Network control software notification with advance learning

Abstract

Techniques are disclosed for notifying network control software of new and moved source MAC addresses. In one embodiment, a switch detects packets sent by a new or migrated virtual machine, and sends a copy of a detected packet to the network control software as a notification. The switch further learns the source MAC address, thereby permitting the entry to be used for normal forwarding prior to validation of the entry and the VM associated therewith by the network control software. Until the network control software has validated the VM, the switch may periodically retry the notification to the network control software. “No_Redirect” and “Not_Validated” flags may be used to indicate whether a notification has already been attempted and thus no retry is necessary, and that the VM associated with the VM has not yet been validated, respectively.

What is claimed is: 
     
         1 . A computer-implemented method for notifying network control software of new and moved source media access control (MAC) addresses, comprising:
 determining that a received first packet includes either a new or moved source MAC address;   inserting or updating an entry in a forwarding database, wherein the inserted or updated entry includes the source MAC address extracted from the first packet;   transmitting a copy of the first packet as a notification to the network control software; and   setting a first flag and a second flag of the forwarding database entry, wherein the set first flag indicates that the network control software has been notified, and wherein the set second flag indicates that the network control software has not yet validated the source MAC address of the forwarding database entry.   
     
     
         2 . The method of  claim 1 , further comprising, forwarding the first packet to a target MAC address indicated in the first packet. 
     
     
         3 . The method of  claim 1 , wherein the first packet was transmitted by a virtual machine. 
     
     
         4 . The method of  claim 1 , wherein the first flag is periodically reset by an aging function which walks the forwarding database. 
     
     
         5 . The method of  claim 1 , further comprising:
 determining that a received second packet has a source MAC address that hits on the entry; and   forwarding the second packet to the network control software only if the first flag for the entry is not set and the second flag for the entry is set.   
     
     
         6 . The method of  claim 1 , further comprising, resetting, by the network control software, the first and second flags if the network control software validates the source MAC address. 
     
     
         7 . The method of  claim 1 , further comprising, adding, by the network control software, an access control list (ACL) rule to block or discard received packets having the source MAC address of the first packet if the network control software does not validate the source MAC address. 
     
     
         8 . The method of  claim 1 , wherein the network control software periodically polls the forwarding database to determine if the entry is still in use.