Server load sharing system

• US 20030108052A1
• Filed: 04/03/2002
• Published: 06/12/2003
• Est. Priority Date: 12/06/2001
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Takeda, Koichi, Inoue, Rumiko
• Granted Patent: US 7,379,458 B2
• Time in Patent Office: Days
• US Class Current: 370/399
• CPC Class Codes: H04L 2101/622 Layer-2 addresses, e.g. medium access control [MAC] addresses
• CPC Class Codes: H04L 61/2517 using port numbers
• CPC Class Codes: H04L 67/1001 for accessing one among a plurality of replicated servers
• CPC Class Codes: H04L 67/1008 based on parameters of servers, e.g. available memory or workload monitoring of computer activity G06F11/30
• CPC Class Codes: H04L 67/1017 based on a round robin mechanism
• CPC Class Codes: H04L 67/1019 Random or heuristic server selection
• CPC Class Codes: H04L 67/1023 based on a hash applied to IP addresses or costs

Abstract

A server load sharing system has a plurality of server load balancers and a relay device. Each balancer includes a module selecting, when receiving a forwarding target packet addressed to a predetermined virtual IP address via one of first and second links, any one of a plurality of load sharing target servers specified in their group on the basis of the virtual IP address and each allocated a unique IP address, and a module rewriting the virtual IP address of the received forwarding target packet addressed to the virtual IP address into the unique IP address of the selected server, and rewriting a source IP address of the received packet addressed to the virtual IP address into an IP address capable of specifying the other of the first and second links. The relay device connected to each of the plurality of balancers via the first and second links includes a module identifying the received packet addressed to the virtual IP address, and a module selecting one of the first and second links for forwarding the identified packet addressed to the virtual IP address to one of the plurality of balancers.

Claims

1. A server load sharing system comprising:

(A) a plurality of server load balancers each accommodating at least first and second links, said balancer including;

(a) a module selecting, when receiving a forwarding target packet addressed to a predetermined virtual IP address via one of said first and second links, any one of a plurality of load sharing target servers specified in their group on the basis of this virtual IP address and each allocated a unique IP address; and

(b) a module rewriting the virtual IP address of the received forwarding target packet addressed to the virtual IP address into the unique IP address of said selected load sharing target server, and rewriting a source IP address of the received forwarding target packet addressed to the virtual IP address into an IP address capable of specifying the other of said first and second links; and

(B) a relay device connected to each of said plurality of server load balancers via said first and second links, said relay device including;

(c) a module identifying the received forwarding target packet addressed to the virtual IP address;

(d) a module selecting one of said first and second links for forwarding the identified forwarding target packet addressed to the virtual IP address to one of said plurality of server load balancers; and

(e) a module forwarding the forwarding target packet received via the other of said first and second links from any one of said plurality of server load balancers to said selected load sharing target server, and forwarding the forwarding target packet sent back from said selected load sharing target server to any one of said plurality of server load balancers via the other of said first and second links.

2. A server load sharing system according to claim 1, wherein said selecting module of said relay device selects one of said first and second links for forwarding the packet to any one of said plurality of server load balancers on the basis of a pseudo random number generated by applying a one-way function to a value of the source IP address contained in the identified forwarding target packet addressed to the virtual IP address.

3. A server load sharing system according to claim 1, wherein each of said server load balancers further includes a module rewriting, when receiving the forwarding target packet sent back from said selected load sharing target server via said relay device and the other of said first and second links, the unique IP address of said selected load sharing target server, which is contained in the received forwarding target packet, into the virtual IP address as a source IP address, and further the IP address capable of specifying the other of said first and second links, which is contained in the received forwarding target packet, into the source IP address as a destination IP address that has been contained in the forwarding target packet addressed to the virtual IP address, and making said relay device forward the packet via one of said first and second links.

4. A server load sharing system according to claim 1, wherein said relay device further includes a module setting said first and second links accommodated in each of said plurality of server load balancers into a group, periodically transmitting a monitoring packet to said first and second links of each group, and ruling out said first and second links as fault links belonging to the group containing the link with no response from selection target links.

5. A server load sharing system according to claim 4, wherein said relay device further includes a module setting, in the case of detecting a fault in said first and second links accommodated in each of said plurality of server load balancers, the forwarding target packet distributed to said normal server load balancer accommodating said first and second normal links in a way that keeps this distributed state, and changing the distributed state to said normal server load balancer with respect to only the forwarding target packet distributed to said fault server load balancer accommodating said first and second fault links.

6. A server load sharing method in each of a plurality of server load balancers each accommodating at least first and second links, said method comprising:

(a) selecting, when receiving a forwarding target packet addressed to a predetermined virtual IP address via one of said first and second links, any one of a plurality of load sharing target servers specified in their group on the basis of this virtual IP address and each allocated a unique IP address; and

(b) rewriting the virtual IP address of the received forwarding target packet addressed to the virtual IP address into the unique IP address of said selected load sharing target server, and rewriting a source IP address of the received forwarding target packet addressed to the virtual IP address into an IP address capable of specifying the other of said first and second links; and

said method, in a relay device connected to each of said plurality of server load balancers via said first and second links, further comprising;

(c) identifying the received forwarding target packet addressed to the virtual IP address;

(d) selecting one of said first and second links for forwarding the identified forwarding target packet addressed to the virtual IP address to one of said plurality of server load balancers; and

(e) forwarding the forwarding target packet received via the other of said first and second links from any one of said plurality of server load balancers to said selected load sharing target server, and forwarding the forwarding target packet sent back from said selected load sharing target server to any one of said plurality of server load balancers via the other of said first and second links.

7. A server load sharing method according to claim 6, further comprising, in said relay device, selecting one of said first and second links for forwarding the packet to any one of said plurality of server load balancers on the basis of a pseudo random number generated by applying a one-way function to a value of the source IP address contained in the identified forwarding target packet addressed to the virtual IP address.

8. A server load sharing method according to claim 6, further comprising, in each of said server load balancers, rewriting, when receiving the forwarding target packet sent back from said selected load sharing target server via said relay device and the other of said first and second links, the unique IP address of said selected load sharing target server, which is contained in the received forwarding target packet, into the virtual IP address as a source IP address, and further the IP address capable of specifying the other of the first and second links, which is contained in the received forwarding target packet, into the source IP address as a destination IP address that has been contained in the forwarding target packet addressed to the virtual IP address, and making said relay device forward the packet via one of the first and second links.

9. A server load sharing method according to claim 6, further comprising, in said relay device, setting the first and second links accommodated in each of said plurality of server load balancers into a group, periodically transmitting a monitoring packet to the first and second links of each group, and ruling out the first and second links as fault links belonging to the group containing the link with no response from selection target links.

10. A server load sharing method according to claim 9, further comprising, in said relay device, setting, in the case of detecting a fault in the first and second links accommodated in each of said plurality of server load balancers, the forwarding target packet distributed to said normal server load balancer accommodating the first and second normal links in a way that keeps this distributed state, and changing the distributed state to said normal server load balancer with respect to only the forwarding target packet distributed to said fault server load balancer accommodating the first and second fault links.

11. A server load sharing device comprising:

a plurality of server load balancing functions of sharing loads to a plurality of servers,

wherein one of said server load balancing functions is specified to execute processing on the basis of source identifying information of a packet received from a client terminal.