Does the EdgeADC provide any pre-written Real Server Monitors?
The EdgeADC is equipped with a number of pre-written Real Server Monitors. These are:
Used to check the availability and responsiveness of servers. It operates by sending Internet Control Message Protocol (ICMP) echo request packets, commonly known as “pings,” to the target server. If the server is operational, it responds with an ICMP echo reply. The monitor measures the round-trip time for the ping and assesses the server’s availability based on whether the response is received within a predefined time frame. This method is straightforward and efficient for verifying servers’ basic connectivity and responsiveness, making it an essential component in network monitoring and load-balancing setups to ensure continuous service availability.
TCP Connection
A TCP connection real server monitor checks the health and responsiveness of backend servers by establishing TCP connections to specified ports. This type of monitor periodically attempts to open a TCP connection to a server to verify its availability and network reachability. If the server completes the handshake and responds within an acceptable timeframe, it is deemed healthy and capable of handling client requests. Conversely, if the server fails to respond, is slow to connect, or rejects the connection, the monitor flags it as unhealthy. This allows the load balancer to reroute traffic away from the problematic server, ensuring continuous and reliable service delivery by directing traffic only to servers confirmed to be operational.
ICMP Unreachable
An ICMP Unreachable real server monitor uses Internet Control Message Protocol (ICMP) messages to determine the availability and responsiveness of backend servers. Specifically, it sends ICMP echo requests (pings) to the target server and waits for a response. If the server is unreachable or fails to respond within a specified time frame, the monitor flags it as down or unhealthy. This type of monitoring is crucial for quickly detecting network issues or server outages, ensuring that traffic is only directed to accessible servers and capable of handling requests, thereby maintaining high availability and performance of the application.
RDP
An RDP (Remote Desktop Protocol) real server monitor continuously assesses the availability and responsiveness of servers that provide remote desktop services. This monitor performs regular health checks by attempting to establish RDP sessions with the servers to ensure they can accept and handle remote desktop connections. By doing so, it verifies that the servers are not only operational but also performing efficiently under load. If a server fails to respond or exhibits poor performance, the monitor flags it as unhealthy, triggering the load balancer to reroute connections to healthier servers. This ensures uninterrupted remote desktop access for users, maintains service reliability, and helps in promptly identifying and addressing any issues affecting the remote desktop services.
200OK
A 200OK real server monitor is used in load balancing to verify the operational status of backend servers by ensuring they return a standard HTTP 200 OK response. This monitor sends periodic HTTP GET requests to the servers and expects a 200 OK response, indicating that the server is functioning correctly and can handle client requests. If a server fails to return a 200 OK response, it is marked as unhealthy, and the load balancer stops directing traffic to it until it recovers. This type of monitoring is crucial for maintaining high availability and reliability of web applications, as it ensures only healthy servers are included in the load balancing pool, thereby enhancing user experience and minimizing downtime.
DICOM
A DICOM real server monitor ensures the availability and performance of servers that handle Digital Imaging and Communications in Medicine (DICOM) data, which is critical in healthcare environments for managing medical imaging information. This monitor continuously performs health checks on DICOM servers by sending DICOM C-ECHO requests and evaluating the server’s responses. If a server fails to respond appropriately or within the expected timeframe, the monitor flags it as unhealthy, enabling automatic failover mechanisms to reroute traffic to functioning servers. This ensures uninterrupted access to vital medical imaging data, supporting timely diagnostics and patient care by maintaining the seamless operation of DICOM services.
