Abstract: In a load balancing system, user-configurable geographic prefixes are provided. IP address prefix allocations provided by the Internet Assigned Numbers Authority (IANA) and associated geographic locations are stored in a first, static database in a load balancing switch, along with other possible default geographic location settings. A second, non-static database stores user-configured geographic settings. In particular, the second database stores Internet Protocol (IP) address prefixes and user-specified geographic regions for those prefixes. The specified geographic region can be continent, country, state, city, or other user-defined region. The geographic settings in the second database can override the information in the first database. These geographic entries help determine the geographic location of a client and host IP addresses, and aid in directing the client to a host server that is geographically the closest to that client.

Abstract: A global server load-balancing (GSLB) switch serves as a proxy to an authoritative DNS and communicates with numerous site switches that are coupled to host servers serving specific applications. The GSLB switch receives from site switches operational information regarding host servers within the site switches neighborhood. This operational information includes health check information that is remotely obtained in a distributed manner from remote metric agents at the site switches. When a client program requests a resolution of a host name, the GSLB switch, acting as a proxy of an authoritative DNS, returns one or more ordered IP addresses for the host name. The IP addresses are ordered using metrics, including the health check metric that evaluates these IP addresses based on the health check information communicated to the GSLB switch in a distributed manner by the distributed health check site switches. In one instance, the GSLB switch places the address that is deemed “best” at the top of the list.

Abstract: In a load balancing system, user-configurable geographic prefixes are provided. IP address prefix allocations provided by the Internet Assigned Numbers Authority (IANA) and associated geographic locations are stored in a first, static database in a load balancing switch, along with other possible default geographic location settings. A second, non-static database stores user-configured geographic settings. In particular, the second database stores Internet Protocol (IP) address prefixes and user-specified geographic regions for those prefixes. The specified geographic region can be continent, country, state, city, or other user-defined region. The geographic settings in the second database can override the information in the first database. These geographic entries help determine the geographic location of a client and host IP addresses, and aid in directing the client to a host server that is geographically the closest to that client.

Abstract: A site switch determines the mapping between public and private IP addresses of VIPs configured on the site switch. The site switch then transmits the public IP address, rather than the private IP address, to a load balancing switch that performs the load balancing for network resources accessible via the site switch. This public IP address has also been configured on an authoritative DNS server for which the load balancing switch serves as a proxy. The load balancing switch updates its address records, containing the VIPs configured on the site switch, with the public address of the VIP. When the load balancing switch reorders a DNS reply from the authoritative DNS server for a domain containing the public address, the load balancing switch correctly identifies the IP address as a VIP on the site switch and applies appropriate load balancing metrics to the received IP address.

Abstract: A smoothing algorithm for round trip time (RTT) measurements is provided to a network device to effectively deal with variations or other potential anomalies that may occur in RTT measurements. The algorithm involves: first determining what should be considered a very high or a very small value for a RTT sample. If a new RTT sample is in an acceptable range, then the network device performs a relatively basic smoothing. If the new RTT sample is much higher than a current RTT value, then the network device ignores the value of this RTT sample a few times. If the network device still detects this large value after ignoring that value for some time, then the network device factors this value into the current RTT value using an additive increase. Similarly, if the value of the new RTT sample is much lower than current RTT value, the network device ignores the value of the new RTT sample a few times.

Abstract: In a network, a user can configure host-level policies usable for load balancing traffic to servers of a domain. A global server load balancing (GSLB) switch provides load balancing to the servers, and is configured with the GSLB host-level policies. Users can define a host-level policy (alternatively or additionally to a globally applied GSLB policy) and apply the host-level policy to hosts in domains configured on the GSLB switch. Thus, the user can enable different policies for different hosts. This allows the user to have the flexibility to control metrics used for selection of a best address for querying clients, as well as the metric order and additional parameters used in the GSLB process, at the host level.

Abstract: In a network, a user can configure host-level policies usable for load balancing traffic to servers of a domain. A global server load balancing (GSLB) switch provides load balancing to the servers, and is configured with the GSLB host-level policies. Users can define a host-level policy (alternatively or additionally to a globally applied GSLB policy) and apply the host-level policy to hosts in domains configured on the GSLB switch. Thus, the user can enable different policies for different hosts. This allows the user to have the flexibility to control metrics used for selection of a best address for querying clients, as well as the metric order and additional parameters used in the GSLB process, at the host level.

Abstract: In a load balancing system, user-configurable geographic prefixes are provided. IP address prefix allocations provided by the Internet Assigned Numbers Authority (IANA) and associated geographic locations are stored in a first, static database in a load balancing switch, along with other possible default geographic location settings. A second, non-static database stores user-configured geographic settings. In particular, the second database stores Internet Protocol (IP) address prefixes and user-specified geographic regions for those prefixes. The specified geographic region can be continent, country, state, city, or other user-defined region. The geographic settings in the second database can override the information in the first database. These geographic entries help determine the geographic location of a client and host IP addresses, and aid in directing the client to a host server that is geographically the closest to that client.

Abstract: A smoothing algorithm for round trip time (RTT) measurements is provided to a network device to effectively deal with variations or other potential anomalies that may occur in RTT measurements. The algorithm involves: first determining what should be considered a very high or a very small value for a RTT sample. If a new RTT sample is in an acceptable range, then the network device performs a relatively basic smoothing. If the new RTT sample is much higher than a current RTT value, then the network device ignores the value of this RTT sample a few times. If the network device still detects this large value after ignoring that value for some time, then the network device factors this value into the current RTT value using an additive increase. Similarly, if the value of the new RTT sample is much lower than current RTT value, the network device ignores the value of the new RTT sample a few times.