Layer 3 switching logic architecture in an integrated network switch

• US 7,079,537 B1
• Filed: 04/25/2000
• Issued: 07/18/2006
• Est. Priority Date: 04/25/2000
• Status: Expired due to Term

• Current Assignee: Advanced Micro Devices, Inc.
• Original Assignee: Advanced Micro Devices, Inc.
• Inventors: Kanuri, Mrudula, Egbert, Chandan
• Primary Examiner(s): Pham, Chi
• Assistant Examiner(s): Harper, Kevin C.
• Application Number:
  US09/558,293
• Time in Patent Office: 2,275 Days
• Field of Search: 370/389, 370/400, 370/401, 370/428, 370/465, 370/469, 370/392
• US Class Current: 370/392
• CPC Class Codes: H04L 49/25 Routing or path finding in a switch fabric
• CPC Class Codes: H04L 49/3009 Header conversion, routing tables or routing tags
• CPC Class Codes: H04L 49/354 for supporting virtual local area networks [VLAN]
• 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 switching module for performing layer 2 and layer 3 (specifically Internet Protocol) switching operations, and a plurality of network switch ports, each configured for connecting the network switch to a corresponding subnetwork. The switching module includes address tables for storing address information (e.g., layer 2 and layer 3 address and switching information). The network switching module is configured for performing prescribed layer 3 switching that enables transfer of data packets between subnetworks, bypassing a router that normally would need to manage Internet protocol switching between subnetworks of the network. Hence, the network switch performs Internet Protocol switching for intranetwork (i.e., inter-subnetwork) traffic, improving efficiency of the router by enabling the router resources to support more subnetworks.

Claims

1. A method in an integrated network switch having a switching module, the integrated network switch configured for switching a layer 2 packet, the method comprising:

determining whether the layer 2 packet includes prescribed layer 3 packet information;

selectively performing layer 3 switching based on the determined presence of the prescribed layer 3 packet information, including determining a switching operation based on at least one of a layer 3 source address and a layer 3 destination address, including;

(1) determining a presence of a subnetwork identifier within the prescribed layer 3 packet information,

(2) searching a first table, configured for storing switching entries for respective Internet Protocol (IP) addresses, for a corresponding switching entry storing the layer 3 destination address, and

(3) selectively searching a second table, configured for storing switching entries for respective prescribed subnetwork identifiers, for a corresponding switching entry storing the subnetwork identifier, the selectively searching being performed based on a determined absence of the corresponding switching entry storing the layer 3 destination address; and

selectively performing layer 2 switching based on the determined absence of the prescribed layer 3 packet information.

2. The method of claim 1, wherein the determining step includes first detecting a presence of an Internet Protocol (IP) header within the layer 2 packet as the prescribed layer 3 packet information.

3. The method of claim 2, wherein the step of selectively performing layer 3 switching includes second detecting whether the IP header specifies a prescribed network identifier and the subnetwork identifier.

4. The method of claim 3, wherein the second detecting step includes comparing a source IP address within the IP header with the second table.

5. The method of claim 4, wherein the step of selectively performing layer 3 switching further includes obtaining layer 3 switching information from the second table based on a match between the subnetwork identifier within the IP header and a corresponding one of the prescribed subnetwork identifiers.

6. The method of claim 4, wherein the step of selectively performing layer 3 switching further includes dropping the layer 2 packet based on a determined absence of any one of the prescribed subnetwork identifiers within the source IP address.

7. The method of claim 2, wherein the step of selectively performing layer 2 switching includes accessing a layer 2 switching table, based on layer 2 packet information, in response to the determining step determining that the layer 2 packet includes one of an IPX frame and a DECnet frame.

8. The method of claim 1, wherein the step of selectively performing layer 3 switching includes dropping the layer 2 packet in response to determining that the layer 2 packet includes a time to live (TTL) field having a value equal to zero.

9. The method of claim 8, wherein the step of selectively performing layer 3 switching includes:

obtaining layer 3 switching information based on the determined presence of the prescribed layer 3 packet information and based on determining that the TTL field has a value greater than zero; and

decrementing the TTL field prior to outputting the layer 2 packet based on the obtained layer 3 switching information.

10. The method of claim 9, wherein the step of selectively performing layer 3 switching further includes:

second determining whether the layer 2 packet includes a destination MAC address specifying a router and a destination IP address specifying a network node within a prescribed subnetwork; and

selectively replacing the destination MAC address specifying the router with a second MAC address specifying the network node, based on the second determining step.

11. The method of claim 10, wherein the step of selectively performing layer 3 switching further includes recalculating an IP checksum and MAC cyclic redundancy check based on the selective replacement of the destination MAC address with a second MAC address.

12. The method of claim 1, wherein the integrated network switch is implemented on a single integrated chip that perfoms each of the steps of determining, selectively performing layer 3 switching, and selectively performing layer 2 switching.

13. An integrated network switch having a switching module comprising:

an evaluation module configured for evaluating a presence of layer 3 packet information within a received layer 2 packet, the evaluation module configured for identifying selected layer 3 switching functions to be perfomed based on the determined presence of prescribed data within the layer 3 packet information;

an address table configured for storing switching entries, each switching entry configured for storing a layer 2 network address, a layer 3 network address, and corresponding switching information;

a subnetwork table configured for storing switching entries for respective prescribed subnetwork identifiers;

an address lookup module configured for searching the switching entries based on at least one of the layer 3 packet information and layer 2 address information in the received layer 2 packet, the address lookup module configured for selectively determining a presence of a subnetwork identifier within the layer 3 packet information, and searching the subnetwork table for a corresponding switching entry storing the subnetwork identifier, based on a determined absence of the corresponding switching entry storing the layer 3 network address in the address table; and

an output module configured for generating a switching decision based on the searching of the switching entries by the address lookup module and the evaluation of the presence of layer 3 packet information.

14. The switch of claim 13, wherein the evaluation module includes:

a rules queue configured for generating status information for the received layer 2 packet; and

an ingress module configured for parsing the received layer 2 packet for layer 2 address information and layer 3 address information and determining whether the received layer 2 packet should be dropped based on the layer 2 address information, the evaluation of the presence of layer 3 packet information, and the status information.

15. The switch of claim 14, wherein the ingress module is configured for identifying within the received layer 2 packet a media access control (MAC) source address, a MAC destination address, an Internet Protocol (IP) source address, an IP destination address, and a nonzero time to live (TTL) field.

16. The switch of claim 15, wherein the ingress module is configured for dropping the layer 2 packet in response to detecting the TTL field having a zero value.

17. The switch of claim 15, wherein the address lookup module includes a source address lookup module configured for selectively storing the MAC source address and corresponding IP source address of a determined non-router network node having transmitted the received layer 2 packet.

18. The switch of claim 17, the address lookup module further including a destination address module configured for obtaining the switching information from a selected switching entry of one of address table and the subnetwork table based on at least one of the IP destination address and the MAC destination address.

19. The switch of claim 13, wherein the output module assigns the switching decision a prescribed priority based on the identified selected layer 3 switching functions to be performed based on the determined presence of the prescribed data within the layer 3 packet information.

20. The switch of claim 19, wherein the output module decrements a detected nonzero time to live (TTL) field within the layer 3 packet information.

21. The switch of claim 19, wherein the output module replaces a destination MAC address in the received layer 2 packet, determined as corresponding to a layer 2 router address, with a second MAC address based on a detected destination IP address in the layer 3 packet information specifying a second network node identified in one of the switching entries.

22. The switch of claim 13, wherein the integrated network switch is implemented on a single integrated chip.

23. The switch of claim 13, wherein the address lookup module is configured for searching the switching entries based on the layer 2 address information in the received layer 2 packet, in response to a determination within the integrated network switch that the layer 2 packet includes one of an IPX frame and a DECnet frame.