Load balancing and destination network address translation middleboxes

Abstract

A controller of a network control system for configuring several middlebox instances is described. The middlebox instances implement a middlebox in a distributed manner in several hosts. The controller configures a first middlebox instance to obtain status of a set of servers and disseminate the obtained status to a second middlebox instance. The controller configures the second middlebox instance to use the status to select a server from the set of servers.

1 - 20 . (canceled) 
     
     
         21 . A method for performing load balancing in a logical network, the method comprising:
 configuring a first plurality of host computers to implement a plurality of logical switches;   configuring a second plurality of host computers to implement a logical router to connect the plurality of logical switches;   configuring the second plurality of host computers to implement a load balancer for the logical router to use to perform load balancing operations on packets sent from client machines connected to the logical network to server machines connected to the logical network.   
     
     
         22 . The method of  claim 21 , wherein a third plurality of host computers are in both the first plurality of host computers and second plurality of host computers. 
     
     
         23 . The method of  claim 21 , wherein the client machines execute on at least a subset of the first plurality of host computers. 
     
     
         24 . The method of  claim 23 , wherein the server machines execute on at least a subset of the first plurality of host computers. 
     
     
         25 . The method of  claim 21 , wherein each of the plurality of logical switches is implemented by a plurality of managed switching elements executing on the first plurality of host computers. 
     
     
         26 . The method of  claim 21 , wherein the logical router is implemented by a plurality of managed switching elements executing on the second plurality of host computers. 
     
     
         27 . The method of  claim 21 , wherein each logical switch connects a plurality of machines that are part of one logical subnet, and the logical router connects the logical switches for the different logical subnets. 
     
     
         28 . The method of  claim 21 , wherein the load balancer performs load balancing operations after the logical router performs logical routing operations. 
     
     
         29 . The method of  claim 21 , wherein the load balancer performs load balancing operations before the logical router performs logical routing operations. 
     
     
         30 . The method of  claim 21 , wherein the client and server machines comprise virtual machines executing on host computers. 
     
     
         31 . A non-transitory machine readable medium storing a program for configuring load balancing operations for a logical network, the program for execution by a set of processing units, the program comprising sets of instructions for:
 configuring a first plurality of host computers to implement a plurality of logical switches;   configuring a second plurality of host computers to implement a logical router to connect the plurality of logical switches;   configuring the second plurality of host computers to implement a load balancer for the logical router to use to perform load balancing operations on packets sent from client machines connected to the logical network to server machines connected to the logical network.   
     
     
         32 . The non-transitory machine readable medium of  claim 31 , wherein a third plurality of host computers are in both the first plurality of host computers and second plurality of host computers. 
     
     
         33 . The non-transitory machine readable medium of  claim 31 , wherein the client machines execute on at least a subset of the first plurality of host computers. 
     
     
         34 . The non-transitory machine readable medium of  claim 33 , wherein the server machines execute on at least a subset of the first plurality of host computers. 
     
     
         35 . The non-transitory machine readable medium of  claim 31 , wherein each of the plurality of logical switches is implemented by a plurality of managed switching elements executing on the first plurality of host computers. 
     
     
         36 . The non-transitory machine readable medium of  claim 31 , wherein the logical router is implemented by a plurality of managed switching elements executing on the second plurality of host computers. 
     
     
         37 . The non-transitory machine readable medium of  claim 31 , wherein each logical switch connects a plurality of machines that are part of one logical subnet, and the logical router connects the logical switches for the different logical subnets. 
     
     
         38 . The non-transitory machine readable medium of  claim 31 , wherein the load balancer performs load balancing operations after the logical router performs logical routing operations. 
     
     
         39 . The non-transitory machine readable medium of  claim 31 , wherein the load balancer performs load balancing operations before the logical router performs logical routing operations. 
     
     
         40 . The non-transitory machine readable medium of  claim 31 , wherein the client and server machines comprise virtual machines executing on host computers.