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Load Balancing

Load Balancing mechanism used for WAF

Overview​

Load balancing across multiple application instances is a commonly used technique for optimizing resource utilization, maximizing throughput, reducing latency, and ensuring fault-tolerant configurations.

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Load Balancing Algorithms​

This field specifies the load balancing algorithm according to the configured website.

  1. ROUND ROBIN: This algorithm is a smart approach to distribute client requests across an array of servers. It forwards the client request to each server in turn. Also, assigns a weight to each server as per current load and idle capacity.

  2. LEAST CONNECTIONS: This algorithm is a dynamic load balancing algorithm. It forwards client requests to the server, which has the least no. of active connections on the server.

  3. LEAST LISTENER CONNECTIONS: This algorithm is a dynamic load balancing algorithm. It forwards client requests to the server, which have a small response time in order to serve requests.

  4. LEAST RESPONSE TIME: This algorithm is a dynamic load balancing algorithm. It forwards client requests to the server, which have a small response time in order to serve requests.

  5. MINIMUM JITTER: This algorithm is a dynamic load balancing algorithm. It forwards client requests to the server, which have served the minimum jitter. NOTE: For this algorithm to work, the server group should have ICMP monitor attached.

  6. IP HASH: This algorithm takes the client's and server's source and destination IP address to generate a unique hash key. This key is used to assign the client to a specific server. In the case of a broken session, the key can be regenerated, and the client can be directed to the same server.

  7. PERSISTENT HASH: This algorithm takes the user input location within the current request to generate a user-defined custom unique hash key. This key is used to assign the client to a specific server. In the case of a broken session, the key can be regenerated, and the client can be directed to the same server. NOTE: In hashing-based load balancing, if a specified value does not exists then the request is served on the basis of client's IP address.

  8. Least Requests: This algorithm is a dynamic load balancing algorithm. It forwards client requests to the server, which have served the minimum amount of requests.

  9. SNMP Metrics: This algorithm is a dynamic load balancing algorithm. It forwards client requests to the server, which have least CPU / RAM usage. NOTE: For this algorithm to work, the server group should have SNMP monitor attached.

How to Use:​

  1. Log into the Haltdos WAF Professional edition web UI console.
  2. Then go to Listeners > Server Groups > Load Balancing
  3. Set the configurations and Save Changes.
ParametersAccepted ValuesDefault
Upstream Retries This algorithm is a dynamic load balancing algorithm. It forwards client requests to the server, which has the least no. of active connections to the back-end server.Integer1
Fail-over ThresholdInteger50
Client IP PoolIntegerBlank
AlgorithmAlgorithm Drop-downROUND ROBIN
Sticky Session CookieStringBlank
Add locationString & IntegerThis toggle button allows you to enable the Web-socket support for servers in the server group.None & Src IP

Description​

Upstream Retries​

This option used to specify the upstream retries. By default, the value is set to 1.

Fail-over Threshold​

This option specify the fail-over threshold in percentage of (active/total) primary servers for switching to backup servers. By default, the value is set to 50%.

Client IP Pool​

Specify list of client IP to use when connecting to upstream. Leave blank for auto

Algorithm​

This option is used to specify the algorithm used by the server group. By default, the value is selected as Round Robin.

Specify enabling sticky session based on specified cookie