International Business Machines Corporation

Valerie Mahe

Pascal Chauffour

Jean-Marc Berthaud

Jean-Claude Dispensa

Eric LeBrun

Paolo Gerosa

A method of synchronizing firewalls in a communication system comprising a server farm wherein any user connected to the Internet can access customer servers, and at least two firewalls using a Virtual Router Redundancy Protocol (VRRP) to set up as primary interface firewall the firewall which owns the primary interface of the VRRP group of interfaces to at least one customer server. The method includes initializing, in a secondary interface firewall, a synchronization message exchange with the primary firewall after receiving a packet for a connection having a state which is incompatible with the received packet or after the standard firewall processing of a packet corresponding to a new connection, and registering in a common connection table the state of any connection if the connection is new or if the connection state has changed.

Method of synchronizing firewalls in a communication system based upon a server farm

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.

Technique for addressing a cluster of network servers

A method for improving network server load balancing in a system that has a plurality of network servers connected by an Internet access LAN to the Internet, a back-end access LAN connected to several database servers, and a network load balancer for selecting one of the network servers according to weights associated with the network servers. Link connectivity is monitored cyclically from each network server, and a status indicator is set to UP if all of the links associated with the network server are available, or to DOWN if at least one link is unavailable. The network servers send their status indicators to the network load balancer. The network load balancer changes the weight associated with a network server to a non-eligible value if the associated status indicator changes from UP to DOWN.

Method for improving network server load balancing

A method of preserving symmetrical routing in a communication system comprising a server farm connected to the Internet through an Internet access router. The server farm includes at least two customer cabinets with at least a WEB server and at least two firewalls. The firewalls use a Virtual Router Redundancy Protocol (VRRP) to set up one firewall as being the primary firewall. The method includes checking in each firewall whether there is a change of the VRRP state from primary to secondary or reciprocally. Such a change indicates that a link between the primary firewall and one of the customer cabinets has failed. The link is disabled from the network to the firewall the state of which has changed from primary to secondary or the link is enabled from the Internet network to the firewall the state of which has changed from secondary to primary.

Preserving symmetrical routing in a communication system based upon a server farm

A cluster system and method accesses from an internet network, a network server within one or a plurality of clusters, each cluster being identified by a single cluster public Internet Protocol (IP) address. The cluster system has a plurality of network servers organized in one of a plurality of clusters and a network load balancer system for selecting a destination network server in a cluster. Each cluster has one or a plurality of identical network servers, the network load balancer system being connected on one hand to an access routing device and on another hand to the plurality of network servers through a private network server subnet. The method includes the steps of at initialization time, on each network server defining, as a non-advertising alias, in an interface table, the public IP address of each cluster to which the network server belongs, and upon reception, by the network load balancing system, of a datagram having an IP header including a destination IP address field and a medium access control (MAC) header including a destination MAC address field, selecting a destination network server within the cluster corresponding to the cluster public IP address identified in the destination IP address field of the datagram IP header, replacing the destination medium access control (MAC) address field of the datagram MAC header by the MAC address of the selected destination network server, and sending the datagram through the private network server subnet, using the MAC address of the selected destination network server. Upon reception, by the destination network server, of the datagram sent by the network load balancing system, the MAC address in the destination MAC address field of the datagram MAC header is identified as being the MAC address of the selected destination network server, and the IP datagram is processed if the identified cluster public IP address in the destination IP address field of the datagram IP header, is defined as a non-advertising alias in the interface table of the destination network server.

System and method for accessing clusters of servers from the internet network

Method of preserving symmetrical routing in a communication system based upon a server farm

A method of preserving symmetrical routing in a communication system comprising a server farm connected to the Internet by an Internet access router IAR. The server farm includes at least two customer cabinets each having a WEB server, and at least two firewalls. The firewalls use Virtual Router Redundancy Protocol (VRRP) to set up a primary firewall that supports communication between a customer server and an Internet user. The IAR selects the firewall to be used as being the firewall corresponding to the interface having the lowest weight in a routing table. The cost assigned to each interface associated with a firewall is automatically generated, at the initial time, according to the priority assigned by the VRRP protocol to said interface associated with said firewall.

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Nice, France

Valerie Mahe