Stateless load balancing of connections
View Patent ↗A capability is provided for statelessly load balancing Transmission Control Protocol (TCP) connections across a set of servers. A load balancer receives a TCP SYN packet from a client, selects a server for a TCP connection for the client, forms a modified TCP SYN packet including an address of the client, and propagates the modified TCP SYN packet toward the server. The server receives the modified TCP SYN packet, forms a TCP SYN+ACK packet including an identifier (e.g., n bits of an address, an n-bit server index based on mapping information of the load balancer, or the like) of the server, and propagates the modified TCP SYN+ACK packet toward the load balancer. The load balancer receives a TCP packet from the client on the TCP connection, determines a server associated with the TCP connection based on information included within the TCP packet, and propagates the TCP packet toward the server.
1. An apparatus, comprising:
a processor and a memory communicatively connected to the processor, the processor configured to:
receive a Transmission Control Protocol (TCP) SYN packet comprising a source address field including an address of a client from which the TCP SYN packet is received and a destination address field including an address of a load balancer;
select a server to support a TCP connection for the client;
form, based on the TCP SYN packet, a modified TCP SYN packet comprising a source address field including the address of the load balancer, a destination address field including an address of the server, the address of the client, a server index of the server, and a value indicative of a size of the server index of the server; and
propagate the modified TCP SYN packet toward the selected server.
2. The apparatus of claim 1 , wherein the processor is configured to select the server based on at least one of:
a hash value computed based on one or more fields of the TCP SYN packet; or
server performance information associated with one or more servers of a set of servers available for selection as the selected server.
3. The apparatus of claim 1 , wherein the processor is configured to insert the address of the client into an ACK field of the modified TCP SYN packet, a TCP option header of the modified TCP SYN packet, or a trailer field of the modified TCP SYN packet.
4. The apparatus of claim 1 , wherein, to form the modified TCP SYN packet, the processor is configured to:
insert at least one timestamp into the modified TCP SYN packet.
5. The apparatus of claim 1 , wherein the processor is configured to insert the server index of the server into an upper n bits of a sequence number of the modified TCP SYN packet or n bits of a timestamp value of a TCP options header of the modified TCP SYN packet.
6. The apparatus of claim 1 , wherein the processor is configured to:
compute a hash value based on one or more fields of the TCP SYN packet; and
identify the server index of the server from a mapping of the hash value to the server index of the server.
7. An apparatus, comprising:
a processor and a memory communicatively connected to the processor, the processor configured to:
receive a synchronization message comprising a source address field including an address of a client from which the synchronization message is received and a destination address field including an address of a load balancer;
select a server to support a connection for the client;
form, based on the synchronization message, a modified synchronization message comprising a source address field including the address of the load balancer, a destination address field including an address of the server, the address of the client, a server index of the server, and a value indicative of a size of the server index of the server; and
propagate the modified synchronization message toward the selected server.
8. The apparatus of claim 7 , wherein the processor is configured to select the server based on at least one of:
a hash value computed based on one or more fields of the synchronization message; or
server performance information associated with one or more servers of a set of servers available for selection as the selected server.
9. The apparatus of claim 7 , wherein the processor is configured to insert the address of the client into an acknowledgment field of the modified synchronization message, an option header of the modified synchronization message, or a trailer field of the modified synchronization message.
10. The apparatus of claim 7 , wherein, to form the modified synchronization message, the processor is configured to:
insert at least one timestamp into the modified synchronization message.
11. The apparatus of claim 7 , wherein the processor is configured to insert the server index of the server into an upper n bits of a sequence number of the modified synchronization message or n bits of a timestamp value of an options header of the modified synchronization message.
12. The apparatus of claim 7 , wherein the processor is configured to:
compute a hash value based on one or more fields of the synchronization message; and
identify the server index of the server from a mapping of the hash value to the server index of the server.
13. A method, comprising:
receiving, by a processor, a Transmission Control Protocol (TCP) SYN packet comprising a source address field including an address of a client from which the TCP SYN packet is received and a destination address field including an address of a load balancer;
selecting, by the processor, a server to support a TCP connection for the client;
forming, by the processor based on the TCP SYN packet, a modified TCP SYN packet comprising a source address field including the address of the load balancer, a destination address field including an address of the server, the address of the client, a server index of the server, and a value indicative of a size of the server index of the server; and
propagating, by the processor, the modified TCP SYN packet toward the selected server.
14. The method of claim 13 , wherein the server is selected based on at least one of:
a hash value computed based on one or more fields of the TCP SYN packet; or
server performance information associated with one or more servers of a set of servers available for selection as the selected server.
15. The method of claim 13 , wherein the address of the client is inserted into an ACK field of the modified TCP SYN packet, a TCP option header of the modified TCP SYN packet, or a trailer field of the modified TCP SYN packet.
16. The method of claim 13 , wherein forming the modified TCP SYN packet comprises:
inserting at least one timestamp into the modified TCP SYN packet.
17. The method of claim 13 , wherein forming the modified TCP SYN packet comprises inserting the server index of the server into an upper n bits of a sequence number of the modified TCP SYN packet or n bits of a timestamp value of a TCP options header of the modified TCP SYN packet.
18. The method of claim 13 , further comprising:
computing a hash value based on one or more fields of the TCP SYN packet; and
identifying the server index of the server from a mapping of the hash value to the server index of the server.
19. A method, comprising:
receiving, by a processor, a synchronization message comprising a source address field including an address of a client from which the synchronization message is received and a destination address field including an address of a load balancer;
selecting, by the processor, a server to support a connection for the client;
forming, by the processor based on the synchronization message, a modified synchronization message comprising a source address field including the address of the load balancer, a destination address field including an address of the server, the address of the client, a server index of the server, and a value indicative of a size of the server index of the server; and
propagating, by the processor, the modified synchronization message toward the selected server.
20. The method of claim 19 , wherein the server is selected based on at least one of:
a hash value computed based on one or more fields of the synchronization message; or
server performance information associated with one or more servers of a set of servers available for selection as the selected server.
21. The method of claim 19 , wherein the address of the client is inserted into an acknowledgment field of the modified synchronization message, an option header of the modified synchronization message, or a trailer field of the modified synchronization message.
22. The method of claim 19 , wherein forming the modified synchronization message comprises:
inserting at least one timestamp into the modified synchronization message.
23. The method of claim 19 , wherein forming the modified synchronization message comprises inserting the server index of the server into an upper n bits of a sequence number of the modified synchronization message or n bits of a timestamp value of an options header of the modified synchronization message.
24. The method of claim 19 , further comprising:
computing a hash value based on one or more fields of the synchronization message; and
identifying the server index of the server from a mapping of the hash value to the server index of the server.