLAN member set table contains VLAN indices identifying the multiple VLANs supported by the corresponding port.

10. The system of claim 9, wherein the VLAN membership system further comprises a VLAN index storage for storing a VLAN index to VLAN identifier table indicating correlation between the VLAN indices and VLAN identifiers of the received data packets.

11. In a network switch having a plurality of ports, a method of enabling each port of the plurality of the ports of the switch to support connections with multiple VLANs, comprising the steps of:

storing VLAN data indicating a plurality of VLAN identifiers corresponding to the multiple VLANs to be supported by each port of the plurality of the ports,

determining a first VLAN identifier of a first data packet received via a port of the plurality of the ports,

comparing the first VLAN identifier with the plurality of VLAN identifiers determined using the stored VLAN data,

forwarding the first data packet for further processing if the first VLAN identifier matches one of the plurality of VLAN identifiers,

discarding the first data packet if the first VLAN identifier does not match one of the plurality of VLAN identifiers,

determining VLAN information corresponding to a second VLAN identifier of a second data packet to be transmitted from the port, and

comparing the VLAN information with the stored VLAN data to determine whether the second VLAN identifier matches one of the plurality of VLAN identifiers.

12. The method of claim 11, further comprising the step of preventing the second data packet from being transmitted from the port if the second VLAN identifier does not match one of the plurality of VLAN identifiers.

13. The method of claim 12, further comprising the step of transmitting the second data packet from the port if the second VLAN identifier matches one of the plurality of VLAN identifiers.