Systems and methods for optimizing layer three routing in an information handling system

1. An information handling system, comprising:

a plurality of racks of servers, each of the plurality of racks having a top-of-rack switch with each top-of-rack switch configured to provide a bridging device;

a plurality of aggregation switches, each aggregation switch being coupled to each of the top-of-rack switches and each aggregation switch configured to provide a bridging device; and

a virtual bridging device providing layer three routing services;

wherein a first one of the top-of-rack switches is configured to:

receive an address resolution protocol (ARP) packet from a connected server on a source virtual local area network (VLAN);

transmit the ARP packet to the plurality of aggregation switches;

receive an ARP reply from one of the plurality of aggregation switches, the ARP reply including an anycast media access control (MAC) address for the virtual bridging device;

receive a data packet from the connected server, the data packet including the anycast MAC address; and

forward the data packet using equal-cost multi-path routing to any one of the plurality of aggregation switches.

2. The information handling system of claim 1 , wherein each of the plurality of aggregation switches is in communication with the virtual bridging device and the plurality of aggregation switches is configured to run a virtual internet protocol (IP) instance, the virtual IP instance spanning one or more of the plurality of aggregation switches and having a virtual IP instance IP address and a virtual media access control (MAC) address, the virtual IP instance IP address and virtual MAC address being associated with the virtual bridging device.

3. The information handling system of claim 2 , wherein each of the bridging devices provided by the plurality of aggregation switches is configured to:

recognize a virtual bridging device identifier indicating that an egress bridging device address of an encapsulated packet is the virtual bridging device;

recognize the virtual MAC address as a destination MAC address in the encapsulated packet received by the aggregation switch;

decapsulate the encapsulated packet, thereby providing a decapsulated packet, in response to the recognition of the virtual bridging device identifier and the virtual MAC address; and

route the decapsulated packet to a destination.

4. The information handling system of claim 3 , wherein each of the bridging devices provided by the plurality of aggregation switches is further configured to:

determine a destination top-of-rack switch for the decapsulated packet using a layer three routing table;

encapsulate the decapsulated packet to create a re-encapsulated packet using a bridging device identifier corresponding to the destination top-of-rack switch as an egress bridging device address in a header of the re-encapsulated packet; and

forward the re-encapsulated packet to the destination top-of-rack switch.

5. The information handling system of claim 1 , wherein each of the top-of-rack switches is in communication with the virtual bridging device and the top-of-rack switches are configured to provide the services of the plurality of aggregation switches in the information handling system, the top-of-rack switches being further configured to run a virtual IP instance, the virtual IP instance, spanning one or more of the top-of-rack switches and having a virtual IP instance IP address and a virtual MAC address, the virtual IP instance IP address and virtual MAC address being associated with the virtual bridging device.

6. The information handling system of claim 5 , wherein each of the bridging devices provided by the top-of-rack switches is configured to:

recognize a virtual bridging device identifier indicating that an egress bridging device address of an encapsulated packet is the virtual bridging device;

recognize the virtual MAC address as a destination MAC address in the encapsulated packet received by the top-of-rack switch;

decapsulate the packet in response to the recognition of the virtual bridging device identifier and the virtual MAC address; and

route the packet to a destination.

7. The information handling system of claim 4 , wherein one aggregation switch of the plurality of aggregation switches is designated as an address resolution protocol (ARP) master aggregation switch, the ARP master aggregation switch responding to ARP requests on behalf of the plurality of aggregation switches.

8. The information handling system of claim 7 , wherein the ARP master aggregation switch synchronizes the ARP reply with all other aggregation switches of the plurality of aggregation switches.

9. A method for optimizing layer three routing in an information handling system, the method comprising:

receiving a packet from a source top-of-rack switch at an aggregation switch;

detecting an identifier of a virtual bridging device as an egress bridging device address in a header of the packet, the virtual bridging device being provided by the aggregation switch and one or more other aggregation switches;

recognizing that the aggregation switch and the virtual bridging device are neighbors in the information handling system;

decapsulating the packet;

recognizing a destination media access control (MAC) address of the packet as an anycast MAC address of a virtual router instance, the anycast MAC address being associated with the virtual bridging device, and the virtual router instance spanning the aggregation switch and the other aggregation switches;

routing the packet from the virtual router instance to a destination top-of-rack switch;

receiving an address resolution protocol (ARP) packet at the source top-of-rack switch from a connected server on a source virtual local area network (VLAN);

transmitting the ARP packet from the source top-of-rack switch to a plurality of aggregation switches;

receiving an ARP reply from one of the plurality of aggregation switches, the ARP reply including the anycast MAC address;

receiving a data packet at the source top-of-rack switch from the connected server, the data packet including the anycast MAC address; and

forwarding the data packet using equal-cost multi-path routing to any one of the aggregation switch and the other aggregation switches.

10. The method of claim 9 , wherein the virtual router instance is a single virtual redundancy router protocol (VRRP) instance operating across the plurality of aggregation switches.

11. The method of claim 10 , further comprising:

decapsulating the data packet at the one of the aggregation switch and the other aggregation switches on behalf of the virtual bridging device;

recognizing, in a header of the data packet, the anycast MAC address associated with the VRRP instance; and

presenting the data packet to the VRRP instance for routing to a different VLAN through a different top-of-the-rack switch.

12. An information handling system comprising:

an aggregation switch, the aggregation switch configured to receive data packets from a plurality of top-of-rack switches and configured to transmit data packets to and receive data packets from one or more other aggregation switches, the aggregation switch further configured to provide a bridging device; and

a virtual bridging device, the virtual bridging device being provided by the bridging device, and the virtual bridging device providing at least one anycast media access control (MAC) address for at least one virtual router instance operating on the aggregation switch;

wherein the aggregation switch is configured to:

receive an address resolution protocol (ARP) packet from a first one of the top-of-rack switches;

transmit an ARP reply to the first top-of-rack switch, the ARP reply including the anycast MAC address for the at least one virtual router instance;

receive a data packet from the first top-of-rack switch, the data packet including the anycast MAC address; and

forward the data packet using equal cost multi-path routing on behalf of the at least one virtual router instance.

13. The system of claim 12 , wherein the at least one virtual router instance is a virtual internet protocol (IP) instance, the virtual IP instance having a virtual IP instance IP address and a virtual MAC address, the virtual MAC address being the at least one anycast MAC address provided by the virtual bridging device.

14. The system of claim 13 , wherein the bridging device provided by the aggregation switch is configured to:

recognize the virtual MAC address as a destination MAC address in an encapsulated packet received by the aggregation switch;

recognize a virtual bridging device identifier indicating that an egress bridging device address of the encapsulated packet is the virtual bridging device;

decapsulate the encapsulated packet in response to the recognition of the virtual bridging device identifier and/or the virtual MAC address, thereby providing a decapsulated packet; and

route the decapsulated packet to a destination.

15. The system of claim 14 , wherein the aggregation switch is designated as an address resolution protocol (ARP) master aggregation switch, the ARP master aggregation switch being configured to respond to ARP requests on behalf of the one or more other aggregation switches.

16. The system of claim 15 , further comprising a second virtual bridging device, the second virtual bridging device being provided by the bridging device, and the second virtual bridging device providing a second anycast MAC address for a second virtual router instance operating on the aggregation switch, the second virtual router instance being a second virtual IP instance, the second virtual IP instance having a second virtual IP instance IP address and a second virtual MAC address, the second virtual MAC address being the second anycast MAC address provided by the second virtual bridging device.

17. The system of claim 16 , wherein the aggregation switch is configured to communicate with at least one other aggregation switch to provide a shared virtual bridging device that provides a shared anycast MAC address for a shared virtual router instance, the shared virtual router instance operating on the aggregation switch and the one other aggregation switch.