Layer-3 support in TRILL networks

Abstract

One embodiment of the present invention provides a switch. The switch includes an IP header processor and a forwarding mechanism. The IP header processor identifies a destination IP address in a packet encapsulated with an inner Ethernet header, a TRILL header, and an outer Ethernet header. The forwarding mechanism determines an output port and constructs a new header for the packet based on the destination IP address. The switch also includes a packet processor which determines whether (1) an inner destination media access control (MAC) address corresponds to a local MAC address assigned to the switch; (2) a destination RBridge identifier corresponds to a local RBridge identifier assigned to the switch; and (3) an outer destination MAC address corresponds to the local MAC address.

What is claimed is: 
     
       1. A switch, comprising:
 layer-2 processing circuitry configured to determine that:
 outer and inner destination media access control (MAC) addresses of a packet correspond to a MAC address assigned to the switch, wherein the packet is encapsulated with an inner Ethernet header, a routable header, and an outer Ethernet header; 
 
 encapsulation circuitry configured to determine that:
 a destination switch identifier of the routable header corresponds to a switch identifier assigned to the switch, wherein the routable header is placed between the outer and inner Ethernet headers; 
 
 Internet Protocol (IP) processing circuitry configured to lookup a destination IP address of a layer-3 header of the packet in a local layer-3 forwarding table in the switch, wherein the layer-3 header is distinct from the routable header, and wherein the destination IP address is a virtual IP address assigned to a virtual IP router, which is formed based on the switch in conjunction with at least another physical switch to operate as a single router; and 
 forwarding circuitry configured to determine an output port and construct a new header for the packet based on looking up the destination IP address in the local layer-3 forwarding table. 
 
     
     
       2. The switch of  claim 1 , wherein the layer-2 processing circuitry is further configured to determine a first virtual local area network (VLAN) tag in the inner Ethernet header; and
 wherein the new header includes a new inner Ethernet header comprising a second VLAN tag. 
 
     
     
       3. The switch of  claim 1 , wherein the switch is a member of a network of interconnected switches, wherein the network of interconnected switches is controlled as a single logical switch. 
     
     
       4. The switch of  claim 1 , further comprising switching circuitry configured to switch the packet between VLANs based on the destination IP address. 
     
     
       5. The switch of  claim 1 , wherein the destination switch identifier is a virtual switch identifier; and
 wherein the virtual IP router is associated with the virtual switch identifier. 
 
     
     
       6. The switch of  claim 1 , wherein the IP processing circuitry is further configured to map the virtual IP address to a virtual media access control (MAC) address. 
     
     
       7. The switch of  claim 1 , further comprising Address Resolution Protocol (ARP) circuitry configured to generate an ARP response for an IP address assigned to the switch, wherein the ARP response comprises a MAC address assigned to the switch. 
     
     
       8. A method, comprising:
 determining that:
 outer and inner destination media access control (MAC) addresses of a packet correspond to a MAC address assigned to a switch, wherein the packet is encapsulated with an inner Ethernet header, a routable header, and an outer Ethernet header; and 
 a destination switch identifier of the routable header corresponds to a switch identifier assigned to the switch, wherein the routable header is placed between the outer and inner Ethernet headers; 
 
 looking up a destination Internet Protocol (IP) address of a layer-3 header of the packet in a local layer-3 forwarding table in the switch, wherein the layer-3 header is distinct from the routable header, and wherein the destination IP address is a virtual IP address assigned to a virtual IP router, which is formed based on the switch in conjunction with at least another physical switch to operate as a single router; and 
 determining an output port and constructing a new header for the packet based on looking up the destination IP address in the local layer-3 forwarding table. 
 
     
     
       9. The method of  claim 8 , further comprising:
 determining a first virtual local area network (VLAN) tag in the inner Ethernet header; and 
 including in the new header a new inner Ethernet header comprising a second VLAN tag. 
 
     
     
       10. The method of  claim 8 , wherein the switch is a member of a network of interconnected switches wherein the network of interconnected switches is controlled as a single logical switch. 
     
     
       11. The method of  claim 8 , further comprising switching the packet between VLANs based on the destination IP address. 
     
     
       12. The method of  claim 8 , wherein the destination switch identifier is a virtual switch identifier; and
 wherein the virtual IP router is associated with the virtual switch identifier. 
 
     
     
       13. The method of  claim 8 , further comprising mapping the virtual IP address to a virtual media access control (MAC) address. 
     
     
       14. The method of  claim 8 , further comprising generating an Address Resolution Protocol (ARP) response for an IP address assigned to the switch, wherein the ARP response comprises a MAC address assigned to the switch. 
     
     
       15. A computing system, comprising:
 a processor; and 
 a non-transitory computer-readable storage medium storing instructions which when executed by the processor causes the processor to perform a method, the method comprising:
 determining that:
 outer and inner destination media access control (MAC) addresses of a packet correspond to a MAC address assigned to the computing system, wherein the packet is encapsulated with an inner Ethernet header, a routable header, and an outer Ethernet header; and 
 a destination switch identifier of the routable header corresponds to a switch identifier is assigned to the computing system; 
 
 looking up a destination Internet Protocol (IP) address of a layer-3 header of the packet in a local layer-3 forwarding table in the computing system, wherein the layer-3 header is distinct from the routable header and wherein the destination IP address is a virtual IP address assigned to a virtual IP router, which is formed based on the switch in conjunction with at least another physical switch to operate as a single router; and 
 determining an output port and constructing a new header for the packet based on looking up the destination IP address in the local-layer-3 forwarding table. 
 
 
     
     
       16. The computing system of  claim 15 , within the method further comprises:
 determining a first virtual local area network (VLAN) tag in the inner Ethernet header; and 
 including in the new header a new inner Ethernet header comprising a second VLAN tag. 
 
     
     
       17. The computing system of  claim 15 , wherein the computing system is a member of a network of interconnected switches, wherein the network of interconnected switches is controlled as a single logical switch. 
     
     
       18. The computing system of  claim 15 ,
 wherein the destination switch identifier is a virtual switch identifier; and 
 wherein the virtual IP router is associated with the virtual switch identifier. 
 
     
     
       19. The computing system of  claim 15 , wherein the method further comprises generating an Address Resolution Protocol (ARP) response for an IP address assigned to the computing system, wherein the ARP response comprises a MAC address assigned to the computing system. 
     
     
       20. The computing system of  claim 15 , whether the method further comprises switching the packet between VLANs based on the destination IP address.