METHODS AND SYSTEMS FOR PREEMPTIVELY PROVIDING FORWARDING ELEMENT CONFIGURATION INFORMATION NEEDED FOR VIRTUAL MACHINE MIGRATION DURING CONTROLLER OUTAGES

1 . A method for efficiently providing logical forwarding element (LFE) information needed for virtual machine (VM) migration to hosts in a software-defined network (SDN), the method comprising:

at a set of one or more controllers that configures a plurality of forwarding elements in the SDN to implement one LFE:

identifying a subset of one or more host computers in the SDN as a group of designated host computers for migrating one or more VMs;

retrieving, from a data store, configuration information for configuring any software forwarding element executing on any designated host computer to implement the LFE; and

providing the retrieved configuration information to each particular host computer in the subset of host computers before any VM is migrated to the particular host computer, in order to pre-configure the particular host computer to implement the LFE without assistance from the set of controllers when a VM migrates to the particular host computer.

2 . The method of claim 1 , wherein the LFE is a logical router and the retrieved configuration information comprises information regarding the logical router and one or more logical router ports of the logical router.

3 . The method of claim 1 , wherein the LFE is a logical switch and the retrieved configuration information comprises information regarding the logical switch.

4 . The method of claim 1 , wherein identifying the subset of host computers as the group of designated hosts comprises receiving a user-specified list indicating the subset of host computers as the group of designated hosts.

5 . The method of claim 1 , wherein the user-specified list is received from a set of one or more management servers of the SDN.

6 . The method of claim 5 , wherein the set of management servers implement a management plane for the SDN.

7 . The method of claim 6 , wherein a user provides the user-specified list to the management plane using an Application Programming Interface (API) call.

8 . The method of claim 6 , wherein a user provides the user-specified list to the management plane through a graphical user interface (GUI).

9 . The method of claim 8 , wherein the GUI comprises a drop down menu for the user to select one or more host computers in the SDN to include in the subset of host computers.

10 . The method of claim 1 , wherein the set of controllers of the SDN implements a central control plane (CCP) of the SDN.

11 . The method of claim 10 , wherein providing the retrieved configuration information to each particular host computer in the subset of host computers comprises providing the retrieved LFE information to a local control plane (LCP) module at each host computer in the subset of host computers.

12 . The method of claim 1 further comprising:

receiving, from each host computer in the subset of host computers, a network address of the host computer;

using the received network addresses to create a network address list comprising a network address for each host computer in the subset of host computers; and

distributing the network address list to each host computer in the SDN not included in the subset of host computers.

13 . The method of claim 12 , wherein the network address list is also provided to each host computer in the subset of host computers.

14 . The method of claim 1 further comprising:

before identifying the subset of host computers and retrieving the configuration information for the LFE:

receiving a set of configuration data for the LFE;

extracting the configuration information from the set of configuration data;

storing the configuration information in the data store; and

configuring the LFE in the SDN.

15 . The method of claim 14 , wherein the set of configuration data is a first set of configuration data, the LFE is a first LFE, and the configuration information is a first set of configuration information, the method further comprising:

after providing the first set of configuration information:

receiving a second set of configuration data for a second LFE;

extracting a second set of configuration information from the second set of configuration data;

storing the second set of configuration information in the data store;

configuring the second LFE in the SDN; and

providing the second set of configuration information to each host computer in the subset of host computers.

16 . A non-transitory machine readable medium storing a program for execution by at least one processing unit for efficiently providing logical forwarding element (LFE) information needed for virtual machine (VM) migration to hosts in a software-defined network (SDN), the program comprising sets of instructions for:

at a set of one or more controllers that configure a plurality of forwarding elements in the SDN to implement one LFE:

identifying a subset of one or more host computers in the SDN as a group of designated host computers for migrating one or more VMs;

retrieving, from a data store, configuration information for configuring any software forwarding element executing on any designated host computer to implement the LFE; and

providing the retrieved configuration information to each particular host computer in the subset of host computers before any VM is migrated to the particular host computer, in order to pre-configure the particular host computer to implement the LFE without assistance from the set of controllers when a VM migrates to the particular host computer.

17 . The non-transitory machine readable medium of claim 16 , wherein the set of instructions for identifying the subset of host computers as the group of designated hosts comprises a set of instructions for receiving a user-specified list indicating the subset of host computers as the group of designated hosts.

18 . The non-transitory machine readable medium of claim 16 , wherein the program further comprises sets of instructions for:

receiving, from each host computer in the subset of host computers, a network address of the host computer;

using the received network addresses to create a network address list comprising a network address for each host computer in the subset of host computers; and

distributing the network address list to each host computer in the SDN not included in the subset of host computers.

19 . The non-transitory machine readable medium of claim 16 , wherein the program further comprises sets of instructions for:

before identifying the subset of host computers and retrieving the configuration information for the LFE:

receiving a set of configuration data for the LFE;

extracting the configuration information from the set of configuration data;

storing the configuration information in the data store; and

configuring the LFE in the SDN.

20 . The non-transitory machine readable medium of claim 19 , wherein the set of configuration data is a first set of configuration data, the LFE is a first LFE, and the configuration information is a first set of configuration information, the program further comprising sets of instructions for:

after providing the first set of configuration information:

receiving a second set of configuration data for a second LFE;

extracting a second set of configuration information from the second set of configuration data;

storing the second set of configuration information in the data store;

configuring the second LFE in the SDN; and

providing the second set of configuration information to each host computer in the subset of host computers.