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Community Member

CSS load balancing questions

I hope that someone can help with 2 simple (i think) CSS questions.

1. When configured properly for load balancing, should the CSS round-robin between servers or will it continue to use only one server until triggered by some event or parameter?

2. If 1 of 2 load balanced servers fails, how does load balancing proceed? Will it continue to try to load balance between the servers or will it give up on the failed server unitil some event or timeout occurs?

Thanks in advance,


Community Member

Re: CSS load balancing questions

Hi Eliot,

The CSS can be configured to perform load balancing in a variety of different ways. Least connections, round robin, ACA etc. Each new connection through the CSS will be round robined over each of the servers in your server group.

If a server fails then the CSS will know it has failed through the use of keepalives (based on TCP connection, ICMP etc) and no longer send requests through to that server. Traffic associated with a previous connection to the failed server will be sent to on of the surviving servers. It is then up to the behavior of the application as to if the user experiences any disruption.

Hope this helps


Cisco Employee

Re: CSS load balancing questions

just a small correction.

Traffic to a service that goes down will still be sent to this service unless you have 'flow-reset-reject' configured.

With this command, the CSS will either reset the connection or move the connection to another server depending on the 'persistent reset [remap|reject]' config.


Community Member

Re: CSS load balancing questions

When Configured properly the CSS will load balance between the servers automatically till it see the services up and running.

When a server fails the service will immediately show the service status as "down" and CSS will then stop sending requests to the failed server.

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