Brocade Communications Systems, Inc.

Foundry Networks, Inc.

Brocade Communication Systems LLC

Prajakta S Joshi

Sridhar J Devarapalli

Sunanda Lakshmi Kommula

David Chun Ying Cheung

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.

Global server load balancing support for private VIP addresses

Techniques are provided to enable a network device, such as a switch, to perform global server load balancing (GSLB) while operating as a proxy to a domain name system security extensions (DNSSEC)-capable authoritative DNS server. The network device preserves an original signature generated by the DNSSEC-capable authoritative DNS server for a resource record set contained in a DNSSEC reply.

Domain name system security extensions (DNSSEC) for global server load balancing

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.

Distributed health check for global server load balancing

Server load-balancing operation-related data, such as data associated with a system configured for global server load balancing (GSLB) that orders IP addresses into a list based on a set of performance metrics, is tracked. Such operation-related data includes inbound source IP addresses (e.g., the address of the originator of a DNS request), the requested host and zone, identification of the selected 'best' IP addresses resulting from application of a GSLB algorithm and the selection metric used to decide on an IP address as the 'best' one. Furthermore, the data includes a count of the selected &#x201c;best&#x201d; IP addresses selected via application of the GSLB algorithm, and for each of these IP addresses, the list of deciding performance metrics, along with a count of the number of times each of these metrics in the list was used as a deciding factor in selection of this IP address as the best one. This tracking feature allows better understanding of GSLB policy decisions (such as those associated with performance, maintenance, and troubleshooting) and intelligent deployment of large-scale resilient GSLB networks.

Statistical tracking for global server load balancing

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.

Host-level policies for global server load balancing

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. If the network device still sees this small/low value after ignoring that value for sometime, then the network device factors this value into the current RTT value using a multiplicative decrease. An effective RTT value results, which can be used singly or in combination with other metrics to load balance network traffic.

Smoothing algorithm for round trip time (RTT) measurements

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.

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Cupertino, CA, United States of America

Prajakta S Joshi