Types of Monitors used in F5 LTM?

Simple Monitoring

--> A Simple Monitoring just checks whether a host is reachable or offline.

--> No Intelligence present.

--> Following are the monitors used in simple monitoring,

1) Gateway ICMP

2) ICMP

3) TCP_ECHO

Active Monitoring

--> In Active Monitoring, BIG IP sends some type of application traffic and waits for a response from the node or pool member.

--> Uses Intelligence.

--> This can be done by using send and receive string configured under the monitor.

--> F5 LTM makes node or pool member offline, if it does not receive the response or if the response is not matching the specific receive string.

--> HTTP and FTP are the monitors used in Active Monitoring.

--> Active Monitoring creates additional traffic and uses additional resources on F5 LTM.





Passive Monitoring

--> In Passive Monitoring, BIG IP does not sends any type of application traffic to know node or pool member is offline or not.

--> Passive Monitoring is also known as Inband Monitoring.

--> In Passive Monitoring, BIG IP LTM monitors the traffic is going to/from pool member.

--> If the pool member does not respond to new connections or existing connections properly then f5 ltm makes pool member as offline.

--> The main advantage of Passive Monitoring is,it does not create any additional traffic to find out the pool member is offline or online.

--> Does not consume more resources on F5 LTM.

--> Passive Monitoring does not check for specific resources which makes f5 ltm slow to identify pool member or node is offline.

--> Inband monitor is the only monitor used in Passive Monitoring.

--> Passive Monitor works depends on the client traffic from F5 LTM to Pool Member.


Ref: F5.com

MD.Kareemoddin

CCIE # 54759

Understanding Status of Virtual Server in F5 LTM

Enabled:

--> Virtual Server is working and able to forward the traffic to the servers.

--> Monitors associated with virtual servers are working.

--> Shows Green circle in the virtual server status icon.

Offline

--> The Virtual server is not working and unable to forward the traffic to the servers.

--> Monitors associated with virtual servers are not working.

--> Shows Red Diamond icon in the virtual server status.

Currently Unavailable

--> The Virtual server is working but unable to forward the traffic to the servers.

--> Monitors associated with virtual servers are working.

--> limiting the connection rate has been set up and the virtual server has no more memory to accept the connections for the virtual server.

--> Shows Yellow Triangle icon in the virtual server status.

Unknown

--> Virtual Server is working and able to forward the traffic to the servers.

--> Monitors are not configured for the virtual server.

--> The traffic received on the virtual server will be forwarded to pool members even they are not working.

--> Shows Blue Square icon in the virtual server status.

Disabled

--> The Virtual server is not working and unable to forward the traffic to the servers.

--> Network Admin has disabled the virtual server manually.

--> If the monitors configured are working properly then shows Black circle icon in the virtual server status.

--> If the monitors configured are not working then shows Black Diamond icon in the virtual server status.

Ref: F5.com

Md.Kareemoddin

CCIE# 54759