Method and apparatus for finding a match entry using receive port number embedded in the port vector

• US 6,445,709 B1
• Filed: 05/13/1999
• Issued: 09/03/2002
• Est. Priority Date: 05/13/1999
• Status: Active Grant

• Current Assignee: GlobalFoundries, Inc.
• Original Assignee: Advanced Micro Devices, Inc.
• Inventors: Chiang, John M.
• Primary Examiner(s): Coulter, Kenneth R.
• Application Number:
  US09/311,367
• Time in Patent Office: 1,209 Days
• Field of Search: 709/236, 370/397, 370/399, 706/12, 706/25
• US Class Current: 370/399
• 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 49/205 Quality of Service based
• CPC Class Codes: H04L 49/3009 Header conversion, routing tables or routing tags
• 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 49/354 for supporting virtual local area networks [VLAN]

Abstract

A network switch configured for switching data packets across multiple ports uses an address table to generated frame forwarding information. The switch receives frame information including a source address and destination address along with a virtual local area network (VLAN) ID, if applicable. A decision-making engine searches a network address table to “learn” Medium Access Control (MAC) addresses without having to store receive port numbers by embedding the receive port number in the stored port vector fields.

Claims

1. A multiport switch configured for controlling communication of data frames, comprising:

a plurality of ports for receiving and transmitting the data frames;

an address table for storing address information including source addresses and port vectors associated with the data frames; and

an internal decision making engine, coupled to the plurality of ports, accessing the address table and configured to learn the source addresses of the data frames and to store corresponding port vectors, each of the port vectors identifying, in a learning mode, one of the ports that received the data frame and, in a forwarding mode, identifying which of the ports are to transmit the data frame, wherein the address table comprises a plurality of table entries, each of the entries having a format comprising;

a static bit for preventing deletion of the table entries;

a hit bit for aging the entries;

an address field indicating a source address of the data frames;

a virtual local area network (VLAN) field; and

a port vector field identifying the ports to which each received data frame should be forwarded for transmission from the multiport switch, the port vector field having embedded therein a port receive number that indicates the one port that received said each data frame.

2. The multiport switch of claim 1, wherein the source address is a Medium Access Control (MAC) address.

3. The multiport switch of claim 1, wherein the address table represents a plurality of bins of address entries.

4. The multiport switch of claim 3, further comprising a hash key generator configured to receive source addresses and to generate a corresponding hash key that is used by the internal decision making engine.

5. A multiport switch configured for controlling communication of data frames, comprising:

a plurality of ports for receiving and transmitting the data frames;

an address table for storing address information including source addresses and port vectors associated with the data frames; and

an internal decision making engine, coupled to the plurality of ports, accessing the address table and configured to learn the source addresses of the data frames and to store corresponding port vectors, each of the port vectors identifying, in a learning mode, one of the ports that received the data frame and, in a forwarding mode, identifying which of the ports are to transmit the data frame, wherein

the address table comprises a plurality of table entries, each of the entries having a format comprising;

a static bit for preventing deletion of the table entries;

a hit bit for aging the entries;

an address field indicating a source address of the data frames;

a virtual local area network (VLAN) field; and

a port vector field representing an embedded port receive number that indicates the one port that received the data frame,

the internal decision making engine is configured to learn the source addresses of the plurality of data frames by;

accessing a frame header associated with a received one of the data frames;

comparing the frame header having an address field and a VLAN field with the corresponding fields of the table entries to determine a match or a non-match;

creating a new one of the table entries, setting a hit bit of the new table entry, and forwarding the corresponding frame header to one of the ports that is designated as a management port based upon the non-match of the address field and the non-match of the VLAN field;

decoding, in response to the match of the address field and the match of the VLAN field, a receive port number from the port vector field of each of the table entries and determining whether the decoded receive port number is in a same trunk as a receive port number of the frame header, wherein the internal decision making engine sets the hit bit based upon the determination that the decoded receive port number is in a same trunk as the receive port number of the frame header; and

determining, in response to the match of the address field and the match of the VLAN field and the finding that the decoded receive port number is not in the same trunk as the receive port number of the frame header, whether the table entry has its static bit field set, wherein the internal decision making engine overwrites the table entry with the frame header information, sets a corresponding hit bit, and forwards the frame header to the management port based upon a non-setting of the static bit field; and

the internal decision making engine sets the corresponding hit bit and forwards the frame header to the management port based upon the match of the corresponding address field, the match of the corresponding VLAN field, the determination that the corresponding decoded receive port number is not in the same trunk as the receive port number of the frame header, and the setting of the static bit field.

6. A method of learning source addresses of data frames received by a multiport switch comprising:

receiving a frame header associated with one of the data frames, the frame header comprising a source address;

assigning a virtual local area network (VLAN) identifier to the received data frames; and

learning via an internal decision making engine the source addresses of the data frames by manipulating an address table having a plurality of table entries and creating corresponding port vectors, each of the port vectors indicating the port that received the data frame, wherein the step of learning updates the address table, each of the table entries having a format comprising;

a static bit for preventing deletion of the table entries;

a hit bit for aging the entries;

an address field indicating a source address of the data frames;

a virtual local area network (VLAN) field; and

a port vector field identifying the ports to which each received data frame should be forwarded for transmission from the multiport switch, the port vector field having embedded therein a port receive number that indicates the one port that received said each data frame.

7. The method of claim 6, wherein the step of learning utilizes a source address that is a Medium Access Control (MAC) address.

8. The method of claim 6, wherein the step of learning has the address table representing a plurality of bins of address entries.

9. The method of claim 6, wherein the step of learning utilizes a hash key generator configured to receive source addresses and to generate a corresponding hash key that is used by the internal decision making engine.

10. A method of learning source addresses of data frames received by a multiport switch comprising:

receiving a frame header associated with one of the data frames, the frame header comprising a source address;

assigning a virtual local area network (VLAN) identifier to the received data frames; and

learning via an internal decision making engine the source addresses of the data frames by manipulating an address table having a plurality of table entries and creating corresponding port vectors, each of the port vectors indicating the port that received the data frame, wherein

the step of learning updates the address table, each of the table entries having a format comprising;

a static bit for preventing deletion of the table entries;

a hit bit for aging the entries;

an address field indicating a source address of the data frames;

a virtual local area network (VLAN) field; and

a port vector field representing an embedded port receive number that

indicates the one port that received the data frame, and the step of learning comprises;

comparing the frame header having an address field and a VLAN field with the corresponding fields of the table entries to determine a match or a non-match;

creating a new one of the table entries, setting a hit bit of the new table entry, and forwarding the corresponding frame header to one of the ports that is designated as a management port based upon the non-match of the address field and the non-match of the VLAN field;

decoding, in response to the match of the address field and the match of the VLAN field, a receive port number from the port vector field of each of the table entries and determining whether the decoded receive port number is in a same trunk as a receive port number of the frame header, wherein the internal decision making engine sets the hit bit based upon the determination that the decoded receive port number is in a same trunk as the receive port number of the frame header;

determining, in response to the match of the address field and the match of the VLAN field and the finding that the decoded receive port number is not in the same trunk as the receive port number of the frame header, whether the table entry has its static bit field set, wherein the internal decision making engine overwrites the table entry with the frame header information, sets a corresponding hit bit, and forwards the frame header to the management port based upon a non-setting of the static bit field; and

setting, in response to the match of the address field and the match of the VLAN field and the finding that the decoded receive port number is not in the same trunk as the receive port number of the frame header and a setting of the static bit field, the corresponding hit bit and forwarding the frame header to the management port based upon the match of the corresponding address field, the match of the corresponding VLAN field, the determination that the corresponding decoded receive port number is not in the same trunk as the receive port number of the frame header, and the setting of the static bit field.

11. A multiport switch configured for controlling communication of data frames, comprising:

a plurality of ports for receiving and transmitting the data frames; and

an internal decision making engine coupled to the plurality of ports comprising;

an internal rules checker controller configured to learn the source addresses of the data frames and to store corresponding port vectors, each of the port vectors indicating, in a learning mode, the port that received the data frame and, in a forwarding mode, indicating which of the ports are to transmit the data frame; and

an address table for storing address information including source addresses and the port vectors, wherein the address table comprises a plurality of table entries, each of the entries has a format comprising;

a static bit for preventing deletion of the table entries;

a hit bit for aging the entries;

an address field indicating a source address of the data frames;

a virtual local area network (VLAN) field; and

a port vector field identifying the ports to which each received data frame should be forwarded for transmission from the multiport switch, the port vector field having embedded therein a port receive number that indicates the one port that received said each data frame.

12. The multiport switch of claim 11, wherein the source addresses are Medium Access Control (MAC) addresses.

13. The multiport switch of claim 11, wherein the address table represents a plurality of bins of address entries.

14. The multiport switch of claim 13, further comprising a hash key generator configured to receive source addresses and to generate a corresponding hash key that is used by the internal decision making engine.

15. A multiport switch configured for controlling communication of data frames, comprising:

a plurality of ports for receiving and transmitting the data frames; and

an internal decision making engine coupled to the plurality of ports comprising;

an internal rules checker controller configured to learn the source addresses of the data frames and to store corresponding port vectors, each of the port vectors indicating, in a learning mode, the port that received the data frame and, in a forwarding mode, indicating which of the ports are to transmit the data frame; and

an address table for storing address information including source addresses and the port vectors, wherein

the address table comprises a plurality of table entries, each of the entries has a format comprising;

a static bit for preventing deletion of the table entries;

a hit bit for aging the entries;

an address field indicating a source address of the data frames;

a virtual local area network (VLAN) field; and

a port vector field having an embedded port receive number that indicates the one port corresponding to the data frames,

the internal decision making engine is configured to learn the source addresses of the plurality of data frames by;

accessing a frame header associated with a received one of the data frames;

comparing the frame header having an address field and a VLAN field with the corresponding fields of the table entries to determine a match or a non-match;

creating a new one of the table entries, setting a hit bit of the new table entry, and forwarding the corresponding frame header to one of the ports that is designated as a management port based upon the non-match of the address field and the non-match of the VLAN field;

decoding, in response to the match of the address field and the match of the VLAN field, a receive port number from the port vector field of each of the table entries and determining whether the decoded receive port number is in a same trunk as a receive port number of the frame header, wherein the internal decision making engine sets the hit bit based upon the determination that the decoded receive port number is in a same trunk as the receive port number of the frame header; and

determining, in response to the match of the address field and the match of the VLAN field and the finding that the decoded receive port number is not in the same trunk as the receive port number of the frame header, whether the table entry has its static bit field set, wherein the internal decision making engine overwrites the table entry with the frame header information, sets a corresponding hit bit, and forwards the frame header to the management port based upon a non-setting of the static bit field, and

the internal decision making engine sets the corresponding hit bit and forwards the frame header to the management port based upon the match of the corresponding address field and the match of the corresponding VLAN field, and the determination that the corresponding decoded receive port number is not in the same trunk as the receive port number of the frame header, and the setting of the static bit field.