Gigabit switch with frame forwarding and address learning

• US 20060120389A1
• Filed: 12/21/2005
• Published: 06/08/2006
• Est. Priority Date: 06/09/2000
• Status: Active Grant

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Kalkunte, Mohan, Ambe, Shekhar, Kadambi, Shiri, Sampath, Srinivas
• Granted Patent: US 7,796,612 B2
• Time in Patent Office: Days
• US Class Current: 370/401
• CPC Class Codes: H04L 12/462 LAN interconnection over a bridge based backbone
• CPC Class Codes: H04L 45/00 Routing or path finding of packets in data switching networks routing or path finding in wireless networks H04W40/00
• CPC Class Codes: H04L 45/16 Multipoint routing
• CPC Class Codes: H04L 45/245 Link aggregation, e.g. trunking
• CPC Class Codes: H04L 45/52 Multiprotocol routers
• CPC Class Codes: H04L 45/742 Route cache; Operation thereof
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/2458 Modification of priorities while in transit
• CPC Class Codes: H04L 47/266 Stopping or restarting the source, e.g. X-on or X-off
• CPC Class Codes: H04L 47/29 using a combination of thresholds
• CPC Class Codes: H04L 47/32 by discarding or delaying data units, e.g. packets or frames
• CPC Class Codes: H04L 49/102 using shared medium, e.g. bus or ring
• CPC Class Codes: H04L 49/109 Integrated on microchip, e.g. switch-on-chip
• CPC Class Codes: H04L 49/15 Interconnection of switching modules
• CPC Class Codes: H04L 49/3009 Header conversion, routing tables or routing tags
• CPC Class Codes: H04L 49/3018 Input queuing
• CPC Class Codes: H04L 49/3036 Shared 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]
• CPC Class Codes: H04L 49/506 : Backpressure
• CPC Class Codes: H04L 49/508 : Head of Line Blocking Avoidance
• CPC Class Codes: H04L 49/602 : Multilayer or multiprotocol switching, e.g. IP switching
• CPC Class Codes: H04L 69/22 : Parsing or analysis of headers
• CPC Class Codes: Y02D 30/50 : in wire-line communication networks, e.g. low power modes or reduced link rate

Abstract

A network switch and a method thereof for network communications include a first data port interface and a second data port interface supporting a data port transmitting and receiving data at a first data rate and a second data rate, respectively. The switch has a CPU interface to communicate with a CPU and a memory management unit to communicate data from at least one of the first and second data port interfaces and a memory. The switch includes a communication channel communicating data and messaging information between the first and second data port interfaces and the memory management unit and lookup tables, including an address resolution lookup table and a VLAN table. The first or second data port interfaces determine an egress port for an incoming data packet from a search of the address resolution lookup table and the VLAN table using a VLAN ID from the incoming data packet.

Claims

1. A network switch for network communications, the network switch comprising:

a first data port interface supporting a data port transmitting and receiving data at a first data rate;

a second data port interface supporting a data port transmitting and receiving data at a second data rate; and

a plurality of lookup tables, the lookup tables including an address resolution lookup table and a VLAN table,

wherein the first data port interface or the second data port interface is configured to determine an egress port by obtaining a class of service.

2. The network switch as recited in claim 1, wherein the first data port interface or the second data port interface is configured to determine the egress port for an incoming data packet received by performing a search of the address resolution lookup table and the VLAN table using an identifier derived from the incoming data packet.

3. The network switch as recited in claim 2, wherein the identifier comprises a VLAN ID.

4. The network switch as recited in claim 1, wherein the second data rate is greater than the first data rate, a header of the incoming data packet contains an opcode used to identify a packet type, and when the incoming data packet arrives at a port of the second data port interface, the second data port interface is configured to forward the incoming packet based on the opcode.

5. The network switch as recited in claim 4, wherein the opcode identifies whether the incoming data packet is a unicast packet, a multicast packet, a broadcast packet or resulted in a destination lookup failure.

6. A method of switching data in a network switch, the method comprising:

receiving an incoming data packet at a first port of a switch;

reading a first packet portion, less than a full packet length, to determine particular packet information;

modifying the incoming data packet to include forwarding and routing information;

obtaining the egress port by obtaining a class of service; and

sending the modified data packet to the egress port.

7. The method as recited in claim 6, further comprising:

deriving a VLAN ID from the first packet portion;

searching a VLAN table using VLAN ID;

searching an address resolution lookup table using the particular packet information and the VLAN ID;

determining whether there is a matched entry in the address resolution lookup table; and

when the matched entry is not in the address resolution lookup, learning the particular packet information and placing the particular packet information as an entry in the address resolution lookup table.

8. The method as recited in claim 6, wherein the deriving of the VLAN ID from the first packet portion comprises:

reading the VLAN ID from a VLAN tag in a header of the incoming data packet, when the incoming data packet is tagged; and

searching a port based VLAN table based on the particular packet information to obtain the VLAN ID, when the incoming data packet is untagged.

9. The method as recited in claim 6, wherein when the incoming data packet is a multicast packet, the obtaining of the egress port comprises:

deriving a multicast index from a result from the step of searching the address resolution lookup table; and

searching a multicast table using the multicast index as a key to obtain the egress ports.

10. The method as recited in claim 6, wherein the obtaining of the egress port comprises obtaining a port bitmap, a module ID bitmap, and an untagged port bitmap.

11. The method as recited in claim 6, further comprising:

determining whether the incoming data packet is to be mirrored to another port;

determining whether a destination for the incoming data packet is a trunked port; and

determining whether a destination for the incoming data packet is on a stacked linked network switch connected to the network switch.

12. A network switch, comprising:

a first port;

means for receiving an incoming data packet at the first port;

means for reading a first packet portion, less than a full packet length, to determine particular packet information;

means for searching an address resolution lookup table using the particular packet information and an identifier;

means for modifying the incoming data packet to include forwarding and routing information;

means for obtaining the egress port by obtaining a class of service; and

means for sending the modified data packet to the egress port,

wherein when the matched entry is not in the address resolution lookup table, means for updating the address resolution lookup table with the particular packet information.

13. The network switch as recited in claim 12, further comprising:

means for deriving the identifier from the first packet portion;

means for searching a VLAN table using the identifier;

means for determining whether there is a matched entry in the address resolution lookup table; and

means for learning the particular packet information and means for placing the particular packet information as an entry in the address resolution lookup table.

14. The network switch as recited in claim 13, wherein the means for deriving the identifier from the first packet portion comprises:

means for reading the identifier from a VLAN tag in a header of the incoming data packet, when the incoming data packet is tagged; and

means for searching a port based VLAN table based on the particular packet information to obtain the identifier,

wherein the means for reading the identifier supplies the identifier when the incoming data packet is tagged and the means for searching a port based VLAN table supplies the identifier when the incoming data packet is untagged.

15. The network switch as recited in claim 12, wherein when the incoming data packet is a multicast packet, the means for obtaining an egress port comprises:

means for deriving a multicast index from a result from the step of searching the address resolution lookup table; and

means for searching a multicast table using the multicast index as a key to obtain the egress ports.

16. The network switch as recited in claim 12, wherein the means for obtaining the egress port comprises means for obtaining a port bitmap, a module ID bitmap, and an untagged port bitmap.

17. The network switch as recited in claim 12, further comprising:

means for determining whether the incoming data packet is to be mirrored to another port;

means for determining whether a destination for the incoming data packet is a trunked port; and

means for determining whether a destination for the incoming data packet is on a stacked linked network switch connected to the network switch.

18. The network switch as recited in claim 12, wherein the identifier comprises a VLAN ID.