Technique for addressing a cluster of network servers

• US 7,480,737 B2
• Filed: 09/30/2003
• Issued: 01/20/2009
• Est. Priority Date: 10/25/2002
• Status: Expired due to Fees

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: International Business Machines Corporation
• Inventors: Chauffour, Pascal, Lebrun, Eric, Mahe, Valerie
• Primary Examiner(s): Blair; Douglas B
• Application Number:
  US10/676,456
• Publication Number:
  US 20040133690A1
• Time in Patent Office: 1,939 Days
• Field of Search: 709/219, 709/226, 709/245
• US Class Current: 709/245
• CPC Class Codes: H04L 61/00 Network arrangements, protocols or services for addressing or naming
• CPC Class Codes: H04L 61/25 of the same type
• CPC Class Codes: H04L 61/2514 between local and global IP addresses
• CPC Class Codes: H04L 61/2532 Clique of NAT servers
• CPC Class Codes: H04L 63/0209 Architectural arrangements, e.g. perimeter networks or demilitarized zones
• CPC Class Codes: H04L 67/1001 for accessing one among a plurality of replicated servers
• CPC Class Codes: H04L 67/10015 Access to distributed or replicated servers, e.g. using brokers
• 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 67/1029 using data related to the state of servers by a load balancer
• CPC Class Codes: H04L 67/1031 Controlling of the operation of servers by a load balancer, e.g. adding or removing servers that serve requests
• CPC Class Codes: H04L 67/1034 Reaction to server failures by a load balancer
• CPC Class Codes: H04L 69/329 in the application layer [OSI layer 7]
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

A single firewall or cluster of firewalls with a public IP address is interfaced to an internet public subnet to receive service requests for a cluster of network servers. A first private subnet with a plurality of private IP addresses is interfaced to the single firewall or cluster of firewalls to receive the service requests after passing through a firewall. A plurality of redundant load balancers with a respective plurality of private IP addresses are interfaced to the first private subnet to receive the service requests after passing through the first private subnet. The load balancers are interfaced to a second private subnet. The network servers with respective private IP addresses are interfaced to the second private subnet to receive the service requests from the load balancers. At an initialization time, a private IP address is defined for the network load balancer system within the internet access subnet. When one of the load balancers becomes primary at the initialization time or switches from a standby state to an active state, the network load balancer system private IP address is defined as an alias in an interface table to be recognized by the one load balancer. When the one network load balancer switches from the active state to a standby state, the network load balancer system private IP address previously defined as the alias is released from the interface table.

Claims

1. A system for accessing a cluster of servers from an internet public subnet using a single public IP address, said system comprising:

a network load balancer system for said cluster, said network load balancer system comprising a plurality of redundant network load balancers;

one or more access routing devices coupled to said internet public subnet, said one or more access routing devices having one or more respective public IP addresses;

a private internet access subnet between said one or more access routing devices and said load balancer system and having a range of private IP addresses;

a private network server subnet between said load balancer system and said cluster; and

means, at an initialization time, for defining a private IP address for the network load balancer system within the internet access subnet, and when one of said load balancers becomes primary at the initialization time or switches from a standby state to an active state, defining said network load balancer system private IP address as an alias in an interface table to be recognized by said one load balancer, and when said one network load balancer switches from the active state to a standby state, releasing from the interface table, the network load balancer system private IP address previously defined as the alias.

2. A method for accessing a cluster of servers from an internet public subnet using a single public IP address, wherein there is a network load balancer system for said cluster, one or more access routing devices coupled to said internet public subnet, a private internet access subnet coupled between said one or more access routing devices and said load balancer system and having a range of private IP addresses, and a private network server subnet between said load balancer system and said cluster, said network load balancer system comprising a plurality of redundant network load balancers, said method comprising the steps of:

at an initialization time, defining a private IP address for the network load balancer system within the internet access subnet;

when one of said load balancers becomes primary at the initialization time or switches from a standby state to an active state, defining said network load balancer system private IP address as an alias in an interface table to be recognized by said one load balancer; and

when said one network load balancer switches from the active state to a standby state, releasing from the interface table, the network load balancer system private IP address previously defined as the alias.

3. The method as set forth in claim 2 wherein said step of defining said network load balancer system private IP address as an alias in an interface table comprises the step of associating in said interface table the network load balancer system private IP address with the physical hardware address of the network load balancer system.

4. The method as set forth in claim 2 wherein said step of defining said network load balancer system private IP address as an alias comprises the step of broadcasting a message on the private internet access subnet, said message comprising the physical hardware address of the network load balancer system and the private IP address of the network load balancer system.

5. The method as set forth in claim 2 further comprising the steps of:

receiving an address resolution request, said request comprising the network load balancer system private IP address; and

checking whether or not the network load balancer system private IP address is in the interface table, and if the network load balancer system private IP address is in the interface table, sending a reply comprising the physical hardware address associated in the interface table with the network load balancer system private IP address, and if the network load balancer system private IP address is not in the interface table, sending no reply.

6. The method as set forth in claim 2 wherein said one or more access routing devices are a redundant system of access routers based on the Virtual Router Redundancy Protocol (VRRP), said access router system comprising a master access router and a backup access router;

each of said access routers being connected to clients though the internet public subnet and to the network load balancing system through the internet access private subnet.

7. The method as set forth in claim 2 wherein each of said access routing devices is a firewall.