Data center networking

1. A method for operating a local area networking system comprising: limiting a number of media access control (MAC) addresses in a forwarding table in each of a plurality of leaf switches comprising the local area networking system, connected to one another by a spine switch, by learning, for each of the leaf switches, only MAC addresses from directly connected hosts.

2. The method of claim 1 , wherein the learning comprises limiting MAC address learning on the leaf switches only to directly connected host MAC addresses.

3. The method of claim 1 , wherein each of the leaf switches do not learn MAC addresses from hosts which are not directly connected thereto.

4. The method of claim 1 , wherein each host is comprised of at least one of physical and virtual machine servers, and wherein a maximum number of MAC addresses required to be supported on the leaf switches is computed from a maximum number of physical and virtual machine servers supported by a chassis/rack in which the physical and virtual machine servers are located.

5. The method of claim 1 , wherein each leaf uplink port of the leaf switches connected to the spine switch do not learn a MAC address from the spine switch.

6. The method of claim 1 , wherein each leaf host facing ports of the leaf switches learn a source MAC address of unicast, broadcast and multicast data frames.

7. The method of claim 6 , wherein the spine switch includes a spine port configured to learn the source MAC address of unicast, broadcast and multicast data frames.

8. The method of claim 7 , wherein when a spine switch detects a MAC migration event regarding migration of a MAC address, it will notify a leaf switch to remove from its layer-2 forwarding table that MAC address.

9. The method of claim 7 , wherein the spine device will learn all destination MAC addresses for a network topology and populate its forwarding table therewith.

10. The method of claim 1 , wherein, upon reception of an unknown unicast frame from host facing ports, each leaf switch will transmit the unicast frame on an uplink port only.

11. The method of claim 10 , wherein, upon reception of an unknown unicast frame on a downstream port connecting a leaf switch, each spine switch will flood the unicast frame across all ports in the local area networking system and also back to an origination leaf switch.

12. The method of claim 1 , wherein, upon reception of an unknown unicast frame from uplink ports, each leaf switch will flood the unicast frame on its host facing ports, except a port where a MAC source of the frame is learned.

13. A method comprising:

receiving a data frame from a layer in a networking system; and

determining whether the data frame was received from an uplink port of one of a plurality of leaf switches, which uplink port is coupled to a spine switch connected to each of the plurality of leaf switches:

if not received from the uplink port, learning a media access control (MAC) source address on the one of the plurality of leaf switches; and

if received from the uplink port, the MAC source address will not be learned on the one of the plurality of leaf switches.

14. The method of claim 13 , further comprising:

receiving the data frame at the spine switch; and

flooding the networking system when the data frame is not a broadcast.

15. The method of claim 14 , further comprising determining that the spine switch has a MAC destination address learned and transmitting the data frame on selected port associated with the MAC destination address where the data frame is not a broadcast.

16. The method of claim 15 , wherein:

when there is no MAC destination address found, determine that the data frame originated on a port connected to sources outside of the networking system and flooding the data frame to all destinations, excluding a source port of the spine device; and

when the data frame originated from inside the networking system, the spine device floods the data frame to all destinations, including the source port.

17. The method of claim 13 , further comprising limiting MAC address information in a forwarding table in leaf switches of the networking system by learning, for each of the leaf devices, only MAC addresses from directly connected hosts.

18. A method comprising:

receiving a data frame from a downstream port of a leaf device in a networking system, wherein the leaf device is one of a plurality of leaf devices connected to one another by a spine switch; and

determining whether the data frame is a broadcast;

if yes, the leaf device will flood to all ports on the networking system, received from an uplink port;

if the data frame is not a broadcast, then determining whether the leaf device has a media access control (MAC) destination address learned:

if a MAC destination address is known, transmitting the data frame on a selected port associated with the MAC destination address;

if a MAC destination address is unknown, determining that the data frame originated from a upstream port on the leaf device and flood the data frame to all host facing ports connected to the leaf device excluding the port where the source MAC address is learnt; and

if the source MAC address is not learnt by the leaf device, the leaf device will flood the data frame to all host facing ports.

19. The method of claim 18 , wherein:

on the spine switch when an unknown unicast data frame is received on the downstream port, flood the frame across all ports in the networking system including a source port; and

when an unknown unicast data frame is received not on the downstream port, the switch will flood the frame across all ports excluding the source port.

20. The method of claim 18 , further comprising limiting MAC address information in a forwarding table in leaf switches of the networking system by learning, for each of the leaf devices, only MAC addresses from directly connected hosts.