Cisco Local Director

[gmarkaj]

Anyone with any LD experience, assistance is greatly appreciated!

Heres the scenario. We have a local director load balancing between two applications servers. The sessions to these servers, once established, are very long and can last most of the day. If one of the two servers goes down, the sessions are directed to the second server. Because of the length of the sessions, once the first server comes back online, all of the established sessions are still with the second server and will not move back until the sessions end and have to reconnect. This seems to have overloaded the second server's CPU on many occasions. This local director was basically an "out of the box" setup and I'm not sure if it was configured to have this function. Is there anyway through configuration that we can have the LD start gracefully switching sessions back to the first server once it is back online to offload the second one?

[noc]

Sorry but this is not possible (I don't even think with CSS or

any thing I have ever heard of) Given TCP and everything I

know about it, I don't think could ever be possible, unless

the load balancer was handling layer 4 and down and doing

all negotiation layers 5 to 7.

Tweaking the predicator (method of determining who gets

NEW connections) will allow you to make sure any NEW

sessions made don't go to the second server (because it

will already have some established connections), but

any EXISTING connections will remain on the server which

has been up for the entire time of the connection.

The Predicator I use is "Least Conns" so the server with the

least ACTIVE connections always gets the new requests for

service off the VIP. If you run Least conns as well, you can be

pretty sure to evenly distribute your connections amoungst the

number of "real" servers in your pool. You should convince your

management that more "real" servers are needed to protect

against this crash that the Local Director (LB) was never invented

for. Say if you had 8 servers instead of 2, then you would not crash

the remaining servers if one failed.

[gmarkaj]

Thanks for the help!